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Doug Harroun
09-03-2009, 02:01 AM
So if it's all right with everyone I'm going to document my furnace build here. Feel free to comment, add notes, etc... this is a work in progress.

I'm building a freestanding pot furnace essentially as depicted in Glassnotes as the Penland Pot Furnace.

Years ago I obtained a Dyson pot 18" OD, I am going to keep it as my standby pot and order one to build around. Probably the 19" EC, unless otherwise guided.

Furnace dimensions, approx: 50" tall, 50" OD, 24" ID.


Wall will be 3" Kast-o-lite 30: 2.945 cu ft. Surround that with 10" of frax, and some sheet metal.

Crown will be ...dunno what yet. Phlocast, Mizzou? ~2 cu ft. With similar frax over lay and a very artistic metal shell.

base will be Kast-o-lite, IFB and hard brick....

Cast various parts from what I have left....

Need advice on burner heads.

will add more as needed, including pics if they'er allowed :)

-Doug

Pete VanderLaan
09-03-2009, 06:38 AM
I would recommend the 19 inch pot from High Temp in Portland. It's a better pot for less money and you don't have to wait for it.

Don't ask them about horseshoes either. They know nothing about them.
Put the ten inches of frax on the crown and eight around the outside. More is simply unnecessary. I would suggest recuperating it. Wake up Hugh! If you do recuperate, the burner needs special consideration and Hugh does sell them I think. I've seen them work and they do it well.
Phlocat will work fine as a crown. Morco 95 would be better but it's hard to get.

Thom Kennedy
09-03-2009, 08:48 AM
i agree with Pete, recuperate. my furnace is a lot like my v-10 F-250 and that's getting old

Eben Horton
09-03-2009, 10:31 AM
i agree with Pete, recuperate. my furnace is a lot like my v-10 F-250 and that's getting old

same here... :(

Doug Harroun
09-03-2009, 11:37 AM
Recuperation will be part of the furnace as well. I'm not entirely sure which scheme I want to go with yet. I can fabricate stainless steel parts pretty easily, but the designs that seem to work well are cast refractory, correct?

Pete VanderLaan
09-03-2009, 11:45 AM
Both. Get together with Hugh. Pay him. You won't regret it.

Hugh Jenkins
09-03-2009, 07:36 PM
You can PM me and I'll reply. I'm on the road for the next two weeks.

Sky Campbell
09-04-2009, 12:29 AM
Furnace dimensions, approx: 50" tall, 50" OD, 24" ID.


Wall will be 3" Kast-o-lite 30: 2.945 cu ft. Surround that with 10" of frax, and some sheet metal.

Crown will be ...dunno what yet. Phlocast, Mizzou? ~2 cu ft. With similar frax over lay and a very artistic metal shell.

base will be Kast-o-lite, IFB and hard brick....

Cast various parts from what I have left....

Need advice on burner heads.

will add more as needed, including pics if they'er allowed :)

-Doug

Welcome to the board! It's think it's great your documenting your build. I always learn a little more with everyone.

Kast-o-lite 30 make sure there are several varieties.

You need to think about your floor. It will see glass and kast-o-lite won't hold it back. Some use mizzou or a ramable clay I used a few inches of mizzou over 2800 brick on our last build (only because they are salvage). Don't forget to cast a drain port this to will need to be resistant to glass attack. You also want to angle your base towards the drain. I placed mine on the back of the furnace with a fiber plug. I do think most have the cleanout in the front.

I used kast-o-lite 30 for my crown and never had a problem. If you want extra strength you can cast a dome shape on the top. I also used it for my door. For a sill I like to use a large clipper brick but there are several castables you can use. .

Burner. I would scrap that idea and go with electric. Seriously you may want to look at gas prices and compare to what you pay a kilowatt hour.

Pete VanderLaan
09-04-2009, 05:18 AM
Start up costs on electric are high but the convenience is incredible, as is the safety, particularly in a hot town, which Albuquerque is. While I vastly prefer, and would advocate for moly, SiC has the advantage of not needing a transformer. New Mexico has pretty reasonable electric rates, so it would cost a good deal less to run.

Insulate your hood. Mine is six inches thick, all steel and insulation. It's very cool in my shop, almost too cool.

Dave Hilty
09-04-2009, 09:46 AM
The guys at Hi-Temp Refractories in MO. supplied me with their Morocast 60 HS (60% alumina) product as a substitute for Mizzou to replace the 3-4" of floor that had gone to mush from pot leaks over the last 12 years. The old floor was unstable at melting temps but hard as rock at room temp. Had to use a rented electric jack hammer to get the old stuff out.

But I have listened to Pete & others long enough to decide to go Moly for the sake of lower fuel bills among other things. Just my maxon blower running 24/7 consumes $100.0 plus a month in electric charges. Now it'll only run while I'm blowing (glory).

Lawrence Ruskin
09-04-2009, 02:01 PM
Ya know what, it might be a good idea to start a thread for guys that are just starting to build or are doing a total rebuild.

We could offer some precepts to follow, for example if you don't have to be in a city, moving to a spot where building standards are easyier to deal with is a good plan. Nice little backyard studio.

Also figure out how many pounds you use a week and designing your equipment around that.

I way overbuilt my studio when I started, I made a huge glory hole and a 150 pound electromelt. This cost me big bucks over 20 years.

Doug Harroun
09-04-2009, 05:12 PM
At first I considered electric elements. Being electrically inclined the wiring and power is a non-issue for me. SiC was out of the question. I know a few people using them and the replacement cost of shot elements would run higher than the cost of gas. Moly elements look better, but the _VERY_ high initial investment was the factor that pushed me back towards gas.

Also, unless you live near a wind farm or hydro plant you power is most likely coal/gas/oil based anyways, why deal with a loss in conversion?

Right now I pay about $0.015-$0.02 per kWh for gas. For electricity it's $0.1085 per kWh.

So I'm still pretty sure I'm building a gas furnace.

...unless someone knows a source for moly elements for less than $100 each.

Eric Miller
09-04-2009, 09:15 PM
Recuperation will be part of the furnace as well. I'm not entirely sure which scheme I want to go with yet. I can fabricate stainless steel parts pretty easily, but the designs that seem to work well are cast refractory, correct?

Yeah, Doug...if you recuperate you will need a completely different burner setup. Its a surface mix burner as opposed to a premix burner.

Charlie Correll also builds and sells them as complete units: the recuperator and the burner.

http://www.correllglassstudio.com/recupburner.htm

http://www.correllglassstudio.com/recuppaper.htm

Pete VanderLaan
09-04-2009, 09:37 PM
Ya know what, it might be a good idea to start a thread for guys that are just starting to build or are doing a total rebuild.

We could offer some precepts to follow, for example if you don't have to be in a city, moving to a spot where building standards are easyier to deal with is a good plan. Nice little backyard studio.


**************************

I think thats a great idea Lawrence. I will take this thread and make it sticky so it's always at the top. as long as it keeps getting added to, I'll leave it there. If it winds up being really good, I'll move it to antiques and classics and stick it there.

Pete VanderLaan
09-05-2009, 07:04 AM
I do think that the floor of the furnace never gets the attention it deserves. First, its walls are the foundation upon which you will build a heavy thing and secondly that glass is the universal solvent and will eat through pretty much anything you stick down there short of rammable coarse grog clays. I don't think a 60% alumina castabe will last that long down there. Kastolite 30 will simply be dissolved wherever glass gets to it. So will IFB. Once you have a glasscrete down there you will have no insulation. The walls have 8 inches of fibre, the crown 10. Consider the floor if you want to look at heat loss.

Dave Hilty
09-05-2009, 08:46 AM
Good point on the floor...My furnace was built by Charlie Correll & we installed in 1997. To be clear about the floor - From the steel up, the layers are 4" of Insblock 19, one course of G20 softs, one course of G26 softs, then the original floor was 3" of Mizzou. When I excavated with the Jack Hammer, pretty much all the Mizzou strata was glassy but fortunately very little of the next layer of G26 was eaten. The old glassy Mizzou peeled away from the ins. brick layer pretty cleanly so I could put in about 4" of the Morocast.

Pete VanderLaan
09-05-2009, 10:57 AM
I have never been satisfied with Mizzou as a refractory for actual glass contact and a floor inevitably has glass contact. It just turns to mush and when it does, heat is really scooting right through it to the steel plate and you never appreciate how much heat is being lost down there since you can't see it. Eight inches in the floor sounds good to me.

David Hopman
09-05-2009, 10:46 PM
[QUOTE=Doug Harroun;82268]At first I considered electric elements. Being electrically inclined the wiring and power is a non-issue for me. SiC was out of the question. I know a few people using them and the replacement cost of shot elements would run higher than the cost of gas. Moly elements look better, but the _VERY_ high initial investment was the factor that pushed me back towards gas.


Everybody keeps bad mouthing SiC for how long the elements last- and I know I have had much better than average luck, but out of the 6 elements that I started with 8 years, 10 months ago, 4 are still running, one is at about 7 and a half years, and one was changed out about 4 years ago and after a trim of the power cable, is ready to go back in as a replacement. So the bottom line is I've bought 9 SiC Starbars total and I still have 2 backups waiting to get installed. That's with running 3 bars in the furnace and 3 in the glory hole.

So what are other people's experiences with Starbar longevity?

Lawrence Ruskin
09-06-2009, 08:10 AM
You're running solid Starbars?

I used two bayonet style elements from I2R and they were 4 plus years old and still going strong when I shut that machine down.

I think those bars will last a long time if you put them in properly in the first place.

Pete VanderLaan
09-06-2009, 11:01 AM
This board primarily has moly users. Brad Shute's board seems populated with SiC people. Both work and both have advantages and disadvantages. Both in fact seem to be susceptible to moisture issues and I used to think it was just SiC. I used to hear tales of the elements falling apart on SiC for no apparent reason but it seems that with good installations, that really rarely happens. Moly elements break too and probably for reasons associated with installation. SiC doesn't need a transformer which is a big plus but the downside is changing resistivity as they age. So there's good and bad points for each. This board just tends towards moly. There's no basis to be snotty about it though.

David Hopman
09-06-2009, 12:37 PM
[QUOTE=Lawrence Ruskin;82294]You're running solid Starbars?

No, the spiral cut Starbars. The one element I lost was due to a pellet popping and landing on the element and eating through it. After that I preheated the pellets and never had the problem again.

Pete VanderLaan
09-06-2009, 02:04 PM
Now there's a reason to get snotty about Molys! I had forgotten! Somehow using elements that react to glass seems like a less than good idea in a ... ( Oh I know) Glass Furnace! Preheating your glass or batch to avoid element failure doesn't seem like a real solution for me.

Lawrence Ruskin
09-06-2009, 02:30 PM
If you don't preheat your cullet that glass will go winging around the inside of your furnace.

I would expect a good solid hit on a moly element would break it, but I really don't want to find out.

Unless someone can come up with another solution, I will preheat until the sad little day I die.

Pete VanderLaan
09-06-2009, 04:41 PM
The only time I have ever lost a moly element was due to my own stupidity, of which I have an ample amount. I load cullet as well as batch . It you want to see something really blast around, try throwing in an entire color rod you don't like. My best understanding was that in an SiC, if a piece of cullet sticks to the element, It's toast and that it's not the cullet popping that does it damage at all. It's the chemical reaction.

Brian Gingras
09-06-2009, 05:55 PM
SiC elements do break down in contact with glass. I went to High Density elements 2 years ago as a result of aging after 9 months. We have seen zero aging now for 2 years after going to HD SiC elements. The downside of SiC is also that it becomes brittle at 1200F. We found this to be a problem recently when we had 3 elements within 6 months break at exactly the same spot. All 3 were determined to be a result of prolonged exposure to 1200F. We had idled the furnace at 1700 for a wekk at a time when this happened and the breaks were at the point where it was estimated to be 1200 degrees. Without the cycle of charging and blowing and the 1200 point changing it literally cut the elements at 7" from the end each time. Each element only broke when we fired back up and within a minute of running at full power you could hear a sizzle and pop and the SiC litterally melted at the break point.

David Hopman
09-06-2009, 09:42 PM
That's strange, because you'd think that with the ends of the elements sticking out of the back of the furnace, that at some place on them there would be a temp of 1200. I guess the lowered overall temp moves that 1200 point from the solid part to the spiral part and allows a crack. Taking the elements down to room temp doesn't seem to cause problems- 3 of mine have been cycled 5 times already with no issues.

Come to think of it, I used to lower the glory hole to 1590 at night. Stopped doing that because of some issues with the superstructure, but the elements seemed unaffected. Did that for at least a couple of years.

I didn't think that preheating the pellets was much trouble at all. I just filled up a stainless steel tray with 40 pounds of pellets, brought it up in the annealer, then dumped it in. It also reduced the temp loss in the furnace on a charge. I haven't been preheating the batch I'm using now, and have had no problems in 9 months.

Brian Gingras
09-07-2009, 05:26 PM
That's strange, because you'd think that with the ends of the elements sticking out of the back of the furnace, that at some place on them there would be a temp of 1200. I guess the lowered overall temp moves that 1200 point from the solid part to the spiral part and allows a crack. Taking the elements down to room temp doesn't seem to cause problems- 3 of mine have been cycled 5 times already with no issues.

Come to think of it, I used to lower the glory hole to 1590 at night. Stopped doing that because of some issues with the superstructure, but the elements seemed unaffected. Did that for at least a couple of years.




no spiral, these are solid bar type TW. the word from engineering was that the 1200F exposure for long enough will cuase the breaks. And since these would sit for a week or more at that point they were getting stressed. When running the temps fluctuate and move around, same thing when charging. Keeping the furnace static at 1750F, with this particular furnace causes the elements to develop micro fractures 5" inside the walls of the furnace.

Brent Hickenbotham
09-09-2009, 05:06 AM
If you don't preheat your cullet that glass will go winging around the inside of your furnace.

I would expect a good solid hit on a moly element would break it, but I really don't want to find out.

Unless someone can come up with another solution, I will preheat until the sad little day I die.

I haven't heard of one person breaking a moly element from cullet or anything else popping on it. If someone has, let me know. Those elements really take a beating in a glassy environment, barring the use of flourines.

Doug Sheridan
09-09-2009, 08:21 AM
hmm...I did break one by bumping it while charging. By beating you mean, works great as long as one doesn't nudge them? Also, since I'm about to change a crucible, are they more fragile after they've been hot for a year?

Pete VanderLaan
09-09-2009, 04:01 PM
They will change shape, more shaped like a flattened wisk so you really need to be careful pulling the passage brick out of the crown. The brick may well be sort of stuck in the crown as well, mine frequently do. Have a place absolutely clear to accept the element and the brick when you pull it. Make sure you have material there to chock it all up as a support.

The only times I have ever broken an element is when I'm changing a pot. I've done it more than once.

Brent Hickenbotham
09-09-2009, 08:42 PM
Doug, I was strictly speaking furnace environment and off gassing. Yes they are still fragile, but handled with care last a long time. Good speaking with you earlier.

hmm...I did break one by bumping it while charging. By beating you mean, works great as long as one doesn't nudge them? Also, since I'm about to change a crucible, are they more fragile after they've been hot for a year?

Rollin Karg
09-12-2009, 07:15 AM
Have a place absolutely clear to accept the element and the brick when you pull it. Make sure you have material there to chock it all up as a support.

The only times I have ever broken an element is when I'm changing a pot. I've done it more than once.

When we finished our first Moly I had a little shot of energy and built a small wood cart on wheels. It's positioned next to the furnace at pot change and stores the elements vertically just like they are in the furnace and in the same sequence. It's been pretty handy.

Rollin Karg
09-12-2009, 07:41 AM
At first I considered electric elements. Being electrically inclined the wiring and power is a non-issue for me. SiC was out of the question. I know a few people using them and the replacement cost of shot elements would run higher than the cost of gas. Moly elements look better, but the _VERY_ high initial investment was the factor that pushed me back towards gas.

Also, unless you live near a wind farm or hydro plant you power is most likely coal/gas/oil based anyways, why deal with a loss in conversion?

Right now I pay about $0.015-$0.02 per kWh for gas. For electricity it's $0.1085 per kWh.

So I'm still pretty sure I'm building a gas furnace.

...unless someone knows a source for moly elements for less than $100 each.

It's a real good thing to survey your environment when considering whether to go electric or gas. Especially paying attention to how the electricity is billed. Can you say Max Demand and Power Factor ? Natural gas prices at the wholesale level are way low right now. Will they say there ? Is your gas supplier passing on the reductions to you ?

Brent Hickenbotham
09-12-2009, 01:52 PM
At first I considered electric elements. Being electrically inclined the wiring and power is a non-issue for me. SiC was out of the question. I know a few people using them and the replacement cost of shot elements would run higher than the cost of gas. Moly elements look better, but the _VERY_ high initial investment was the factor that pushed me back towards gas.

Also, unless you live near a wind farm or hydro plant you power is most likely coal/gas/oil based anyways, why deal with a loss in conversion?

Right now I pay about $0.015-$0.02 per kWh for gas. For electricity it's $0.1085 per kWh.

So I'm still pretty sure I'm building a gas furnace.

...unless someone knows a source for moly elements for less than $100 each.



You can Idle an electric furnace lower than a gas furnace, speaking in consumption terms.

How did you come up with the conversion of KWh for gas costs?

After shipping and customs clearance, even buying in large bulk from China, molys are still more than $100. But they last a long time if taken care of.
SiC can last a good time as well in the right settings.

Charles Friedman
09-14-2009, 04:18 PM
[QUOTE=Brian Gingras;82323]no spiral, these are solid bar type TW.


Brian, Not to split hairs, but I think the TW in your bar type, means Thin Walled. Mine are TW as well and I can see all the way thru, to the other side of the furnace.

Jim Engebretson
09-15-2009, 11:01 PM
Brent,
I'm pretty sure we broke two elements by charging recycled cullet on top of batch. Both broken elements showed up the day after charging.This is in a 600lb. stadelmelter. We've halted recycling until we can process the cullet (quench) to a smaller, less explosive size.

Ben Solwitz
09-16-2009, 12:31 AM
You could also preheat the cullet in an annealer.

David Hopman
09-16-2009, 03:13 AM
I preheated all the pellet/cullet charges for 8 years- it's not a big deal to do it. Stainless restaurant steam table pans make nice containers to heat in, and are about $25, so reasonable. One 4" deep pan holds about 40 pounds of pellets, a 6" deep one will hold a lot more.

Glenn Randle
09-16-2009, 08:03 AM
Seems you could sort out the largest chunks of cullet to preheat, saving you the bother & time of preheating most of cullet. The smaller pieces don't explode like the baseball+ sized chunks do.

Brian Gingras
09-22-2009, 03:07 PM
[QUOTE=Brian Gingras;82323]no spiral, these are solid bar type TW.


Brian, Not to split hairs, but I think the TW in your bar type, means Thin Walled. Mine are TW as well and I can see all the way thru, to the other side of the furnace.

yes thin wall, high density, solid as in not spiral type, but yes they are a tube.

Sky Campbell
10-06-2009, 02:58 PM
Worst furnace build thread ever! The only thing I learned is that Doug has the cheapest gas on the planet. Maybe I'm just jealous.
So since this hasn't gone anywhere is it time for it to start it's slow decent off the front page?

Pete VanderLaan
10-06-2009, 04:25 PM
It's the type of thread fraught with peril. The promised documentation failed to appear. Leave it alone. If it gets any quality junk in it, I'll edit out the superfluous stuff.

Lawrence Ruskin
10-08-2009, 12:42 PM
It should be rolled over into a thread that reads:

How to build a low cost, low overhead studio.

So that these ideas will be easy to pick out of the archives

Pete VanderLaan
10-08-2009, 01:04 PM
curiously, I can't edit a thread's name at all. I can move stuff from one board to another board and I can cherry pick posts but it is time consuming and spare time is not something I really have. It's easier to delete superfluous stuff. ( which is usually my contribution)

Jim Bowman
01-05-2010, 05:40 PM
I am building a gas fired, freestanding 300 lb crucible furnace. My question is about the platform / base.

I am starting with a 3" x 3" x 1/4" angle iron frame mounted to 4" steel casters. 3/16" plate steel rests in this frame, and the bricks are are layed on the pale steel. I was thinking of doing a one inch layer of ceramic fibre insullation board on the bottom, then a layer of 2300 soft brick, then a layer of hard brick. (Clippers)

Henry's book shows a layer of hard brick, then alayer of 2300 soft brick,then another layer of hard brick. Is the bottom layer of hard brick necessary? It seems the insullation board on the bottom would conserve more heats.I want to keep the gathering port as low as I can, and that would shave an inch and a half off the hight.That would add up to37" as the hight for the sill of the gathering port. On my old furnace, the sill was at 33", and I was comfortable with that hight.

Any comments or suggestions on the make-up of the base would be appreciated. Also is there any standard for the hight of the gathering port?

Slate Grove
01-05-2010, 05:55 PM
Jim:

It sunds like your plate of 3/16' steel is one solid piece of plate...is this correct? Have you used this design before, and if so how did the heat effect this plate with regards to heat expansion? I would think that with a big plate like that, the heat would cause some weird warpages, but I may be way off base (pun intended),

Here's a good link to check out a steel base (futon) that works really well and is public domain on the spiarl arts website...http://www.spiralarts.com/tech/documents/975_Futon_drawings.pdf

It would seem more logical to me to have the steel base, then soft brick, then 2 layers of hardbrick, instead of softbrick sandwhiched between two layers of hardbrick.

There's actually really good documentation of the 1000lb. tank furnace rebuild at Corning on the spiral arts website in the tech section. I know you're building a freestanding pot furnace, but there may be some stuff documented there that will help you out.

Jim Bowman
01-06-2010, 11:53 AM
I have used that base design before, and it worked OK. Maybe for a furnace three times bigger that what I'm doing, a sturdier base would be in order. Thanks for the link, though, There is some really good information there.

Cecil McKenzie
01-06-2010, 10:48 PM
Jim.... I was curious if you were replacing your moly or just adding a new one to your capacity?

My schedule for insulation starting at the bottom was 3 inches Insblock, 2 layers of 2300 F soft brick, one layer of hardbrick, 3 inches of cast mizzou. I think this was similar to a noted furnace builders schedule circa late 80s. I think his schedule used 1800 F brick for the lower level of soft brick which would make sense because they are better insulators I believe. I used the 2300 F softbrick because I had salvaged them.

Where my crucible sets I believe I made solid all the way down on the recommendation of a friend whose pot tipped over when the softbricks dissolved after a leak.

Pete VanderLaan
01-07-2010, 08:13 AM
I have a real problem with putting material under something that weighs 2000lbs that is soft like Insblock or fiber. I think it is just asking for a shift off of level. I can see building it with an outer foundation load bearing wall and filling in the central area with better insulating materials, but not ever using them in a load bearing part..

Floors of furnaces are the most neglected part of them. It is a huge face for heat loss and it is never in our consciousness since we can't see it or feel it. It's there. It needs at least eight inches of insulation.

Kyle Gribskov
01-19-2010, 12:16 PM
I'm sold on moly's at this point. One thing I've turned to in building a furnace is to give up on the clean out port. Sounds daft I suppose; but I get so much time out of my free standing pot in a moly furnace that I prefer to chip out any leakage when pot change occurs rather than take the chance that unnoticed spillage or leakage can invade the joints of a furnace built of various parts either dry assembled or cemented. I think those folks who are sticklers for cleanliness and frequently check their clean outs for accumulation of glass can get along fine with any set up. Those who don't check frequently might want to consider a big cup to contain the crucible and avoid a big rebuild. I've gotten 3 years as a rule on my EC cruces and usually get to them before they go away; but when I haven't, the monolithic casting I use in the bottom seems fairly bullet proof. I've had the same one in the furnace for 12 years with no leakage.

Pete VanderLaan
01-19-2010, 01:15 PM
I really like the cleanout on moly's but not for cleaning it out. It's a great place to stuff an Exact torch into the furnace when you are bringing the pot up to temp and Moly's are really bad for heat stratification from top to bottom. I measured the furnace in Eugene which had a 34" and it was 1100F at the lip while it was 500 F at the foot. Mine gives the same readings and that is very hard on the pot to be kind about it. The cleanout offers the only way to balance the temps short of dropping elements way below glass line.

Marcel Braun
01-20-2010, 07:51 PM
Why is this such a taboo in design?

Is it because they would shock the pot from being too close/ reguire too much cubic footage to be far enough away?

Conversely.... the area above the pot is necessary for some reason and to have the extra space (for the elements) completely above the glass line is less total than the extra girth required to be next to the pot plus the required space above the glass line?

Pete VanderLaan
01-21-2010, 06:27 AM
The current approach with moly's has been to keep the chamber as tight as possible so the pots almost hit the walls. Passing the elements down towards the floor makes that space too small. The elements should ideally have about two inches clearance from the pot.

I have read your third sentence three times and do not understand it at all.

The area above glass line is pretty much dictated by the size of the door opening. That casting needs some structure above the opening or it will collapse.

This is really only a problem on the 28 inch and 34 inch sized furnaces. It has been worked around with the heating of the foot of the pot. My 28 inch has these problems and I just go slowly. I have never lost a pot in a moly furnace.

Marcel Braun
01-21-2010, 12:48 PM
OK thanks Pete!

Yeah that third sentence is a tad unclear.... thats what I get for trying to keep it short. See if you can get it now.....

IF one could figure out a way to get the elements down next to the pot without going too excessive on overall cubic footage would there be any other advantage? Better glass? Faster charge?

Pete VanderLaan
01-21-2010, 05:00 PM
I would think you would get a better melt because it melted more evenly. I thought not wrecking your crucible was more than enough justification. It is not easy to do it though, or it would be done. It would cost more to run.

Kurt Walrath
01-22-2010, 12:02 PM
Marcel
I think you have the right idea IMHO. I saw a moly furnace over 10 years ago that had all the elements hanging behind the pot at the back of the furnace.
the crown was higher at the front where the gathering port was and angled
down to the back where the elements hung. the pot was changed thru the
front like a conventional gas furnace.

you can get the chamber size much smaller with this configuration than
the way most are currently built (ie stadlemelters )

steves design seems to be optimized for easiest and lowest cost to build,
not for smallest chamber size / best economy.

eventually someone will build a moly unit that addresses these issues,
chamber size, pot replacement, heat loss through door.

I wish I could afford to experiment with it...

Pete VanderLaan
01-22-2010, 01:04 PM
I do not subscribe to the notion of putting all the elements along the back, nor would I think that having them hanging at differing heights to be a good idea either. The goal is to heat the crucible evenly.

Marcel Braun
01-22-2010, 07:35 PM
Marcel
I think you have the right idea IMHO. I saw a moly furnace over 10 years ago that had all the elements hanging behind the pot at the back of the furnace.
the crown was higher at the front where the gathering port was and angled
down to the back where the elements hung. the pot was changed thru the
front like a conventional gas furnace.

you can get the chamber size much smaller with this configuration than
the way most are currently built (ie stadlemelters )

steves design seems to be optimized for easiest and lowest cost to build,
not for smallest chamber size / best economy.

eventually someone will build a moly unit that addresses these issues,
chamber size, pot replacement, heat loss through door.

I wish I could afford to experiment with it...


Well I MIGHT have an opportunity to give it a shot in the future. My thinking is to cast cubbies in the liner walls to give the elements clearance to the pot and avoid some of the problems of dropping through a steeply arched crown. It would be a very complex casting though...for both the crown and the walls.

Cecil McKenzie
01-22-2010, 09:52 PM
Marcel.... While I have not built a moly furnace I have thought that the elements could be put in indentations in the wall.

When I built my gas furnace I tried to address the minimizing volume issue by making a throat on one side of my lid which is two part castable. The opening is vertical so there is less chance of debris falling into the glass. The back half of the lid is only about 4 inches above the edge of the crucible. The door is like the old Denver doors that lift straight up. I know that many don't like the Denver style door because it can't be opened half way. It does have advantages.. one is the area to the sides of the door can be better insulated and it can be made to have a pretty tight fit. When I change the crucible which means removing all the insulation and cast pieces [ much harder as I get older] I make a gasket of zircon impregnated fiber gasket to seal the door .

The idea of basically making a cup or tub to hold the glass if the crucible fails seems like a good idea. Of course if the clean out could be attached with seamless integrety to the tub itself and the tub was large enough to hold a total blowout then you wouldn't have to worry about glass seeping through joints. You would have keep the bottoms of your moly elements from hanging low enough to be wetted by the rising glass level from a blow out.
I'm not sure if I have been that clear about how my lid is constructed but could get a photo sometime if any one is interested.

Kurt Walrath
01-23-2010, 02:06 AM
My thinking is to cast cubbies in the liner walls to give the elements clearance to the pot .

Marcel,
this is how fred metz at spiral arts builds his moly glories...looks a bit like
a buttress to protect the elements, not really complex at all.

the interior walls of my furnaces have always been machined 2600 ifb.
quicker to build than a form for a casting... and they insulate
really well. I replace my pots before they blow out ( so far anyways and
my furnace gets shut off and on every time I go to a show)

I like the sound of your idea. hope you are able to try it out.

Lawrence Duckworth
01-06-2011, 10:42 PM
what would you folks think of a design that seperates the furnace body from the floor. this design could use off-the-shelf 3" thick castings.

anyone have any idea how hot the backside of the 3" thick casting is in normal operating use?

is 2.5 inches enough clearance between the pot and wall castings for moly tubes?

Jordan Kube
01-09-2011, 01:29 AM
What happens when your furnace top is stuck to the furnace floor with glass?

Pete VanderLaan
01-09-2011, 07:01 AM
I would not put a channel into the furnace wall. I don't know of a castable I would use to withstand the 2800F that a moly element has on the surface temp. Further, since a moly element changes shape some when it heats up. I think it could break it.

The jelly roll problem that exists in Steve's furnaces comes from having a cold joint at the floor. The floor aea needs to be impermeable so that a full pot dump can be accommodated in that area leading to the cleanout hole. Getting away from the whole notion of lifting off the crown to change the pot is going to be part of what Charlie and I do. Bashing your crown around is just not a good idea if you want any longevity at all.

You might use those off the shelf castings but completely close the joint up with rammable plastics coming up about 6 inches.

Lawrence Duckworth
01-10-2011, 11:42 AM
What happens when your furnace top is stuck to the furnace floor with glass?

i was thinking as long as the parting line is above full pool of a pot crash it wouldn't be a problem.

_______________
I can see lifting the entire top/body of the furnace as a solid fixture as a way of limiting the risk of damage to tubes and such. however, I’m not so sure it’ll be that big a deal for me to swap out a pot with the existing Stadelman design.....l00ks likeits dooable:)

btw..I’m not familiar with the “Jelly Roll” or cold joint problem?? Also, what are the issues with the crown?

Pete VanderLaan
01-10-2011, 04:41 PM
I will go to great extremes to avoid moving a furnace crown.

Jordan Kube
01-10-2011, 06:38 PM
Agreed.

How is everything going to be contained in the upper chamber when you lift it up? What's keeping the castings and insulation from falling out the bottom?

Pete VanderLaan
01-10-2011, 07:29 PM
I should make it clear that I really like my furnace that Steve built me. Sometimes its easy to bash without having a good overview. It has made my life a lot easier. Thanks Steve.

Lawrence Duckworth
01-11-2011, 08:06 PM
Agreed.

How is everything going to be contained in the upper chamber when you lift it up? What's keeping the castings and insulation from falling out the bottom?

Jordon, the base of the body would have to be supported just under the wall castings. The deal breaker here would be if the heat on the backside of the casting is to much for a half inch metal plate. But,…what if the casting and the metal ring failed at the same rate…..:)

Pete VanderLaan
01-11-2011, 08:41 PM
Steel "fails" at 800F which is not very hot. Those were the numbers we always used in the fire service to determine whether a steel beam was no longer viable. Also keep in mind that at those temperatures as it gets hotter, it expands almost ten percent, which is huge. A car on fire under an overpass can destroy the overpass if the I-beams are not insulated from the heat. If there is pre or post tensioned concrete in a heated situation, where the steel cable in the concrete can heat to that level, the steel fails and then so does the concrete because it's no longer in tension.

The cold face of a three inch refractory casting is going to be a lot hotter than 800F.

Lawrence Duckworth
01-13-2011, 06:43 PM
so how HOT are these furnace when swaping out pots?

....will your front loader be available in a kit?

Pete VanderLaan
01-13-2011, 10:45 PM
I get it cold enough that I can handle everything. When it's first coming apart I use Kevlar mitts.Then I go away for a while. Patience is a virtue. If it needs air chiseling, I want it down around 140F.

Charlie and I are sitting down this weekend bashing on design issues. It's way too early to think about kits. Right now we're working on a prototype for the 24 inch pot that has the elements going down below pot line by about five inches. I want to see the lower half of the furnace getting some heat.

Scott Novota
01-18-2011, 02:41 PM
Hey Pete,


Go back and look at those pictures from Norway. They had the moly elements running all the way down the sides of the pots. Then again there was like 12 of them in there if I remember correctly.

http://talk.craftweb.com/attachment.php?attachmentid=2668&d=1263959333

Pete VanderLaan
01-18-2011, 03:43 PM
Going all the way to the bottom will create an element that is very as in (VERY) hard to ship as well as a lot more expensive. I don't think the furnace needs 12 elements based on my experience. Six is quite adequate for a 300 lb pot. We don't actually know the capacity of the Norwegian pot in that picture. Going down five inches should do it in my mind since the pot curves in towards the center after five inches. Getting the pot off the furnace floor and on to a pedestal will really help as well. Having the pot right on the floor really creates a cold spot for the pot which in turn creates stress.

Lawrence Duckworth
01-19-2011, 10:05 PM
Are the heaters and crown so fragile that moving or rolling the furnace with the heaters installed a bad idea? Will that lill bit of vibration break ‘em?


I fear I’ve screwed up before even getting started. I may not have the overall headroom to pull the heaters out from the top unless I roll the furnace out into the open shop....[i have an 8 foot ceiling behind the 7 foot hood aprin.]

Pete VanderLaan
01-20-2011, 07:05 AM
It's a problem and part of why the 500mm hot zone elements aren't being used anymore.

I had to account for the heater length when I built my hood. I think rolling a furnace on a smooth floor will probably ( probably mind you) work but it depends on the construction and seating of the passage brick. Simply put, they're fragile. I see lots of stuff. I had one man methodically break every one of his elements, one after another trying to pry them out of the bricks from inside the furnace instead of pulling the whole unit. In my shop I once had the elements all out and on the marver and Mary Beth came and sat on them...

Scott Novota
01-20-2011, 04:34 PM
It was your fault.

Pete VanderLaan
01-20-2011, 04:50 PM
well, that's what she said too.

Larry Cazes
01-20-2011, 05:31 PM
Yes, Dear :)

Pete VanderLaan
01-20-2011, 07:09 PM
I have been married for 37 years , Thank you for asking.

Larry Cazes
01-21-2011, 12:19 AM
Only 15 years coming this March but I am a fast learner.

David Patchen
01-21-2011, 02:22 AM
I really like the idea of a design where the pot and front of the furnace are basically a cart that can lower and roll out for changes. The current design where you have to move the most fragile and critical parts of your furnace (elements, crown) to get to the part you're going to trash (old pot) seems like it could use some re-engineering.

Pete VanderLaan
01-21-2011, 07:38 AM
Even in a kiln car design. you had better pull the elements. Things get stuck together in a glass furnace and getting them loose takes force. The difficulty in the design in which the crown remains in place is always the same- the span of the crown that is unsupported.

Lawrence Duckworth
01-21-2011, 09:10 AM
Lets say you have the castings for a 400# stadelman, and a 200# pot. cutting about 8” or so off the length of the three curved wall castings lowering the overall interior height but allowing the heating elements to hang between the 200# pot and the larger diameter 400# wall castings. this would lower the furnace height allowing more room to pull the heaters and get some heat down lower too….…..and if’n you don’t like the castings maybe just use those tiny tiny ifb to lay up a chamber like they did in the Norway furnace.




I’d be curious to here some crown improvement ideas

Josh Bernbaum
01-21-2011, 10:19 AM
Or preferably use some hard bricks instead of the IFB's.
You'd have to know someone with a huge diamond saw to cut the castings down I'd imagine. Sounds interesting as far as getting elements lower and more room for them around outside of pot, but wouldn't you be sacrificing space for your soft insulation between the casting and the steel exterior? Unless you expand the steel shell as well I suppose.

Have folks had problems with breaking the crowns on moly furnaces while doing a pot change? If it sounds like the elements and passage bricks need to be removed even if the furnace design is a front-pot access, is it that much more problematic to remove the crown too and stick with the more straightforward top-pot change design which should allow for maximum structural integrity of the furnace?

Pete VanderLaan
01-21-2011, 10:25 AM
In conversation with Charlie this morning, he want to pull the pot from the crown. He says he has an evenly split crown with arch support and that it works great, so I am going along with his design since he has built a boatload of them. The trouble with my rectangle is that there is a lot of unused space you have to pay to heat. This doesn't bother me and I put three pots in the furnace anyways, not one. I do it out the front because I've always done it out the front.

You have to pay attention to the watt loading that each element provides based on both the hot and the cold zones. Each one changes as it's sizing changes. Mine runs about 20,000 watts. The wattage has to be able to drive the size of the furnace or you will have the equivalent of a VW bug on a hill with a ton of lead in the back seat. One of the big troubles with the wire furnaces which are really just converted ceramic kilns is that while they might have the physical capacity for a large pot, they do not have the amps to get it hot enough to not drive a pro shop nuts.

Pete VanderLaan
01-21-2011, 10:35 AM
Have folks had problems with breaking the crowns on moly furnaces while doing a pot change? If it sounds like the elements and passage bricks need to be removed even if the furnace design is a front-pot access, is it that much more problematic to remove the crown too and stick with the more straightforward top-pot change design which should allow for maximum structural integrity of the furnace?
******************
The problem I see with the existing crowns are that they are flat, not arched. Most of the parts replacements we are doing are related to the kind of glass being melted. Sadly the Spectrum nuggets are a common denominator in most of the parts failures. We just finished a long test comparing Engineered Ceramics pot to High Temp pots using the nuggets. In both cases the pots experienced really substantial pitting in short order to the point where we are just not going to recommend high alumina pots to people insisting on using Nuggets anymore. Our next set of tests will involve melting SP87 in the same containers and seeing how they do comparatively. We will have all the test samples at Seattle GAS. What was interesting in the testing was that there were no signs of free alumina in the melted glass which would indicate to me that the China Clays in the formulation are what is being attacked and dissolved readily. You have to have some clay in the mix. . That would be consistent with the damage we see on fireclay and silicate parts to the furnaces as well. ( the door area).

The other thing that has to be considered in these failures is operator inexperience. It's quite formidable in many cases. The bigger furnaces have the biggest problems. Anything above a 24 inch pot has a very big unsupported area and the crown really wants to sit down.

Getting vents on these furnaces is going to be critical.

Thomas Chapman
01-21-2011, 10:54 AM
When I last visited Glass Eye about 6 years ago they had an Italian furnace (Fiorni--sp?). It seemd to be designed so that (to change pots) the entire bottom was unbolted and the old crucible dropped out along with its insulation and steel jacket. Remove and discard, then bring in the new component, jack it up to position and replace the fasteners. (It was a gas-fueled unit, if I recall.) Seemed like a good approach.

Pete VanderLaan
01-21-2011, 12:45 PM
I have real insulation problems with the falorni. I don't like bottom fire furnaces much at all.

David Russell
01-21-2011, 05:52 PM
i have had good>great experiences in the past with charlie's two part arch crown on a 200lb pot.

while it takes some muscle, the ability to manual lift the crown of yourself is nice, one piece at a time usually, unless i am feeling really good that day......

over a few years the two halves receded from each other only a little bit and that space was easily stuffed with frax.

a pot change was always a little work but it was simple, direct, effective and done alone.

i think charlie makes great equipment and is a great guy........my 2 cents worth

Jordan Kube
01-21-2011, 06:15 PM
You can roll the furnace out with the elements in place. You'll be going about six feet or so and the concrete floor should be a smooth ride. I don't know that I've ever had one break from rolling a furnace around, even on less than perfect floors.

I've thought a lot about those designs Lawrence and I haven't ever got past that one problem. Steel will fail. Try and keep things simple. Don't overbuild it.

Lawrence Duckworth
01-21-2011, 08:57 PM
I've thought a lot about those designs Lawrence and I haven't ever got past that one problem. Steel will fail. Try and keep things simple. Don't overbuild it.






all I want to do is make a glass pumpkin:)

Pete VanderLaan
01-22-2011, 06:16 AM
copy that to the thread on making a good red glass.

Lawrence Duckworth
01-24-2011, 07:51 AM
Jordon

say I put a piece of half inch in a forge and let it get white hot, unless the steel is upset or stressed it shouldn’t lose shape until somewhere around 2600f. so…how fast would the steel ring fail, wouldn’t it be the equivalent of an annealing every time it cooled to change out the pot and likely last at least as long as the castings?



Btw,..I ordered the Stadelman 200# castings and a pot the other day :)...keepin-it-simple

Doug Sheridan
01-24-2011, 08:17 AM
I've tried venting with a 1" inside diameter vent out the top. Using the nuggets, the vent was destroyed quickly. Buildup around the ceramic tube and then eventually total failure, meaning the tube dissolved.
In the larger furnaces, I can't imagine anything working to vent the nugget fumes. It's like trying to find a container for the world's strongest acid.
Now with SP, and no vent, I've really not seen a need for venting, at least for my 250 lb. and 80 lb. furnaces.

Pete VanderLaan
01-24-2011, 09:12 AM
You have to ream it out periodically. I would make a good sized hole and just cover it with a brick when not being used. It doesn't have to be slick.

Jordan Kube
01-24-2011, 07:56 PM
It will loose shape and it won't be steel anymore either. Leave that forge on for six months with that chunk of steel in there and see what you get.

Pete VanderLaan
01-24-2011, 08:11 PM
Hey, cover a piece of steel with fiber on a furnace and the next morning there won't be any steel at all.

Lawrence Duckworth
02-04-2011, 11:39 AM
the concrete floor should be a smooth ride.
.


We finished smoothing the floor yesterday :)

http://www.clevelandsteel.us/art2htlm.html

David Patchen
02-04-2011, 11:46 AM
Beautiful! It's too nice for a hot shop :)

Pete VanderLaan
02-04-2011, 01:29 PM
Good thing it's not a gas furnace. The vibration from the blower could make the furnace start moving around the building late at night by itself.

Brian Gingras
02-04-2011, 02:13 PM
I work on a floor like that, I used to clip and slide all the time...a little bit of glass dust and away you go.

Ted Trower
02-04-2011, 02:38 PM
That's how the floors are finished at the Toledo Museum of Art studios.

Sky Campbell
02-04-2011, 03:41 PM
Wow those floors are beautiful! I guess that would be considered terrazzo? I always thought that style floor would have a come back. I can only imagine what that would look like with glass for aggregate instead of stone. Either way very classy looking and easy to clean I'm sure.

Lawrence Duckworth
02-04-2011, 09:51 PM
This is polished concrete and in some way I guess the process and equipment are similar to terrazzo but grinding and polishing the buildings ordinary concrete slab is a bunch cheaper than the real deal.. http://www.bluefieldfloors.com/ give ‘em a call :)

Pete VanderLaan
02-05-2011, 06:54 AM
I remember when I was a kid and I was making adobe bricks for the first time. I made stationary forms that held four bricks each and I would lay them down and put the red dirt, sand and straw mix in and smooth them perfectly with a wet towel and then let them dry overnight before I pulled the forms and stood them on edge to dry. They were absolutely perfect. I could make about 60 a day that way working hard..

My friend JJ Gonzales came over and looked at it and went off and made a form out of crappy 1x4's and came back and just wet down the entire dirt pile for about an hour with a big pool of water in the center. He threw in the straw and a couple of guys he always broguht up from Chihuahua stomped around in it with their feet. Then they took the single form and proceeded to fill it, mush it down and smooth the top with an old rag. They then jerked the form then and there and moved on to the next one. They made about 750 adobes in a few hours. In seven days we had enough to build the house

At the end, JJ said, "PV, your adobes are made with too much love."

Lawrence Duckworth
02-07-2011, 09:56 AM
Nice story…PV

I remember when I was a kid helping my grandfather shingle the toe house atop the ski hill, the highest point around for miles mind you, and him cussing around about me not keeping the shingles square and straight. I said, “Why Grandpa, no one will see this way up here”…..then summmore cussing ensued.

I suspect the 750 brick were of a lesser quality. but like you say, ya got the house built

Pete VanderLaan
02-07-2011, 10:35 AM
Actually, the ones JJ made were better. Since you pull the form when it's so sloppy, the corners rise up slightly and dry that way. The brick is laid with that face down. You lay down a line of mud and then plop the brick on. The upturned corners facing down create a suction. If the face was flat, the brick would slide around.

My point is to keep the eye on the prize, in my case a place to live, in yours a place to make good art. . The adobes were part of that process but were never the house. I see a lot of studios where the shop is gorgeous and nothing really good ever gets made in it . I implore you , Don't do that. IMHO.

But it is really nice.

Lawrence Duckworth
02-08-2011, 06:04 PM
I’ve never laid an adobe brick…the modern wood molds might be sorta like the adobe in that they have a recess, we always called that recess a “frog” [I laid a lot of brick in my first life]
Heres a photo of the brick wall separating the shop from the guest instructors living area

Pete VanderLaan
02-08-2011, 07:09 PM
Well, it's really beautiful Lawrence. When do I instruct?

Virgil Jones
02-23-2011, 01:40 PM
What temp. do you bring the batch up to? I understood that it got goopy after a certain temperature, Thanks, Virgil

I preheated all the pellet/cullet charges for 8 years- it's not a big deal to do it. Stainless restaurant steam table pans make nice containers to heat in, and are about $25, so reasonable. One 4" deep pan holds about 40 pounds of pellets, a 6" deep one will hold a lot more.

David Hopman
02-24-2011, 01:03 PM
What temp. do you bring the batch up to? I understood that it got goopy after a certain temperature, Thanks, Virgil

950, still rock hard at that temp.

Virgil Jones
02-26-2011, 12:24 PM
thanks, david.
i'll give it a try

950, still rock hard at that temp.

Pete VanderLaan
02-26-2011, 02:49 PM
[QUOTE=Virgil Jones;9453

I understood that it got goopy after a certain temperature, Thanks, Virgil[/QUOTE]

************************
That's called melting Virgil. That's what it's supposed to do.

Scott Garrelts
03-02-2011, 12:46 PM
When doing a pot change... does it matter (for the elements sake) at what rate you cool it down? Can you open the door to speed up the process or could this cause some stress? At what temperature would one say it is safe to open the door and start to disassemble?

Pete VanderLaan
03-02-2011, 01:17 PM
I read the super Kanthal handbook and it indicates that the elements are not prone to thermal shock. It is certainly true that you can hot change an element. I don't try to tear things down until I can actually touch the materials without wanting to drop them. I think that would be a good goal when handling the elements or passage bricks. Don't drop them!

So, while there are a myriad of ways to break elements, thermal shocking would not be one of them. Try putting them in a trebuchet and see what that gets you. Shoot for the Nebraska Line.

Lawrence Duckworth
03-10-2011, 09:29 PM
This is the start of my 200# furnace build.
Please feel free to jump in with any questions or advice!


Okee-dokeeeee…here's what the 200# stadelman castings look like.

Pete VanderLaan
03-11-2011, 07:07 AM
don't forget to flip them over. The pallet goes on top.

Rick Sherbert
03-14-2011, 04:31 PM
Are the heaters and crown so fragile that moving or rolling the furnace with the heaters installed a bad idea? Will that lill bit of vibration break ‘em?


I fear I’ve screwed up before even getting started. I may not have the overall headroom to pull the heaters out from the top unless I roll the furnace out into the open shop....[i have an 8 foot ceiling behind the 7 foot hood aprin.]


Lawrence,
That's a sweet looking hood. What material is that? Can you talk about the construction?

Lawrence Duckworth
03-14-2011, 08:08 PM
Lawrence,
That's a sweet looking hood. What material is that? Can you talk about the construction?

Galvanized slab form decking…do you think that will get hot enough to be a health hazard?

Lawrence Duckworth
03-17-2011, 10:09 PM
............44" dia. base

Rick Sherbert
03-20-2011, 04:45 PM
Galvanized slab form decking…do you think that will get hot enough to be a health hazard?

If you're talking about the zinc getting airborne, I don't think so.

I'm starting to build a 300# moly with the castings from Pete. The more details, the better. On your base, what gauge steel for the drum?

Pete VanderLaan
03-20-2011, 05:26 PM
If I might, both Charlie and I think the floor on those could use more insulation. Accounting for that need would be a good plan in my mind when planning that steel depth.

Lawrence Duckworth
03-20-2011, 07:35 PM
These are actual dimensions taken from the 200# castings.

The center support piece in the tub is a 3x2x1/4 sq.tube w/ 2x2x3/16 angle fitted.
scrap pieces of stretched metal make up the flooring.
The tub is 12”x ¼ x 44”dia.<(200#)
three casters n brackets welded permanently.

As far as insulating the bottom end, I’ll be using a layer of tin foil, 5 layers of 1900 insblock fiber board, one course of 2300 brick layed flat, plus the 4” of casting….

__________________________________________________ ____
I’m needing a 50 kva single phase transformer…so far ebay hasn’t worked out so good...can you help?
_____________________________________

Patrick Casanova
03-20-2011, 08:42 PM
Look at the Classified Ads... Jim Bowman has everything you need listed for sale. If I was going to go Molly at some point in my future I'd take a serious look at what he has for sale.

Pete VanderLaan
03-20-2011, 08:54 PM
I am very sure the Bowman stuff is sold and it was 208 volt three phase anyway. I would look with local demolition contractors in the Atlanta area.

Lawrence Duckworth
03-20-2011, 09:16 PM
I really don’t know much more than that I need a single phase 50 kva 4 to 1 step down (whatever the heck that means)…does this look like the ideal transformer for a 200 elbeerer?

Dennis Hetland
03-20-2011, 11:47 PM
This appears to be a 4to1/2to1 step down transformer. You're not showing the entire nameplate There's more info on it, like the KVA.
I can't be 1000% positive, but I'm assuming this is rated for 480v on the primary. If you have a 240v service going to your primary and you wire X1 to X3 and X2 to X4 you should get 60v out of your secondary.
The 1 through 6 on the primary are taps for adjusting to high or low voltage coming from your service. Like if you're supposed to have a 480v service, but you're actually getting 500v you can tap it so your secondary is putting out the proper voltage. You could play with those taps to get slightly more or less than 60 volts. If you wanted to for some reason.
You should post another picture that shows the entire nameplate.

Charles Friedman
03-20-2011, 11:50 PM
So, I was just wondering what the intended use of this furnace? At this point in construction and placement of this object that is going to be the warehouse of a marketable commodity, I would be thinking about putting a scale under this unit, as well as an adjustable height and leveling mechanism.
Just a thought.

Pete VanderLaan
03-21-2011, 06:18 AM
And what you want is sixty volts run with a single bank of five of the elements we'll provide wired in series.

Lawrence Duckworth
03-21-2011, 09:23 AM
This appears to be a 4to1/2to1 step down transformer. You're not showing the entire nameplate There's more info on it, like the KVA.
I can't be 1000% positive, but I'm assuming this is rated for 480v on the primary. If you have a 240v service going to your primary and you wire X1 to X3 and X2 to X4 you should get 60v out of your secondary.
The 1 through 6 on the primary are taps for adjusting to high or low voltage coming from your service. Like if you're supposed to have a 480v service, but you're actually getting 500v you can tap it so your secondary is putting out the proper voltage. You could play with those taps to get slightly more or less than 60 volts. If you wanted to for some reason.
You should post another picture that shows the entire nameplate.

Dennis that’s it for the photos, but is the bottom line a transformer that puts out 60 volt from a 200 amp single phase service? Is this what I ask for at the sales counter?

> this deal has 6 molly tubes, 240 single phase power <

Pete VanderLaan
03-21-2011, 12:11 PM
No. The transformer, assuming it is the correct unit would have an input of 480V. That would break it down to two 240V taps and a 120V tap, plus the correcting taps. You however are going to run 240V in to the thing and it can't perceive the difference between 480 and 240, so it is going to give you two 120V taps and a sixty volt tap instead. You are looking for the sixty.

So you are looking conventionally for a 50KVA transformer 480 volt input with three taps for 240 and 120 secondary outputs. It may have adjusting taps as well.

Or you can custom order a transformer with 240 volt input and 36 volt secondary output through either me or a local supplier, I don't know what your deal is there. I use the 36 volt in my furnace. That works out to two banks of three elements at 12V if wired in series.

Dennis Hetland
03-21-2011, 12:25 PM
Exactly what you want is not common so it's likely to cost a lot, but a 480v to 240/120v is common. If you put 240v to the primary of a 480v transformer you'll get 120/60v out of the secondary. If the load on your secondary is 200 amps you'll draw 50 amps from your panel to you primary.(If the secondary is wired for 60v).
A 50KVA 4 to 1 stepdown transformer rated for 480volts on the the primary should work for you.
I should point out that while I have installed transformers I have not built a moly furnace yet. I think it would be worth the money to pay someone like Cheyenne Malcolm for some advice. Especially if you don't have a lot of experience with electrical installations. I'm sure he could tell you where to get the best transformer for your money.

Dennis Hetland
03-21-2011, 12:30 PM
Yeah. What Pete said.
(I need to learn to type faster.)

Dennis Hetland
03-21-2011, 12:38 PM
No. The transformer, assuming it is the correct unit would have an input of 480V. That would break it down to two 240V taps and a 120V tap, plus the correcting taps. You however are going to run 240V in to the thing and it can't perceive the difference between 480 and 240, so it is going to give you two 120V taps and a sixty volt tap instead. You are looking for the sixty.

So you are looking conventionally for a 50KVA transformer 480 volt input with three taps for 240 and 120 secondary outputs. It may have adjusting taps as well.

Or you can custom order a transformer with 240 volt input and 36 volt secondary output through either me or a local supplier, I don't know what your deal is there. I use the 36 volt in my furnace. That works out to two banks of three elements at 12V if wired in series.

What about welders? I thought I heard something about people using welders for their transformers.

Larry Cazes
03-21-2011, 01:13 PM
What about welders? I thought I heard something about people using welders for their transformers.

A welder is NOT a transformer. Most are not designed or built for 100% duty cycle meaning 24 hours/day. We have EZTherm furnaces at the shop I rent at. They use Miller welders. I would not suggest you go there.

Pete VanderLaan
03-21-2011, 04:11 PM
What about welders? I thought I heard something about people using welders for their transformers.
***************
When EZ Therm built their shortlived moly, a cooperative adventure between Henry Halem and Mark Jesson from Duralite, they asked Miller for a welder that would perform continuous duty. Miller said "sure" and supplied them with a unit that supplied continuous duty- for an eight hour work shift. This was an exceptionally unfortunate miscalculation and speaks volumes for testing a product for a year before it gets put on the market. It was only one of many problems.

Use a transformer, a real one.

Larry Cazes
03-21-2011, 06:55 PM
***************
When EZ Therm built their shortlived moly, a cooperative adventure between Henry Halem and Mark Jesson from Duralite, they asked Miller for a welder that would perform continuous duty. Miller said "sure" and supplied them with a unit that supplied continuous duty- for an eight hour work shift. This was an exceptionally unfortunate miscalculation and speaks volumes for testing a product for a year before it gets put on the market. It was only one of many problems.

Use a transformer, a real one.

Yup. Even the user guide shows 100% duty cycle is actually 8 hours instead of 24 as most would assume. Specsmanship at it's best.

Pete VanderLaan
03-21-2011, 07:52 PM
And I would note: Take care of your transformer or it won't last forever either.

Lawrence Duckworth
03-22-2011, 01:11 PM
You guys have helped….thanks







Progress--- :)

Rick Sherbert
03-22-2011, 01:37 PM
I am very sure the Bowman stuff is sold and it was 208 volt three phase anyway. I would look with local demolition contractors in the Atlanta area.

Check is on the way to Jim as we speak:)

Pete VanderLaan
03-22-2011, 03:07 PM
You guys have helped….thanks







Progress--- :)
I still think the floor could use more insulation.

Lawrence Duckworth
03-22-2011, 09:42 PM
I still think the floor could use more insulation.

I finished up with the wall castings and the sill height ended up being 2’-6” off the floor. Is that height worth compromising by adding additional insulation?….

Btw, is the pot lip higher, lower or level with the sill?

Pete VanderLaan
03-23-2011, 05:18 AM
a tiny bit lower is best but put the pot on a stilt that completely supports it.

Mark Wilson
03-23-2011, 06:31 AM
if a transformer is designed for an input of 480 volts and has a 50 kva output power, and then is used with 240 volts, it now can only supply 12.5 kva or only 25% of the power it could before. the size of the wire used in the transformer is the limiting factor.

Steve Stadelman
03-23-2011, 11:10 AM
if a transformer is designed for an input of 480 volts and has a 50 kva output power, and then is used with 240 volts, it now can only supply 12.5 kva or only 25% of the power it could before. the size of the wire used in the transformer is the limiting factor.

No, 25 kva. Redo your math.

Mark Wilson
03-23-2011, 02:26 PM
No, 25 kva. Redo your math.

off by a factor of 2.....the story of my life!!!!

Pete VanderLaan
03-23-2011, 04:21 PM
Christine Lavin has this great song called " Don't Push Send."

Lawrence Duckworth
03-25-2011, 09:42 PM
Steve S. recommended a 15kva 240 input, 45v output single phase transformer with standard 5% and 10% voltage compensation taps.

Do you guys plug the cleanout with brick and fiber? :confused:

Tim Bassett
03-26-2011, 02:22 AM
My stadelman has a layer or two of hot face fibre close to the crucible and then a few layers of standard fibre to back it up. I would not suggest using bricks in case you do need to do a big cleanout. The worst case scenario is that the fibre can never be actually "glued" on place by the glass, you can always shred it and pull it out. I would hate to have to shred a brick that has been glued in place. Hopefully you will have to use the cleanout port very infrequently. I opened my cleanout port after charging at least weekly for 18 months and was surprised that there seemed to be so much glass on the floor...maybe 1/2 an inch. I spent quite a while gathering it all off the floor and it added up to be about three kilos. Best of luck with your build
Tim Bassett

Rollin Karg
03-26-2011, 05:52 AM
If you want your furnace to run efficiently for a long time you should clean the bottom out on a regular schedule. At least once a month if not every other week.

Pete VanderLaan
03-26-2011, 06:07 AM
and I might add, three kilo's isn't much at all. I am really encouraging people to use the cleanout to heat the lower end of the furnace when turning it on, so it's nice to keep it clean. I have folks sticking their bench torches in the cleanout on a pilot flame. This has eliminated problems with thermal shocking pots or so it seems. It's really only an issue on the 28 and 34 inch furnaces.

Pete VanderLaan
03-26-2011, 06:11 AM
Steve S. recommended a 15kva 240 input, 45v output single phase transformer with standard 5% and 10% voltage compensation taps.

Do you guys plug the cleanout with brick and fiber? :confused:
***********************
And while that is absolutely the best unit for the job, you aren't going to find it off the shelf. It's a custom transformer.

David Russell
03-26-2011, 10:04 AM
what is the best method to clean out my port without shutting down?

Pete VanderLaan
03-26-2011, 10:19 AM
Get the furnace really hot, pull the cleanout material and look it all over. If it's really bad, there is going to be a solid plug of glass to stare at. If it's clear, look up the hole. Make a little rake out of angle iron and drag the crud out. If solid, heat up the glass plug with a torch, as big as you can find. If there is really a lot of crap, be ready to contain it and keep valuable combustibles away from the cleanout.

This is not a fun job.

David Russell
03-26-2011, 10:46 AM
thanks pete. alright, really hot, do i need to go as hot as 2275?

should any coating on the floor be cleaned out regardless of thickness?

in the past i have been sure to load batch real careful and wait for the pot change for a big cleanout, but the part of me that pays the bills is demanding maximum efficiency!

Pete VanderLaan
03-26-2011, 01:55 PM
I would go up to 2350F. Either that or hold it at 2275 a long time. You need this stuff to flow and there's no heat source at the floor.

Jordan Kube
03-28-2011, 02:15 AM
If you gather clean you don't need to clean it out at all. Maybe when you shut down. Weekly is totally overkill for most shops unless you're putting 100 pounds of glass on your floor every week. Rollin runs a large production shop.

Pete VanderLaan
03-28-2011, 10:15 AM
I load crap in the pots that sometimes want to get out of the pot. Cad Sels are the worst next to enamel white. It's inherent in making color. It's not the gathering that gets me.

Mark Rosenbaum
03-28-2011, 10:44 AM
This is how hot you need it!
Go with the flow! 2300....

Thomas Chapman
03-28-2011, 12:29 PM
That's quite a flow!

Mark Rosenbaum
03-28-2011, 01:29 PM
That's quite a flow!

yes, a sh*t-load of glass...never thought there was that much wrapped around the crucible in a "jelly roll"!

Scott Novota
03-28-2011, 03:08 PM
wow....and ouch all at once.

Pete VanderLaan
03-28-2011, 06:01 PM
I forgot to add, be ready to protect your concrete. While dramatic looking, Mark's dump is not all that unusual. The radiant heat from it is substantial and you really need to be aware of what might get damaged.

Lawrence Duckworth
03-28-2011, 10:03 PM
I got a chance to visit with Tadashi Torii at the Duckbill Studio in Atlanta awhile back and he let me take a bunch of photos of his shop. Heres a photo of the 300lb. Stadelman. I’m guessing this shop takes a beating with the renters and newbee students…If I remember right he said it was five yrs. old.

Brian Wong Shui
03-28-2011, 11:08 PM
Lawrence, since I'm the one who looks after the technical aspects of this shop and you are posted a photo of our equipment, I guess I should contribute to this thread.

Everything that you've read on this thread about venting, gathering ports, crowns, insulation, wiring, etc. is true. Listen and try and take care of the problems now while it is apart.

The seal between the door and the gathering port is worth about 10% in energy consumption. We reface the gathering port and change the door once a year without fail to keep a good seal and a gap on the bottom edge of the door helps with the dribbles and allows most of the gases to vent without too much heat loss (found out after much experimentation). The picture that you posted is one of the experiments.

We had hole once and found the drain port in this version of the furnace to be lacking. It ate the bricks and got into the insulation. It was a pain to clean out. Your drain port seems to be a little better designed but it should stick out beyond the metal of the cylinder.

We charge batch weekly and pull our crucibles religiously at 72 charges and always have a spare on hand.

Like Pete, I've always thought that the bottom and the front face of the furnace is a little underinsulated. If you scan it with an IR thermometer it will be a higher temperature than the rest of the cylinder.

Since your furnace is under a hood, ensure that there is enough space work and to pull and install the elements. You'll be doing this hot one day. Using a piece of Angle Iron around the corners of the passage bricks makes a good extraction tool and can aid installation to allow the brick to slip in without getting hung up on the insulation.

Get a high temp IR Thermometer. It will help you find hidden trouble spots and hot connections. Grid the skin and take measurements when new. It will help to identify when tunnels are being formed in the insulation. Get a 1000A True RMS Clamp Ammeter and take readings (primary and secondary) when new. It will provide a baseline for your monthly measurements and identify when something is changing in your furnace. Try and take the readings under the same operating conditions.

Put a dialer on the Watlow. Elements break in the night with a full pot of glass. You'll need to know.

Put a time delay relay on a warning light for the door. People will leave your door ajar and you'll wonder why your furnace temperature is dropping.

Allow the stainless panel on the front to move. This panel buckles under the heat. Expansion allowances may help. (Not tested)

Build a maintenance checklist and follow it. Perform Root Cause Analysis on every failure. No one ever said that this was a maintenance free furnace but it makes great glass.

Pete VanderLaan
03-29-2011, 04:09 AM
what Brian said about the stainless is true. I removed all the screws from mine and it stopped hanging. Pretty but dysfunctional.

I have never had an element fail unless I was involved in making it fail.

Josh Bernbaum
03-29-2011, 08:05 AM
Put a dialer on the Watlow. Elements break in the night with a full pot of glass. You'll need to know.



Hey Brian,

Could you elaborate on where to find this auto dialer and how/where to connect to the Watlow. I'd be interested in installing one here.

Thanks!

Rollin Karg
03-29-2011, 08:32 AM
Brian

When you replace the gathering port, are you replacing the whole ring including the port? Or did you make your own replacment port and modify the ring ?

Thanks
Rollin

Dennis Hetland
03-29-2011, 09:19 AM
Hey Brian,

Could you elaborate on where to find this auto dialer and how/where to connect to the Watlow. I'd be interested in installing one here.

Thanks!

Sensaphone www.sensaphone.com/index.php

You should be able to find where to connect it in your Watlow manual.

Andrew Boatman
03-29-2011, 02:21 PM
When the time comes to begin to prepare for a crucible change. Be sure to have everything you need before you begin.
Elements - eight, just in case.
Crucible - as pete says always have one on the shelf
Parts - cables, air tubes, new wiring, screws
Crown - Looks like another week of waiting

Pete VanderLaan
03-29-2011, 02:46 PM
In the summer, castings dry fast. In the cold season, they just never seem to dry at all and they can't be pushed so therein is the risk of not having a casting when you need it. It's true of the pots too. There is an undeniable pace and rhythm to it.

Lawrence Duckworth
03-29-2011, 07:26 PM
Brian, thanks so much for your help. I’ve been down there a couple times now and sure wish I would’ve bumped into you…

I’m getting close to tackling the door and s/s front. The expansion is something to ponder for sure…and the weight of the door too, maybe a counter weight on the backside of the bridge assembly.

The skin is 26 ga.coil stock from the local metal roofing supply house, probably should have gone with something heavier, (16ga.nmaybe??) anyway, fastened with a strap and 2- ¼-20x5/8” ea. I’m guessing the skin is in four sections for expansion, otherwise a sheet of stainless would have been a bunch quicker and less hassle…but then wrenching all the nuts down kept my middle granddaughter busy:).

Brian Wong Shui
03-29-2011, 11:45 PM
Brian

When you replace the gathering port, are you replacing the whole ring including the port? Or did you make your own replacment port and modify the ring ?

Thanks
Rollin
Rollin,

We don't replace the gathering port. We chip away the glass and resurface with a phosphate bonded patch. Grefpatch-85 from HWR. It seems to hold up for about a year. It is a pretty picky product for dryout. Put it on and let it set up for 24 hours and then follow the dryout. It has absolutely no green strength. Thermbond is another phosphate bonded patch but doesn't seem to bond as well as the Grefpatch to the old castable.

Sure would be nice to be able to yank out the gathering port and replace but the Stadelmeister wasn't designed that way. (Hint to Pete :-)). I thought about getting Larkin Refractory to build a mold for the front so that I could change the design but didn't get around to it.

The face of the gathering port and the sill should be considered a consumable and designed accordingly.

Brian Wong Shui
03-29-2011, 11:48 PM
Hey Brian,

Could you elaborate on where to find this auto dialer and how/where to connect to the Watlow. I'd be interested in installing one here.

Thanks!
Josh,

The Power Series SCR has an alarm output. You should be able to connect to the dialer spec'd by Dennis. I haven't put one in as yet it is on the list of things to do.

Brian Wong Shui
03-29-2011, 11:57 PM
what Brian said about the stainless is true. I removed all the screws from mine and it stopped hanging. Pretty but dysfunctional.

I have never had an element fail unless I was involved in making it fail.
Pete,

Our last element failure occurred at the end of the transition from the shank to the hot zone. There was a sharp machining mark at the end of the transition. My hypothesis is that the sharp machining mark created a stress concentration which turned into a crack which fatigued during heat cycling. The crack propagated over time. The broken parts had that classic look of cyclic fatigue failure.

I don't think that it was caused by us winging the element.

Brian Wong Shui
03-30-2011, 12:22 AM
Brian, thanks so much for your help. I’ve been down there a couple times now and sure wish I would’ve bumped into you…

I’m getting close to tackling the door and s/s front. The expansion is something to ponder for sure…and the weight of the door too, maybe a counter weight on the backside of the bridge assembly.

The skin is 26 ga.coil stock from the local metal roofing supply house, probably should have gone with something heavier, (16ga.nmaybe??) anyway, fastened with a strap and 2- ¼-20x5/8” ea. I’m guessing the skin is in four sections for expansion, otherwise a sheet of stainless would have been a bunch quicker and less hassle…but then wrenching all the nuts down kept my middle granddaughter busy:).
Lawrence,

26GA is awfully thin. Our furnace skin is at least 11GA if not closer to .125" (I'm going off of memory here). Remember that the skin is holding the 3 castings on the inside together. You might think that they are heavy and won't move but they will.

Did you use the correct fiber against the castings? Inswool HP (or equivalent) won't cut it. The continuous operating temperature limit for HP is 2150F. Use something like a Inswool HTZ which has a continuous operation temperature limit of 2450F.

Pete VanderLaan
03-30-2011, 05:38 AM
I agree with Brian. That metal needs some pushback capacity to it or the castings will go out of alignment. I haven't yet faced the door issue but I will soon. I have one spare but it is such a heavy thing that I want to lighten it up and go with a bunch more fiber and a ceramic shell on the hot face.

Brian, how long was that element in service? I occasionally hear about failure's like that. I've just never had one. I just usually melt the connectors.

Brian Wong Shui
03-30-2011, 07:05 PM
I agree with Brian. That metal needs some pushback capacity to it or the castings will go out of alignment. I haven't yet faced the door issue but I will soon. I have one spare but it is such a heavy thing that I want to lighten it up and go with a bunch more fiber and a ceramic shell on the hot face.

Brian, how long was that element in service? I occasionally hear about failure's like that. I've just never had one. I just usually melt the connectors.
The element was in service about 3.5 years.

Pete VanderLaan
03-30-2011, 08:16 PM
That's not bad. I have heard it said that they have no known lifespan if run at 2400F but I don't believe it. I have broken most of mine through conventional raw stupidity well before they have gotten that old.

Lawrence Duckworth
03-30-2011, 09:46 PM
Did you use the correct fiber against the castings? Inswool HP (or equivalent) won't cut it. The continuous operating temperature limit for HP is 2150F.


Brian,

I used the Inswool HP.....

Brian Wong Shui
03-30-2011, 11:34 PM
Brian,

I used the Inswool HP.....
Lawrence, I'm not quite sure if the castings are made with an insulating castable. (I suspect not). The worse case is that it isn't. So for a 4" thick casting with 8" of HP in a vertical cylinder you are looking at the following. (I ran the numbers through HWR HEATransfer 2003)

Batch Cook
Hot Face: 2350F
Casting/Frax Interface: 2113F (Wall), 2199F (Roof)
Shell Temperature: 220F (Wall), 245F (Roof)
Ambient: 78F

Operating
Hot Face: 2050F
Casting/Frax Interface: 1875F (Wall) 1940F (Roof)
Shell Temperature: 188F (Wall); 206F (Roof)
Ambient: 78F

The best case is that it is an insulating castable with similar thermal properties to Kastolite 30 where you would be looking at the following temperatures:

Batch Cook
Hot Face: 2350F
Casting/Frax Interface: 1909F (Wall), 2048 (Roof)
Shell Temperature: 193F (Wall), 222F (Roof)
Ambient: 78F

Operating
Hot Face: 2050
Casting/Frax Interface: 1702F (Wall), 1817 (Roof)
Shell Temperature: 168F (Wall), 189F (Roof)
Ambient: 78F

HP has a max service temp of 2300F and a continuous use limit of 2150F. So you'll be above the continuous use limit under certain conditions but below the max service temp for all conditions. If you haven't sealed up the top yet, I would replace 2" of HP for 2" of HTZ for the frax against the crown.

Lawrence Duckworth
03-31-2011, 05:32 AM
Now that’s the kind of information I’m looking for!! the site required a registrationn though…maybe tonight.
I was looking at HP melt temperatures and Spruce Pine Cullet operating temps??.

Anyway I’ve had my breakfast and am off to the @#$%&* ART making process again.....

Pete VanderLaan
03-31-2011, 06:30 AM
When Brian uses the figure of 2350 for a batch temp, it's not inaccurate but it is high for what you need. When I did the performance tests for SP Cullet, I really didn't need to melt above 2195F. If I was melting SP87 as a batch, I would want 2350F for about a five hour burst. So, you have to ask yourself if you really ever plan on getting away from the cullet. In a 300# furnace, you might push it to 2250 max. I do all of my batch melts now at aboput 2225F. I just take a bit longer. The glass is better for it.

The reality for me is that ALL fiber gets stressed after a few years and the insulating value begins to collapse. If you look at the elements and the passage brick, the element is operating at 2800F at the bottom of the brick so the casting is really being exposed to that temperature for a lot greater time than you might think. The result has been deformation at the holes in the crown and sometimes cracking. That is probably a cost of doing business.

So, if you want real flexibility in the furnace, switch to the higher temp fiber. It's simply more coin. If you really think you are going to run the cullet, which is great stuff, I think you will be fine. Your furnace and crucible will love you for it and so will your electric bill. And if you change procedures down the road, you will be taking the furnace apart again .

Mine has deteriorating performance from when it was new two years back. I will open it up in May and we will see where the problem is. I know I have 1.5 inches of glass on the floor but that shouldn't do it. I have to assume the passage brick is compromised. Charlie Correll and I will be making passage brick for sale as well.

And the castings are not insulating castings. It's a proprietary in house refractory mix.

Lawrence Duckworth
04-04-2011, 08:55 PM
The door has 5 layers of superwool, and about 3 inches of castolite-30
The door assembly has an adjustable counter weight on the back side of the bridge allowing a very light touch and rolls ez on the two wheeled end truck.

.....that’s about it till the transformer and molly’s get here.

Anybody ever run across a complete electrical drawing for these molly furnaces?

Lawrence Duckworth
04-04-2011, 09:40 PM
One bag poured the door with maybe a handful left over.

Pete VanderLaan
04-05-2011, 06:59 AM
I will gt the elements shipped by the end of the week Lawrence. Steve says you should have more spare straps than I was going to send. I suggest 20 in that case. The schematic you are looking for is in the Ark of the Covenant. ( there really really really isn't one).

I also did have yet another bussblock issue with my furnace two days back , coming in to a bank of elements being down and had to replace one on a Sunday. Spares are good. It's the second time in two years doing the same one in the transformer. I had to cut the cables back about eight inches. Steve said I'm the only one to ever have transformer issues. My straps after two years look like they are brand new on the other hand.

You are doing a great job on that furnace.

Pete VanderLaan
04-05-2011, 07:00 AM
I will get the elements shipped by the end of the week Lawrence. Steve says you should have more spare straps than I was going to send. I suggest 20 in that case. The schematic you are looking for is in the Ark of the Covenant. ( there really really really isn't one).

I also did have yet another bussblock issue with my furnace two days back , coming in to a bank of elements being down and had to replace one on a Sunday. Spares are good. It's the second time in two years doing the same one in the transformer. I had to cut the cables back about eight inches. Steve said I'm the only one to ever have transformer issues. My straps after two years look like they are brand new on the other hand.

You are doing a great job on that furnace.

Dave Hilty
04-05-2011, 07:43 AM
[QUOTE=Pete VanderLaan;95734] "Steve said I'm the only one to ever have transformer issues. My straps after two years look like they are brand new on the other hand."

Not. I had the very same issue last year and sourced the aluminum blocks from a local electrical supply house.

John Riepma
04-05-2011, 08:29 AM
Lawrence I sent you a PM

Pete VanderLaan
04-05-2011, 09:06 AM
[QUOTE=Pete VanderLaan;95734] "Steve said I'm the only one to ever have transformer issues. My straps after two years look like they are brand new on the other hand."

Not. I had the very same issue last year and sourced the aluminum blocks from a local electrical supply house.
******************
Turns out they are made just down the road from me in Manchester. I don't know if I can buy them direct yet. My latest failure was with the fan always running. It was not nearly as severe. and I credit the fan.

Lawrence Duckworth
04-05-2011, 08:09 PM
Lawrence I sent you a PM

Please check your PM mail box again.
thanks

Charles Friedman
04-07-2011, 01:07 PM
One bag poured the door with maybe a handful left over.


This is when a vent could have been cast in place. Threw the door and up, in a pipe attached to the door trolley, “Door /Vent”

Lawrence Duckworth
04-12-2011, 04:47 PM
The mollys showed up today and I tested all the tubes for continuity before signing off on the UPS ticket….maybe they’re not really all that fragile after all :)

For what its worth, I hooked the furnace from the top to load and offload. I put the crown and the pot in after we got every thing over to the barn.

Pete VanderLaan
04-12-2011, 06:43 PM
.maybe they’re not really all that fragile after all :)

.
**************
Hah! I had six broken elements in my last shipment. You're supposed to say that the crate was really intelligently designed and prevented these gossamer wing thingys from shattering. ( Just wait...). I bet your UPS driver was just thrilled.

That shop in the background by the way is beautiful.

Lawrence Ruskin
04-12-2011, 07:48 PM
So what happens if one or more of those elements flunks a continuity test?

This is my first moly element shipment

Pete VanderLaan
04-12-2011, 08:05 PM
The very last thing I did today before placing your elements in their crate was to test their continuity. You do it through the end of the box where the round larger ends protrude if you poke about gently in the foam rubber. DON'T TAKE THEM OUT OF THE PACKING you will just be tempting the fates. Just probe with a continuity tester on the ends. There are two in each box. If they have continuity, leave them alone until you need them.

The crate has two wooden bulkheads at each end. It has bracing struts 12 inches down the box on the top and bottom. In the middle of the crate is an inner wooden box built out of chipboard and 1x2's. Most of it is hotglued in place like the other bracing but the top 12x12 is screwed. Remove the screws and take the elements out in their cardboard inners.

When you do get at the elements to use them, they have two wooden braces in the elements themselves to prevent compression or tension. You will have to remove the wood on the cold zone. Do it very carefully. On the hot zone, let it burn out. If you try to pull it, you'll break it.

These things are well packed. Yours are better packed than the ones for the other Lawrence since his were more locally shipped. It's coming via an expensive fed ex air delivery. It's the only way I do international. UPS is just unreliable.

Jordan Kube
04-13-2011, 12:16 AM
It's a good idea to keep them in the packaging but it's also a good idea to get a spare element packed into a brick to have on hand in case of inconvenient element failure. Put it in a padded box or something if you're worried about breaking it.

Lawrence Duckworth
04-13-2011, 07:41 AM
When drilling the holes in 2800fb do you guys over size the first 6 inches or so and size the last 3 ?

John Riepma
04-13-2011, 07:50 AM
Everyone will have a different opinion/method on this, but here's what I did. I drilled two holes the length of the brick on 2" centers with a 1/2" aircraft length drill on a boring mill. The bricks, while 2800's, are still punky enough to drill easily. The holes are slightly larger than the element shank (.040"-.060") and the element slips in easily. To prevent the chimney effect I cut pieces of high-temp fiber paper the size of the end of the brick and die-punches two holes in them slightly smaller than the element shank. I slipped these onto the top of the shanks above the brick and below the electrical connections where they would be cool enough to not degrade and tight enough to prevent the chimney draw from starting. We have not seen any problems at all after 3 years. Melting Spruce Pine batch, leaving the door cracked open slightly when charging to vent.

Pete VanderLaan
04-13-2011, 09:10 AM
The on center for a 6/12 element is 50mm. The on center for a 9/18 element is 60mm. The diameter of a 6/12 is 12mm or a touch under 1/2 inch. The diameter of the 9/18 is more like 3/4 inch.

When making a passage brick for a 9/18, you need to use a 3" thick 2800 IFB

Charlie and I will be making and selling passage bricks.

I don't really see the need for having an element/brick unit made up. It only takes about fifteen minutes to have it ready and when you have lost an element, you have pretty much lost the blowing session anyway. While one person is dismantling the old unit, the other can be readying the element, unless there is only one of you of course, a rarity it seems in hot shops.

Lawrence Duckworth
04-14-2011, 09:09 AM
No boring mill here. We'll see what happens with flipping them over and drilling from both ends

Lawrence Ruskin
04-14-2011, 04:10 PM
Got them, and they were very well packed.

All elements intact even though fed ex put a nice ding in the side of the box.

Thanks

....L

Lawrence Duckworth
04-14-2011, 05:30 PM
.............

John Riepma
04-14-2011, 05:51 PM
I see you made your own boring mill Lawrence. It takes a determined guy to lay the head all the way over on a Bridgeport. Actually it's easy to get it down, a large pain in the ass to get it back up. Did you use the table feed to drill them or didn't you have a long enough drill?

Lawrence Duckworth
04-14-2011, 08:21 PM
Both, all the spindle and the rest of the way with the table….power feed would’ve been nice. Everything fit good so it was worth the pain to set up.

Lawrence Duckworth
04-15-2011, 08:00 AM
How's that dip stuff working out for you guys when changing pots and mollys? Is the stuff just to keep the insulation in place and If so what woild you folks think of using something like a fire blanket instead.

Pete VanderLaan
04-15-2011, 09:06 AM
Jeez, we just used a 5/8th spade bit with an extension on a drill press.

Lawrence Duckworth
04-15-2011, 02:32 PM
Jeez, we just used a 5/8th spade bit with an extension on a drill press.
3.875 over! How do you live with yourself...

Pete VanderLaan
04-15-2011, 03:20 PM
Well, I've learned from bitter experience that the elements are really easy to break, your math not withstanding and that IFB expand when heated ...

Lawrence Duckworth
04-16-2011, 08:05 AM
:)..so the math is good until ya flip the switch.

Are there any recommended torque specs for the support clamps and strap connections to the mollys. I’m worried they can be over tightened and crush the tubes.

Pete VanderLaan
04-16-2011, 11:37 AM
I will look in the super Kanthal Handbook but I don't recall any. Make them good and snug if that helps. Once the thing has been turned on and run for two days, go back and tighten everything again. Use the Noalox but never on the elements.

Jordan Kube
04-16-2011, 02:53 PM
The elements aren't hollow Lawrence. Don't worry about crushing them.

As far as having an element made up I guess it's a personal choice. It's one less thing I have to deal with when an element goes out. It's what I recommend to people when I do installations. Why waste fifteen minutes doing it when you can do it in five? It's also a bad time to have to hunt around for stuff, clear some space, etc. You know you've got one ready to go. The blowing session doesn't have to be totally lost.

Rollin Karg
04-16-2011, 03:58 PM
I in the corner of having one ready to go and all the tools necessary in one place. Just in case it breaks at an inopportune time. Let's make it as easy as possible.

Lawrence Duckworth
04-17-2011, 08:15 PM
Ready for dip stuff and straps.

Jordan Kube
04-18-2011, 01:08 AM
Forgive me for asking but how do you plan on getting those elements out? They look like they're completely fraxed over. I wouldn't cover any metal parts.

Doug Sheridan
04-18-2011, 06:12 AM
I agree with Jordon. Did you cut the frax out from around the top of the brick? The element would get too hot covered like that.

Lawrence Duckworth
04-18-2011, 08:19 AM
There is one inch of insulation covering the ceramic/metal clamps. In the duckbill photos I have it appears to me to be covered in dip also... Its not a problem to cut the insulation out of the way if you guys think leaving them covered is a disadvantage.

Pete VanderLaan
04-18-2011, 09:31 AM
It is a problem. If you leave them covered they will fail very quickly - possibly in less than two weeks if you run hot at all. The clamps and the straps need to be completely exposed and air cooled if you want any life from them at all. What you are doing is great for my boat payment plan, but it offers no other benefit at all. Steve and Brent built air cooling manifold which help keep the straps cool. I would strongly suggest you do the same.

Don't ever try to cover up metal with insulation in a furnace. It usually takes just a few days for it to vaporize.

Tom Bloyd
04-18-2011, 11:40 AM
Rollin Karg posted a air cooled manifold awhile back. Look in the archives it looked pretty nice.

Lawrence Duckworth
04-18-2011, 12:58 PM
See what you guys think of this.

Tom, i'll look at tat tonight...thanks. (just now learning to type with my thumbs)

Pete VanderLaan
04-18-2011, 04:01 PM
That seems fine to me.

Tom Bloyd
04-18-2011, 07:36 PM
Lawrence, it"s under the thread "moly cooling". If I wasn't such a ludite I would link you to it,but.......

Lawrence Duckworth
04-18-2011, 08:57 PM
Lawrence, it"s under the thread "moly cooling". If I wasn't such a ludite I would link you to it,but.......

Thanks Tom, I found it. Good discussion and information, great photo of the strap connections too.



:) Transformer showed up today........could get ugly

Hugh Jenkins
04-19-2011, 05:03 AM
I have to agree, electric gets ugly really quickly!!!

Lawrence Duckworth
04-19-2011, 10:03 AM
Actually....electrical work is simple. It either works or it doesnt.

Brian Wong Shui
04-19-2011, 10:37 AM
There is one inch of insulation covering the ceramic/metal clamps. In the duckbill photos I have it appears to me to be covered in dip also... Its not a problem to cut the insulation out of the way if you guys think leaving them covered is a disadvantage.
Lawrence,

It isn't covered. The frax is right up to the edge of the brick. We use diplag to hold everything together. Cool the elements. Don't bore the bricks too tight. Things expand.

--Brian

--Brian

Lawrence Duckworth
04-19-2011, 11:58 AM
Thanks Brian
I reamed the brick with a half inch all thread rod to give some breathing room....might have been over kill

Pete VanderLaan
04-19-2011, 08:14 PM
You have to make sure that the clamp is tight though. I had an element slip through the clamp on my first furnace and it dropped down and touched the pot. That proved to be pretty exciting when I had been gathering all morning and saw the contact. That furnace did not have a door kill switch. Nothing happened. You just don't conduct below 50 volts.

Kenny Pieper
04-19-2011, 09:05 PM
So do you really need a door kill switch?



You have to make sure that the clamp is tight though. I had an element slip through the clamp on my first furnace and it dropped down and touched the pot. That proved to be pretty exciting when I had been gathering all morning and saw the contact. That furnace did not have a door kill switch. Nothing happened. You just don't conduct below 50 volts.

Julian Duerksen
04-19-2011, 09:21 PM
I am replacing the pot in my #300 molly and I am wondering what the best height is for the pot in relation with the rim to the sill. Previously the rim of the pot was about an inch bellow the sill. With the bricks I have I can go with two inches below the sill or with the lip of the pot almost level with the sill. Will it be harder on the pot the closer the rim is to the sill and the elements? How close can the elements be to the rim of the pot?

Pete VanderLaan
04-20-2011, 07:46 AM
I would never advocate for not having a kill switch ( what an appropriate name for it). I am simply telling you what happened to me when I made contact with the crucible while it in turn was touching the element live. There is such a thing as liability.

On my existing furnace, if you open the door far enough, it makes the kill switch roll over and the furnace goes live again, which I find useful in my continuing mistreatment of this great tool. I was over at Josh Biernbaums studio in Vermont yesterday and was amazed to see how clean his moly is. Mine on the other hand has crap all over it, a sticky door, and generally looks pretty trashed, sort of like the rest of my shop. Josh's is pristine.

As to the crucible, I don't like it getting closer than one inch from the lip. I do think that the torch heat up through the clean out will help enormously on any size pot.

I really have to clean up that glass I spilled in December...

Lawrence Duckworth
04-20-2011, 12:07 PM
Well I'm in a holding pattern till I get an electrical parts list and a plan of attack .

I ended up using a fire blanket to cap the insulation. Hope it works,, they have a melt temp of 1000

Oh yeah, I did put another quarter turn on the clamps:)

Lawrence Duckworth
04-22-2011, 08:18 AM
I am replacing the pot in my #300 molly and I am wondering what the best height is for the pot in relation with the rim to the sill. Previously the rim of the pot was about an inch bellow the sill. With the bricks I have I can go with two inches below the sill or with the lip of the pot almost level with the sill. Will it be harder on the pot the closer the rim is to the sill and the elements? How close can the elements be to the rim of the pot?
Based on the drawings I've seen there should be a brick or something to elevate the pot, but that would put mine too high so I spread a bit of sand under t o lift and help hold it from rocking . I'd say the pot is about an inch below the sill.

Charles Friedman
04-22-2011, 11:59 AM
Well I'm in a holding pattern till I get an electrical parts list and a plan of attack .

I ended up using a fire blanket to cap the insulation. Hope it works,, they have a melt temp of 1000

Oh yeah, I did put another quarter turn on the clamps:)


Lawrence, That top looks beautiful, outstanding job on the whole build!

Would using a torque wrench be of use at this point?

Lawrence Duckworth
04-22-2011, 09:22 PM
Thanks Charlie, but itz a bit to early to be celebrating the furnace….needs to get wired and melt some glass first.
So far though its been good and from building this thing its become purdy clear that a lot of thought was given to the design....so ya gotta kinda tip yer cap to the cat that did the castings, design and development work on these things.

Btw I tried finding torque specs on the clamps but couldn't.. so I decided to just tighten them till i heard the ceramics start to groan :)

Scott Novota
04-25-2011, 04:41 PM
Lawrence,

I find your whole journey very interesting. From the building to the equipment it has been fun to watch.

I am sure everyone here, even those that think you might have done it anouther way here or there, will be toasting your success come opening day.

Always looking forward to your next set of pictures. All the best and I hope everything fires off without a hitch.


Scott.
.

Lawrence Ruskin
04-25-2011, 05:10 PM
Where do you get that dip lag stuff?

A search of the archives turns up zilch.

Pete VanderLaan
04-25-2011, 05:53 PM
EG Bartell Seattle.

Lawrence Ruskin
04-25-2011, 08:10 PM
Thanks for the help...

Lawrence Duckworth
04-25-2011, 08:52 PM
Lawrence,

All the best and I hope everything fires off without a hitch.
.


thanks Scott,...me too:)

Lawrence Duckworth
04-27-2011, 08:37 PM
Question....

The castings I have, have just one hole for the thermocouple. All the pictures that I have show two, presumably the second is for a temperature limiting device. My question is is there a device that does both and that’s why there is only one opening?

Rollin Karg
04-28-2011, 05:27 AM
It's possible to have two thermocouples in one tube. Talk to these people and ask for Richard Roberts.http://www.precision-measurements.com/

Lawrence Duckworth
04-28-2011, 08:13 AM
Good idea. Thanks Rollin.
Looks to be about an inch dia. hole.

I'll give him a call

Pete VanderLaan
04-28-2011, 11:05 AM
Be prepared for serious sticker shock. Don't succumb to the temptation of getting a finer than 22 gauge platinum wire. It's just too damn delicate and you'll break it looking at it. . Get a spare thermocouple protection tube while you're at it and inspect once a year. They melt eventually. You can get by with type "s" on the thermocouple type. When you set up your controller make sure it's programmed for type "S". You get lots of choices.

Lawrence Duckworth
04-29-2011, 02:27 PM
$856.00 for type s or $27.50 for a type k.......They don't give those watlows away either.

(And to think I could have had a new set of clubs and a membership at a cheap course.)

Jordan Kube
04-29-2011, 05:04 PM
Wait till you figure out the cost of operation.

Larry Cazes
04-29-2011, 06:15 PM
$856.00 for type s or $27.50 for a type k.......They don't give those watlows away either.

(And to think I could have had a new set of clubs and a membership at a cheap course.)

Membership? That is truly a cheap course :)

Pete VanderLaan
04-30-2011, 06:25 AM
Well, the signature hole is being rebuilt right now so it's discounted. The nose on the clowns face needed some termite damage repair and the mouth needs sanding from all the misplaced putts.

Lawrence Duckworth
05-07-2011, 08:36 AM
Here's the transformer. About $1,800.00 dilivered but that might eventually work out because of the less expensive controls and power savings down the road.

Judd, from watlow will be here tuesday to help work up a control system and pricing....

Lawrence Ruskin
05-09-2011, 01:55 PM
So I'm still looking for a small amount of ''dip lag''

At Bartells you have to buy a whole box for $550.

Any more ideas?

Does dip lag have another name? Is it rewettable cloth or something like that