mini wire melter design...

[Garner Britt]

Yet another thread about someone wanting to build a wire melter

Here's what I need:

I plan to roll up pre-fused panels and cane work of the pastorelli. I need clear glass for collars, punties, and small (2-3 gather bubbles). I can achieve the collars and punties out of my kiln and glory hole, but not bubbles.

I'm not planning on working big and can get to a 300 lb furnace if I need to. I also won't blow daily and don't want to have a furnace running 24/7. I think the typical week would find me working hot 2 days a week. If things change and I need to expand, this becomes a color furnace or special batch furnace or a footstool.

Here's what I plan:

EC 2928 pot, 38lb, flat bottom
hexagonal IFB hot face, backed with a bunch of fiber and insboard.
2 @ 2200 watt elements + one as a booster/spare
scr/ssr, controller, tc, etc
rolling door ala scott dunahee,and others
other construction details tbd based on all the info and designs on the board.
I have some of the materials I need and I think I can build this for $400.

Here's how I'd like to use it:

Turn on Late in the week, ramp up to working temp and melt S96 nuggets by Sat morn. Blow Saturday, charge sat afternoon/evening, Blow Sunday, empty pot (if anything is left) and shut down.

Here's what I want to know:

Once seasoned (dried out) how rapidly could I bring this little guy up to temp? and down?

Will 4400 watts be enough to hold temp? Interior volume is barely 1 cubic foot. As stated, I plan a 3rd booster/spare element that can be switched on and off. This element could be used for charging if needed

What's wrong with this plan?

Is there a better idea for the weekend warrior furnace. I'd consider an invested pot gas but I've never heard of one so small and I don't want to deal with a gas furnace

let it fly

garner

[Jim Vormelker]

Garner,

I was right where you are when I started design. The first help I got was a really strong piece of advice to not use that pot size, but go with a 75# unit.

The reason is that your actual current usage will be almost the same as you would use for the smaller pot, and you save by not having to charge as often. I started with a 40# Denver; the one I built is a 75#. I have never regretted it; my current usage per day went down.

I'm not as good at estimating/calculating wattage requirements - but remember that 'enough to do it' will put more strain on the elements than if you over engineer a little on that item.

Also, see the Mayne Island site [Mark Lauckner] for a video on a wire melter design that lots of people have used for a point of departure in design.

And, of course, the archives. This has come up before here, and a lot of people have signed in on the topic.

[Garner Britt]

Jim,

thanks for the advice. I originally planned for a 100 lb but wanted to scale down considering my needs at this point. I've scoured the archives and found tons of great information on the 100 lb wire melters that I will apply to any design I build.

I've seen the video and the results of the Mayne Island design. The big thing I'd change is from square to hexagonal.

Perhaps I will redesign for the 75lb pot and see what I come up with in terms of price. I really like the price of my 38lb design.

Maybe Richard Huntrods will chime in, He's the only person that I'm aware of on the board using the 38 lb pot.

garner

[Richard Huntrods]

I'll just say that the Lauckner design is a proven technology. I'd simply recommend building his furnace and go with that.

The way you want to blow is the way Mark blows (turn on, heat, blow, shut off). It works.

As for heating, the critical temp is between 900F and 1300F, where the crucible goes through the quarts inversion. Go slow there and you should be fine heating full bore elsewhere. You can fine tune the temps but I've just given the broad range.

Cheers,

-Richard

[Randy Kaltenbach]

Originally posted by Richard Huntrods
quarts inversion What would this be in litres? :p :D

[Richard Huntrods]

3.9782657


give or take a hectare.

-R

[Garner Britt]

actually, the 38lb pot would hold 8 quartz.

Thats 2 gallons of glass which is more than I thought...should be plenty for what I want to do.

Richard, what happened to your old tin roof website? I found the equipment section very usefull.

two questions for you

How many watts are you running in your 40lb-er?

Is your pot the flat bottom version? If so, how difficult is it to get the last of the glass out of it say, before a shut down?

garner

[Steve Stadelman]

Garner, give some consideration to a 5692 round bottom by E.C. (it is on pete's website. It holds 31lb theroretically and has a heavy wall so it will withstand repeated shutdowns easier) (unexpected crashes too) and be easy to clean out.

That is, if it's enough glass.

[Richard Huntrods]

Originally posted by Garner Britt
actually, the 38lb pot would hold 8 quartz.

Thats 2 gallons of glass which is more than I thought...should be plenty for what I want to do.

Richard, what happened to your old tin roof website? I found the equipment section very usefull.

two questions for you

How many watts are you running in your 40lb-er?

Is your pot the flat bottom version? If so, how difficult is it to get the last of the glass out of it say, before a shut down?

garner

http://tinshack.huntrods.com/

although this is the new tin shack. I'm in the process of re-posting the old site, but need to link it.

Can't recal the exact watts at the moment, but 4A @ 240V idling at 1850F.

I use the square bottom pot, and don't really bother scraping it clean before a shutdown - about 1" left in the bottom. It has never given me a problem.

-R

[Jim Vormelker]

Originally posted by Garner Britt
The big thing I'd change is from square to hexagonal.
garner

I went father than a hexagon, but I'm not sure you have to. I got so round that there is not much space for the thermocouple and it tends to read element heat more than crucible temp.

Main point is that when you use the square, you are heating a lot of air in the corners, which is not necessarily the best conductor you could use. Getting closer to the outside surface of the crucible is a good thing.

[Pete VanderLaan]

The 2928 is a very thin walled pot ( 1/2 inch) and I think it will give you shit if you turn in on and off. The 5718 is twice the thickness and holds the same amount of glass and is a little workhorse. As steve points out, the 5692 is easier to clean, is the same thickness and diameter but holds slightly less given the round interior bottom. I have all of those pots in stock in the barn. I think Jim Vormelker is right about the 75 lbs though.

[Mark Wilson]

the 5692 is a great crucible. i have been using it for many years. i would not go to a bigger crucible unless you need the extra glass. a bigger crucible will take more time an energy to heat up. i fill my crucible with washed 4c cullet at room temperature, and start ramping up on wednesday evening right before bed time. it is at temperature (2150F) in less than 24 hours and by the time i blow on friday morning, it has been at temperature for 12 to 18 hours. and that is with 3200 watts.

[Richard Huntrods]

Originally posted by Jim Vormelker
I went father than a hexagon, but I'm not sure you have to. I got so round that there is not much space for the thermocouple and it tends to read element heat more than crucible temp.

Main point is that when you use the square, you are heating a lot of air in the corners, which is not necessarily the best conductor you could use. Getting closer to the outside surface of the crucible is a good thing.

Jim, in the Lauckner 40lb design, the hot chamber is 1 cu. ft. The amount of space in the corners is really so small at this size that you are not heating much dead space at all.

For 75lb and up, I do agree that hexagonal is probably better.

Cheers,

-R

[Garner Britt]

I hadn't noticed how thin the walls of the 2928 are. I agree not likely to handle being turned on and off. I had picked that one simply by outside diameter which would fit perfectly inside a hexagon of ifb on edge. I had planned 3/4" at the narrowest distance between the crucible and IFB.

How close is too close?

It seems that even with the lower capacity the 5692 may hold as much usable glass as the 5718. I know 31 lbs is not much glass but I think for what I'm wanting furnace glass for, it would serve me fine for now.

And to my logic, the more glass that can be removed before shutdown, the happier the pot would be over time.

I'll play with the 11" diameter in my 3d model and see how things will fit, maybe a sevenagon(?) which actually would give me a bit more room for elements.

thanks for the advice

garner

[Scott Dunahee]

3/4" is way too close to your walls for your pot. I'd go with 2" as that has worked well for me in my now 108# (formerly 75#) wire melter but that's just my opinion. I do think you'll get to blow out of a new pot more often if you go with such a tight fit though...

Also, carve your element channels deep when you get to that step. It really helps with keeping the coils in the grooves.

BSD

[Mark Wilson]

you can just buy an aim kiln which is 14 inches diameter and 11 inchs deep that will fit the 31 pound crucible nicely. it only costs $895 ready to use with a controller. then someday, when you want a bigger crucible, you can still use this one as a color pot, so it won't be money wasted.

http://aimkilns.com/html/1411_1713.html


i have been using a similar evenheat kiln for nearly 7 years with good results and low operational costs. i built a pneumatic lid lifter so all i have to do is step on a foot switch and the lid lifts out of the way. that way i have both hands free for gathering.

[Garner Britt]

Mark, I have about half of the materials I need left over from other projects and I love to build equipment,( I'm sick that way) I did at one point think about buying an aim and adding extra insulation. Instead, I'll just build it from scratch (at some point)

I redrew the plan in Sketchup and determined that an 11" pot will sit in a 7 sided polygon (what are those called?) with 1 5/8" clearance. Seems ok to me. Could get a bit more by not mitering the bricks all the way to the outside corner...

I had a little shakedown session last night and rolled up two pieces in my clamshell and gloryhole. I used a total of 2 lbs of clear glass for collars and punties. I think 31 lbs will be plenty for now. Do a few smaller blown pieces of the top of the pot and use the bottom of the pot for roll up collars/punties.

I was trying to work solo and figured out I really nee to practice the solo punty. Neither piece made it to the box.....:headbang:

garner

[Dave Bross]

Definitely two inches between the pot and the wall.

That's from cruel experience.

[Pete VanderLaan]

Originally posted by Garner Britt
I hadn't noticed how thin the walls of the 2928 are.
thanks for the advice

garner
********
Originally, all of the pots at EC were flat bottom pots. I inherited the 2928 as an existing pot when I began to retool the pots for EC. I think it's OK in a furnace that isn't turned on and off frequently but it is really a ladle liner for pouring stainless steel and in that industry, it is used for one day and discarded and is not ideal for glass working. I made the mold for two other pots in the range, first the 5718 which increased the wall thickness on the 2928 to one inch. It costs more since there is more material in the pot. It significantly outperforms the 2928 and is a favorite workhorse in my own melts.

The 5692 was a variation I did on the 5718, making the interoir a round bottom with the same diameter as the 5718. It holds less glass but is much easier to clean. I actually prefer the 5718 in my own shop but they are both nice.

When the pots are purchased from me, you are supporting the person who paid to have all these molds made and also represents the company to the glass community. The folks at EC are nice but do not know a thing about glass or applications beyond stainless melts. You can buy them direct from EC and I will get nothing for my efforts you will not save a dime and the service will usually be a lot slower.

I appreciate the business.

[Garner Britt]

Originally posted by Dave Bross
Definitely two inches between the pot and the wall.

That's from cruel experience.

Oh, do tell...


Pete,
I will certainly buy what ever crucible I need from you. Thanks for the explanation of the evolution of the EC glass crucibles. What is your expert opinion on the pot to elements space required?

[Ken Peterson]

I started thinking about my little furnace with a 40 lb pot, it then turned into a 75 lb pot, and I ended up building it as a 100lb pot. The 100 lb pot is not tat much bigger than the 75 lb pot. I'm very happy I did it. The thing works great so far. Thank you stadelman team for yo9ur help.

I work with murrini and make cups a lot recently which sounds like how this thread first started. I've been dreaming about a little furnace that has two of pete's smallest (15lb?) pots side by side in a rectangular chamber. If you could fit enough elements into the two long sides of the furnace the thing would be the easiest thing to build ever. And this way you could melt really dense colors without ruining a big pot. The pot changes would be really easy.

[Pete VanderLaan]

There are two different mixes for this pot type. The first is a coarse grained tabular alumina and it is very thermal shock resistant. It would put up with only 3/4 inch clearance but it is only used in thicker walled pots. Pots such as the 2928, and the one that Lauckner uses are both FMS or fine material size and are more shocky based on the finer structure. They would really need two inches and a somewhat more cautious firing approach. They are still quite resistant but not as good as the coarse pots.

EC pots always look like shit in the coarse mix but it really serves you well to have that coarse material. It will just not every look very good but will work really resist thermal issues.

and no, the smaller pots can't be made with the coarse material, they are too thin.

[Richard Huntrods]

I used the EC crucible:

Hycor #100 Crucible CP-4314

in my 40lb Lauckner styled furnace.

It's still in almost perfect shape after four years.

I check it every time I'm down for maintenance, but it's very thick walled and has held up remarkably well.

The only wear it shows is a small ring depression at the 2/3 mark where I left it sitting for 4 months at 1850. Won't make that mistake again. ;-)

That said, I ALWAYS raise the temp using a 100F/hr ramp, except between 900F and 1300F, where I go 25F/hr.

Even going from idle (1850) to blowing (2100), I use 100F/hr.

I used to worry about getting all the glass out before I turn down the furnace (either off or to 1300 for short term holding). However, in 4 years I've found that 1-2 inches of glass in the bottom really doesn't give any problem.

The Lauckner design allows about 3/4 inch between furnace refractory and crucible, with the elements located in grooves in the brick. There's a bit more space at the corners, but not much over an inch.

-R

[Pete VanderLaan]

well, I love success stories since it makes the product look good. I still maintain the caution about their care and feeding. I had a guy recently who fired a large pot for sixty cycles and he was complaining that the pot looked like it was developing a line on the interior wall but was not leaking. He wanted a total replacement for no cost which I said was not going to happen. I even offered him a discount on his next pot but he was pissed and went to LaClede. Sometimes I think the expectations for crucibles and the manufacturers responsibilities are unrealistic given the utter lack of control over their usage.

I talk to people doing stupid things to pots every day who seem to get away with murder. Richard is doing it right but I would still clean it better.

[Richard Huntrods]

Originally posted by Pete VanderLaan
...

I talk to people doing stupid things to pots every day who seem to get away with murder. Richard is doing it right but I would still clean it better.
Thanks, Pete.

Cleaning out has been a process of diminishing returns, and I usually find that the last inch is the sticky point. Besides, this *IS* the problem with the square bottom pot, and I accepted that when I bought it.

I'm going to make a small ladle soon, and try some casting to pull that last bit out.

-R