Furnace build regarding moly's largely

[Pete VanderLaan]

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]

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]

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]

This is how hot you need it!
Go with the flow! 2300....

That's quite a flow!

[Mark Rosenbaum]

Originally Posted by Thomas Chapman

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]

wow....and ouch all at once.

[Pete VanderLaan]

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]

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]

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]

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]

Originally Posted by Brian Wong Shui

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]

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]

Originally Posted by Josh Bernbaum

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]

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]

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]

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]

Originally Posted by Rollin Karg

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]

Originally Posted by Josh Bernbaum

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]

Originally Posted by Pete VanderLaan

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]

Originally Posted by Lawrence Duckworth

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]

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]

Originally Posted by Pete VanderLaan

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]

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]

Originally Posted by Brian Wong Shui

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.....