Large Low Mass 22kw Resistive Electric Furnace

So far yes, but after only one heat cycle, it's too early to declare success, but I think chances are very good it will be successful.

On my smaller furnace, I had the same shape shelves, and although it takes many heat cycles, the coils would still grow (actually shrink) out of the grooves. I solved that by just applying dabs of moldable ceramic fiber to retain the coil. The MCF can be cut with a blade for removal.

I guess this happens because when the wire in the coils is 75ft long, and when they get hot, they grow (a lot!), compresses the coil, which takes a set because metal is so hot and malleable, and then proceeds to shrink as it cools. Why this seems to accumulate over cycles I'm not sure, other than the wire oxidizes as it ages. Although that oxide is what allows it to be long lived, it also makes the wire brittle, so there is high risk of breakage if you try to re-stretch oxidized wire.

The downside to using six separate coils is having to connect them all in parallel. The upside, if one fails you still have 5/6 power and only need to replace 1/6 $ as much. I use the same 14ga KA1 for both furnaces, just wound at different coil diameters and modestly different wire lengths, so I buy KA1 in bulk to have on hand if ever needed.

Best,
Kelly

 

Yes, hopefully within the next couple of days, weather dependent.

Best,
Kelly

 

I used the furnace today for the first time casting. I updated post #5. The update is at the bottom of the post starting under "11-24-2024 Update".

Best,
Kelly

 

I completed and inserted the build video at the bottom of Post #5 under 11-30-2024 Update.

Best,
Kelly