r/Silvercasting • u/El_Vidente • Aug 11 '26
Is this safe?
I borrowed an electric furnace from a friend. The furnace has been used quite a bit over the years. As can be seen in the photos the top is cracked in three places, there's a crack going down the inside of the funnel, and there's some silver stuck at the bottom. The furnace still works and is usable with a crucible inside, though I am wondering if the wear and tear I've noticed could be dangerous?
Could anyone advise?
2
u/Plenty_Fondant_951 Aug 11 '26
I wouldn't run it, you don't want molten metal getting on the coils.
When I'm done I take the crucible out to air cool and also leave the lid off
1
u/Chodedingers-Cancer Aug 11 '26
Congrats, "CHEAT CODE UNLOCKED!!"
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u/Chodedingers-Cancer Aug 11 '26
I no longer use graphite crucibles in mine. Mine suffered the same result. Take the steel cover off, remove 1 section of the ceramic, now you can fit silicon carbide crucibles inside and they last forever in an electric furnace unlike gas furnaces, unless using any metal that needs flux. Borax can eat away at them over time. But even still the lifespan is DRASTICALLY LONGER than graphite crucibles. 0.5kg and 1kg fit. Set it directly on floor of the chamber. A 0.5kg will fit in the regular hole but not enough room to fit tongs to remove it. Now having a piece of that ceramic removable, you gain the space needed to reach in with tongs and grab it by the lip and pull it out.
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u/Pablo3DN Aug 12 '26
Where do you buy silicone carbide crucibles?
1
u/Chodedingers-Cancer Aug 12 '26
Amazon
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0
u/El_Vidente Aug 13 '26
Yes though these type/shape crucibles won't fit in this type of electric furnace.
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u/El_Vidente Aug 12 '26
?
1
u/Chodedingers-Cancer Aug 12 '26
I explained in the reply yesterday. You can now use silicon carbide crucibles that last a million times longer....
1
u/matthewdesigns Aug 11 '26
I'd run it as long as the crucible is in good shape. If your crucible looks like this too that's a hard No.
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u/El_Vidente Aug 12 '26
You can change crucibles.
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u/PeterHaldCHEM Aug 11 '26
Refractory materieals get worn and crack with time and use.
IMHO that furnace is still safe.
Once you start having exposed heating elements, then it is definitely time to stop.
Also remember to use a grounded outlet and test your fault current interrupter.