kiln elements -

kiln elements

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kiln elements

Postby jolly » Sun Dec 16, 2018 2:01 am

I bought a large used kiln but it heats up slowly. Can I shorten the lengths of all the elements to make it heat more quickly. The elements don't ever get red even at full power for an hour. Shorter elements would reduce the ohms which would increase the amps which should make it hotter. Does this make sense?
Originally, the kiln was on 480v 3 phase but I have 208v 3 phase and I have rewired it to compensate so it works but slowly.
There is more to life than increasing its speed.-Mahatma Gandhi

Aaron Solt
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Re: kiln elements

Postby Aaron Solt » Tue Feb 19, 2019 2:26 am

Been a while since I took Electricity and Magnetism.
If it used to have twice the voltage, then cutting the resistors in half will give you the same amps it used to have. Check the circuit breakers of the new house to see if they will handle the amps.

But thar only helps a bit. Power is proportional to voltage squared time current. You will still get a fourth the power, which is better than 1/8.

Maybe keep the cut halves in there, using them in series. But that would reduce the resistance further.
Better to add more full length elements. That gives room to lower the resistance, but adds more heat without exceeding the max amps.

I'm building my own kiln.
Please tell me how many ohms those elements are.
How are the elements attached to the walls?
What kind of transformer, if any, is used, down to how many volts?
Any pictures of the wire going through the wall?

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Re: kiln elements

Postby Marty » Tue Feb 19, 2019 10:42 am

Aaron- Do your own homework- get Henry Halem's book, Ed Schmidt's too. Go visit glass shops and offer to compensate anyone who will spend time with you.

jim simmons
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Re: kiln elements

Postby jim simmons » Wed Feb 20, 2019 1:47 pm

What Marty said. You do not want to monkey around with electricity unless you are really qualified.
It is REALLY dangerous stuff.
The other Jim

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Re: kiln elements

Postby jolly » Wed Feb 20, 2019 10:21 pm

To answer myself in case anyone cares: I will have to change the elements at some point so I will have the place I buy the elements from calculate what I need. It works but the kiln is only 8 inches deep so when I am bending glass on a form I am placing two layers of firebrick around the perimeter to give me the height. it only gets up to 1250 F with the extra cubic inches but I don't need that much for bending and slumping. It is tedious but once the kiln has paid me back the money it owes me, i will reconstruct it to my needs.
There is more to life than increasing its speed.-Mahatma Gandhi

Kevin Midgley
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Location: Tofino, British Columbia, Canada

Re: kiln elements

Postby Kevin Midgley » Wed Feb 20, 2019 11:55 pm

Jolly check your messages

Ed Cantarella
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Re: kiln elements

Postby Ed Cantarella » Wed Feb 27, 2019 3:27 pm

The Kiln Book by Frederick Olson has a decent section on electric kilns and calculating electric element lengths, etc. *Get the 3rd edition.
HER last words were, "I'm melting, melting . . . " Dissenting opinions generally welcome for comic relief or personal edification. Sometimes both.

Bert Weiss
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Re: kiln elements

Postby Bert Weiss » Sun Mar 03, 2019 2:25 am

Jolly, yes you can shorten elements to get them to glow hotter. They will draw more wattage and more amperage. I would consult with Duralite. They can make you new coils designed with an exact amperage and watts per cubic foot inside your kiln.

Meanwhile, I would make sure you don’t have a relay stuck open and not powering it’s elements. The other possibility is that your kiln was designed for 240 volts, but you only have 208. That would result in under powered elements.

Bert Weiss Art Glass*
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Re: kiln elements

Postby jolly » Sun Mar 03, 2019 3:29 am

Bert, the kiln was on 480 3 phase but now it is on 208 3 phase. It would have been easier if I had 240 v but I had to refigure the wiring and I shorten the kiln by unhooking one loop of elements and filled that end with fiber. Now I can still do a 3 foot x 8 foot piece. Once the kiln pays me back for the investment, I will put new elements in it and be able to do a 10 piece. It is only 8 inches deep (they just did tiles in it) so when I had to bend some fused pieces, I had to put two layers of brick to make it deeper. It only gets up to 1250 F but of course that is more than enough for bending. It's a pain to take the bricks off again when I need to get to fuse temps but I'll get by for the next few months until it has paid for itself. I used the Bartlett Genesis since I have 3 zones. It used to be 4 zones but I couldn't figure out how to operate the Partlow controllers. I have 200 amps of 3 phase in that shop for my kiln so I'm not lacking power once I replace the elements. Thanks for all the help you have given me over the years.
There is more to life than increasing its speed.-Mahatma Gandhi

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