Kiln building questions

andrewh2011

andrewh2011

Joined
Jan 6, 2014
Messages
161
My first question is how should I go about adding a door switch? I can only find pre built door switches for their respective brand kilns

Second:For 120v at 16 amps (1920 watts) I should use high temp 12 gauge wire. correct?
(For power cord and element connections)

Would it be ok to use 12 gauge wire for the signal wire between PID and SSR?

Ive read 14 guage for this.
But It would just be cheaper for me to order an extra foot of 12 than to find 14 guage
 
High temp wire can handle more current than standard power cord type wire at the same gauge. For example, 16awg high temp wire is usually 29 amps, whereas your twist copper would be 12 amps or so. Check the specs though! For your case, i would expect 14awg high temp wire to be way more than adequate, but you have to see what the manufacturer says.

I cant help you on the door switch, i dont have a door on my (vertical) kiln, just a small hole.

My kiln is 120v and draws 10amps, and i use 16awg high wire rated for 29amps and the wires run cool. It is a tiny 4x4.5x6.5 kiln for folder parts.

This link may help you
http://www.worldwidewire.com/high-temp-wire/high-temp-wire-tggt.htm
 
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I’m not sure about handling more amperage or not. But the reasion its high temp is because it can get hot in the areas around the element connections. If you used normal wire the sheath would melt off.

The signal wire gauge does not matter as it’s just a small amount of volts. Your best bet is just to go to an auto parts store and buy some small gauge wire there.

The power cord is just a normal power cord. Does no good to go all fancy here as your only able to draw what your breaker allows.

A door switch is nothing more then a switch that is pressed when the door is closed. There is two ways to do it. You can have the door push the switch when it’s closed or push the switch when it’s open. If your door does not open down then DO NOT use a switchbthst is pushed when it open. If your door opens to the left or the right then just have the switch pushed when the door closes. You will want a “NO” switch. And this switch is inline with the SSR signal wire. So when you open the door the switch opens which disconnects the signal from the SSR and does not let it turn on.

By the way at 120v/16a I hope your oven is small. It’s going to take a LONG time to heat up. And your almost guaranteed to not hit the high temps needed for stainless.

If you have any more questions let me know.
 
Screw on a 2.2" ( approx) piece of metal so part of it is sticking out below the door bottom.
Mount a NO limit switch ( roller type would be best) so the plate depresses it when the door is closed.
Wire the switch in one of the DC lines to the SSR.

Open door, SSR shuts down = no power to the coils. Close door = power to the coils.

I like to hook up the connections between the SSR and the coils with high-temp wire with fiberglass insulation. 12 gauge will be fine for your oven.
 
I misread the OP. 14awg is smaller wire than 12awg, so if you can get 12awg cheaper then there is no reason not to use it.
 
My next oven build or elamemt replacement would probably use a duel element set up. That way I could control the power density so to speak. Run the elements in series for low power and parallel for high power. This way I can really kick the oven in the ass when warming up. Then once it hits temp it would switch to series and cut the wattage in half and just idle along at temp.
 
Thank you all for taking your time to answer my questions.

the kiln I'm trying to build will be 1.5' x .5' x .75' which comes out to .56 cubic feet. That would come out to 3428 watts/cubic foot
If insulated and sealed well would this be sufficient to reach SS heat treat temps?

Also i forgot to ask can someone point me in the right direction for the main power switch?
I've been looking but it keeps giving me normal house switches
 
This may be a stupid question, but when you guys say kiln, are you referring to a heat treating oven? If not, What do you guys use kilns for in knifemaking?
 
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andrewh2011 said:
My first question is how should I go about adding a door switch? I can only find pre built door switches for their respective brand kilns...
Click to expand...
Try find "Honeywell door switch" or look up directly to this link:
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=2ahUKEwiGhM-s2endAhWLaFAKHcxvCUIQFjAAegQICRAC&url=https://sensing.honeywell.com/honeywell-sensing-micro-switch-ac-basic-product-sheet-004981-1-en.pdf&usg=AOvVaw0zZdt2xhlvj8nsCebbx_PB

These switches are usually "Normally open" or "NO" but have "Normally closed" or "NC" connection too.
 
JTknives said:
My next oven build or elamemt replacement would probably use a duel element set up. That way I could control the power density so to speak. Run the elements in series for low power and parallel for high power. This way I can really kick the oven in the ass when warming up. Then once it hits temp it would switch to series and cut the wattage in half and just idle along at temp.
Click to expand...
If You have two same elements that are normally in parallel and switch them to series it will cut Your wattage to 1/4, not to half.
 
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