Upgrading a kiln for heat treating

Josh Rider

Josh Rider

Stuff maker
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Sep 2, 2014
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I recently came across a front opening jewelry kiln that I couldn't pass up.
It is in great shape and runs off of 110 with an analog temp gauge.
Is it possible or necessary to upgrade to 220
and install a PID so i can heat treat O1 and cpm 154?
Thanks for any advice.
 
Upgrade to 220, maybe, maybe not. Add a PID, you bet. It's been several years since I did the same thing, but IIRC, I bought my stuff from Auberins. There might be instructions in the stickies?
 
S.Alexander said:
You don't necessarily need 220. My evenheat is 110 and it works just fine.
Click to expand...

I have a 110v 8x8 front loading cup kiln that I added a PID to. It heats up MUCH faster than my 220v full sized oven. You're dealing with a small space... 110 will likely be fine.
 
Think of it this way- all that the PID is, is a switch that turns power to the heating elements on and off according to information from the thermocouple.
If I were doing it (I am, actually- top loading kiln that I'll most likely use as a tempering oven) I'd throw away the existing thermocouple and get a set from Auber, PID and TC. Pretty cheap, and the support has been great.
 
Thanks for all the replies, so I'll keep it 110.
Rip out the old tc.

elementfe said:
Think of it this way- all that the PID is, is a switch that turns power to the heating elements on and off according to information from the thermocouple.
If I were doing it (I am, actually- top loading kiln that I'll most likely use as a tempering oven) I'd throw away the existing thermocouple and get a set from Auber, PID and TC. Pretty cheap, and the support has been great.
Click to expand...

Is this the PID recommended with the ramp/soak
http://www.auberins.com/index.php?main_page=product_info&cPath=1&products_id=4
 
greenjebadiah said:
Thanks for all the replies, so I'll keep it 110.
Rip out the old tc.



Is this the PID recommended with the ramp/soak
http://www.auberins.com/index.php?main_page=product_info&cPath=1&products_id=4
Click to expand...

Thats the one you want....you should also look at a case/box to support it...here is a "Tip" put two switches on the box to the PID one for Power so you can turn it on/off so you don't have to fool with unplugging the furnace and the other switch to turn the Heating Coil on and off you don't want to touch that coil with the blade by accident that is BAD....I also added two Lights one Green for the power and one Red for the Heating coil so I can tell at a glance if the system is on and if the coil is on or off. Not sure if you mentioned it but is there an "Interrupt" switch to cut power to coil when the door is opened.
 
That's the unit I have, it took me some study to get my brain around just how it works (it's not a set-and-forget thermostat), but it's actually really simple and has a lot of features.
Each step is a ramp from "here" to "there", temp-wise, if that makes sense- but if it's "ramping" from step 2 1500 deg to step 3 1500 deg, then it acts like a thermostat, holding one temperature...but you have the option to ramp to a lower temp to equalize and so forth, or set several programs.
Most of the info you actually use is in the part 2 supplement of the manual, and there are some great example programs included.
 


This is the kiln. It has a thin layer of fire brick? With slots where the coils are for protection probably so I don't electrocute myself.
Not sure about an interrupt switch, I'll try to download a manual.
 
That fire brick is thicker than you think it's at least as wide as the top and sides of the structure. Most Furnace/Kilns have the coils inset like you see here in the photo I would bet that there is an interrupt switch on the far side where the chain is attached or on the bottom of the door hinge so when the door is open it opens the circuit. It does have a Red Power light not sure if that is connected to the coil and the light goes off when the door is open or if its just an ON light letting you know the unit has power. I've seen the aftermath of what can happen when a piece of metal gets away and hits the coils not a pretty sight killed the coils killed the control unit of a VERY expensive unit here where I work (like $80K and lucky the operator just got some minor injuries). It's hard to tell from the photo if the controller would fit that Back Splash where the existing controls are?
 
Jewelry kilns aren't made to work much above 1500F. They are fine for carbon steel HT, but few will hold at 1900F...and can take a very long time getting there. The climb from 1450F to 1900F could be an hour or more. Also, coil like will be greatly shortened if run at those temps. Adding a PID is super simple. the stickys have all the info.

Would it be possible to completely rebuild it for 220VAC...perhaps. It would be almost like making a kiln from scratch, and I would not suggest trying it.
 
Stacy E. Apelt - Bladesmith said:
Jewelry kilns aren't made to work much above 1500F. They are fine for carbon steel HT, but few will hold at 1900F...and can take a very long time getting there. The climb from 1450F to 1900F could be an hour or more. Also, coil like will be greatly shortened if run at those temps. Adding a PID is super simple. the stickys have all the info.

Would it be possible to completely rebuild it for 220VAC...perhaps. It would be almost like making a kiln from scratch, and I would not suggest trying it.
Click to expand...

It does take a while to get up to temp. I was wondering if it would be more cost effective to wire it for 220, but sounds like it's unnecessary.
I didn't have any plans of even doing my own heat treat for the more complex steels. I've been using Aldo's 1084 exclusively
and using a propane firebrick forge. I bought some 01 and cpm154 but haven't used them for anything yet.
What is the major difference between a jewelry kiln and a knife kiln? Is it how it's insulated?
 
Stacy, you were correct on the time it takes to get this thing to temp.
I could have probably hardened 4-5 blades in my two brick propane forge in that time.
I found the sticky on upgrading to a PID and definitely only doing carbon blades in this kiln if I even keep it.

For anyone that knows, will a PID actually heat this kiln up faster?
Another thing is how fast the temp dropped with the door open for a few seconds...then more waiting...:yawn:
 
A PID doesn't change the rate of the oven, it just controls it accurately.

The old proportional control dial on the kiln just controlled the ON/OFF time. At 1 it was on for 1 second and off for 9. At 5 it was on for 5 and off for 5. At 9 it was on for 9 seconds and off for 1...and at HI it powers the coils all the time. When installing a PID, you set the control on HI and plug the kiln into a SSR controlled socket (or wore it directly to the SSR). The PID turns the SSR on and off as needed to regulate the temperature.

Because a jewelers kiln isn't intended to be opened until it is done firing enamel or doing a burnout, and the chamber is usually large, the heat dumps on opening. It takes as much as 10-15 minutes to rebound.
 
Stacy E. Apelt - Bladesmith said:
A PID doesn't change the rate of the oven, it just controls it accurately.

The old proportional control dial on the kiln just controlled the ON/OFF time. At 1 it was on for 1 second and off for 9. At 5 it was on for 5 and off for 5. At 9 it was on for 9 seconds and off for 1...and at HI it powers the coils all the time. When installing a PID, you set the control on HI and plug the kiln into a SSR controlled socket (or wore it directly to the SSR). The PID turns the SSR on and off as needed to regulate the temperature.

Because a jewelers kiln isn't intended to be opened until it is done firing enamel or doing a burnout, and the chamber is usually large, the heat dumps on opening. It takes as much as 10-15 minutes to rebound.
Click to expand...

Ahso.
Thanks Stacy, you're the man.
 
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