DIY Heat Treat Oven Build

[Tarkus]

Stacy .. that s very true. The angle I am chasing though is his comment that kind of whatever he does, the elements come on full bore when he drops below setpoint. With the effect of I and D minimized, he *should* be able to set P so that he has a really, really wide proportional band ..
And when he drops below setpoint by a few degrees, the elements are just barely nudged on...

i *think* the P parameter for the inkbird is a raw temperature band (units of F) ... But the manual is totally vague on that point...

Sorry if I didn't make this clear! When P=<8, the elements are nudged on and off anywhere from 8% to 56% power and it will hold temp for a couple seconds, but then fall and the power maxes out, overshooting temp by 15-30 degrees.

 

[Cushing H.]

Again ... do you have the ssr,s wired to the #6 and 8 terminals on the PID? After looking back at your description of behavior that It really kind of sounds like the controller is running in relay mode...

 

[Tarkus]

Again ... do you have the ssr,s wired to the #6 and 8 terminals on the PID? After looking back at your description of behavior that It really kind of sounds like the controller is running in relay mode...

Yes sir! Negative to 6 and positive to 8. Should I try switching the polarity???

 

[Cushing H.]

Tarkus- are you able to call me? 6128128764 (USA)

 

[Tarkus]

Tarkus- are you able to call me? 6128128764 (USA)

Can I text you? I'm in Canada and don't have long distance calling

 

[Cushing H.]

Ok ... go ahead

 

[Stacy E. Apelt - Bladesmith]

Stacy .. that s very true. The angle I am chasing though is his comment that kind of whatever he does, the elements come on full bore when he drops below setpoint. With the effect of I and D minimized, he *should* be able to set P so that he has a really, really wide proportional band ..
And when he drops below setpoint by a few degrees, the elements are just barely nudged on...

i *think* the P parameter for the inkbird is a raw temperature band (units of F) ... But the manual is totally vague on that point...

??? the elements come on at full power whenever the SSR is energized. The proportional is in timing, not power.

 

[Cushing H.]

??? the elements come on at full power whenever the SSR is energized. The proportional is in timing, not power.

Yeah - but the controller should be doing pulse width modulation. On for a fraction of a second, off for many fractions of a second, yielding some percentage of max output averaged over time

 

[Tarkus]

I've gone through every setting in this controller and changed things from minimum values all the way up to maximum values, tried different input and output settings, I let things sit for 5 minutes and for 30 minutes, even tried changing alarm settings. No noticeable change in temperature fluctuation occured at any point. This controller is absolutely defective.

Just a warning to anyone with an Inkbird ITC-106VH: if you run into issues, it may be faulty equipment.

 

[Stacy E. Apelt - Bladesmith]

Yeah - but the controller should be doing pulse width modulation. On for a fraction of a second, off for many fractions of a second, yielding some percentage of max output averaged over time

Not to argue the point any more than needed, but that is like trying to dim a room by switching a light on and off real fast. It really doesn't do it very well.
PWM works OK in some devices, but I feel it is best done by the original program of the PID on an oven.

I find that letting a PID auto-tune for a while will teach it how long to stay on to rise the needed amount. I think most folks try to change all the settings too soon and get the performance more messed up that solved. My advice to most folks who email me about PID problems is to reset the factory settings and let the auto-tune figure it out. I also tell them to let the oven run a couple of hours the first few times so it has time to figure things out.

 

[Tarkus]

Follow up!
I switched the controller to a NAIS KT4 and it responds perfectly and quickly to every setting change. I have it dialed in to hold temp within a degree Fahrenheit at just about every heat and recover from door open in under 3 minutes.

I've been told that this is a very high end controller but I got it second hand so I don't know. However, the very fact that it markedly responds to setting changes reinforces my earlier statement: I can't speak for all of them, but the Inkbird ITC 106VH I had was defective.

Edit: I was able to dial in the settings under the teachings of Mr. Cushing.

 

[Tarkus]

You don't want a sleeved TC. You want a 8 to 10 gauge bare TC and a TC block on the outside to hold it.. here is what you want. Remove the insulators as needed and shorten the leads to make the tip stick in about 2":
View attachment 1065980

Where did you get this? My sleeved TC recently died and I want something proper this time.

 

[Stacy E. Apelt - Bladesmith]

A sheath is used to protect the TC from hot corrosive gases in a forge.

In a HT oven you normally have an exposed junction (the end of the TC) and ceramic insulators separating the two leads. A sheath over the TC would slow down the response time and cause overshooting swings.

 

[Tarkus]

A sheath is used to protect the TC from hot corrosive gases in a forge.

In a HT oven you normally have an exposed junction (the end of the TC) and ceramic insulators separating the two leads. A sheath over the TC would slow down the response time and cause overshooting swings.

The tiny little thermocouple was fine until the wires broke from heat stress. Where did you get the bare TC in the picture you posted?

 

[Stacy E. Apelt - Bladesmith]

Ebay, Amazon, Auberins, Omega ... everyone has them.

Here is one of many found by searching "Type K thermocouple high temperature "
https://www.ebay.com/itm/High-Tempe...=383582122337a944c14f8b27462eb7697f0838fdc92a

This is the Ebay page on that search:
https://www.ebay.com/sch/i.html?_fr...=0&_odkw=type+k+thermocouple+high+temperature

 

[Tarkus]

Ebay, Amazon, Auberins, Omega ... everyone has them.

Here is one of many found by searching "Type K thermocouple high temperature "
https://www.ebay.com/itm/High-Temperature-k-type-Thermocouple-Sensor-Ceramic-Kiln-Furnace-2372F-1300C-2-5/383582122337?_trkparms=ispr=1&hash=item594f46b161:g:6r0AAOSwCgRe3zsM&enc=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&checksum=383582122337a944c14f8b27462eb7697f0838fdc92a

This is the Ebay page on that search:
https://www.ebay.com/sch/i.html?_fr...=0&_odkw=type+k+thermocouple+high+temperature

I see, thank you! I wanted to make sure I wasn't throwing away my money.

 

[ren01228]

Planning out my DIY HT oven. Going to be about 0.16 cubic feet running on 120v (not ideal, I know, but it's the only real option for me right now). Anyways based on my math I'd be around 9600 watts/cu ft, whereas the average according to DC knives is around 5400 for commercial ovens with the highest at 7200. My element surface load falls under the recommended, I still have some other numbers I want to play around with but I guess what I'm asking is can you make your oven too powerful? Would I be better off lowering the Watts from 1500 down to something lower? Thanks

Here are some helpful articles I've been using in addition to the awesome threads on here

https://knifedogs.com/threads/heat-...ign-and-calculate-the-heating-elements.21072/

https://dcknives.blogspot.com/p/electric-forge.html

 

[JacksonRobinson]

Incredible resource! I just found this via Red Beard Ops's video/link. Thank you!

I'm working out the details of my own DIY Heat Treat oven and would love some second eyes of my calculations before building and plunging stuff in.

These are my calculation based on the Ohms Calculator Spreadsheet you provided.

Voltage - 240
Desired - W 3500
Number of Elements - 2
Amperers - 14.583
Ohms - 32.914
Coil Diameter - 0.375

Length of wire 16awg
Coil length - 6'
Stretched Coil length - 12'

I know this may be very straightforward, but I would rather ask than burn something down.

1. When I input the number of elements being 2, that refers to me using two different heating elements running in parallel, correct?
2. If it says my "stretched coil length" should be 12', does that mean I need to split the 12' in half and have two elements that are 6' long, each with 16.457ohms (32.914/2)? OR Do I need two coils that are both 12' long with ohms of 32.914 each?

I hope that makes sense. I appreciate your help.

 

[Brad Martin]

1. When I input the number of elements being 2, that refers to me using two different heating elements running in parallel, correct?

Red Beard in his video does mention that his oven is wired in series.

 

[JacksonRobinson]

Correct, I'm asking more for myself. When I choose to use 2 elements I need to run them in parallel, correct? Red Beard uses two runs but because they are wired in series it acts as one element.