DIY Heat Treat Oven Build

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Why is a sleeved TC a bad thing? My oven has a longer TC that is shielded, and has never caused me issues. The TC stops right above the knife rack inside the chamber.
 
scott kozub said:
First off, I give all credit to Dan Comeau Custom knives. He has an incredible site with all kinds of builds that are extremely detailed. For this build he even has an excel sheet to calculate you coil design so thanks to Dan for this. I'm a Civil Engineer, not electrical so if I made a mistake anywhere, please feel free to correct me.
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I know you based it off of Dan C's oven, but do you have a wiring schematic? I saw Dan's, but I really would like to see one from someone who has built one exactly the way I am building mine. 240v, PID, dual SSR, Door interrupt (moos), 2 fuses, power switch and the dual indicator lights! I couldn't believe it when I found your post, it's literally what I was looking for.

Also, do you have a complete parts list? Doesn't have to have Amazon links. I just want to make sure to get the right fuse parts and lights.
 
Bumping on an old thread but I'm building the same oven as yours and I got the inkbird and same thermocouple and I have a question about the thermocouple, where you installed yours? That thing is big and if I install the probe on top of the oven then the blades would touch that.
Thanks
Luis

Edit: Just saw the video and I see that's installed on top towards the back.

scott kozub said:
scott kozub said:
Controller and box.

For my controller I used an Inkbird PID from Amazon. $50 and it cam with 1 SSR.

https://www.amazon.ca/gp/product/B01LQ8TPA0/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

I ordered a second SSR as well $13.99. This is important because I used 240v, If I didn't, I wouldn't be able to turn the elements off when the door was open which could lead to a potential shorting of the elements when putting in a knife. If you do a 120v design, you won’t need the second ssr. The SSR link is here:

https://www.amazon.ca/gp/product/B06WD65K6K/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

I also needed a new thermocouple as the one that came with the inkbird only goes to 400 degrees. I bought this $15.30

https://www.amazon.ca/gp/product/B00XJB4DYQ/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1.


I hope this helps anybody looking to make one of these. I'll to answer any questions you have. I've learned so much on this forum, that I hope to give back a little.
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Finished the oven and cost me less than $300, used 25 soft bricks and cost me $120, the kandal wire cost me $30, then the pid i got from amazon was around $30, the only metal I had to buy was the angle bar which cost me around $5 per 4 feet, I never though was that cheap because i would had built one long time ago. Still learning how to use the pid and I would like this pid had the timer option (got the inkbird itc-106vh).
 
Does your pid controller have an auto tune feature. It might be labeled AE in the pid menu.
 
JTknives said:
Does your pid controller have an auto tune feature. It might be labeled AE in the pid menu.
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This pid has what they call "self-tune" which I never used, the only thing I do is setting the temperature I want then when the temp reaches the target I just check the time on my phone/watch and turn off soon I pull the blade out. I would like something that would keep the temp target for the time I wanted before turning off in case I went inside home getting a beer and got busy talking with my son and forget the oven :)
 
Luis Barros said:
Finished the oven and cost me less than $300, used 25 soft bricks and cost me $120, the kandal wire cost me $30, then the pid i got from amazon was around $30, the only metal I had to buy was the angle bar which cost me around $5 per 4 feet, I never though was that cheap because i would had built one long time ago. Still learning how to use the pid and I would like this pid had the timer option (got the inkbird itc-106vh).
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L Luis Barros Congrats on the oven build. I'm going to start on mine in a couple weeks. Do you mind uploading some pics?
 
Luis Barros said:
Finished the oven and cost me less than $300, used 25 soft bricks and cost me $120, the kandal wire cost me $30, then the pid i got from amazon was around $30, the only metal I had to buy was the angle bar which cost me around $5 per 4 feet, I never though was that cheap because i would had built one long time ago. Still learning how to use the pid and I would like this pid had the timer option (got the inkbird itc-106vh).
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It is that price difference that got me interested in doing a build. Glad this worked out well for you
 
Auto tune or “self tune” as yours says is a valuable feature. It adjusts the pids settings so it preforms optimally at temp. It allows it to account fir cycle time and other factors. I would look through your manual and make sure that’s what the self tune is. But if you built the oven and that pid was never tuned to it I would highly recommend doing it. When I do it I get the oven up to the temp I use the most and then start auto tune. It will then shoot past the set temp and then let it drop and repeat. It’s calculating how fast the oven responds to the coils and then saving that to memory. This allows it to know when to stop so it does not overshoot your set temp and helps to keep a nice tight temp swing.
 
Oh and let’s see pictures of your oven
 
JTknives said:
Auto tune or “self tune” as yours says is a valuable feature. It adjusts the pids settings so it preforms optimally at temp. It allows it to account fir cycle time and other factors. I would look through your manual and make sure that’s what the self tune is. But if you built the oven and that pid was never tuned to it I would highly recommend doing it. When I do it I get the oven up to the temp I use the most and then start auto tune. It will then shoot past the set temp and then let it drop and repeat. It’s calculating how fast the oven responds to the coils and then saving that to memory. This allows it to know when to stop so it does not overshoot your set temp and helps to keep a nice tight temp swing.
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That's a big +1 from me. I overlooked this feature when I built my oven many years ago, and noticed that my temps would swing 5 or 10 (sometimes even 20) degrees. I wrote it off as normal for my oven design. I later found out about the autotune feature (hysterisis? Or maybe that's something different) and went through the very simple process of "tuning" it, which I think involved pressing only one or two buttons on the keypad. I immediately noticed improvement where instead of swinging 10-20 degrees, it stayed within 1 degree of set point from then on. I had to kick myself for not paying better attention to the instruction manual for my PID when I first built the oven. Not that the 20 degree swing was ruining my blades, but if I can keep within a degree of set point, then why not do it?
 
I've been using a home built PID for a number of years for bullet casting and the autotune feature is a must use. My firebricks (24) showed up today, rest of my parts for my HT oven build will be here by Tuesday at the latest. Looking forward to playing with it and finally heat treating my 26c3 blanks I have so I can start on my kitchen knives.
 
Seeing as this has been brought back to life I have a couple updates and can maybe answer some questions. Please don't take this all this as gospel. I posted this so hopefully someone who takes this project on can learn from my mistakes.

1. The way i mounted my control box was no good. too much heat was leaking into the controls causing problem. As noted earlier, I added a small fan to the that turn on with then oven and everything stays nice and cool now.
2. In a couple years I have burnt out 3 of the thermo couples. The sleeve oxidizes and eventually falls apart. They're so cheap I always have a few extras but I'll probably try the TC that Stacey suggested
3. I redid my latch. Instead of a screw, I bolted a small aluminum tube with a notch cut in the top. I then took my screw, put a spring on it with a tab for faster latches. No more screwing the door shut.
4. Yes the TC is long so i simply slid some nut over it before inserting it through the top. It stick up out of the oven but whatever
5. I don't have a wiring diagram. I used Dan's design and just figured it out. (Huge props to Dan, his website is awesome so I want to give him props ever chance I can).
6. The Inkbird PID does have an auto tune feature but I'm not sold on it. When I do set it to auto tune it flashes AT for a bit but then goes away after a few minutes so I'm not sure it stays on. The instructions are pretty crappy.
7. The oven seems to run well. It wont sit at 1975 and hold. It'll bump up an down from 1965 to 1980. When the elements turn off it takes maybe 10 seconds to drop 10 degrees and maybe 20 second to climb back up once they kick back on. I keep a 4" by 1" by 8" steel bock in the oven to act as a heat sink to better control the temperature fluctuations. It means the oven takes longer to heat up but runs more stable.
8. I used to have a couple knives in at a time but now what I do is one knife at a time. I open the door, insert a new knife and remove the old. Put the old in the quench plates. Blow compressed air while watching the oven recover temp. Once I hit 1975 I start my timer (takes a minute or so) and continue to cool my first blade until it's cool to the. Then it goes in the LN. This process has given me very consistent 62-62.5 HRC AEB-L which climes to 64 after my first temper. I have JT tempering chart for AEB-l to thank for that.

I think I stated this before but just to reiterate. I am a hobbyist who makes knives when I have time and sells them when I can. If I was dependent on this, I would purchase a proper oven. But I enjoy making things and learning while doing it. I think I have more fum making tools and jigs than using them. If I ever make another oven I'll use heavier gauge wire, make deeper grooves to support the wire, and make a door that lift up instead of swings.
 
Trying to use imgur to share pictures and so far I'm not lucky, I was thinking in replacing the PID with another one from Auber which has soak and ramp, not sure if we need that or getting the Inkbird timer and make another panel with the 2 units, again not sure if will work and I'm surprised I couldn't find an unit made for heat ovens to control the temperature and add a timer without the mass confusion of a PID.
 
K2KfPmL.jpg
 
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Luis Barros said:
Picture too big any option to resize the pictures?
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If you are using windows, just open the picture in local photo viewer, make physically smaller, and use the windows snipping tool to copy to clipboard, then paste into your post
 
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25 soft bricks
kanthal A1 16 gauge (59'), 3kw, 240V.
Inside dimensions W=8.5 L=15.5 H=6.75
PID - Inkbird ITC-106VH with 2 SSR's
3M oven sealant (2000F) - the top bricks I also drilled steel rods between the bricks in case the sealant fails.
The bricks was the most expensive item which cost me $120 for 25 bricks everything else was not bad with the PID and the wire $30 each and the sealant was $15 for 2 tubes.
 
Cushing H. said:
If you are using windows, just open the picture in local photo viewer, make physically smaller, and use the windows snipping tool to copy to clipboard, then paste into your post
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After messing around with Imgur I found out an option to resize the pictures
 
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