Heat Treat Oven - WIP

Kosa_PL said:
As for me there is too less insulation.
(...)
TAP control unit...

If they not implement in software a proper Auto-adaptation and self calibration algoritm, and maybe a Fuzzy Logic you will have a lot of problems with overshot.
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They didn't. The software has no adjustable parameters, and no self calibration. Mine went out of whack when I switched the TC for a faster one. The kiln always overshot, but with the faster TC the controller suddenly realized it, and instead of adjusting, it bails out aborting the firing.

Initially I had a helpful conversation with the software engineer/CEO. Yes, the one and only, I hope he has good health. Tried a few experimental firmware releases, without success. After a while, he went silent, and I've been chasing him for a month and a half. Asking EvenHeat didn't help: they have no clue about how the controller works, and sadly they don't even have a clue about how it works in their own kilns...
 
Wait, wait , wait...

They put in they kilns a control unit, that they don't know how it's work!?
It's insane...

On my Lumel RE72 I have all mentioned futures.
And after setting this stuff with laptop I just set temp and I never had overshot more than 0,5*C.
In full working range ( 4 PID sets of parameters.)
 
Kosa_PL said:
(...)And after setting this stuff with laptop I just set temp and I never had overshot more than 0,5*C.(...)
Click to expand...

To be fair with the evenheat guys, as measured by their own TC, it's always +- 1*C...
Have you tried measuring yours with an independent, thin gage, naked thermocouple? You may be surprised.
 
I know it's not going to be perfect right out of the gate but I have had many good conversations with the tap owner/programmer and he is very interested in giving the tap options that make it more metal heat treating friendly. He has been open to any and all ideas I have passed along and is planing on doing some great things with some upcoming updates.
 
Maybe it's a little late, but the TAP controller can use two thermocouples to control the over in a "zoned" fashion. Of course, you need two different heating circuits, but it could help enormously to ensure a stable front-to-back temperature.
 
Well guys the day i was dreading. The day when I try and stuff this coil into the roof of the oven. Not just stuff it but bend the coil into a zig-zag with the same number of coiles per rod and proper spacing lol. I first had to count every single coil and devide my 20 because I was not going to just guess and the length over each rod by measuring. I want the exzact same number of coiles on each rod that way each rod should have the same amount of watts of heating power. So I marked the coil ever 21 loops and headed to the shop to figure out how to do this.

And this is what I came up with. 2 1/2" rods clamped in the vice with 1.5" spacing from center to center.
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It actually only took me like 10 min to bend the entire coil. I was concerned that it would be hard to bend because I went with 13ga wire. Oh yeah 13ga should last a while. But that's one advantage of this system. Larger coiles and more of them so I can stuff thicker ga wire in the oven.
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Then it was time to see if my crazy hair brain idea would work. But to my surprise the coil went right into place. The wire does have some tension in some places but once heated that will relax and everything will settle down. I might heat the ends with a torch gently to let them relax and fall into place perfectly.
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So that's it for today, I just had a few min to spare so I thought I would get the stressful part out of the way and I'm glad I did. Now just waiting for the last package to arive that has the mis electrical things for the elements. Pass through tubes, 10ga insulated wire, termanial blocks and high temp spade connectors. I have the power core and plug just need to install it. I'm tossing around the idea of painting the cabinet the same black that I will paint the oven but now sure yet. The cabinet is powder coated so I don't know how well the paint will stick. Thanks guys for fallowing along.
 
Was able to do some more work on the oven tonight. My hole was to get he oven ready for painting which ment drill all the needed holes for controller standoffs, elaments and thermal coupple. And I would have been done if I had the correct tap for the screws that hold the Thermal couple termanial block in place. Thoes will be done tomarow after I pick up a tap. But so far everything is falling into place.

Here is the elament box and the 4 standoffs to hold the control box. A ceramic pass through tube is inserted from the back side and the bricks keep it in place.
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Here is both elament boxes mounted and the ceramic pass through tubes installed. You can also see the thermal coupple sticking out of the side. It's just sitting there to look fancy for the picture.
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Here is an inside shot showing the bricks holding the tubes in place as well as the thermal coupple just peaking through the brick. I installed the TC dead center from front to back and 1" off the floor as I believe that will give me the best average temp location. In the future when multi TC option is turned on in the tap control I will be adding a front and rear TC but Intel then I will just use one.
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I also finishe cutting and drilling all the needed holes in the control box and will be finish wiring it up tonight.
So we are at the home stretch with this project and this is the time when its best to take your time and not rush the project even though your so excited to fire it up. You need to think with a clear head and do everything in a organised methodical order or you will regret it. Not a time to cut corners and go off had cocked.
 
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After diner I tackled the control box. The wife wanted to help so I had her paint a red box around the power switch lol.
In this pic you can see the little black nub on the bottom left corner of the box. This is the disconnect for the elaments. I went a different way then normal conventional thought. Commercial ovens normally have the disconnect on the face and are triggered on when the door is closed. My idea is the switch is on all the time but once the door is fully opened it will press the switch and disconnect the elaments. My thought on this is keeping as much heat in the oven at all times even when you crack the door open for a quick peak. This approach removes the on off cycle time of the elaments when the door is cracked open for a little looksee. But when you open the door all the way the switch is triggered and the SSRs are turned off.
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Here is the back. You can see the conduit clamps for the elament wires as well as the TC plug. I left enough space for 2 more TC plugs for the future update for the tap.
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And here is a peak inside the box. This is what your brain looks like on JT, facepalm.
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Ok we fired up today and I'm more then happy with the results. I still need to add the trigger disconnect bar but that's just a bit of welding. The test run was to 1475° from a cold oven and took under 15min to reach. I then let the temp even out and soak the bricks and then cranked it to 2000°. It hit 2000° in 5min from 1475°:eek: can't complain with thoes results. After 1hr of running through the tests and heat treating some 5160 at 1475° I measured the shell and the hottest I could find was 125-150deg then I shut it off and let it cool to 400° and it took a good 2-3hrs and the entire time I could touch the shell. It was hotter now but not boiling water hot so I say it gets a thumbs up.

Here she is all painted and the control box mounted. Turned out rather good looking I say.
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Here is the back side. I went kinda steam punk for the elament power lines and used flexible copper tubing. But it worked really really slick for what I was trying to do.
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Here is a shot of inside the oven at 1475°, it's rather mesmerising to look at and even more so at 2000°
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I will get some more pictures tomarow as well as a video of it in operation. I was happy with the amount of control I had as well as the controls ability to hold temp. Went first coming up to a set point it would bounce around a tiny bit but never more then +5deg as the bricks warmed up the bouncing would stop and it settled right down. You could hear it adjusting the on and off times as the coil makes a quite humming when on. But so far my strategy for hitting a temp dead on is to just set a set point like 10° lower and set there for a few min then go up to my desired temp and go.

It's tempering right now so we see how it goes. A nice feature is the data logging and real time graph display which allows me to track the temp over time so I can see if something went funky.

Thanks guys for fallowing my along this crazy build and hope it inspired others to eat her relize thy can build one or that it's over there head and thy should just buy one lol.
 
JT, That is a really nice oven. The finish is also first class. Many don't go that extra step. Yours shows how much that step improves the overall look.

At first I was unsure about your coil disconnect method, but I see how it will be pushed by a trip arm on the door hinge shaft. That should work, but I think a limit switch of some sort would be better than a push button ON-OFF for the switch. The On-OFF type can be damaged by being over pressed. The plastic can also wear and/or break, especial in hot places. Here is a push type limit switch that would be a better choice:
http://www.ebay.com/itm/HONEYWELL-M...351432?hash=item58b62a5c08:g:yQUAAOSw6btXRShN
 
This is very impressive to say the least. Great job on the build, and I'm always impressed to see anyone attempt (and be successful!) at building their own tooling. Awesome.
 
That's definitely the nicest home brew HT oven I've ever seen. Makes me want to go out and re-build mine! Truth be told, it's about time to re-brick most of mine any how, and a new coil probably wouldn't hurt. I really like the rod through coil option and getting everything to just one side.

How much $$ do you think you have tied up into this all together, if you don't mind me asking?
 
Hey JT, nice job! Yer a real craftsman, not just with blades.
But you do realize, you built it upside down? Gonna be hard to reach it on the ceiling like that...:p
 
JT,

I noticed you didn't recess the door into the oven, or do any kind of gasket. How is that working out for you? I am planning on attaching a piece of inswool I have left over to the interior of my door to act as a gasket and to add some more insulation. Does this sound workable?
 
kdogmcg said:
JT,

I noticed you didn't recess the door into the oven, or do any kind of gasket. How is that working out for you? I am planning on attaching a piece of inswool I have left over to the interior of my door to act as a gasket and to add some more insulation. Does this sound workable?
Click to expand...

Surprisingly, there is little heat loss from a flush fitting door. A gasket or recessed door is fine, but there isn't a big reason for it, which is why most all commercial ovens don't use anything.
 
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