What do I need to look for in a heat treat oven controller?

S

Scaniaman

Joined
Jun 15, 2012
Messages
1,421
Hi!

I am seriously considering getting my own heat treat setup. The most likely scenario is an oven that takes 23" and is powered by 8.2 kW elements. The standard controller is a Bentrup TC66. It basically let's you make and save 6 programs, and every program can have a maximum of 2 dwell/hold temps. From their homepage:

"Delay Start 0:00-10:00 hours, First ramp 5°C/h to
999°C/h or full-on to adjustable first setpoint, Se-
cond ramp 5°C/h to 999°C/h or full-on to
adjustable second setpoint, Dwell 0:00-10:00
hours, Cooling Ramp 5°C/h to 999°C/h.
6 user definable programmes.
4-digits LED, firing curve, units"

http://bentrup.com/product/tc88/

http://bentrup.de/wp-pdf/downloads/prospekte/TC44_TC66_TC88_en.pdf

This should do it right? Or do I need anything else (more advanced) as time passes and I get more and more into heat treating?

Thank you for any input!
 
I highly and I mean HIGHLY recommend the TAP controller. It was a rocky start at first but thy have really smoothed things out with the firmware updates. In today’s day and age I’m alittle worried when things like this limit the number of programs. Memory is dirt cheep and to say “save 6 programs” that’s nothing. It’s nothing to brag about that’s for sure. That right there is a deal breaker for me. But my situation is alittle bit diffrent then mosts.
 
Ok, thanks. So the number of programs may be an issue there.
Anything else? Would I ever need more than one or two dwelling temps for example?
 
What's available depends a lot on what part of the world you're in.

What you need depends a great deal on the use - full time professional shop doing HT for other folks. Full time knife shop doing on your own HT. OR - hobby use doing 10 blades a yr. Here's a few of the commercial units:
IF" you want a PID controller that seems to be the best (I think this is the one JT uses) around: https://www.kilncontrol.com/shop/conversion-kits/

OR, a step down from that but has been around for a LONG time:
https://shopevenheat.com/index.php?main_page=product_info&cPath=100_106_128&products_id=1481

Or with fewer features at less cost (this is the one I have):
https://shopevenheat.com/index.php?main_page=product_info&cPath=3_12&products_id=1479

Here is a link that gives a brief description of each controller.
http://www.sunshineglass.com/rcol/b_fusing/kilns-ramp2.htm

Reply
 
JT has commercial needs. A normal joby knifemaker will rarely need more than 6 stored programs. If you need to change a program for a new steel or special HT, just change the settings on the one you use the least.

I wonder if you can use a USB stick and expand the program storage? I might talk with Mike at Evenheat about that.
 
Ken H> said:
What's available depends a lot on what part of the world you're in.

What you need depends a great deal on the use - full time professional shop doing HT for other folks. Full time knife shop doing on your own HT. OR - hobby use doing 10 blades a yr. Here's a few of the commercial units:
IF" you want a PID controller that seems to be the best (I think this is the one JT uses) around: https://www.kilncontrol.com/shop/conversion-kits/

OR, a step down from that but has been around for a LONG time:
https://shopevenheat.com/index.php?main_page=product_info&cPath=100_106_128&products_id=1481

Or with fewer features at less cost (this is the one I have):
https://shopevenheat.com/index.php?main_page=product_info&cPath=3_12&products_id=1479

Here is a link that gives a brief description of each controller.
http://www.sunshineglass.com/rcol/b_fusing/kilns-ramp2.htm

Reply
Click to expand...

Thanks. I fall into the hobbyist category, but I sure hop I'll do more than 10 pc a year.. :) The unit I'm looking at I guess is something like the Set-Pro.

I'm in Europe, so I'm going with Bentrup. Top notch German brand. They are on many top of the line industrial ovens over here.
 
Last edited:
Stacy E. Apelt - Bladesmith said:
JT has commercial needs. A normal joby knifemaker will rarely need more than 6 stored programs. If you need to change a program for a new steel or special HT, just change the settings on the one you use the least.

I wonder if you can use a USB stick and expand the program storage? I might talk with Mike at Evenheat about that.
Click to expand...

I think you make a good point, on the number of programs. The TC66 does not have the USB Connection. Bentrup do have newer more hi-tech controllers with that feature (plus Bluetooth, WiFi-connection etc..), more comparable to the TAP I guess :

http://bentrup.com/product/tc-705/

But it's something like another $400 to upgrade to that, and it already has room for 99 (!) programs.
 
Stacy E. Apelt - Bladesmith said:
I wonder if you can use a USB stick and expand the program storage?
Click to expand...
The limit will be designing the user interface, not storage capacity. <10 programs and you can just scroll through them, if you have 10,000 you need a better system. Either way you don't need much actual memory
USB connectivity could be useful though, saves looking up heat treat regimes on your phone in the shed
 
Whatever you use, it is nice to have the option of setting a short output cycle time, (unless you are using a true analog output, which is unusual).

Most of the dedicated kiln controllers I looked at a few years ago had a fixed output cycle of 30 seconds and I felt that that was much too long for an HT oven, though perfectly fine for a ceramics kiln.

The controller will power the elements for part of the output cycle time and leave them off for the rest. The effective power input will be the element power times the proportion of "on" time. While powered, the oven temperature will rise, while unpowered, it will fall. If you measure the temperature in the oven using a fast-responding pyrometer, it will show a saw-tooth temperature variation.

If you have an oven that needs 1500 Watts to hold a given temperature and it has 3000 watts of elements, the proportion of "on" time will be 50%.

With a 30 second cycle time, 50% on time is 15 seconds on and 15 seconds off and you will have big saw-teeth. If you have a 5 second cycle time, 50% on time is 2.5 seconds on and 2.5 seconds off and you will have much smaller saw-teeth.

I did some testing on my first homebuilt HT oven and found that the temperature definitely became more stable as I reduced the cycle time to 5 seconds. There seemed to be a further small improvement by taking the cycle time down to 2 seconds, though I could have been kidding myself. There was no improvement I could measure taking the cycle time down from 2 seconds to 1 second. I was using some pretty fancy measuring equipment and a high-end ($800+) industrial controller, all borrowed from work.

I ended up buying industrial ramp/soak controllers for my later ovens because I simply could not get similar performance from kiln controllers. This may have changed in the last 6-7 years. The TAP in particular seems to be constantly improving and I don't know what the latest software version can do.
 
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