New to Knife Dogs - Need Help with HK Huppert furnace

T

techymechy

Member
I bought a really cute little KH Huppert 236DL 240V furnace. It was given to the owner and I couldn't test it for the owner really didn't know what the furnace was and he had no way to plug it in at his house. I gave it a 50/50 chance that it would work but the price was right... I got the furnace home and changed the plug so it fit my 240 outlets and the darn thing seems to work!

I have done some packed carburization surface hardening in my shop. I have another small furnace that can fit the sealed box for packed carburization and I am going to use this little furnace for quenching and annealing. I have a number of punches and dies to make and I'm hoping that this will help speed up my process (the carburization takes about 1 day to heat up and cool off - I can do both processes in parallel now).

I think I'd like to change the furnace over to a digital controlled furnace.

1. Does someone have a recommendation for a programmable soak/ramp PID controller for this furnace
2. Does someone have the actual manual/wiring diagram for this furnace?
3. I need a little kiln plate - does anyone know where to get this?

I am thinking of using multiple SSR's so that this is safe. I want to run this overnight and have it shut itself off in an alarm condition

Please help me find an inexpensive, but capable programmable soak/ramp PID controller for this furnace.
 
I searched the web and I like the look of this controller alot:

Wi-Fi 1/16 DIN PID Temperature Controller with Ramp/Soak [AW-SYL-23X2P] - $129.99 : Auber Instruments, Inc., Temperature control solutions for home and industry

wifi wi-fi wireless PID temperature temp controller module 1/16 DIN 48*48
www.auberins.com


But I don't know who else makes a programmable slope, dwell controller that can be programmed (and possibly has a phone app).

I think I'll use 2 SSR's (one for each circuit on my oven) so if a SSR fails closed, I can control with the second one.

Here's a link on the Knife Dog's post for the oven I have. I have the 240V oven:

Converting 1962 Huppert's Delux Furnace Model 236dl 240v, 7.5a

Hi everyone. I recently bought at auction a 1962 heat treat oven (wasn't cheap). Paid $500 for it. It's really heavy and looks very well built. The temp display stopped working and wasn't reliable even while it worked. I'm wondering if I should just replace the thermo couple with a type S or K...
knifedogs.com


The Infitrol is an interesting controller with a bimetallic strip and a built in heater. I'm not too sure how the Hart switch works. It almost seems like a potentiometer but has three outlets (two hot and one ground?). I'm not sure if it is a tapped potentiometer or if it is stacked pot with one return. I'll have to try to figure this out.

I'll probably be into this for a couple of hundred dollars before I'm done, but it will be a nice little oven. I have another, larger, dental burn out oven that I use for my packed carburization and it can have multiple ramp soak times per program. I really like that oven. I think that using one for carburization and one for the heat treatment and annealing would be the ticket.

Does anyone have a suggestion of where to get kiln shelves for this besides Amazon?

Thanks again for your input.
 
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I know Evenheat makes programmable controllers that you can use your phone for. Probably be able to make a shelf yourself with a couple firebricks from the hardware/fireplace store. Sorry I can't help more, good luck.
 
Sounds like you're going to have a really good oven. I'm using two of the SYL-2362 model Auber PIDs, not the one you linked to. That looks like a really nice one. Good luck with your build and I think you'll be happy with it.
 
EvenHeat's TAP controller is the best controller I've seen on the market for heat treating. If you contact them they will sell you a controller directly .
 
Thanks for the reply.

I priced out a complete system from Auber with the 2.5GHz wifi connection and it comes to about $230, postage paid, for a controller, 2 SSR's, 2 Heat Sinks, a lighted buzzer, and a new thermocouple. I'm pretty sure I have a lighted switch to power off the system completely.

They sell two thermocouples: an 11 gage and an 8 gage. Should one go with the thicker gage TC or is 11 gage fine?

In addition to a switch, I've been considering using a panel mount, 10A circuit breaker. This will help protect the system if there is a short to ground. Currently, my 240V circuit has a 30A breaker at the panel. I'm thinking that it might be better to have an appropriately sized breaker at the device. The rated amperage/voltage is 7.5A, 240V. This will add another $15 to the cost.

I'll contact EvenHeat to discuss their controller.

Please let me know what you think of the thermocouple wire thickness and the need for a 10A, panel mount, circuit breaker.
 
I have a few more questions:

Please look at the knife dogs post I listed previously.

What type of wire would you recommend for rewiring the elements on the outside of the furnace? Would you invest in high temperature wire?

Also, I plan on using two SSR's, one for the sides circuit and one for the top/bottom circuit. There are currently three wires powering these two circuits. Do I need to separate the two circuits and have two leads for both the top/bottom circuit and the side circuit?

Thanks for your help.

Dave
 
I found a great article on building/retrofitting a furnace:

www.hobby-machinist.com

Heat Treat Furnace Build

I have come to a point with a couple of projects that have parts that will need to be heat treated so it is time to build a furnace. This will be my version of the many examples out there on the interweb. Specifications: Heat chamber is 7" x 7" x 16" Dual heating elements wired in series...
www.hobby-machinist.com www.hobby-machinist.com

I like the idea of using 1 SSR and a contractor. I also am thinking I should incorporate a door interlock switch and a more appropriately sized panel circuit breaker. The little Huppert furnace has filaments on the side walls, top and bottom of the chamber which leads me to believe that there are ample opportunities for things to roll around and short out stuff even with a kiln shelf on the bottom. I want to insure when the door is open, the filaments aren't powered and if a short occurs, the breaker trips at 10A rather than the panel 30A rating. Hopefully, the breaker will protect the filaments in an inadvertent shorting event or even protect a life :) .

This is becoming an interesting project!
 
You can check out Bartlett Controllers they make the touch control for Paragon ovens. Paragon calls it the Sentinal and Bartlett called it the Genesis 2.0 I believe?
 
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