# Retrofitting a used heat treat oven with a new PID



## seanb (Jan 11, 2021)

I ecently won this muffle furnace at an auction
i am thinking about adding a PID to it 

Has anyone done that? 
Any advice?

 I have not tested it yet because as you can see it has no controls

I got it with some other stuff so its basically free. 

If it doesnt work how expensive would it be to rebuild it


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## JimDawson (Jan 11, 2021)

Pretty easy, the following is about all you need.



			https://www.automationdirect.com/adc/shopping/catalog/process_control_-a-_measurement/temperature_-z-_process_controllers
		




			https://www.automationdirect.com/adc/shopping/catalog/process_control_-a-_measurement/temperature_sensors_-a-_transmitters/thermocouple_sensors
		




			https://www.automationdirect.com/adc/shopping/catalog/relays_-z-_timers/electro-mechanical_relays/power_relays,_open-style,_40a_(ad-pr40_series)


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## Gaffer (Jan 11, 2021)

I picked up Cress kiln a while back and will be adding a PID controller with soak capabilities. It looks pretty straight forward. This is a good how-to video. I'm a fan of Automation Direct. I bought my VFD from them and they are great to deal with.


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## seanb (Jan 12, 2021)

Thanks guys, I plugged it in last night and it started warming up so I think it’s still functional

Not sure where the heating elements are on it though


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## Larry$ (Feb 4, 2021)

I installed a PID control on an industrial machine. Bought it from Automation Direct. That was over 10 years ago still works fine. 
While programing it I didn't understand something and had to call their help line. Took them 5 minutes to get me straightened out. 
An OEM replacement was $843, The Automation Direct one was about $140 & was made in Japan. I also had to buy a power supply for it to match the machine. That was very cheap. The instructions for programing are available on the Automation Direct web site. All sorts of ramping, set points etc.


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## Winegrower (Feb 5, 2021)

I’ve done this.  Go to eBay, search for “PID controller kit”.   They come with an excellent controller, a K type thermocouple, which is what you want, and a solid state relay (SSR) that switches the AC line power directly.   About $24 for everything.

The controller has a self learn mode to set the PID coefficients, so no need to brush up on control theory.


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## Marbles (Feb 6, 2021)

I have used the $25 Temperature controllers with included the thermocouple and solid state relay. The replacement part from the oven manufacturer was over $800.  I guess a new oven is $15000 but it's been running with the $25 unit since I swapped it over.

It's an insulated box with a door, a vent, elements, maybe a fan, and control.  save your money for fun things.


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## Janderso (Feb 6, 2021)

I would love to have one.


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## SLK001 (Feb 6, 2021)

seanb said:


> Thanks guys, I plugged it in last night and it started warming up so I think it’s still functional
> 
> Not sure where the heating elements are on it though



That was going to be my question.  It looked to me that the elements had been removed.  It might just be a low temp heat treating oven, maybe 500º F tops.


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## Papa Charlie (Feb 6, 2021)

I did a search on the internet, this unit is rated up to 2000F. From the images I see online I don't see any of the elements so they might be under the base plate. The wire in the back appears to be the temp sensor.



			Barkmeyer M-525 SII Furnace


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## aliva (Feb 6, 2021)

I put a PDI on my Bradley Smoker. Much easier to control the temp rather than using the cheap slide temp switch that is on the smoker.


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## pdentrem (Feb 6, 2021)

http://www.hobby-machinist.com/threads/heat-treat-oven.9929/ this might help. 
Pierre


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## Ianagos (Feb 6, 2021)

My oven has the elements buried along the walls in the stone. It’s rated for up to 2000 degrees aswell. 

I’d also like to put a new controller but the old school control is working fine as of right now.


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## keeena (Nov 18, 2021)

@seanb - would you be able to provide the interior dimensions for this unit? One of these popped up local and I'm debating buying as a heat-treat oven. Did you ever attempt the PID?


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## rwm (Nov 18, 2021)

So what will be the primary use for this? Knife making? I assume you are treating steel?


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## Ianagos (Nov 18, 2021)

rwm said:


> So what will be the primary use for this? Knife making? I assume you are treating steel?



I use mine for annealing steel. Also some case hardening and hardening of air and oil quench steels.


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