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Upgrading and old kiln

I have a very old burn out oven that I have really never used. I have finished rewiring it and getting rid of the mouse droppings. It works, but I would like to add controls that are a bit more precise. I don’t need a burnout controller because I will only be using it to anneal or heat harden coils of metal. Any suggestions on how to build or buy a controller with digital readouts and the ability to maintain a set point are appreciated. Thanks…Rob

Hi Rob I have used many parts for heating control from I’m sure you can find what you need there.

Thanks! looks like a good place to start. I will call them on Tuesday for a quote. I spent a few years in technical service as a technical trainer where I learned a lot about control theory. Much of what I read on this site makes sense to me and I can apply it to digitally controlling my little kiln.

I have been experimenting with my now rewired and working kiln. I was able get it to hold a steady temperature to anneal a small coil of wire. I then tried to re-harden it holding it at about 300C for two hours. It held the temperature with a little minding but the coil remained dead soft. Any thoughts on heat hardening sterling silver would be appreciated. I have looked through the archives and the advice seems to be all over the place regarding time an temperature. Karl…It looks like Auberin sells an already made controller for less than $200 that will do exactly what I want to do. I don’t think that I could build it for $200…Rob

I use a PID controller for my burn out kiln, my wax injector,and my steam dragon steamer.
Do a search for PID controller and you will find a lot of info and wiring diagrams.
The wiring is very simple if you have some experience in that kind of work.
It will hold a temperature very steady for you and it is simple to set the temperature.
An additional advantage to this controller is that it is more gentle to the heating coil and will make it last longer.
The cost of the controller, the ssr (solid state relay), and the heat sink for the controller is less than $50 USD.
These are readily available and cone be found from a number of sources including Amazon.
Most often the controller comes with a heat sensor that is not useful to you. Your kiln may have one anyway. It is a K type of sensor.
The ssr needs to be able to handle 15 amps at 120. Most are able to handle 40 amps.
The heat sink is important as the ssr will run hot.
I have provided only a general explanation but if you want to know more, just ask.

Hi Rob,
I looked and I only see one set of figures for sterling heat hardening…heat to 1300-1400F for 30-60 minutes, quench in water and then heat to 572F for 30-60 minutes. From what you said, you left out the quench after the first heating. Instructions in McCreight’s Practical Metalsmith leave out the first heating and quenching, but IDK whether this is an error or not… HTH, royjohn

Franklin…Thanks for the information. I am familiar with controllers, relays and wiring having taught electro mechanical control theory to technicians back in the 80s. I just need to upgrade this theory a bit an put it to practice. In a previous post Karl steered me towards They sell all the pieces and parts as well as complete kiln control units. For my purposes, the parts would be around $100. The complete unit is $160. I have also looked at Amazon. The controls on my 40 year old kiln seem to hold readily at 300C and 700C so I don’t need the controller right away. It would just be convenient to not have to mind it so closely. Stay tuned…Rob