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I Forge Iron

Dual control blown forge

Fred Rowe

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Building your forge with both a manual and automatic [pid] option, has many advantages; but the key word is control.

I run my forge on manual, most of the time; adjusting the air with the manual side rheostat and the gas with the manual side needle valve.
When the temperature needed, is in the 14 to 18 hundred degree range, I find the manual side controls to be the best option.

When I am working in the 1800 and above range, I use the automatic [pid controlled] option.

When using the auto option, you are using the manual controls for your base temperature, with the auto side adding the extra gas/air mixture to bring and hold the forge to set temperature.

“Make sure to wire your system with safety in mind”.

When I activate the main electrical switch, for this system, three things take place: the pid is turned on, the blower fan turns on and electrical current is sent to the switch that will send power to the main gas solenoid, when I am ready to light the forge. When you wire your system in this manner, you can’t turn the gas on without the blower fan running.
The auto side has an inline switch that allows you to turn it off and on at will, while still allowing the pid to be used as a thermometer.

Each burner on your forge should have its own needle valve. This makes “tuning” your forge much easier. Each burner operates slightly different, depending on its location in the forge body.

Forge atmosphere is readily adjustable with this system.

Installing two rheostats on the blower fan is not a necessity, but it does give you just a little more control on the auto side. Without the second rheostat, the fan will operate at max when the pid is activated.

My main objective, when I started building this system, was: No Whoosh, when the pid turned the gas, off and on. This always made me a little nervous.
I was looking for a set up that would maintain a base temperature, which I could set manually and that would be in operation as long as the forge was lit, along with an auto controlled [pid] option that would add the extra gas/air mixture, to the system, that would bring the forge to set temperature.

I got more than I bargained for. The control options are endless.

Vulcan’s Chariot will hold set temperature from 1400 to 2400 fh. within
two degrees. You can also adjust the forge atmosphere to whatever your need may be.

It is obvious, I am not an artist. [loud laugh] If I can help to clarify the drawing, give me a yell.

Take the time to study it first. It took me a bit to figure it out when Bladesmith first got me started on it. It is in reality quite simple.

Thanks again Stacy. It has been a very enjoyable project.

Fred Rowe
<-Bethel Ridge Forge->





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  • 1 month later...

Ok I just want to understand this.
Base temp is at 1400 (manual) and I want to increase to 1900(auto).

I set the PID to 1900

The thermocouple sends signal to PID to open auto gas solenoid to increase gas volume thus temp.

And at the same time closes switch to auto fan rheostat to increase fan speed?

Is this correct?

I have an old electric burn out kiln that I want to use for heat treat and have just recently become aware of PID controls, so just trying to understand.
Thanks Mark

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