temperature in your forge

[DoubleLung]

How do you monitor the temperature in your forge for heat treating. I know alot of people rely upon colors but I've also heard of some using some type of thermometer? Also how do you ensure that the blade heats up slowly and evenly? Is that why some people heat up the blade inside a pipe inside the forge? Thanks for the help once again guys.

[Steve Nuckels]

Tim, I attended a ABS Intro to Bladesmithing school we used a pipe inside the forge to ensure even heating and checked with a magnet.  If you use a pipe be sure it is NOT galvanized, as I understand high temp will cause galvanized material to produce dangerous gas.

Steve
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ABS Apprentice
Potomac Forge
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IN GOD WE TRUST

[tomh]

A thermo couple and a PID is what you want. The thermo couple goes in the forge and reads the temperature, and it is wired to the PID which has a digital readout, and shows the temp. That is the simple version, other guys have their forges set up to be temperature controlled by the pid and solenoids, etc.

I think some guys use other types of pyrometers but this is what I have.

[gables]

I've been searching the forum and decided to bring this one back up.

What diameter pipe for even heating?

Is it bettter to read the temperature of the forge or of the steel?

[kbaknife]

Originally posted by gables:
I've been searching the forum and decided to bring this one back up.

What diameter pipe for even heating?

Is it bettter to read the temperature of the forge or of the steel?

Whatever size will fit in your forge door and will accommodate your blades.
It would be pretty difficult to read the temp of your blades. The thermocouple reads the atmosphere of the forge.
Keep in mind that most steels require MUCH higher forging temps than are used for heat treating. This is to minimize induced stresses during forging.
Of course, this results in lots of grain growth, irregular dispersal of carbon and alloys, etc.
So, forging is ALWAYS followed by LOWER temp grain reduction and post-forging stress relief thermal cycling. This is when you lower the temp of you forge - less air and fuel.
The post-forging steps are almost more important than your forging temps!
As well, always start your forging at your HIGHEST temp and gradually reduce the temp or time in the forge as you approach the end of your forging.
I always try to forge during late afternoon, just prior to sunset, or what ever time/daylight/overcast conditions/etc. allow me to see my colors.
I don't use thermocouples.
I watch for decalescence and recalescence - which are the shadows in the steel indicating crystaline changes as you approach proper forging and austenizing temps.
Watch for them and you'll know when the time is right!
But, you won't be able to see them if the surrounding light is too bright.

[Doug Campbell]

Used to do like Karl but now I've got the thermocouple/pid setup like Tom is talking about and love it. Picked up the pieces on the big auction site a few years ago for very reasonable. Since then I've added another thermocouple and wired both to a three way toggle switch. One is in my forge the other "portable" but does most of it's duty in the heat treat pipe. I put a cap on one end of the pipe and plug the other with ceramic wool after putting the blade inside. Provides a very inert environment for the heat-treating blade and I know the exact temps inside the pipe...

[Lin Rhea]

Doug,
     Beautiful idea!!!

I take it you gently remove the wool plug and your ready to quench. Great. That's one of them slap your forhead ideas.

  Have a I told you that we're glad your here?    Lin

[kbaknife]

I agree Lin.
That's a cool idea, Doug.
One of those upgrades looming on my horizon.
Would you do us a favor and maybe a little tutorial on the thermocouple and readout application with part #s???
Please, ol' buddy?

[Doug Campbell]

Thanks guys, musta been one of those "blind sow" kinda things...    Gotta run the sweet little wife to town right now but I'll get some pics and post something soon.

Later...