"Karl Townsend" wrote in message
...
I bought a VERY old heat treat oven quite a long while back...

I'd like to check that it is reasonably calibrated before heat
treating this part. Is there some sort of thermocouple and high
temp
wire I can buy and take a voltage reading? I only know of this
concept, not any specifics.

I made a custom bolt out of 4340 for my 30 ton shop press. Looks
like
I should heat to 1525 and quench in oil. Then temper to 450.
correct?
I'll use SHMBO oven for tempering (when she goes shopping)

Karl

The accurate, inexpensive way is to buy a second-hand temperature
controller and some high-temp Type K thermocouple wire.
http://www.omega.com/ppt/pptsc.asp?ref=XC
http://www.ia.omron.com/product/69.html

Be sure you can find the controller's operating manual on line. They
can be very tricky to set.

You could put a relay in a box with the controller and plug the oven
into it. The controller's PID function reduces power as the
temperature approaches the set point, so the oven doesn't overheat.

I have similar thermocouples from a different local supplier. Don't
try to cheat on the temperature rating. Cheaper 1200F glass braid
rapidly turns to dust in a candle flame at 1500F.

There are also hand-held battery powered thermocouple thermometers
like my Fluke 52 but they don't usually go cheap.

jsw