Evenheat question...

[kvehikite]

I can run a temper cycle in my oven from cold with no problems. Example would be, room temp to 425 F for 1 hour. No issues.

But...if I run a heat treat cycle and then let the oven cool to a little below 425 F and start up my temper cycle the temperature just continues to climb. Is this just the normal? Do I need to let the oven cool to room temp?

 

[S.Alexander]

The oven has residual heat from your heat treating cycle. It needs time to cool down and equalize at the lower temperature.

Example. You heat treat your knife at 1500 degrees. Leave the door open until you hit 400 degrees then place your knife inside and close the door. The firebricks are still much hotter than 400 degrees and they effect the ambient temperature inside the kiln. They will bring the temp inside the kiln much higher than your desired temp.

 

[kvehikite]

Copy. So, I should leave the door shut to get an accurate reading. This make since. This seems to render the oven useless for tempering. The time required to cool the oven enough to run a temper cycle has to outside the window for tempering a freshly heat treated knife. Or is that window between heat treat and temper wider than I understand. I do my first temper cycle as soon as the blade is cool enough to handle.

 

[Stacy E. Apelt - Bladesmith]

While it is best to do the temper as soon as the blade reaches Mf (room temp for carbon steel), it won't ruin anything if you have to wait 4-5 hours.

Open the door and let the oven cool until it is about 200F. Then close the door and start the temper cycle. Once the oven stabilizes at the set point ( 425°), place the blades in.

 

[kvehikite]

Thank you Stacy.