Pre-Heat Question

CDHumiston

CDHumiston

Well-Known Member
When I read heat treating guides that say "Pre-Heat to 1400° and Equalize" does that mean I bring my oven up to temp first and then load the blades in?

Or do I load the blades in as the oven is coming up to temp?
 
CDHumiston said:
When I read heat treating guides that say "Pre-Heat to 1400° and Equalize" does that mean I bring my oven up to temp first and then load the blades in?

Or do I load the blades in as the oven is coming up to temp?
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As I understand, all of the preheat instructions are: (1400 for example), wait till the furnace is at 1400 degrees, load the blades, then you start timing your preheat AFTER the blades have reached 1400 degrees. About the only way you will know when they have reached 1400 would be to watch your readout and wait till it bounces back up to your preset temp.
 
Edwardshandmadeknives said:
As I understand, all of the preheat instructions are: (1400 for example), wait till the furnace is at 1400 degrees, load the blades, then you start timing your preheat AFTER the blades have reached 1400 degrees. About the only way you will know when they have reached 1400 would be to watch your readout and wait till it bounces back up to your preset temp.
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Thanks, that's what I thought.
 
Run this experiment:
Harden a blade or tab that you put in at 1400F and proceeded with the HT (I assume you are talking higher temps than plain carbon steels). Do not turn off furnace. Quench, cryo, check hardness, temper, check hardness.
After the first quench, toss a tab (wrapped) in the furnace at austenitizing temps and start timing about 2 minutes after it reaches temp again.
proceed as above and compare. Be sure to remove decarb layers completely prior to testing but don't overheat while grinding.

I have seen Larrin Thomas mention testing pre-heats and eschewing them for our thin-cross-sectioned blades versus directions adapted from industry.

PS: keep exquisite records of all steps of HT on every knife in a bound journal, along with experiments. That log stands one well in subsequent years.
 
Thanks for the idea and the note about keeping a log. I have failed to take notes, but I'm early in enough that I haven't lost much information. I will start a log today when I heat treat some blades.
 
Yes, I highly recommend keeping a long on every knife that you build. What steel and heat treatment and handle material. You might even want to include a photo. Why do I say this? Because I haven't and now I have a bunch of blades I have little idea of how they were made.

Doug
 
Doug Lester said:
Yes, I highly recommend keeping a long on every knife that you build. What steel and heat treatment and handle material. You might even want to include a photo. Why do I say this? Because I haven't and now I have a bunch of blades I have little idea of how they were made.

Doug
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As someone once told me...... "a short pencil is better than a long memory"
 
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