Finish before heat treat?

Make sure ya don't grind too thin, otherwise you have greater risk of cracking during the quench. At least that's my understanding. Luckily, even though I really went too thin on one today, it managed to come through without a crack, least that I've been able to find yet.
 
You'll get a varied answer to that question. Many makers often will leave blades a little thick and carefully grind to the finished state after heat treat.

I usually take the blade to it's finished grind and up to 320 grit or so before heat treat. I've seldom had more than ten minutes or so of hand sanding to restore the finish and then continue to finer grits for hand rubbing.

Terry Primos takes his blades up to a finished state also but he uses an anti-scale product made by Brownells called PBC. His blades come out of the quench looking pristine (after the remaining PBC is dissolved off the blade in hot water).

It's been my experience that blades that are fully immersed in the quench have very little scale on them, it tends to flake off in the quench. Edge quenching however leaves steel at critcal temperature and exposed to oxygen and creates a stubborn line of scale. I fully intend to try the PBC soon although I've heard it works better in an electric oven than a propane forge which I would be using.
 
I've done it both ways and I really don't think it makes a big difference. One of the reasons to leave some is to eliminate burning the carbon from the thin edge. I don't think that is the problem many make it out to be. One reason to finish grind before is to prevent the dreaded blue spot. With proper grinding and sharp belts, that's an overstated problem......Try them both and choose!:eek:
 
That dratted blue spot! That's a good one Peter! How about the tip disappearing in a little wisp of smoke when you are regrinding? Don'cha just hate that?
 
After a couple years of grinding off scale and very tedious hand sanding, I tried Primos' method and started using the PBC mentioned in the earlier thread.

Get the blades to a dull red, sprinle on the PBS and treat as normal.

ALL the scale came off with boiling water.

I now finish the blade through final grind at 400 grit before heat treat.

Good luck,

Dave
 
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