how fa to take the grind down before heat treat?

B

BLADECARVER

Joined
Apr 8, 2007
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i have read different opinions on this subject, what is the best method? grind the blade down then heat treat then put the edge on it? or grind put the edge on then heat treat? if i am going to put the edge on after heat treating how far is the best to take it down to?
 
I have heard to grind the steel to about 75-80 percent heat treat then finish. I would have thought to grind till about 95 percent so you do not have to grind hardened steel but I do not know the best way either. I am sure the pros will answer this for us both.
 
I heard something to do with dimes... 1 dime i think?
I like it a little thinner than that though. (I cant do any filing after heat treat like some of you guys and you kmgs :grumpy: )
 
Depends on the size of the blade for me.A3-1/2"-4" blade on a hunter I leaveat .035"
On a small knife like a caper or bird I usually take them down to .020" befoe heat treat.
 
Too thin and it can (probably will) warp. I wouldn't take it past a dime thickness.
- Mitch
 
i also go to around a dime maybe a hair thiner but then agen my NWGS just grins at hardened steel and bites in.
 
yes mom. its onley 11.45

hay sam you going to blade this year. i hopeing to go for the first time this year wife or no wife. she told me she would go with me but who knows. she might go t vegas with her sisters
 
I take 01 down to about .020, with PBC decarb protection. When I get warp, it is in the spine as well, not just the edge.
 
JTknives said:
yes mom. its onley 11.45

hay sam you going to blade this year. i hopeing to go for the first time this year wife or no wife. she told me she would go with me but who knows. she might go t vegas with her sisters
Click to expand...

What's blade?
 
I have heard about .035 to give yourself protection from decarb and cracking, Kevin Cashen's microscope pictures of the decarb area even of supposedly protected blade edges took away any illusions I had about the safety of taking the edge too close to finished before hardening, now I always give myself plenty of sacrificial metal to make sure that the edge my customer gets is the best that my technique and the steel can give them

-Page
 
I'm presuming that most of the responses here have to do with oil quench steels that need some refinishing after quench. If everything goes right with a well wrapped, plate quenched blade, it won't need much more that a buffer to clean it up. Many of my customers take their finish to 800g or more before they send them to me. I ask them for an unsharpened edge - about .020 if possible but some come way smaller than that and with very little problem. I have had a couple where a needle sharp tip pokes through one or both envelopes, but I think that happens as I set them on the plate to quench, so only a few seconds hot exposure.

Rob!
 
My understanding of Kevin Cashen's slides (I hope he will correct me if I am wrong . . . Kevin?) is that the slide he showed of an edge that had been "protected from decarb" that still exibited a layer of decarb that was a couple of thousandths thick was a blade that had been wrapped in the HT foil envelope with a carbon source etc.

I could be wrong in what I remember, and I do not have my lecture notes accessible here to check back to.

-Page
 
JTknives said:
...my NWGS just grins at hardened steel and bites in.
Click to expand...
What is a NWGS? It sounds useful.

Edit: Looks like this is answered in another active thread. I guess I'll ask a more relevant question.

Does the kind of steel matter for this problem? Can some steels be safely heat treated with a smaller edge than others?
 
Depends on the steel, you can take stainless and air hardening steels to nearly final thickness before HT, oil and water quench steels I'll leave thicker. Thin edges don't cause warp - uneven grinds, stress and quench media can.
 
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