Thickness of O-1 edge before heat treatment?

V

VIKING DK

Joined
Aug 28, 2002
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Firstly, I need an advice regarding the minimal thickness of an O-1 edge before heat treatment. Since I'll be using handtools exclusively for this knife I really want to go as thin as possible on the edge/grind BEFORE heat treatment. The heat treatment will be taken care of by a firm specialized in this for industrial applications. The O-1 blade will NOT be cryo treated and NOT selectively tempered.

Secondly, which levels of HRC do you recommend for a knife made from O-1 tool steel for:

4-5" blade; optimized pure cutter for meat end wood, full flat or full convex grind.

8-11" blade; optimized wood working chopper, full flat primary and sub mm secondary grind or full convex grind.

Thanks,

VIKING DK
 
I try to leave 1/8 or so but since you are using hand tools I'd take it down very close to a finished edge.

The hardness is going to be what it is when you heat treat. I would guesstimate about 58-59. Don't worry too much about how hard it is, just work on getting a good heat treat. Hardness is a benchmark, not a level that has to be reached. Many knives that have a softer edge, take and hold an edge quite well. Many people prefer a softer edge, Myself included on some types).

On the type of knife you are talking about, I would do a full flat grind.

fpr your 8-11 inch blade try a convex grind although how you are going to do it without a slack belt grinder is beyond me.
 
Peter, I can do a damn good convex grind with my cheap 4X36 grinder. I just roll the blade as I go. It's not super accurate but it comes out looking fairly nice.

With hand tools it's gonna be hard. You're using a file I'm guessing? You could try rolling the file as you cut.
 
If you do a search in the Himalayan Imports forum in last week or so someone posted a howto on getting a convex edge without a belt grinder. Think it was abusing a dremel, but don't remember. :) I have two belt grinders, so try to avoid paying attention to any thread that will encourage me to abuse my other tools when I should just be using them. :)
 
Stu, I thought when he said "hand tools" he ment files, Etc. The little 4X36 works fine although it's a little fast in most cases.
 
Viking -

A good thickness is about that of a dime. That's probably around .060". Commonly, they are taken a bit thinner by many, down to around .030" at 220-400 grit, prior to HT.

You are gonna find yourself between a rock and a hard place, to some extent. "Pro" HT firms often don't know how to work with blades because of the thin and changing cross-section; they often warp them.
You have to have it thick enough that it will be a bit more stable but not so thick you can't finish it. I would personnaly try it at about .060". That will make it difficult to file, but you might use stones to make a convex edge. One thing to make sure of is to have the "scratches" along the edge running lengthwise when you send it for HT. This helps a small bit to eliminate warpage. I have HT'd blades as thin as .015" at the edge without warpage, so it can be done.

As for the hardness, I would recommend 59-60 for a cutting knife, 56-58 for a chopper. Those seem to be the best for O-1. While I personally really like O-1, I think there may be better choices for strength in a chopper. Hope this works out well for you, and hope these words helped. Good luck.
 
He probably did Peter, I'm just pointing out that you don't really need any slack in your belts, just a little ingenuity.

I can't even imagine trying to make a knife with just files but I'm sure you can manage a convex grind like that too. Good luck.
 
DK no thinner than .045 if you do the edge will wrinkle on you
you may be able to push .040 then finish around .025 - .030
that stuff is a piece of cake. 58 R is good if your chopping with
it you don't want it to Hard and go a little thicker
just My 2 cents
 
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