BTE thickness & durability

noseoil

noseoil

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Apr 24, 2013
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This is something I'm curious about & wonder what opinions people have about it in general. I've refined a blade design for the second time on a fixed blade (it was originally a "Mule Team" type of pattern, which was changed along the way) but this time I used two different steels to make them, O1 & D2. I made 2 knives with each steel that are about 9" long, 1 1/2" wide with stock removal, starting with 1/8" material. I had them heat treated to about HRC 61, finished them & put the scales in place. They're much better than my first 2 blades (thankfully) & I'm happy with the progress I'm making, if not my technique in finish & design yet. Small steps & painfully slow.....

Here's a D2 knife with black canvas micarta, it's thick behind the edge
1-d2-2nd_zpsvqgurw0w.jpg


The O1 blades were ground very fine, at about 0.015" BTE & then given an edge at 15 DPS. They cut very well & sharpen easily. The D2 blades were done thicker, at about .025" & .035" BTE with 19 degree bevels, since I was concerned about toughness & durability out in the field. They are a bear to sharpen & in thinking about it, it really isn't a good way to go for a practical use knife where sharpening out in the woods might be an issue due to the hard material & thickness.

So here's the question, what BTE thickness would you think would work for a field use knife of this design, if it sees some hard use but needs to keep cutting? I'm not talking about chopping bricks or battoning through oak knots all day, but for a knife which is working outside the durability, strength & toughness of the edge are all a consideration. Too many compromises need to be considered (steel type for example), but BTE thickness is a measure of cutting ability & too thick means too much work, too thin & durability of the edge & blade becomes a problem.

I'm still just getting my feet wet with all this stuff, still a nimrod at 65 years old, but I guess I'm looking for a guideline to use for my grinding which will be effective & give a good blade for general field work. Is 0.015" the thinnest you would go & 0.025" the thickest, or would you use different guidelines for finishing the blade?

One of these knives will go to my son as a gift. We find out this morning if he made it through Ranger School & graduates, it's been a long couple of months. I want him to have something to show our appreciation for his hard work & tenacity. Thanks in advance for your input on my question!
 
I believe your blade thickness of .124 is good up to say .140 and down around .093 or even less for the smaller ones.
Frank
 
I take my knives to .010" before sharpening and haven't had any problems so you'll be fine. Congrats and thanks to your son! Nice looking work.
 
The idea that we need @.030" bte comes from the days of heat O1 or 1095 in the forge and quench. With optimal steel structures, unless one is making an extreme survival knife, 0.015" is about as wide as I go, with 20dps.
 
i usually grind to .010, sometimes less, max of .015
as you said "They cut very well & sharpen easily"
I would start thin, if the user finds its not robust enough it can be adjusted with sharpening
as you sharpen back up it get's thicker BTE anyway
 
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I have a Cold Steel Lite Hunter that is 0.01 at the to of the edge bevel after sharpening. I lowered the edge angle after sharpening the first time, but it's still less than 0.015 at the top of a 12 degree edge bevel. I think you'd be safe with 0.02 on the D2.
 
The one thing about an edge that is "too thin" is that it can be "corrected" much more easily than one you have to thin out by grinding away material behind the edge assuming that you have a grind that permits it. A few years back, I had the opportunity to talk with a couple of the guys at the GuildShow in Orlando who had perfected the CPM M4 "race knives"used in big cutting competitions. They said that they would take the edge down to under .015 and if it was too thin, they would just sharpen it back until it worked.
 
Yep I go to .010" as well with a 20* edge. Never had an issue so far. On a larger knife I might leave it at .015" but probably never as high as .020".
 
Thanks guys, helpful input & nice to know that 0.015" is good for most things I'm going to be doing. Sharpening a thick edge (D2) is really terrible & giving a thick blade to someone is not much help to them. Appreciate the input & from now on 0.015" will be what I go with, until there's a reason to change things. I just want something which will cut well & do it's job, without too much work to keep it cutting into the distant future.
 
As long as the heat treat is done right, 0.015 is plenty durable for most applications. Backyard heat treat, not see much.
 
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