Edge thickness before heat treat

Nathan House

Nathan House

Joined
Feb 14, 2000
Messages
1,204
I am needing input on the edge thickness before HT
does the difference in steel change the edge thickness before Ht
I am using 1/8 D2 and it seems like it can take a thinner edge
before Ht and hold up.with a Rc around 60 to 61 My blades are almost done before I send them out for the HT I have very little to do when I get them back,I can hand rub them out to get the color back then
I am ready to do fit and finish,does any one else do it this way.
Thanks for any input.:)
 
:)

I'm just the opposite. I grind everything after heat treatment, especially the "S" steels. Barehanded, 3M 967 belts, and slow speed.
 
I know alot of folder maker grind after Ht,I am not to folders yet
I am going to master the fixed blades then work into folders.
I have been thinking about grinding my blades after Ht also I see alot
of benefits to it
 
Nathan,

You have a lot more experience than me so I hesitate to answer, but I did try leaving 3 d2 blades thick before heat treat. The first 2 took sooooooo long to finish with 60 grit zirconia belts that I'm going to throw away the 3rd blade - I could make 2 new ones in less time.

I asked my heat treater (Pacific Heat Treating in Sunnyvale) how thick I can leave them. Of course no direct answer, but the problem he explained was not the thickness, but rather the difference between the edge and the spine. It seems the warping is caused by the blade cooling at different rates due to thickness.

My last set of S30v I had 3/16" and 1/8" all were taken down to .030 on average. No warping.

Next set I'm gonna finish out to 400 grit. Grinding (and heating up) hardened steel is too big a hassle.

Steve
 
Steve
I am pretty new at knife making also,I have used 440 c for my first blade.I am trying D2 because I like the edge holding ability of it.
I have ground a couple out and I am sending them to Paul Bos for Ht
I ground them up to 400 grit they are right around 25 thousandth
I called Paul and spoke with him about the edge thickness on them
and he said that it would not be a problem.At 60 to 61 Rc the D2 would hold a very good edge?
 
Nathan,

The 2 knives I finished in D2 have a sweet edge on um. I left them too thick to really shave thin. However, they both be made to shave hair. The shocker to me was how they went thru cardboard.

The edges dulled faster than I expected, but I think it's because I haven't found the proper angle yet.

Mine tested out at 60RC and those edges took a long time to grind.

One thing I did find out it you can't hack up a piece of wood with them. I don't know if the problem was the steel, heat treating or me. But the edge seems to chip pretty easy. Then again I don't think D2 is known for its toughness.

A friend was over to the house when my daughter came by to have me cut her shoe laces. I said sure, but they were leather. I took out a 5" D2 blade and popped the laces like a piece of thread. My friend's eyes popped out of his head.

If I had it to do over I would have done EXACTLY as you. .025" sounds perfect. I can't wait to hear back from you on how they perform.

Steve
 
BTW,

Pacific Heat Treat said that D2 doesn't really benefit from cryo treating, like 440 and others. So I didn't get that done.

I'm reallllllly interested in what Paul Bos says about cryo and D2. Are you having that done?

Steve
 
Steve
I have found a thinner edge cuts better than a thicker edge
On the toughness of D2.D2 is a tool steel made with enough chrome in
in to make is stainless(11%).D2 is knowen for it's toughness they make dyes from it which it takes very roughed steel to withstand that
About Pacific Heat Treat,I do not know why they would tell you that
the D2 does not need to be cryoed.I spoke with Paul and I think the cryo would benefit any steel.So to some it up D2 is a very tough steel with excellent edge holding ability.I may go out on a limb on this but I think a proper HT D2 blade will hold it's on on the sharpness part up there with the New Steels(s30v etc).I think on your next batch of knives,I would send them to Paul and watch the performance you will get from your blades.A knife is only as good as it's Heat Treat
;)
 
Hi Nathan,
My experience has been that D2 blades from Paul Bos do not come
back warped at all. I have ground them to final size. one thing
that I was always concerned about was that D2 has a rather low tempering temperature, so if you overheat it, the temper is gone. I use a belt grinder that runs very fast, so what is a concern for me but maybe not for others who can slow down their grinders. It is real easy to overheat the edge to above 400-450 degrees F. with a fine belt and fast speed. BE CAREFUL! I have also wondered, at times, that some people have had bad experiences with D2 because of this and thought it was the alloy.
 
Don
Thanks for the input,I trust Paul with all my blades.
I have a VS grinder so I run slow.I do not grind fast even when hogging,I find I have more control at a slower speed,Maybe as I grow better at grinding then I may speed it up,but for HT blades slow is the key.:)
 
Don & Nathan,

This is a very good thread.

So, there might be a problem with my blades from overheating. Because they were so thick before HT I had to do a lot of grinding. While I didn't discolor (ie burn)them and tried to watch the temp, who knows? Maybe they did hit 400.

BTW: Since then I have bought belt grease. It makes an amazing difference in overheating with course grits.

So 2 things I've learned:

1. Cryo might benefit D2 - enough to give it a try.
2. Grinding down to final dimensions has a number of benefits - Less time, chewing up fewer belts, less risk of overheat. The potental downside is warping - but that my not be as big an issue as I thought.

Thanks guys,

Steve

PS I don't want to give the impression I'm not happy with these D2 blades. I am happy with 'em. They are awsome cutters. They just edge chip easier than I thought.
 
A couple of years ago, Pacific Heat Treat told me that 440C and ATS34 don't benefit from cryo either, so they don't do it unless specifically requested.

Paul Bos treats all my blades now.
 
Steve
With much better HT you will see a big difference in the overall
performance of your knives.Stick with Paul he knows his stuff.
:)
 
Guys On any blade mat. leave at least .030 on edge. I do cryo all steels, The reason I do this is because all the tests we have done shows it dose help on edge retention and thougness, I dont know the scientific reason why but it works. On the tool steels I do it after the first temper, on the stainless I do it after the quench. I know other people might do it different, This is just the way I do it and it seemes to work.On my process for D-2 I temper @ 950 Deg. F for a 60-61 R/C, D-2 also has a secondary temper like ATS-34 and 154-CM Paul.
 
Pacific Heat Treat is an OK place - seems they do a lot of tool stuff. Knives are on the side.

I took in some S30V and asked for 1950 for the hardening and 650 for the temper and a long cryo( based on spec sheets from CM and what Paul has posted). They wanted to do 1900 cause that's where they normally run the ovens. And then wanted a 400 degree temper. I told 'em nope I wanted what I wanted. They said they did it, but I just didn't get the feeling that they were interested in the same things I was. Their priority was their own convenience.

I guess it's time to use Paul.

Steve
 
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