Advice on Post Heat Treat Grinding of CPM-154 and D-2

TK Steingass

TK Steingass

Troglodyte Knifemaker
Knifemaker / Craftsman / Service Provider
Joined
Oct 16, 2010
Messages
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Hey Fellas:

I'm going though 60 grit discs like shit through a goose when I grind the flats after heat treat of CPM-154 and D-2. I do my own HT in stainless foil on blades ground to 60 grit prior to HT. When cleaning up the flats to remove the discoloration and take it to 600, I may have to go through two 60 grit zirc oxide cloth PSA discs to remove the discoloration and get it dead flat as it was prior to HT......I temper to Rc 60-62. Is this a normal amount of material use and labor or is there something you fellas do to reduce your costs?

Does taking the annealed blade to 250 prior to HT help?
 
I grind down to a 120 grit prior to HT and take advantage of the annealled steel to bring the knife to as close to completion before doing any HT. Afterwards I only have to deal with removing discoloration and put on the finish. Once steel is hardened it is much more difficult to remove material, so its best to do all that work prior to hardening. I work with 440C and it wouldn't be any different for other steels.
 
Take that stuff down finer TK before the HT . I go to 120 or 220 . It will still eat paper after HT though , at Rc61, that stuff is hard .
 
Even with 1080 and no foil I'm going as far as 320 and sometimes 400 before heat treat. Then after HT I let it sit in some vinegar to remove most of the scale and can finish up pretty easily. I still start back at 120 but progress through to finer grits and then any hand sanding fairly quickly, I'm just removing the oxidized layer and exposing fresh steel rather than trying to remove scratches that are now super hard.

It was a real boost to my speed and belt economy when I started going much further in my finishing before ht. I take the edge down thinner, finish smoother... then after ht let the vinegar remove the hard scale before I even touch a belt to it again.
 
To all:

Man, these are excellent comments! This is going to make my living easier for sure!! You guys should go tell your bosses that I said you deserve a raise. :D:D

Best,

TK
 
TK,

I have found that on 154, which I heat treat myself, that the closer to finish you are, the easier things clean up. Using sealed heat treat foil with a small piece of paper inside almost completely eliminates any de-carb.

I carry my 154 blades through the belt grits to 220, then use hand sanding through 280 prior to heat treating. After heat treat, I put on a fresh 220 belt to lightly take the blade on down to final thickness, then finish by hand starting back at 220, 280, 400, 600, 1000, then a final "hand-pull" to either 600 or 800 grit.

Robert
 
Sorry I am just now getting your question TK. Anyway what I do is finish the flats to 400 grit before HT and then after heat treat I will go back to 220 then 320,400,600,800 and 1000. The hard steel will tend to wear the discs out a little quicker of course.

Alan
 
I work in a lot of CPM-154, and I go to 400 before HT.
By that, I mean a proper 400 finish. If there are 120 grit scratches in the blade, it isn't a 400 grit finish....it is just a smooth 120 grit finish. Those deep scratches will come back to haunt you. Get them all out and do any shaping needed. It should look like a finished knife before you HT it.
Post HT I usually drop back to 220 and go from there to whatever fineness I want.

I find that if CPM-154 is ground to an almost sharp edge, and sanded to a good finish ...it will only take a little work to finish it up after HT.

D-2 and CPM-S35VN are even worse after HT, so get them smooth and clean first,too.
 
Well guys, thanks for all the comments. I just HT some D-2 and took it to 400 prior to HT - polishing the flats afterwards was a heck of a lot less work - I've been trying to polish D-2 and CPM-154 with a 60 grit finish after HT - it's just too much hard stuff to remove to get the scratches out!!

Thanks again,

TK
 
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