Recommendation? Grinding post heat treat

E.Carlson

E.Carlson

Joined
Mar 28, 2016
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At what thickness do you guys start heat treating before the bevel grinding? I'm looking to start making some kitchen knives and picked up some 15N20 in .072 and .064 to start playing with. I'll be using an evenheat for heat treat. At these thicknesses would you heat before or after?
Also, for those of you that grind post heat treat, do you run all the tempering cycles before grinding?
 
Anything under .090 is where I start grinding post-HT, so yes to both those thicknesses for me. Yes, after all tempering is complete, as that's also where I'm trying to get them straight - nice to start with straight/flat blanks at the grinder. 15N20 grinds pretty easily when hard IME.
 
I've always done all my grinding AFTER full heat treat & temper. I have been using CPM3V & CPM20CV almost exclusively. And having Peters doing my heat treating. I've done thickness up to .208" thick. Have never had a problem doing this.

I am building my own heat treating oven right now, and will start doing the heat treat on my own. (Peters will still do my 3v & 20cv for awhile. I'm going to be using 52100 & 80CRv2 more). I am planning on doing *some* grinding prior to heat treat. But on stock under .100, I will continue doing ALL grinding post heat treat & temper. Especially stock as thin as .064! I see no reason to grind at all that thin before heat treat. Just keep temps below your temper point while grinding. This is easy using a 5gal bucket of cold water. Dip the blade every, or every other pass. Like I said... I've never had a problem. I'm only doing it to hopefully save on 2x72 belts some.
 
I grind virtually everything after heat treat.

However, I grind wet to prevent heat build up.

You will need to do the same for the thicknesses you mention.
 
Do you mess with a foil wrap? I imagine decarb isn't really an issue if you are going to be grinding post HT. Speaking of decarb, does a bit of wood inside the foil wrap really do much to prevent it? (If you can't tell, I just ordered my oven this morning and I'm pretty excited about it.)
 
I find it distasteful to question WHY another knifemaker does something different from how I do......but I'll answer..

I always wanted to make sure that my knifes were heat treated perfectly, and that there would be no chance of warpage. Also was not doing the heat treating, I always felt it would be as easy as possible for Peters to heat treat blades at full thickness. I have been studying and learning for about 6 years, but have only really been making knives for about 3. As I said, I will be grinding pre heat treat on knives OVER .100"(basically 1/8" & thicker knives I do).

I hope that effectively answers you. No need for anything else, as I'm not interesting on debating whatever you feel the need to debate.
 
You can't really foil wrap the oil quenching steels and get it unwrapped and quenched quickly enough. When I am doing all the grinding post HT on things like AEB-L that require high temperatures and soaks, yes, I foil wrap because even though you're going to remove a lot of material, the high temp and time creates a lot of decarb that I don't particularly want to deal with. Pitting even.

The only time I foil wrap oil quenching steels is during normalizing and thermal cycling. That keeps them relatively decarb free so I'm only creating a thin layer during austenitizing.
 
E.Carlson said:
Do you mess with a foil wrap? I imagine decarb isn't really an issue if you are going to be grinding post HT. Speaking of decarb, does a bit of wood inside the foil wrap really do much to prevent it? (If you can't tell, I just ordered my oven this morning and I'm pretty excited about it.)
Click to expand...

Decarb & scale would still be an issue, even grinding post heat treat. I would still ALWAYS use foil or anti-scale compound. WITH EXTREME HEAT.

Yes, I believe the piece of wood or paper is EXTRA care, as it will ignit and use up any O2 trapped in the foil with the blade. I want to try compound before using foil.
 
I send my blades to Peter's so I feel comfortable going down to 0.015" on air hardening steels and 0.03" on oil for stock 0.1" and thicker. They come back straight as an arrow. I like having most of the grinding done before HT. I can crank up the speed and go through fewer belts. After HT I grind slower and dip every pass. On thin stock I profile and send it out.
 
DavidHoback said:
I find it distasteful to question WHY another knifemaker does something different from how I do......but I'll answer..

I always wanted to make sure that my knifes were heat treated perfectly, and that there would be no chance of warpage. Also was not doing the heat treating, I always felt it would be as easy as possible for Peters to heat treat blades at full thickness. I have been studying and learning for about 6 years, but have only really been making knives for about 3. As I said, I will be grinding pre heat treat on knives OVER .100"(basically 1/8" & thicker knives I do).

I hope that effectively answers you. No need for anything else, as I'm not interesting on debating whatever you feel the need to debate.
Click to expand...

Yes, it certainly did.
 
DavidHoback said:
I find it distasteful to question WHY another knifemaker does something different from how I do......but I'll answer..

I always wanted to make sure that my knifes were heat treated perfectly, and that there would be no chance of warpage. Also was not doing the heat treating, I always felt it would be as easy as possible for Peters to heat treat blades at full thickness. I have been studying and learning for about 6 years, but have only really been making knives for about 3. As I said, I will be grinding pre heat treat on knives OVER .100"(basically 1/8" & thicker knives I do).

I hope that effectively answers you. No need for anything else, as I'm not interesting on debating whatever you feel the need to debate.
Click to expand...

Knowing Kuraki as I do, I'm sure he was not questioning your methods, or looking for a debate. I took his question as just curiosity and perhaps learning a different (and perhaps better) way of doing things.
 
What Kevin said, I believe the why was the same as mine, innocent question, always looking for a better way.
 
E.Carlson said:
At what thickness do you guys start heat treating before the bevel grinding? I'm looking to start making some kitchen knives and picked up some 15N20 in .072 and .064 to start playing with. I'll be using an evenheat for heat treat. At these thicknesses would you heat before or after?
Also, for those of you that grind post heat treat, do you run all the tempering cycles before grinding?
Click to expand...
I work mostly with O1, 0.09 or thinner and do my own heat treat. I grind till the edge is about 0.025 to 0.03, at least to 120 grit. I oil quench till black, then between aluminum plates in a vise to room temperature. the blades go into a pre-heated furnace and typically soak 8 to 10 minutes. I temper before finish grinding. not much difference, as I usually temper to Rc62-64. finish sanding is done wet at slow speeds to prevent over heating the blade. the only time I heat treat before grinding is when using thin stock(0.03 or less)
 
Kitchen knives, I grind all post heat treat. I use mostly .091" stock for those. For 1/8" stock and above, not kitchen knives, I do grind pre heat treat.
 
Well, if I mis-characterized a contemptful "WHY", than I do apologize.

Happy I could help an inquisitive nature. Cheers!
 
Many of us even after years of knife making and involvement with forums still have that investigative mind. I know next to nothing about heat treating and a lot of other stuff for that matter but I often want to be involved not to discredit but to enjoy and so what if the member knows even less than me? I can understand him wanting to be involved as I do.
Frank
 
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