Grinding-Before or after heat treat?

[Osprey Guy]

Although the conventional method is to do the bulk of your grinding prior to heat treat, I've read about a number of guys who just rave about the merits of heat treating a profiled-only blade, and then grinding (some do suggest at least grinding off the corners first, prior to heat treat).

I've spoken/e-mailed with a few who also share this opinion (at least one of the guys with whom I spoke is a very well known and experienced maker).

I have a good friend who's a gifted, full-time knifemaker...He has heatreated a couple of blades for me and has offered to continue to do so (He's got a large Paragon oven). When I mentioned the idea of grinding after heat treat he responded with, "why in the world would you want to do that?"

I was hoping to hear from others on this subject...both pro and con.

Thanks...


Dennis Greenbaum

Yeah Baby!

[Ed Caffrey]

On folders I tend to heat treat before grinding to avoid any possible warping problems. If it's a large bladed folder I will do a little rough grinding, but generally leave the edge fairly thick. In response to the gentleman who said "why in the world......" Once you have a folder blade down to less than .125 and it warps, your pretty much done.......I've tried to straighten them and it's just a nightmare.
On the other side of the coin, I wouldn't do it with straight knives......just too tough to grind, and too easy to ruin the heat treat.

[GANNMADE]

The main reason would be getting the blade to hot at various area's thus not maintaining a even temper.

[cactusforge]

Almost all of my grinding is done after heat treating the reason being that there has been no warping. I forge to sharp as much as possible then clean up the profile between normalizing, Have not had a problem with damaging the heat treat by using sharp belts and quenching often. This also saves a step, grind once insted of twice. Gib

[striper28]

Espically with folder blades, if you leave them .010 oversize, then heat treat you have plenty of stock to surface grind down in case it does warp. You just have to keep them cool when grinding. It also helps if you grind in a lead-in grind to help get you started.

[Frank Niro]

I do liner lock folders only and heat treat my blades before grinding. Besides avoiding the possibility of warping I find that for me the greater resistance helps me to keep the grinding under control. Frank

[txwoodchip]

I grind folder blades and small fixed blades after ht. Like Gib says, it saves a step. I also think it saves $ on belts. For small folder blades, I start grinding with 220 grit. I figure if I don't put any deep scratches in the blade, I won't have any to grind out. It's a little slow, but I think it saves time in the long run. Then again, I may change the way I do it any day

[Gary Mulkey]

I believe as Frank said that it is easier to control your grind with the added pressure of a hard blade. It is also harder to "hog" the steel off. For that reason I usually will leave my blades thick enough to avoid warpage problems and finish grind after H/T. This also has the advantage of removing any discoloration from the H/T. (Since I mainly use air quench steels that's most of the time.)

For me anyway, it seems easier to do a finish grind on the bevels after I have fitted the handle to the blade. I finish grind the flats before that only out of necessity. It also seems easier to true the plunge cut with a hardened blade. However, one disadvantage to finish grinding after the H/T is that it definately wears the belts out faster.

Gary

[Osprey Guy]

Interesting how it was so ingrained on me that heat treating before grinding was always the norm...I only began to suspect otherwise after reading a few comments here and there.

I know it's been discussed before, but i really think we should have a forum devoted solely to heat treat...and maybe grinding technique.


Dennis Greenbaum

Yeah Baby!

[cactusforge]

Dennis, For what it is worth, I had a large fishing knife order for a good customer made from 440C, this knife had a 12" blade to be hollow ground. I talked to Paul Bos about the heat treat and he suggested that I profile it and drill the holes and heat treat it, then do the grind. This turned out to be one of the easiest knives that I have made. Gib

[Osprey Guy]

I'm working on making an unusual blade to replace the one that came with the Typhoon balisong knife kit. The (stainless damascus) blade requires 4 very precisely drilled holes (they form a diamond, two pivot holes, which are side-to-side, and two stop pin holes, which are above and below)...these demand far less forgiving tolerances than the single pivot hole needed for the last folder blade I made (the one I lost with the nude carving on the spine).

To further complicate matters, I've come up with a rather complex profile. If I'm to pull this off, it's critical that I get it just right (you'll understand when you see it).

Given all that, I need to really nail the grind on this one (I've tackled a toughy) ...That's why I've been thinking about grinding after heat treat.

BTW- I'm still waffling back and forth as to whether I should go with a hollow grind or flat...I've been busy practicing both.


Dennis Greenbaum

Yeah Baby!

[cactusforge]

Dennis, It is easier to grind a hard blade than a soft one AND GET IT RIGHT without going too far. Gib

[Geno]

My S/S blades are fully gound(except cutting edge) before H/T.
Wrapped in foil, digitally controlled in an oven.
My damascus is a diffefent story.
Quenched steel has scale, so here we go again.
I forge as close as possible and harden the blade, leaving the tang soft for drilling later.
It saves time both ways, one way for S/S, the other for quenched steels(not air quenched)
The size, shape, and thickness play a part as well.

[Osprey Guy]

The couple of small, ATS-34 folder blades I made were nearly ground to completion prior to heat treat. As I mentioned earlier, these were heat treated by my good friend Larry Mensch in his Paragon oven. They came out great with only minimal clean-up required.

He only uses ATS-34 and stainless damascus mostly because (as Larry says), he feels he's "got the heat treat down to a science". (BTW- Larry got his protocal for heat treating ATS-34 from his longtime fellow Central PA Knife Club member, Ken Steigerwalt).

I wanted to use Damascus for this blade...I might have prefered a carbon damascus (for a little more contrast than I'll get from the stainless damascus), but with Larry doing the heat treat I felt safer with the Norris Stainless Damascus.

My biggest issue/concern with this blade is how to deal with the areas that are to be fairly heavily carved. It's one thing to grind after heat treat, another to attempt fine carving on a hardened blade (Most of the heavier carving is behind the plunge...as I type, it occurs to me that maybe I could spot anneal the area to be carved with a fine torch, using a heat sink paste to protect the rest of the blade)...hmmmm.


Dennis Greenbaum

Yeah Baby!

[Don Robinson]

I use air hardening steels for folder blades. ATS 34. 154CM. D2, etc.

With air hardening steels there is no problem with warping during heat treat.

Warping is caused by uneven cooling during an oil quench.

I finish my baldes before heat treat, then just grind enough to clean them up before putting the edge on.

Like Geno said.