Do you grind pre or post ?

JBS TOOLMAKER

JBS TOOLMAKER

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May 4, 2009
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Alright guys, recently I have talked to a couple of other makers who told me they grind bevels post heat treat. I have always done all my grinding pre heat treat. Usually very little clean-up afterwards and I don't have warping issues. So I'm asking are there advantages to post heat treat grinding ? I would think you go through more belts and have to deal with getting the blade too hot.
I would like to hear from experienced makers pros and cons of pre and post grinding.
Or...you can say to hell with you Stout...It's my prerogative.
 
A little of both. I try to grind as much as I can before heat treat, without getting into warpage issues. Fine line, too; because, if you grind too thin, you get a wavy cutting edge and crookedness. Basically, I grind about halfway, leaving plenty of edge thickness and a decent amount of spine unground.
 
In a DVD I watched on Hollow Grinding, the gentleman ground his folder blades after HT because they were small and didn't take long.
 
It really depends on the blade... and my own damn preference, Stout!:grumpy:
 
I'd say 80% pre and sometimes more than that on larger blades. I don't mind grinding the hardened steel but you have to use fresh belts and that can get expensive quickly. I can use 1 36g blaze and hog out maybe 10 blades with only a few quick passes at 120g pre ht. Then usually 1 fresh 120 blaze and a 65x Norax per blade to prep for sanding. If I did all the stock removal after HT I'd use several new belts per blade.

I do like to grind more intricate features after HT when the steel is not "gummy" but crisp.
 
At least 90% pre-HT. On really small or thin blades it's not worth the risk of warpage, though.
 
I leave 1mm or so on the edge pre-HT, and often put the edge on with a diamond flat file.
If grinding post HT, it's 1 pass and dip every time.
File knives are often done post HT, because they're pre-hardened, so it makes sense to do the grind and then just temper in a domestic oven.
Especially if you haven't got a HT oven.
 
I've gone to doing most grinding post heat treat. I'm not seeing a huge difference in belt life as long as I'm using things like the cubitron II's, Blaze... Heat isn't a big issue unless I'm trying to over use a belt. It's slightly slower, but on the other hand, I'm not duplicating work. On the belts, I DO see a difference in how fast they go from "I should probably switch to a new one" to "this one's history for beveling" but the real bevel lifespan doesn't seem to change much. It just burns your fingers if you are trying to use one past the point it should have been retired to profiling or the trash.

I mostly work in 3/16 and thinner steel though. Depending on the thickness and design I'm either just putting 45's on the edge after profiling and drilling or doing half height grinds at the angle I plan to use or at least close. I leave the edge fairly thick, not brought down to where I would if I was doing most of the grinding before HT. The half height grind just speeds things up a bit. I'm still playing with it to see what size blade makes this worthwhile versus just the 45's.
 
One last thing outta me...pretty much all the advice given here depends what kind if steel and stock thickness you prefer to use. If you like 1080 then you can get by with a lot more post HT grinding than you can if you need to grind a hunk of 10V etc.
 
Thanks guys, Like I said I know a couple of damn good makers who do all the bevel grinding post heat treat. I am always looking for more efficient methods, no matter how crazy it sounds. I definitely will give it a try. There is also some belief that ceramic belts may even last a bit longer when grinding hardened material...maybe a constant resharpening of the grit ?
Marchand....I figured you would be the one to tell me go back to trollville :D ....Canadians :rolleyes:
 
FWIW, almost all knife factories grind post-HT. And I think you're right about the ceramic belts "self-sharpening" as they break down.

Try it and see how you like it, neither way is 100% right or wrong.
 
Depends on the spine thickness. Thin kitchen knife gets gound down flat and most of the beveling is done after HT. Normal knives get forged and ground to about 90%.
 
I use .100-.115 on my gents folders so I'll grind just enough to get the bevels and plunges started then heat treat. only take a few min to grind a small blade. Sometime I can use 1 80 grit belt for 2 gents folder blades, depending on the size.
 
I'm firmly in the post heat treat camp. If I made a lot of large blades from thick stock, I'd probably do some of the grinding before. Doing the edge layout just once and having flat stock to plate quench works well for me.
 
I make slipjoints/lockbacks and grind just about 100% post-heattreat. A few whittler blades require pre-heattreat grinding because of the nail nick. The majority of my blade stock is 3/32 with many pen blades and secondary blades .055 to .075.
 
I grind all of my large blades prior to heat treat.

On smaller blades, I'll occasionally grind one before heat treat.

Grinding after heat treat is tougher on belts, but eliminates any warpage.
 
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