Post HT Bevel Grinding?

A

Augus7us

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Oct 9, 2014
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Is there any advantage to grinding bevels post heat treat? I thought that was just a rookie mistake but, unless I am misunderstanding something, I've seen quite a few posts from makers I have a lot of respect for saying they grind bevels post HT! If they mean cleaning up bevels and putting an edge on then clearly I've misunderstood, however if folks are grinding full bevels post HT, show me light and tell me what I'm missing!

Thanks
 
Yes some makers do their bevels post heat treat. Survive knives is one and Randy Ellis from Entrek profiles and bevels post HT! Less chance of warpage doing this and I'm sure other reasons as well, of course you will be burning up belts quicker.
 
It reduces warp to as close to 0% as you can get and with ceramic belts a lot of steels actually seem to grind better after being hardened.
 
Many people who make folders grind after the steel has been heat treated. With larger knives in carbon steel, taking them to .045 at the edge and then finishing the grind after heat treat is a common practice. Personally I want to forge as close to shape as possible, grind as close to finish as possible before heat treating a blade leaving less to do afterwards. Steel does grind differently after it has been heat treated, it grinds cleaner or leaves a smoother finish after the pass along the belt. Most makers, I believe, do there best to get the blade as close to finished as possible before heat treating trying to push it just to the point where the blade will not warp during quenching. The more knives you make the closer you can push this.
Fred
 
I do all of my bevel grinding post HT. Since I build all of my knives from start to finish, one knife at a time, I can give them the attention they require when grinding to not ruin the temper. I've just found it easier, for my tooling set-up, to do it this way. Those 984F Cubitron ll's don't care if the steel is hardened or not. Like Leif mentioned, they seem to perform better when the steel is hardened. And I agree with his comment about warp as well. Once I moved to this method (which was pretty early on), warp from heat treatment has been a nonissue.
 
With thin steels below .090", it is pretty much the most sensible way. With .060" steel, it is the only good way to grind the bevel. At most, on thin steel I only do the distal taper.
 
I profile and drill my blades and then wrap them and cook em. After HT, I surface grind then grind the bevels to completion. I just make sure I don't overheat the blades while grinding which basically means a dip after every pass, especially when the edge starts getting thin. You definitely need to be using high quality belts. I use Blaze 50's and three grits of Gators.

Bob
 
Thanks for the response fellas. My thought process is pretty much what Fred described and my only logical reason to grind post HT is what Stacy described, steel is just too thin to begin with.

When I said there are makers I respect that grind post HT, Bob you are one of them. What I understand from what you are saying is the risk of doing things this way are damaging your HT, more frequent dips and possibly additional wear on belts. To me those are issues you don't have to worry about so much grinding pre HT. So by doing it this way what are you gaining, if you don't mind me asking?

Thanks!
 
BTW, a 7-9" long grinding magnet ( twin bar type) is your friend here. I grind a pass, and then dunk the whole thing in the tank. Everything stays straight and there is no flex.
 
If you are using S30V, S35VN, M390, Elmax, you want to grind as much as possible pre-HT. According to Brad at Peters, you are safe going down to a .01 edge. Grinding post-HT eats up the best belts like they were made of newspaper.

Tim
 
tim37a said:
If you are using S30V, S35VN, M390, Elmax, you want to grind as much as possible pre-HT. According to Brad at Peters, you are safe going down to a .01 edge. Grinding post-HT eats up the best belts like they were made of newspaper.

Tim
Click to expand...

In the case of S35VN, this is NOT true. I can't speak to the others because I don't use them. I have roughed the bevels (85% of finished?) in on a batch of 4 of my fixed blade EDC's on one 50 grit Blaze belt and seen very little difference from first blade to last.

Bob
 
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