Reprofile or Regrind?

[ssblood]

I got a new Emerson Commander but am not a fan of the chisel grind at all. I guess the blade is a sabre grind and that's not a big deal for me. Would I be better off to reprofile the edge to something that would make the edge easier to use and maintain or to have someone regrind the blade?

 

[richard j]

i would sharpen it to a v edge which would make it easy to maintain just like a normal grind blade.

 

[Ankerson]

I got a new Emerson Commander but am not a fan of the chisel grind at all. I guess the blade is a sabre grind and that's not a big deal for me. Would I be better off to reprofile the edge to something that would make the edge easier to use and maintain or to have someone regrind the blade?

If you get the blade reground it would need to be tempered again to relieve the stress caused by the grinding.

That can get expensive depending on who does it.

 

[Atlas Knife Company]

Retempering would take 30 minutes and he could do it himself. Remove the blade, reshape to a V edge and drop in the deep fat fryer at 400° for 30 minutes.

 

[cziv]

Retempering would take 30 minutes and he could do it himself. Remove the blade, reshape to a V edge and drop in the deep fat fryer at 400° for 30 minutes.

Cool tip man - thanks! :thumbup:

Edit: Sounds like a really bad tip now. Sorry dude. :thumbdn:

 

[hkpokes_you]

If you get the blade reground it would need to be tempered again to relieve the stress caused by the grinding.

That can get expensive depending on who does it.

For knives? I really do disagree with that. Someone who has a lot of experience with regrinds -- like Richard J or Tom Krein -- can chime in on this, but if you keep the blade under the initial tempering temperature, you won't have a problem; ever. Tom even grinds his blades after heat treatment. Just keep them cool.

If you do your grinding with a belt grinder you don't create the sorts of stresses that shears, dies, or drills can cause. You don't cause enough deformation relative to abrasion to create any significant stress in the material.

Unless you're doing something amazingly stupid to begin with....

 

[Ankerson]

For knives? I really do disagree with that. Someone who has a lot of experience with regrinds -- like Richard J or Tom Krein -- can chime in on this, but if you keep the blade under the initial tempering temperature, you won't have a problem; ever. Tom even grinds his blades after heat treatment. Just keep them cool.

If you do your grinding with a belt grinder you don't create the sorts of stresses that shears, dies, or drills can cause. You don't cause enough deformation relative to abrasion to create any significant stress in the material.

Unless you're doing something amazingly stupid to begin with....

Take 2 blades that are the same and grind them both thin, say .010 or so behind the edge. Re-temper one of the blades after grinding and leave the other not re-tempered.

Now stress test the blades by pushing the those thin edges the same way and tell me what blade fairs better.

 

[hkpokes_you]

...stress test the blades by pushing the those thin edges the same way and tell me what blade fairs better.

Use good belts, keep it cool, and my money is on it not making any difference.

Unless you commercially heat-treat knives I'd be more worried about temper embrittlement from a raw-dogged secondary heat-treatment. Especially if you throw it in a deep-fryer; if you can get accurate temp ranges from it a deep fryer, or any sort of liquid bath setup, it is not a bad way to temper a blade -- but it's such a powerful piece of equipment I would REALLY caution anyone against using it cavalierly. You could easily wind up with a Darwin Award.

 

[Ankerson]

Use good belts, keep it cool, and my money is on it not making any difference.

Unless you commercially heat-treat knives I'd be more worried about temper embrittlement from a raw-dogged secondary heat-treatment. Especially if you throw it in a deep-fryer. :jerkit:

Take those blades and a piece of wood like hard pine push the edges in the wood like you are whittling and snap those blades out sideways a few times then come and talk to me.

 

[richard j]

i reground an emerson a-100 for joezilla and he said the blade was holding up great when i asked him a few months ago how it was doing. i would say that joe has done exactly what you are saying would make the blade fail.

 

[hkpokes_you]

Take those blades and a piece of wood like hard pine push the edges in the wood like you are whittling and snap those blades out sideways a few times then come and talk to me.

Really, ask someone like Tom Krein about the durability of regrinds without secondary heat treatment if you don't believe me.

And you could really easily screw up the initial temper with a secondary heat treatment that didn't austenize the blade all over again. Especially with a .01" edge. I really think you'd see blades re-ground without additional temper-jobs being more durable.

Did you do the test? Who did the regrinds? Get that guy to defend it.

 

[Ankerson]

Really, ask someone like Tom Krein about the durability of regrinds without secondary heat treatment if you don't believe me.

And you could really easily screw up the initial temper with a secondary heat treatment that didn't austenize the blade all over again. Especially with a .01" edge. I really think you'd see blades re-ground without additional temper-jobs being more durable.

Did you do the test? Who did the regrinds? Get that guy to defend it.

Did you do the testing yet?

Do the testing and see what happens and I am not talking about being careful with them either.

I am talking about stress relief, not heat.

 

[pwet]

Ankerson how do you about this ? Have you done the tests you're talking about ? I want to know

Never heard about this but all i know is that i won't try to retemper any blade at home especially in à deep fryer ...

Anyway, if you're right every single people who sharpen à belt sander should worry about their blades ... if well done, à regrind shouldn't be way more stressful than applying an edge to à belt ... you're supposed to cool the blade often when grindibg, even before heat treat, à burned blade is screwed even before HT.

Just.my thoughts

 

[Ankerson]

Ankerson how do you about this ? Have you done the tests you're talking about ? I want to know

Never heard about this but all i know is that i won't try to retemper any blade at home especially in à deep fryer ...

Anyway, if you're right every single people who sharpen à belt sander should worry about their blades ... if well done, à regrind shouldn't be way more stressful than applying an edge to à belt ... you're supposed to cool the blade often when grindibg, even before heat treat, à burned blade is screwed even before HT.

Just.my thoughts

Not talking about sharpening here, I am talking about regrinds, thinning the blades out, removing a lot of metal.

Not going to point fingers or anything....

I have seen production knives that would chip, crack or roll or fail in some way without too much trouble if they are really pushed.

Production blades run around .025 to .030" thick behind the edge usually.

Cut that in half by regrinding them to .010 to .015 and they will fail that much easier and that's not even adding the stress of removing the metal.

Customs are a whole different ball game though, or should be depending on the makers.

 

[pwet]

i know what you're talking about. it's just that removing a lot of metal is exactly the same as sharpening if you cool the blade frequently. the only thing that can change something in a regular HT'd steel is heat. not talking about special steels that work hardens.

but seriously have you taken the tests ?

for the OP, i would keep the knife as is, i had the same feeling when i received my cqc-8, now i don't care anymore. i've not found any benefit to the chisel sharpeningbut i'm just used to it. the more ankward is the angle the beveled side is ground at but keep in mind there's almost no angle on the other side, so this side is ground steeper to keep a normal inclusive angle. lift the spine when sharpening, and use some sharpie marker the first week...

 

[Sparljo]

Ive done a bit of testing with regrinds.

You can pull it off by keeping the blade cool for sure. Best results here with simple carbon steels. Ive messed up alot of stainless.

Normally a blade will get too hot to hold long before you will affect the temper. Having a handle to hold on to changes this a bit, makes it easy to heat up the blade too much.

You can burn a blade out before turning it blue though in my experience. when this happens it no longer takes a good edge, but flops around a bit.

Cool idea on using a deep fryer to temper, never thought of that.

Could be wrong on this, but I dont think you can just re-temper a burned out blade to fix it, you would have to reharden and then temper. Not sure how the deep fryer would work for a stress relief, probably fine.

 

[pwet]

Could be wrong on this, but I dont think you can just re-temper a burned out blade to fix it, you would have to reharden and then temper.

that's it. a tempering cycle would be helpfull only if by an incredible luck you first heated the blade enough to anneal it then, let it cool, reheat to the exact quenching T°C and let it air cool if it's an air hardening steel.

for information s30v needs to go as high as 400°f to affect the temper can you keep your fingers on bare steel at 400°F. i'm a chef and i can't. any amateur knifemaker knows that grinding should be done without gloves for this very reason.
for carbon steels the temperatures are a bit lower but not much

imho no big risk if the regrind is done by a real knifemaker.

again i'm no metalurgist or knifemaker, this is just my understanding, if it's not correct, correct me.

 

[hkpokes_you]

Did you do the testing yet?

Do the testing and see what happens and I am not talking about being careful with them either.

I am talking about stress relief, not heat.

Stress relief not heat? If you want to do the stress relief by heating it above 250f -- unless you austinize it again -- you can create new problems. Martinsite can only benefit from being tempered so many times, or for so long. The first few tempering cycles after quench lower the RC and make the blade more ductile. But, you get diminishing returns the more you temper. First you flat-line for improvements in ductility. Then you start making the blade more brittle by tempering too many times.

Really, if I had to guess WHY some reground blades were brittle I would blame it on the heat caused by a bad regrinding job; I think it's thermal rather than simply mechanical brittleness. Especially if you're noticing the edge chip or crumble. That's where you'd see it most.

 

[cziv]

Is there any consensus regarding the the OP's question? Could he re-profile his Commander to a V grind and be okay?

 

[Rat Finkenstein]

I got a new Emerson Commander but am not a fan of the chisel grind at all. I guess the blade is a sabre grind and that's not a big deal for me. Would I be better off to reprofile the edge to something that would make the edge easier to use and maintain or to have someone regrind the blade?

If you don't like chisel grinds, avoid them. But for ease of maintenance, a chisel grind is super easy to sharpen. I would probably sell the knife and get something useful with grinds how I like them to start. I like chisel grinds on my chisels.