Caly Jr. ZDP 189, reground by Tom Krein

[Cliff Stamp]

To be fair, I'd say a relief grind is about the best solution for the situations generally posed.

For individuals yeah, only a handful of people like Thom have the patience to regrind primary grinds without powertools. I am still waiting for him to hollow grind Krein style by hand with sandpaper or stone.

-Cliff

 

[thombrogan]

Cliff,

I'm a bit lost here:

Aside from sharpening the spine, when isn't thinning behind the edge adding a relief grind?

 

[hardheart]

I thought that a relief grind was just an intermediate grind between the primary and the edge grinds. F'rinstance, if you got a knife with a primary grind of ~7, and an edge at ~15, if you make a few passes on the Sharpmaker at 20, you convert the edge bevel to a relief just by the fact that it is now a grind between the primary and edge grind angles. Not so much that the user has to do the relieving, but that it is just a secondary grind. If you go flat to the stone. or have Tom recut your primary, then you aren't putting in an intermediate grind, but changing the primary.

 

[thombrogan]

Could be. In Juranitch's book, I saw edge-to-spine relief grinds shown and praised, so I thought any change short of laminating extra material onto the blade was a relief.

 

[thombrogan]

I am still waiting for him to hollow grind Krein style by hand with sandpaper or stone.

Actually, I've taken to using the corner of an 8" wet wheel to raise a burr and then my D8XX to flatten it out. So power tools do get used; just not my sander (which won't flat grind without repercussions and apparently is armed with the wrong belts for anything but sharpening the final edge).

 

[db]

Even grinding with the spine down on the hone can be called adding a relief. Your just putting on a very thin releif grind. For example a hollow ground blade with a relief added with the spine so low it is on the hone.
Nice to see Cliff back to his old tricks and edit his post more than 11 hours later to take a cheap shot at me.

 

[HoB]

I have been measuring cutting ability and noting the results for ten years. I even have a detailed webpage where I give a number of tests I use and how they measure cutting ability and what is the manner of quantification. This seems fairly ridiculus, I would expect this from db.
-Cliff

Oh, comm'on Cliff. I haven't said that you have never defined cutting ability or that you are not able to. But in this thread you haven't. When you make such a statement, you can not expect every reader to refer back to your webpage....not even me.

A knife with an edge relief vs a primary grind recut, that is what we are discussing. Since the edge will be thicker on a knife with a edge relief the angle has to be more acute to have the same level of cutting ability (as an average of distances around the edge bevel).
-Cliff

When you read your own statements back yourself I think you will find that they read as if you are advising that relief grinding is a bad idea to increase cutting efficiency, and that is absurd, apparently this is not what you intended, but that is why I posted. It also seems absurd that it needed stating that a reground knife is superior to a relief ground, because when you have a knife reground you can optimize it spine to edge to your intended purpose, that should be obvious. [Finally, what I am supposed to refer back to when you say that the edge will be thicker on a knife with a edge relief? The drawing that I posted for that precise reason shows that this is not true. It is thicker *behind* the edge (which is a true statement only on an edge bevel grind, but on a zero edge grind your statement would be nonsense as you could never apply a relief angle smaller than the flat to zero edge), yes, and to determine by how much you would have to decrease the edge angle in order to offset the reduction in cutting efficiency due to the increase in thickness behind the edge seems a very difficult proposition to me and I would even doubt that it is possible all cuts on all materials]..........(thinks long and hard).......average around the edge bevel.....I think I finally understand what you mean. You want to take the average thickness ahead and behind (from the edge) the edgebevel to compare cutting ability (disregard what I wrote in the square brackets, now that I finally understand what you mean). Well, that seems sensible for cuts that are about 1/8" (or maybe even 1/4") deep, but for shallower cuts like shaving, the relief ground will likely perform better while for deeper cuts the spine to edge ground knife will still be way ahead.

I still think that saying that a relief ground blade makes for a weaker edge at comparable cutting ability is a very strange and rather misleading statement. I think it would be far more beneficial to keep the edge and everything behind the edge separate in the discussion. And to me the relief is always applied *behind* the edge. In that case the relief ground blade will never achieve the cutting ability of a spine to edge ground knife (well depending on the grind of course, but as shown in the picture I mean) but it will also NOT affect edge stability. Then we can discuss what you can do with the edge as a separate issue by which you might be able to recover some cutting ability.

P.S. I must say I agree with hartheart and Thom. I see essentially a spin to edge regrind not any different than adding the maxium relief. As you can see from the picture the full flat grind to a thinner edge is a natural progression from the relief grind, and the hollow grind is simply a differently shaped relief. I just looked through Juranich and he most certainly does not say that a relief grind is ideal. He makes very clear that when grinding a relief you are trying to fix something that should have been thinner to begin with.

 

[HoB]

To be fair, I'd say a relief grind is about the best solution for the situations generally posed. When someone asks what to do with knife X in their collection, spending a few minutes cutting a relief with their sharpening stones is probably more plausible than asking the person to get a piece of power equipment and practice, or pay what may be a sizable portion of the cost of the knife to ship it to someone like Tom for a regrind. Even sharpening flat to the stone may be too damaging to the appearance of the knife, or require more work than is reasonable to the individual. Of course, there's also suggesting a knife with better geometry for the task, but that again doesn't really address the question about what a particular user should do with a particular knife to improve cutting performance. When a guy wants his knife to look the same, but 'cut better', it's a bit limiting.

I think that sums it up for me. Now I have to bite the bullet myself and get me a Krein TK-3....have to wait for my tax refund though .

 

[nozh2002]

Mike,
WOW! Thanks for the kind words! glad you are happy with the Caly!

For those that are interested, I charge $35.00 for a regrind. I can do flat or hollow grind and can take them pretty close to what ever thickness you request. Feel free to give me a call Tuesday-Friday in the shop if you would like to discuss a project.

Thanks again!

Tom

Hi Tom,

I was under impression that regrinding may damage HT, obviousely this is no a case. I have small belt Grinder and now want really bad to try to regrind not Caly but Delicas ZDP wich has pretty thick edges and I assume Endura has also thick edge.

Do you think it is possible to do without you skills and experience and if so how not to damage HT?

Thanks, Vassili.

 

[sodak]

I think that sums it up for me. Now I have to bite the bullet myself and get me a Krein TK-3....have to wait for my tax refund though .

It will be money well spent. For the record, I had Tom re-grind a Benchmade mini grip in D2 (Cabelas), a Caly Jr. in ZDP 189 and a Caly 3 in VG 10. I'm still testing, cutting, etc., but man! Already I can tell you, what a difference.

Here's the deal. On my larger camp knives, I thin the edges out, and, if necessary, put in a microbevel. This works great. I'm talking CS Trailmaster, Recon Scout, Busse Steelheart E, Swamp Rat CT, etc. You get the idea. It gives these knives much better cutting ability, and they have the steel that can handle it. I might also add, my smaller Swamp Rats, such as the Howling Rat, Bandicoot, etc., really respond to this treatment also. I don't want to give up toughness, so I don't get them re-ground. I leave the primary grind alone.

Now, on my small folders, I sent a representative sample to Tom Krein. They come back thin enough that they all can tree-top trim my arm hair, and they keep their edge far longer, and they sharpen in under a minute. You don't have to worry about edge bevels, 3 to 5 strokes on a DMT hone, and you have completely re-ground the edge. Completely. It's just another world altogether.

It works great on the smaller blades that are dedicated cutters. I'm probably pushing the envelope here on the edges being delicate, but the cutting and sharpening is so delightful, I'm willing to learn and accept any damage that I might do. The damage is quite do-able, so if you want to see what this kind of performance is like, accept the fact that you will probably chip a blade or two until you get the hang of it. I did.

Not sure I'd want to do this to a larger camp knife, though. Still need something that I can get stupid with! Just my $0.02.

 

[Cliff Stamp]

...when isn't thinning behind the edge adding a relief grind?

When you adjust the primary grind.

When you make such a statement, you can not expect every reader to refer back to your webpage....

I would, unless they were new in which case I would summerize it with a reference. That is why you write such FAQ's.

When you read your own statements back yourself I think you will find that they read as if you are advising that relief grinding is a bad idea to increase cutting efficiency ...

I said it is the worst way to do it and as noted many times, for users it may be the only way.

... but for shallower cuts like shaving, the relief ground will likely perform better while for deeper cuts the spine to edge ground knife will still be way ahead.

If that was the constraint then you would just adjust the edge angle on the reground blade accordingly and it would be the equal of the relief ground blade in cutting ability with a much higher ease of sharpening.


-Cliff

 

[db]

sodak, would you mind telling any more about the blade you chipped?

 

[thombrogan]

when isn't thinning behind the edge adding a relief grind?

When you adjust the primary grind.

Okay, thanks. That still doesn't make adding less-than-primary-obliterating sound like the worst way to enhance performance. In fact, it just sounds like it allows the user to enjoy a thinner blade faster, at the expense of occasionally adding a new relief. Even if the primary grind is altered and we don't have to refer to it as a relief, it, too, will eventually need regrinding and take much more time if manual-powered tools are used.

 

[sodak]

Sure, I thinned out a Queen 4180 in D2. Very thin, probably around 15 deg included, maybe less. I would outcut almost anything else in cardboard (didn't have CPM 10V back then, I won't say that now), but once I started carving in wood with it, I took some pretty large chips out of the blade. I was using a scooping motion, and it really damaged it, probably 1/8 to 1/4 inch long chips. The edge was so thin, I was able to sharpen 90% of the damage out in about 5 minutes.

 

[Cliff Stamp]

Even if the primary grind is altered and we don't have to refer to it as a relief, it, too, will eventually need regrinding and take much more time if manual-powered tools are used.

Yes and that is the optimal method in terms of results, basically the combination of cutting ability, durability and ease of sharpening. However, as you noted, sometimes you can't take the optimal path. For example I would like to reduce the edge thickness on my Wilson 10V blade as it has climbed to over 0.015" with extensive use, but trying to do that by hand is not practical. So I live with a relief grind to the bevel and a very wide edge which has the drawbacks noted. Soon I will send it to Wilson and have the primary reground.

-Cliff