what do you think of these edge measurements?

hardheart

hardheart

Joined
Sep 19, 2001
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These are just thicknesses behind the edges of my clipped folders, which are the knives I use most outside of the kitchen.

BM Rittergrip, M2 .017-.019
Spyderco Paramilitary, S30V .025-.029
Byrd combo edge Cara Cara (plain edge only measured) , 8Cr13MoV .036-.037
Boye boat knife, dendritic cobalt .016-.019
CRKT S2, ATS34 .024-.034

I measured at 4 spots on each blade. The S2 thickens considerably at the tip.
 
My most often carried EDC folder, a VG-10 Calypso Jr., measures from .011-.014" behind the edge. This is reprofiled to a uniform 12 degrees per side.

I've recently been doing some tests with an EKA compact, after taking the primary down to 10 degrees per side thickness behind the edge runs from .008-.011".

I wouldn't care to use either of these two knives for any work that put much torque on the blade, or for prying, etc. For heavier tasks like that I have with me a Becker BK11, resharpened to 10 deg./side, thickness .026-.045" (thicker in belly and approaching tip.) My other folders either have convexed edges which would make measurement kind of arbitrary, or are thicker than the EKA or Caly Jr.

I've never used a Byrd, though I know the Cara Cara is not a small knife, however the thickness on that one surprises me. The rest sound reasonable to me for an all-round EDC.
 
The Cara has a one sided edge bevel, so the edge is taller/higher up the hollow grind. I guess that's why it's thicker. It was quite sharp oob, push cutting over an inch and a half past my grip on newsprint, and is the knife I will use the hardest due to it being about a fifth to a sixth the price of the Spydies and BM.
 
Dog of War said:
I wouldn't care to use either of these two knives for any work that put much torque on the blade ...
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Such as?

My other folders either have convexed edges which would make measurement kind of arbitrary ...
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Curves are as distinct as straight lines, just need more than two points to define them.

hardheart said:
BM Rittergrip, M2 .017-.019
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I have not used a Benchmade in a long time, nice to see the thickness has dropped. What is the angle.

-Cliff
 
hardheart said:
The Cara has a one sided edge bevel, so the edge is taller/higher up the hollow grind. I guess that's why it's thicker. It was quite sharp oob, push cutting over an inch and a half past my grip on newsprint, and is the knife I will use the hardest due to it being about a fifth to a sixth the price of the Spydies and BM.
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Interesting .... are you saying it's actually a chisel ground edge, or just the edge applied unevenly from side-to-side from the factory? The Caly Jr. mentioned barely had any edge applied at all on one side, which was also much more obtuse, as it came from the factory.

Cliff Stamp said:
DoW said:
I wouldn't care to use either of these two knives for any work that put much torque on the blade ...
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Such as?
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Cutting/stripping cables and wires, prying things and other stuff a small precision knife probably shouldn't be used for. :) Perhaps I'm being overly cautious? I've seen a lot of reports of tip breakage on Caly Jrs., and since I really like this knife and can't easily replace it.... The little EKA I'm still doing edge retention work with, but since I bought it mostly to gauge EKA's 12C27 in anticipation of buying one of their fixed blades, I'll get around to durability testing.

DoW said:
My other folders either have convexed edges which would make measurement kind of arbitrary ...
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Curves are as distinct as straight lines, just need more than two points to define them.
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True. I was just giving hardheart dimensions from single bevel edges easily measured with a dial caliper, which seemed the comparison he's looking for. The BK11 for example, because of its more obtuse grind geometry towards the tip, I've actually convexed in that area as the primary is very close to the blade grind. Depending on how I chose to measure, this area of the blade could probably be reported as anywhere from about .050-.075"
 
Dog of War said:
Interesting .... are you saying it's actually a chisel ground edge ...
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The partially serrated ones are chisel ground in the plain edge section.

Perhaps I'm being overly cautious?
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I generally restrict lighter work to hollow ground blades as the edges are thinner and the primary is below ten, the flat grinds are more durable because of all the metal above the edge. Even on the flats like the Opinel they are really thick compared to some of the hollows I have. The big thing is avoid twisting the blade, but that becomes second nature after awhile and there is little I won't cut with even the acute hollows I carry and for something like the Pacific Salt which is full flat with a 10 secondary, it gets really rough use - but the steel is really tough there anyway.

The BK11 for example, because of its more obtuse grind geometry towards the tip, I've actually convexed in that area as the primary is very close to the blade grind. Depending on how I chose to measure, this area of the blade could probably be reported as anywhere from about .050-.075"
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Yes, you need at least two points, one at the top of the bevel and one towards the edge. The two straight lines which intersect these two points and the edge itself will define the curvature. It may seem arbitrary which point to use towards the edge but due to how convex edges on knives are ground the small difference it would make in the curvature approximation are beyond you ability to measure the the thickness/widths anyway.

-Cliff
 
Dog of War said:
Perhaps I'm being overly cautious?
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Not only no, but heck no! Was prying open a briefcase today (it stores my daughter's art set and its lock was reset to a combination neither my wifey nor I knew) with my Nim Cub and, well, it doesn't have a point and there's a disappointingly large chip in the edge near the belly. This was the M2 version. Used it because my go-to RatIcePick (52100 steel ice pick 3/16" thick) was too thick.

Sometimes you have to had a few ounces of force into the cuts you're making to keep your knife from losing a few bits of steel. Not too much, of course.
 
yep, bone stock. Only stropped a few times on loaded leather.

I always have a Lman with me for light prying, and a toolbox in the truck with screwdrivers and a crowbar.
 
thombrogan said:
DoW said:
Perhaps I'm being overly cautious?
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Not only no, but heck no! Was prying open a briefcase today (it stores my daughter's art set and its lock was reset to a combination neither my wifey nor I knew) with my Nim Cub and, well, it doesn't have a point and there's a disappointingly large chip in the edge near the belly. This was the M2 version. Used it because my go-to RatIcePick (52100 steel ice pick 3/16" thick) was too thick.

Sometimes you have to had a few ounces of force into the cuts you're making to keep your knife from losing a few bits of steel. Not too much, of course.
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Appreciate your perspective, Thom. As I was posting I was thinking maybe I'm a bit hypocritical, being an ardent defender of really strenuous knife tests but then having certain knives I use regularly that I tend to 'baby'.

Your story about your Nim Cub is kind of ironic, too, because I often wish more of these modern folders had tool steel blades, and was thinking about that as well at the time. Of course M2 isn't noted as one of the tougher tool steels, but I assume it's appreciably tougher than VG-10 or 12C27. A Caly Jr., or one of the new Caly III's in M2 or even A2 at 61 HRC+ ... I'd really welcome something like that.
 
Cliff,

Space/safety constraints limited me. Nagdabbit, now I want to put Big Trouble In Little China in my to-rent list.

Dog of War,

M2 seems tougher than 154CM, VG-10, and S30V, but that's like comparing the eggshells of Perdue's chickens to those of a fourth-world nation. Had I just broke the lock instead of trying to pry it from the case, only would've had deep (i.e. 0.3" deep) chip(s) in the edge. My SWAG is that, had the edge been thicker, any of those steels would've done well. SWAG2 is that 12C27 is tougher than M2 (only a guess; my C-notch and V-notch Charpy machines haven't been delivered yet and won't be).

There's supposed to be a Calypso III in ZDP-189 in 2007. Though prying metal with its tip might be silly even if Spyderco chose 3V, A2, A8-mod, 8670-mod, or Crucible's Labelle #2 Silicon.
 
I don't know what you do for a living, Thom, but I think you could have a great future as a humorist .... a knifenut version of Dave Berry maybe? :)
 
I just measured my Cara Cara, which I did a slight reprofile with the sharpmaker using a rod as a teeter totter to decrease the sharpening angle. It really wasn't much of a change from the factory angle as it went extremely quick on the diamond rods. Edge Thickness was .025", with an angle of 10.5 degrees (using trig to figure the angle, turns out close to what I thought it was). My R2 was sent off to Ben Dale to sharpen, he said he slightly reprofiled it at the 17 degree setting on the edge pro, which seemed way obtuse compared to what I thought it was, as 15 degrees was only microbeveling the factory angle, but the edge pro doesn't account for the flat grind angle of the whole blade. Edge thickness is .018-.019 at the top of the bevel, with an angle around 11 degrees (again using trig). Looks like I need to flatten that out to the 8 degree range. I will try to measure my reprofiled Jess Horn and get back with the measurements. The angle measurements could be a lot more accurate, as I'm just doing my best to eyeball the hypotnuse as best I can with the calipers next to the bevel, but the angles seem in line with what I thought they were. Any other suggestions for more accurate measurements of the angles without expensive equipment?
 
gunmike1 said:
The angle measurements could be a lot more accurate, as I'm just doing my best to eyeball the hypotnuse as best I can with the calipers next to the bevel, but the angles seem in line with what I thought they were. Any other suggestions for more accurate measurements of the angles without expensive equipment?
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I don't know if this is the way you're doing it, gunmike, but I find it easier and much more accurate to use the inside diameter "jaws" of a caliper as shown here:

101906edge.jpg


Thickness behind edge is actually where I'm more likely to screw up. It's kind of an awkward two-handed proposition, making sure I'm measuring right at the back of the bevel and keeping the caliper perpendicular to the blade; a little wiggling as you work the adjustment on the caliper helps.

The above blade I sharpened to about 12 degrees per side. Thickness is .034" behind the edge, with the bevel .086" wide. This works out to about 11.4 degrees/side ( inverse sine of (.034/2)/.086 ) .... probably fair to say I eyeballed this one very favorably :) but generally you should get pretty close.
 
If the andle width or thickness is really small it will be next to impossible to measure the angles directly to anything but a coarse estimate. You can usually get a better measurement by doing the trig of the angle the blade makes with the sharpening stone.

-Cliff
 
Dog of War said:
I don't know if this is the way you're doing it, gunmike, but I find it easier and much more accurate to use the inside diameter "jaws" of a caliper as shown here:

101906edge.jpg


Thickness behind edge is actually where I'm more likely to screw up. It's kind of an awkward two-handed proposition, making sure I'm measuring right at the back of the bevel and keeping the caliper perpendicular to the blade; a little wiggling as you work the adjustment on the caliper helps.

The above blade I sharpened to about 12 degrees per side. Thickness is .034" behind the edge, with the bevel .086" wide. This works out to about 11.4 degrees/side ( inverse sine of (.034/2)/.086 ) .... probably fair to say I eyeballed this one very favorably :) but generally you should get pretty close.
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That's exactly how I did it. Both of the knives I measured have very distinct edge bevels, where my Jess Horn and Endura Wave have horribly smeared primary grinds from pounding away on the DMT X coarse. Cliff's method of using the trig off of the stone will be the best way to get the angle on those.
 
gunmike1 said:
... have horribly smeared primary grinds from pounding away on the DMT X coarse.
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If the bevel isn't distinct then just use a marker to create a point of reference and measure to that. Check several points along the blade to determine the deviation.

-Cliff
 
Cliff Stamp said:
If the bevel isn't distinct then just use a marker to create a point of reference and measure to that. Check several points along the blade to determine the deviation.

-Cliff
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Yeah, on the Horn I need to have Krein grind the hollow much thinner so I can have a nice, distinct bevel again. I'll try the marker trick, using the very imprecise flat to the stone math (length from edge to where the sabre ends, and the width at the sabre) I get 8.1 degrees at the fattest part by the choil.
 
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