Real World User Experience Sharpening CPM 15V

[Evil D]

It's always puzzling to me when I read people talking about cutting oodles of cardboard, rope, etc., then claiming they can still shave arm hair (and this is not exclusive to 15v - I've seen this claim about various super steels). This has never been the case me for me with any steel, either with the factory edge or with my own edge fully reprofiled down to 14-15dps. I was hoping 15v would be the unicorn, but alas, it seems not. Maybe I'm cutting wrong, or maybe the cardboard I get is especially dirty.

Yeah, I'd say that is normal. I also lose that hair shaving edge quickly on cardboard. Some steels continue to dull quickly after they stopped shaving, but others (like K390) stay sharp enough to keep gliding through cardboard for months without stropping etc, in my experience. But they certainly stopped shaving soon.

I'm still forming an opinion on 15V. I noticed that the factory edges on my Manix and M2 also did not last long, but I am not taking that too seriously. I'm staying away from non-diamond abrasives on these high carbide steels to avoid burnishing. I'll reserve an opinion until I get more miles on a few more edges...

@ejames13

This has been my experience too, and it's no surprise when you understand (as you put it) corrugated boxes are indeed absolutely filthy, the paper itself is not just paper pulp but has fun stuff like clay and sand in it (depending on the quality of course) and the glue that holds it all together is made of starch and is so hard when dried that it might even chip an edge if you tried to whittle a block of it (I'm actually going to find this out).

I have carved hardwood knots and come out with an edge that still shaves (or really more scrapes hair off) but I don't think I ever have with boxes. There are certainly better sharpeners out there than me though so I can't say it's impossible, just definitely not my experience with any steel that I've owned.

[ejames13]

@Evil D and @Brock O Lee appreciate the feedback.

[Brock O Lee]

@ejames13

Quick test to demonstrate how quickly I lose shaving sharpness. Perhaps other people see better results? If so I'd like to know their secret!

Two sharp knives, both shaving arms hair with and against the growth:

Native Chief REX45 (safe queen)
- new factory edge with what appears to be a DMT fine or SM ceramic (?) micro bevel @20 dps
- maybe stropped once I cannot remember
- cut up a sheet 1m x 2m of dirty double wall corrugated cardboard (dusty from lying flat on my concrete garage floor)
- not shaving arms hair afterwards

Manix 15V
- Fresh 2nd edge after factory edge, 1000 grit diamonds @16dps
- 1 micron diamond strop
- cut up a large dirty double-walled corrugated cardboard box, which contained a 3x3m foldable gazebo.
- not shaving arms hair afterwards

Stropped both:
- 1 micron diamonds on basswood, only 3 passes per side
- clean kangaroo leather, only 2 passes per side

Both shave arm hair again, with and against the growth. Not quite hair "popping" like a fresh edge, but clean shaving. They can both slice fine sigarette paper, not quite as cleanly as a fresh edge, but 90% there.

Shaving sharpness on cardboard is fleeting in my experience, longer lasting if you only cut soft media like food.

Posing for a picture after cleanup...


If I define "sharp" as hair popping, and "dull" as not cleanly slicing cardboard", I'd say the shaving sharpness lasts perhaps less than 3% of the life of the edge (my own bold subjective estimate). I lose shaving sharpness after 1 box, but could break down another 30+ before I'd want to resharpen, with K390.

We pay the big bucks for these steels because, unlike their low carbide brothers, they keep this "low-sharpness" plateau for a long time. And a few other reasons of course.

[vivi]

what in the world. I can make PE H1 do what you tried to do and still shave.

[Brock O Lee]

what in the world. I can make PE H1 do what you tried to do and still shave.

Kindly demonstate with a test? Maybe you can teach us something?

Please include edge angle, edge finish, abrasives used and other details.

Perhaps also include a high carbide steel at a similar edge angle and finish I used above as a control.

[ejames13]

what in the world. I can make PE H1 do what you tried to do and still shave.

Kindly demonstate with a test? Maybe you can teach us something?

Please include edge angle, edge finish, abrasives used and other details.

Perhaps also include a high carbide steel at a similar edge angle and finish I used above as a control.

Yes, would appreciate any tips or additional info from you @vivi, as my experience is similar to @Brock O Lee.

[jwesley235]

what in the world. I can make PE H1 do what you tried to do and still shave.

Kindly demonstate with a test? Maybe you can teach us something?

Please include edge angle, edge finish, abrasives used and other details.

Perhaps also include a high carbide steel at a similar edge angle and finish I used above as a control.

Indeed, I too am interested in the outcome of this test.

[vivi]

what exactly do ya'll want me to do? make a video of me cutting a box with a pacific salt then shave some arm hair? are we talking about cutting a box so it fits in a bin or cutting a box into 1" pieces like a psycho?

i'm about to head out for the weekend again but maybe I can do something today

[ejames13]

what exactly do ya'll want me to do? make a video of me cutting a box with a pacific salt then shave some arm hair? are we talking about cutting a box so it fits in a bin or cutting a box into 1" pieces like a psycho?

i'm about to head out for the weekend again but maybe I can do something today

1" pieces like a psycho, of course.

But seriously, maybe you could approximate how many linear feet of cardboard you're cutting until the edge will no longer shave and then give us a rundown of your sharpening process.

[Brock O Lee]

I've now seen one example of how the fine edge retention depends a lot on the type and condition of cardboard you cut, which makes a lot of sense.

I retained arm hair shaving sharpness with and against the growth after cutting up 2 medium sized boxes. Unlike the previous test, these were single-walled boxes, and they appeared to be relatively clean. This was not a massive amount of work, but the results were still encouraging.



The previous was a thick dusty box, which was not kind on the fine edge.

Perhaps also I am seeing a stabilization of edge retention on edge nr 4. On the next edge I plan to go from 16 dps to 15 dps, and drop the micro bevel.

[Cycletroll]

Could we standardize the discussion of cardboard cutting in linear feet cut? A pile of cut cardboard is hard to reference for comparison sake. Just a thought.

[Brock O Lee]

[Skylark427]

@ejames13

Quick test to demonstrate how quickly I lose shaving sharpness. Perhaps other people see better results? If so I'd like to know their secret!

Two sharp knives, both shaving arms hair with and against the growth:

Native Chief REX45 (safe queen)
- new factory edge with what appears to be a DMT fine or SM ceramic (?) micro bevel @20 dps
- maybe stropped once I cannot remember
- cut up a sheet 1m x 2m of dirty double wall corrugated cardboard (dusty from lying flat on my concrete garage floor)
- not shaving arms hair afterwards

Manix 15V
- Fresh 2nd edge after factory edge, 1000 grit diamonds @16dps
- 1 micron diamond strop
- cut up a large dirty double-walled corrugated cardboard box, which contained a 3x3m foldable gazebo.
- not shaving arms hair afterwards

Stropped both:
- 1 micron diamonds on basswood, only 3 passes per side
- clean kangaroo leather, only 2 passes per side

Both shave arm hair again, with and against the growth. Not quite hair "popping" like a fresh edge, but clean shaving. They can both slice fine sigarette paper, not quite as cleanly as a fresh edge, but 90% there.

Shaving sharpness on cardboard is fleeting in my experience, longer lasting if you only cut soft media like food.

Posing for a picture after cleanup...


If I define "sharp" as hair popping, and "dull" as not cleanly slicing cardboard", I'd say the shaving sharpness lasts perhaps less than 3% of the life of the edge (my own bold subjective estimate). I lose shaving sharpness after 1 box, but could break down another 30+ before I'd want to resharpen, with K390.

We pay the big bucks for these steels because, unlike their low carbide brothers, they keep this "low-sharpness" plateau for a long time. And a few other reasons of course.

That's really weird. As I mentioned in a previous post, I was able to take my factory edge on my 15V Shaman through a 4~ inch round oak log a few weeks ago, with nothing but a strop beforehand, and it still shaved hair on my arms. I didn't strop afterwards.

My factory angle was roughly 20° per side, 0.021" BTE thickness. I only ran it through one small log. Not sure how that compares to what cardboard you are cutting.

[Skylark427]

@Deadboxhero

Just finished giving the 15V Manix a new edge. It by no means needed it, I just wanted to get a feel for Spydercos, and you're, special heat treatment on the blade. How'd I do? (Be honest lol I've been sharpening quite a while but I'm not as good as you or others).

I used my WorkSharp Professional Precision Adjust, went up to 800 grit on the diamond plates because that's all I currently have in diamond/CBN (saving for an EdgePro and bonded stones, expensive but will be worth it, as my freehanding isn't what it used to be).

Took it to 15° per side, followed by stropping with 1 micron diamond emulsion. Was very easy to sharpen, was very easy to deburr. That's what I love about this steel. Cuts like a lightsaber, sharpens and strops in 20 minutes.

Thank you again for making this possible. This is exactly what my wife would've loved.

Jacob

Edit: Second picture added(shown as first picture) after a few more minutes on the strop on various grits of diamond compound, then back to the 1 micron diamond emulsion. It's now slicing free hanging paper towels.

[Brock O Lee]

I was able to take my factory edge on my 15V Shaman through a 4~ inch round oak log a few weeks ago, with nothing but a strop beforehand, and it still shaved hair on my arms. I didn't strop afterwards.

Splitting wood is not tough on an edge. The wedge geometry usually splits most of the wood fibres at the apex, leaving the apex with not a lot to do.

It would be a different story if you were to slice the bark off a dirty sandy log.

[Evil D]

Please excuse the Sage in these pics, but I've been playing around with different diamond plates on my Sharpmaker and 15V really likes them vs ceramic. I know ceramic is technically hard enough to sharpen any steel but it feels like I'm doing more burnishing than cutting when I sharpen on the brown rods.

These are Gritomatic Edge Pro plates. I just use double sided tape to hold them onto some 3D printed adapters.

[Skylark427]

I was able to take my factory edge on my 15V Shaman through a 4~ inch round oak log a few weeks ago, with nothing but a strop beforehand, and it still shaved hair on my arms. I didn't strop afterwards.

Splitting wood is not tough on an edge. The wedge geometry usually splits most of the wood fibres at the apex, leaving the apex with not a lot to do.

It would be a different story if you were to slice the bark off a dirty sandy log.

I'll have to keep that in mind to try next time, thank you for the advice. Still, you'd be surprised how many manufacturers knives and different steels/heat treatments do not survive that simple test alone. Even with similar edge angles and spine thicknesses, and similar BTE thickness.

Now I know what to do next, as these logs definitely are not clean.

Edit: More knives have actually failed at the apex going through those logs (through the diameter) than have passed. I'm a bit new to Spyderco knives though, so I only have other brands to compare so far.

Edit 2: @Evil D

Wait didn't you mention that cutting through branches that are 1 inch thick is decently hard use? I've been reading older threads. Wouldn't cutting 4 inch logs be considered decently hard use as well?

[Skylark427]

Please excuse the Sage in these pics, but I've been playing around with different diamond plates on my Sharpmaker and 15V really likes them vs ceramic. I know ceramic is technically hard enough to sharpen any steel but it feels like I'm doing more burnishing than cutting when I sharpen on the brown rods.

These are Gritomatic Edge Pro plates. I just use double sided tape to hold them onto some 3D printed adapters.

That's actually a really good idea. I haven't owned a sharpmaker since before the robbery, but that makes me want to buy one again.

Also, I believe ceramic will sharpen the steel matrix, but not cut the carbides themselves for 15V.

Edit: I'm stupid those are Rex 121 I do believe the carbides are still harder than the ceramic itself though.

[Wandering_About]

Vanadium carbides are harder than ceramic sharpening media. 15V is designed to be very rich in vanadium carbide.

Here's a helpful graphic I borrowed from the Knife Steel Nerds site. Vanadium carbide is VC on this chart, compare to alumina and silicon carbide (sharpmaker ceramic rods are alumina)

[Evil D]

Edit 2: @Evil D

Wait didn't you mention that cutting through branches that are 1 inch thick is decently hard use? I've been reading older threads. Wouldn't cutting 4 inch logs be considered decently hard use as well?

Hardwood knots are pretty nasty especially when dried out. Cutting green wood is very different from cutting any dried wood. I think it's harder use on the lock and pivot than the steel, but hardwood can definitely chip an edge.