CPM 15V Sprint sharpening and performance thread

[blueblur]

Interesting.

I took a 52100 blade up to a very high polish once and when running along a couple of those little air filled packaging “pillows”, the edge was blunting fairly quickly. That is when I realized a coarser, toothier but refined edge has its place and its not always beneficial to take edges to high grit levels.

When I sharpen the mule I’ll bring this edge back to life and keep an eye on it.

I’m curious to hear others’ experiences with how their edges are lasting.

Hmm, to me it kind of sounds like you're creating a wire edge which rolls over very easily. That's very easy to do when relying primarily on edge-trailing passes, and by the sounds of your progression, you do a lot of those. Granted, since you can't exactly use an edge-leading pass on a strop with soft substrate, you may want to try kicking the angle up ever-so-slightly--if you're doing this on a guided system, just increasing it by .5-1 degree should be adequate. This helps kind of "break" the wire off. If you do this in between grit transitions, and then on your finishing grit just keep the angle constant, I think it will probably mitigate pulling any wire out while also achieving the high apex refinement you're seeking. The downside is that it creates an ever-so-slight microbevel which makes it hard to determine--if it solves the issue--whether it was down to a wire edge or geometry.

I would try taking the edge down to the 600 and 1200 plates and do no stropping, but finish on them with edge-trailing strokes. If it's an issue of forming a wire edge, then there's a good chance you'll see the same rolling even when finishing on those and can rule out it being a difference between coarser and highly polished edges. On the other hand, finishing on 600/1200 with edge-trailing strokes might reduce a wire edge just by the effect of doing many less passes than when transitioning up through grit--the reason wire edges form is because we're basically drawing metal off of the plane of the bevel and into a strand sticking off the apex, almost akin to a spider drawing silk out of its spinnerets. That being the case, I would say to do as much edge-trailing finishing strokes on the 1200 grit as you would through the entire progression of grits, but being mindful to reduce pressure quite a bit. So for example, if you'd normally do 50 strokes on the 1200 grit, then 50 on the 1 micron, 50 on the .5 micron, and 50 on the .25 micron, just do 200 on the 1200 grit by reduce the pressure you're using by about half at every 50 stroke interval. If you end up with the same kind of rolling even finishing like this on the 1200 grit, then I'd say that would rule out it being the difference between low and high grit finishes.

The reason the wire edge theory seems so plausible to me is your anecdote about 52100 rolling after cutting into those plastic air pillows. To me, that signals that there is a very ductile wire hanging off of the apex, and if you're getting that on the 52100 blade as a result of your method/technique, it's reasonable to assume it's happening on the 15V too. The factor that would normally make me doubt a wire edge, however, is that they're typically a lot more common to encounter on softer, tougher steels because the ductility imparted into the wire created. Even on moderately hard and less tough steels, a wire edge is more likely to break off of the apex, and so with 15V not being that tough, and being hardened to 65 HRC in the Shaman, it's kind of hard to imagine creating one. On the other hand, one thing I have seen remarked on quite frequently about the 15V in these folders is that it is much easier to sharpen than most anticipated, so I could see that translating into it being as easy to create a wire edge on them than anticipated too.

Maybe we could get @Deadboxhero's opinion on this. He's surely a much more experienced sharpener than I am, and of course designed the heat-treat we're using on this steel, so he could poke holes in my theory if it's unsound, but that's my $0.02.

That’s a lot of great info, thank you. I’ll try out some of your recommendations this weekend.

[Deadboxhero]

Sharpness Test

[RustyIron]

ROLLS and CHIPS



Here's pics of my Manix 2 in 15V.
Maybe it has a bad heat treatment AND the edge was burned during sharpening.

[dull&blunt]

^Maybe I'm missing context but what did ya use that blade to cut?

[RustyIron]

^Maybe I'm missing context but what did ya use that blade to cut?

Weren't nothin' more than a small chunk of fuel hose in a remote location high on the mountain.
Oh... and the hose had some steel reinforcing wire.

A little later I'll whip out some stones and put on an edge suitable for the most delicate manscaping tasks. The knife did was it was supposed to do. If the knife wouldn't cut the hose, then it would be a failure and I would have thrown it down the mountain. All is well.

[vivi]

Whenever I'm cutting something with steel in it, if it's possible I try to do it on a hard, flat surface and push it straight through, or even lightly baton it straight through. In my experience this minimizes edge damage VS slicing. Of course when out doing work there isn't always a suitable spot for doing that.

[electro-static]

^Maybe I'm missing context but what did ya use that blade to cut?

Weren't nothin' more than a small chunk of fuel hose in a remote location high on the mountain.
Oh... and the hose had some steel reinforcing wire.

A little later I'll whip out some stones and put on an edge suitable for the most delicate manscaping tasks. The knife did was it was supposed to do. If the knife wouldn't cut the hose, then it would be a failure and I would have thrown it down the mountain. All is well.

Definitely not a task that would have been expected from a steel like 15V. Let us know how the sharpening tasks go.

[RustyIron]

Definitely not a task that would have been expected from a steel like 15V. Let us know how the sharpening tasks go.

It's all good now. Like I predicted, it's more than sharp enough for its intended use. Before replying, I stuck it under the scope. There are still a couple little dings visible, but they're fine. To polish them out would seem wasteful.

The knife and the steel performed as expected. I guess the point I'm trying to make is that you should use the knife to do a job, and if you need to sharpen it afterwards, it's just part of owning a knife. The sharpening took less than 20 minutes, and that included touching up the edges on a couple other kitchen knives.

[RustyIron]

Here's another 15V shot.
The Manix 2 is the perfect knife for cutting up cauliflower.
For dicing onions, it's too short. But it was already dirty, and I didn't want to clean two knives.

[Wandering_About]

Nice! Put that 15V to work! It's not just for collecting.