20CV grind and edge deformation

[chrisjohn]

See evidence of my 7yo. How are your 20CV delicas holding up?

[TkoK83Spy]

Looks like all kinds of different grind angles too. Time for a nice reprofile!

[Evil D]

What kind of bench grinder sharpened that?

[Michael Janich]

When it comes to CPM 20CV, I've always found this summary on the ZKnives website compelling, especially the sentence in italics:

Excellent performance with both, coarse and high polished edges. You still need about 15° per side edge to get the best performance and edge holding. Thinner than that, and you will run into the issue with the thin edge not being able to support all those carbides to make the edge perform. Working hardness can reach 62HRC, and most of the production knives I've seen are in 60-62HRC range. Overall, it is of the best performers as far as corrosion and wear resistance go, and because of that it is a popular choice for high end, and the limited edition knives. Aside from very good edge holding ability, maintaining the edge is very easy. And one more thing worth noticing, there's no stubborn burr forming during sharpening, therefore, there's no risk to form a wire edge either.

Stay safe,

Mike

[chrisjohn]

That's the factory edge.

[chrisjohn]

That's the factory edge.

Thanks for the information!

[TkoK83Spy]

That's the factory edge.

Thanks for the information!

Really!?! That's pretty surprising it would be sent out like that, looks like an obvious variance in grind angles in that bevel.

[GarageBoy]

No way I'd consider that the factory edge. I see at least 3 separate bevels on it

[Evil D]

No way I'd consider that the factory edge. I see at least 3 separate bevels on it

That horizontal line down the middle of the bevel sure makes it look like there are at least two angles on the bevel and I thought it looked a little wide for a factory bevel but sometimes it's hard to tell by a pic.

[chrisjohn]

That is the factory edge, as received from DLT. Sigh...

Took Michael Janich's advice, KO sharpmaker at 15 degrees, no problem.

[awa54]

Some steels (and some factory edge grinding methods) will leave a brittle apex, compared to what you get with a second sharpening... while I haven't noticed this being an issue with the M390 family steels before, that could at least partially account for the damage seen on your edge.

I've had excellent luck with my M390 Delica so far. It's mostly cut tape, cardboard and envelopes, but has also been use on some nylon zip ties, general vegetation and a few end grain cuts on very hard hardwoods. All on the factory edge, with just a few minor touch ups on the SM or a strop.

Hopefully the touch up will cure it, if not a full reprofile is likely to.

My M390 PM2 and CTS 204P Millie have both had plenty of use, some venturing into the edges of "hard use" and they're both at 15dps with no micro bevel (at least until they get touch ups), and I've had no damage on either... but that's Golden HT and the other two M390-ish steel variants, so that may not fully apply to the Sakai blades.