Advice needed re: M390 Blade Steel

[Rhodies]

Waiting on a Para 3 coming my way in this blade steel. I can assume that diamond stones are needed for sharpening and maintaining, correct? Any other bits of information would be appreciated e.g. ease or complexity of sharpening this steel, thanks.

 

[maximus83]

I have been able to get my several M390 blades up to a sharpness of shaving arm hair using other abrasives including SiC, and AlOx stones. Other members here have reported that they can get an M390/20cv blade with a good factory edge, and maintain it quite successfully on Sharpmaker using only the included ceramic stones, and a strop. So apparently, multiple abrasives can 'work' at some level.

But having acknowledged that, I've observed hands done with each M390/20cv blade I own: I get the BEST results when I use diamonds in the entire sharpening progression. I even tested some mixed progressions: do the coarse work ~300 grit with a SiC stone, then use diamonds such as DMT F (600), or DMT EF (1200), to finish. This works too, but I got noticeably better results using diamonds end-to-end. It was easier and faster to the results, and the edge was noticeably more refined based on how cleanly and easily it sliced through newsprint.

So my observations from my small set of M390/20cv blades are:

• Use diamonds end-to-end for best results in sharpening. If you strop with compound, make sure you also use diamonds or cbn compound.
• These PM steels are less prone to forming a burr than many other steels. I often get very minimal burr formation even during coarse sharpening. So don't be surprised/disturbed if you don't see a big burr forming even when resetting your bevels.
• I never need to use more than 2 diamond grits and a strop to get these steels to shaving sharp. In many cases, I can get by with merely a coarse diamond grit like the DMT coarse, followed by a strop. I'm not suggesting that more refinement has no effect--it does--it's just that for ordinary folders and user knives like mine, I don't find the additional refinement makes a huge difference or is worth the investment of time.

 

[Rhodies]

M maximus83 - Thanks for sharing your experience and advice. I am planning on ordering Venev Bonded Diamonds for my Hapstone Sharpener but will have to wait until their stock is replenished, early January I was told. I got some time to play with, Para 3 not due until later part of next month.

 

[Insipid Moniker]

For regular sharpening/maintenance I find ceramics are fine and just use the Sharpmaker. For any kind of reprofiling you're really, really gonna want diamonds.