So I just bought a new Spyderco Sharpmaker and a Benchmade 940 Osborne...

I've got an arm-shaving 40* inclusive on my rat-3, and it's a winner. Not sure I'd want to go much sharper on a knife. It will push cut newspaper, and slice-cut cheap gas station toilet paper held between thumb and forefinger (you know, how you hold a piece of paper to cut test).

It would honestly scare me to use it if I went to a 30 degree inclusive with a 40deg back bevel I think.
 
Obsessed with Edges said:
It's still going to take a good while, even with the diamond rods. S30V is notorious for it's abrasion-resistance, which is great from an edge-holding perspective, but also means it resists sharpening (by abrasion) as well. Thinning a thick edge in S30V is a project best undertaken with patience. :)

The only sure-fire way to know when you've reached the apex is to watch for burr formation. A good magnifier (10X or better) is a big plus for this, and use it under very bright light. Don't move beyond the diamond, until you've formed the burr from both sides.
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Ok, great. Once these diamond stones come in I'll probably work with the edge. I've heard some people say it's taken as long as 12 hours to reprofile S30V on a sharpmaker, is that actually... accurate!? Holy crap that's a while.
 
Boias.John said:
Ok, great. Once these diamond stones come in I'll probably work with the edge. I've heard some people say it's taken as long as 12 hours to reprofile S30V on a sharpmaker, is that actually... accurate!? Holy crap that's a while.
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If done only with the ceramics, I don't doubt it took at least that long. There's a double-whammy with ceramics, in that if you have to grind away for very long, they load up with steel swarf and become even less aggressive, almost non-functional. That slows things down exponentially. Even with the diamond, don't be surprised if it takes a few hours, depending on how much metal needs to come off. The downside to using Sharpmaker-sized hones is that it takes more time, due to the small working surface area. A full-sized bench hone in diamond will do the job much faster. Just take your time, and don't rush things. Fatigue is the enemy, and results get sloppy when one starts getting tired.
 
Then I will definitely hold it for a day when I have off, or a day when I come home from work early so I'm full of energy.
 
Boias.John said:
Then I will definitely hold it for a day when I have off, or a day when I come home from work early so I'm full of energy.
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Taking a break for a nice meal helps too. I used to have some rather long sessions with my Lansky kit, with similarly-small hones on some abrasion-resistant steels like S30V (reprofiling a ZT-0350) and D2 as well. Always felt better after having a good steak or something similar for dinner, and the results reflected that. ;)
 
Hell, a steak sounds really good right about now and I haven't even done anything yet. :D
 
My diamond stones just arrived, and so I tested them on a few knives for practice. My Spyderco tenacious, sharpened at purely 40° through multiple resharpenings with the sharpmaker to reduce a small nick, was reprofiled to 30° within the space of about 30 minutes, and brought to hair-shaving sharpness very quickly afterwards. I did notice the appearance of the edge, seeing the rough scratches to gauge my progress in the formation of the new bevel, once the entire edge was rough scratches and I confirmed the formation of a burr, I moved on to the grey coarse stones for 20 passes per side, then to the white fine stones for 20 passes per side. After that, the edge was beyond sharp enough for my purpose. I haven't even gotten my Ultra Fine stones yet, and I'm loving the edge I was able to put on my Tenacious. I did a secondary test with my Cold Steel XL Voyager. I'm unsure of the angle on the edge on this one, but I do remember it was quite obtuse since I could barely slice cardboard with it out of the box. Now with it's new 30*° edge, it slices and dices like a saber.

On a day where I have ample time and energy to devote to the task, I will attempt to reprofile my BM 940 now that I am more confident in my ability to do it. I will most likely practice reprofiling on one more knife, my Skyline, to become even sharper than it is now, and it's pretty damn sharp at 40°. I'm excited to get cracking on this project, honestly.
 
Sorry for multiple posts, but... I've done it! I have successfully reprofiled my 940 to 30 degrees. It, surprisingly, didn't take as long as I thought. I don't have a jeweler's loupe for pinpoint accuracy, but I did notice when I had a complete new edge formed by how much of the black coating I took off. The "metal" color shows as being a lot larger than it was before with the stock edge, and with the diamond stones, the entire bevel was covered in rough scratches. I proceeded to the coarse stone, with began to polish the edge to form smaller scratches. Once I saw minimal scratching on the edge, I moved on to the ceramics, which removed most of the scratches from the edge. This thing is a monstrosity in terms of sharpness now, easily the sharpest thing I've held in my hands. I was able to fold a piece of paper in an upside-down U shape, then slice the paper across. I could never pull that off with any knife, even my Tenacious sharpened at 30 degrees as well. I'm immensely impressed with this result, and I've fallen even more in love with this knife now. The total time was rougly 1 hour.
 
Nice work! :thumbup:

Always good to hear when these projects go according to plan, or sometimes better than planned, if we're lucky. :)
 
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