bm's s30v

S

skitertank

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Jun 12, 2009
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i have a benchmade 940 osborne with an s30v blade. i like the design and the axis lock but im not sure about the steel. everyone loves s30v and praises it for being a super steel but i have had nothing but trouble when it comes to sharpening it. i hand sharpen and can put a razor edge on all my other knives but this one just seems to get close to razor sharp but not quite. it roughly cuts paper and it wont shave hair. i have recently convexed it and it made a big difference but its still lacking that "edge". any experiences with this and sharpening tips?

josh
 
Mark the edge with a sharpie and sharpen to make sure you are hitting the edge, what grit do you finish with?
 
I have a BM Activator in S30V that isn't a problem with my Sharpmaker. I did, however, have a problem with my D2 Spyderco Paramilitary. It was a bitch to sharpen until I got a course DMT whetstone. I just got an Edgepro Apex two weeks ago and now all my knives aren't a problem.
 
What are you using to sharpen with?

I have found that on my S30V knives, diamond seems to get a better edge.

I have been stropping with diamond paste of late and it seems to get a better edge when stropping S30V versus the old chromium-oxide, too.
 
when i had a beveled angle edge i used everything from smith diamond stones,arkansas stones, and the lansky kit and i always ended up with a rough edge that wouldnt even cut paper. i have since convexed the edge using wet dry sandpaper starting with 600 and ending with 1800 to get the convex and then i have a good leather belt to strop on. now it has a much better edge than before that will slice paper but i still cant get it shaving sharp. i dont have this problem with my sog, sak's, bucks,or anything else. my bravo 1 needed a touch up so i used the leather belt and a couple strokes later it was back to being silly sharp so its not the leather and i wouldn't think its my technique if everything else is fine..

i have read a few reports on s30v chipping at the microscopic level, which is usually caused by a poor heat treat.. but bm has a pretty good heat treat i would think since i never had a problem with thier 154cm..maybe i got a bad heat treat..?
 
A bad heat treat could be a possibility.

If all else fails, as it appears it has, try Benchmade's customer service. They may replace the blade for free with luck.
 
skitertank said:
i have a benchmade 940 osborne with an s30v blade. i like the design and the axis lock but im not sure about the steel. everyone loves s30v and praises it for being a super steel but i have had nothing but trouble when it comes to sharpening it. i hand sharpen and can put a razor edge on all my other knives but this one just seems to get close to razor sharp but not quite. it roughly cuts paper and it wont shave hair. i have recently convexed it and it made a big difference but its still lacking that "edge". any experiences with this and sharpening tips?

josh
Click to expand...

orthogonal1 said:
What are you using to sharpen with?

I have found that on my S30V knives, diamond seems to get a better edge.

I have been stropping with diamond paste of late and it seems to get a better edge when stropping S30V versus the old chromium-oxide, too.
Click to expand...


Diamond hones should give you a better edge. S30V has enough Vanadium carbide in it that I would think you would need diamond hones. Vanadium Carbide is harder than any common sharpening medium except diamond.

I get a much better edge on D2 using diamond hones than I do with aluminum oxide. And D2 has less Vanadium Carbide than S30V.
 
One theory I've toyed with is that the Vanadium Carbides get ripped out of the edge when using some sharpening stones.

S30V is the reason I've been investing in diamond sharpening implements.
 
Spyderco ceramics are purported to be harder then the vanadium carbides.

FWIW I've never had a problem sharpening Spyderco S30V (and ZDP-189/S90V) all the way up to the ultra fine ceramic rods for that hair popping edge. :thumbup:
 
I think the chart is intended for use with coatings, but I think it makes the desired point that the common ceramics may not be up to sharpening some steel alloys.
 
I had the same problem with a Skirmish a few years back, sharpening wouldn't take, rough edge, felt glass-like when sharpening it. I contacted Benchmade, and they replaced it due to bad heat treat. Not sure if that's the case here, but Benchmade made mine right.
 
Josh K said:
Interesting chart, never seen that before. I wonder how they got a titanium carbide, as far as I know titanium doesn't form carbides.

Yes, they are technically synthetic sapphires. :) I seem to remember Sal saying they had a hardness of RC 97 or something though.
Click to expand...

Both ruby and saphire measure ~2,000 on the Knoop scale. Vanadium Carbide measures 2500. Ruby and Saphire are both essentially aluminum oxide. See chart below.

Carbidehardnesses.jpg
 
Personally I found the 940 to be a bit of an odd ball. To get an angle I felt acceptable for the blade I had to remove the thumbstuds and sharpen it much steeper than possible with them attached. After that it was about the sharpest knife I ever owned or own.
 
The fact that the carbides are harder than the stone has no effect on its ability to sharpen said knife. I laugh at those that say you can't sharpen steels like S90V on a spyderco stone.
 
depends on your definition of "sharp", I suppose.
I can sharpen D2 on my Sharpmaker, but I can get it sharper with a smoother edge using diamond hones.

A triboligist will tell you that when you rub two objects together, it is the softer one that wears. Since Vanadium carbide makes up only a small percentage of even S90, yes, you can wear away the steel around the carbides to form an edge. You cannot smooth the carbides to have the same profile as the rest of the blade. It will be close, the carbide in both S30V and S90V are small. Nevertheless, the result is a tendency for a "toothy" edge, which is what the OP stated he obtains.
 
I understand your point but real world uses tell a different story, like they say "looks good on paper". I do not doubt that diamonds give the best edge I use diamond everything and know its true but ceramics will still sharpen S30V to a very similar level. The toothy edge that the OP obtained is due more to the fact that S30V is a big leap in sharpening when you normally sharpen something like AUS8. The key is to spend more time working the edge and use progressively lighter strokes as you finish up.
 
I use DMT hones and can put a scary sharp edge on my Mini-Rukus. Takes a while to work the burr off but the result is rewarding.
 
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