S30V Question

[thombrogan]

This is mainly for the other experimentical types over here:

How thin can you grind S30V before it becomes 'too thin?' Around or slightly beyond those bounds, how thick would an edge bevel have to be to limit damage with mundane cutting?

My Yojimbo is extremely thinly ground (don't even know its previous edge angle, but it was likely less than 20 included degrees - it's about 42 included degrees now) and its edge experienced microchipping while cutting drywall. It's just cardboard and gypsum. Supposing I nab a micrometer, is there a thickness below which the edge of an S30V blade shouldn't be?

Many thanks!

[JD Spydo]

Hello Thombrogan: I have 3 of those Yojimbos and I have noticed the extremely thin grind on them. Also I know you have noticed it too that there have been a lot of complaints about S30V having a chipping problem under adverse conditions. Being that VG-10 was originally designated an "agricultural steel" for garden tools and the like. With that being said maybe it can accomodate a thinner grind than S30V can endure. I personally don't think the "Thinness" of the grind is as much as a factor as some would think. I also think that maybe S30V should be used on big beefy blades only. Although I haven't had any bad luck with these blades made from S30V I still think that the jury is still out on these newer blade steels. :spyder:

[Samhain73]

Hmm, I'm not sure. My lil' temp is great, hasn't chipped or even dulled and I've used it on plastic, cardboard and rope, where as I have a BM 630 which gets nicks in it sharpened any lower than 25 deg. And that is a much thicker blade.
So maybe it depends on the blade geometry? As far as I'm concerned, S30V is hit or miss. I guess I'm gonna have to start on the VG10 bandwagon if any other knives do the chipping. Hmm.. maybe S30V should be flat ground only??

[severedthumbs]

I would say .008

[thombrogan]

Thanks to our resident Microholic, Severed Thumbs! Guess a micrometer's in my future. How'd you arrive at that width?

JD Spydo,

My particular Yojimbo is so thinned out that the production version looks like a girder in comparison. I suffer from edge-o-rexia and, apparently, it's deleterious after a certain point.

Samhain73,

I'm told that there was either a bad batch of S30V or BKC had a batch of Skirmies with a botched heat-treatment. I'll chip every steel I touch (ATS-55, AUS-6A, AUS-8A, D2, S30V, VG-10, 154CM, 5160, 52100 - still working on ATS-34, S7, 440A, and 440C; just give it time).

I find S30V relatively tough when it's between RC59-61 based on my experiences with Spydercos (only one, my first ATR, tested RC59 - the rest were at RC58. I shudder to think what my Manix might be), but then I get greedy and regrind just a hair too far for the combination of hardness and toughness to matter. Still, when my S30V super-steel blade gets microchips doing tasks which merely dull picayune box-cutter blades, it makes me wonder.

[severedthumbs]

I just mic'd the cutting edge of my Manix and my Para. Manix no chipping Para some chipping and Para mic'd somewhere aroung .004-.0055, while the Manic mic'd about .008.

I am a machinist by trade so I assume I measured right. I have a complete 0-12" set of Mitutoyo mic's. With the tenths markings.

[thombrogan]

That's what I was looking for! Thanks again, Severed Thumbs!

[CKE]

I have had chipping in some of my S30V blades. I could mic them tomorrow but I think Severed has that covered :) I wonder if it has to do with the grain structure being more coarse on S30V as opposed to VG-10(say), meaning that my S30V Spydies have a coarser grind than my VG-10 ones. Things that make you go HMMMM!!!!!

[spydutch]

I foud out that VG10 chips too. The other day when I cut some carpet with my HarpySS/SE I noticed little chips. When I cut up a empty beer can with my Military/SE I didn't noticed any chips(I checked with my printer's loupe)

[thom lambert]

When you measure the edge, where do you measure? I ask, because it seems to me that all edges eventually thin out to virtually nothing, so wouldn't they be the same thickness right at the very edge of the blade?
T

[HoB]

I have never taken the time to grind any of my S30V blades to less than 15 deg. per side...simply a time issue. At 15 deg. they perform very well. Never seen any chipping on my S30V blades. When I hit something hard, they tend to roll rather than chip. I do NOT use a microbevel. The blade behind the edge (were the edgebevel ends) is 0.027 in on my Manix (don't know about the others, had the Manix in my pocket) and the edge bevel is 0.053 in deep, which comes out to 14.3 deg. but since I sharpen free hand I am likely to rock the blade abit. Still less then +/- 1 deg. free hand ain't too shabby I would say. Mmmh, never really calculated that. Now I am really proud of myself :D .

[thombrogan]

Ooh! Yay HoB and Pythagorean Theorem!

I know S30V has great edge-retention (especially Wilsonized!) and its corrosion resistance is great, but I wasn't seeing the advertized toughness. Looks like a micrometer is in my future.

Thanks guys!

CKE,

I owe you emails. May I please have baby pics?