Some Super Steels don't seem to hold a fine edge

Glad some folks brought up a possible poor heat treat. The high V and composition can make it a trick to heat treat. Sounds like your on your way to working things out. Good. DM
 
I was having similar problems with a CRK Umnumzaan. Problem's now completely gone, and in retrospect, I believe that I was underestimating how small a burr that steel could form. I believed I had removed the burr, but really is was still there and folding/breaking after initial use (even very light use). Now that I've learned this possibility, I have experienced excellent performance in both my S30V Zaan and my S35V Zaan.
 
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Officers Match hit the nail on the head IMO. A company like spyderco will be heat treating hundreds of blade simeltaneously in large ovens/baths. If one were heat treated improperly the enire batch would be. Not something a company such as spyderco is going to miss.

If its an overheating issue (while unlikely) it will go away after the first couple sharpenings.

I strongly suspect that you have a micrscopic burr that is breaking off. Carbide tearout just is not a factor at this coarse of a finish.
 
The edge over heating isn't happening during the HT process. If it were, then the entire blade would be bad and there would be no "good" steel to get to. Usually it's during the post HT grinding and shaping that overheats and ruins the edge steel. And then you add in the rapid quenches in water during the grinding.
 
I don't claim to know exactly what's going on here... it's part of the reason I posted. :) I did two more days of minor testing on this blade. It's now gone through a total of around 40 feet of cardboard, and yesterday I opened a Hello Kitty flashlight in a blister pack. Some of these blister packs are made of surprisingly thick plastic, though this one was a more reasonable thickness. The 3 year old that owned the light was thrilled to have it in her hand BTW.

After all of this testing the results are very similar to after the first round: It only cuts phonebook paper very roughly and parts of the edge won't even catch the paper. Printer paper cuts mostly very cleanly, though it's "loud" indicating a rough edge. There are a few spots that catch a bit on printer or magazine paper, which is to be expected I think. Perhaps most importantly of all, that flat reflective edge has NOT reappeared. I'm sure it will eventually, but I hope only after a bunch more cutting.

This is much more like it. An edge that will clean slice printer paper for a very long time is very useful to me day to day. Now, what I would LOVE to have and I'd pay premium money for, is an edge that will go through this and more and hold a shaving edge. I don't think it would necessarily be very much more useful from printer paper slicing to shaving... but it would be really fun!

Did I have a very small burr? Frankly I kind of doubt it, but it's possible. If it's *my* technique that's causing this flat edge to appear after light use, I'd expect it to happen again eventually. If it does, I'll be honest and post about it here.

Brian.
 
In my case is wasn't so much technique as is was repetition. I just found I needed to use magnification to carefully examine the apex and many more lighter strokes to finish the job. I usually keep a piece of a softer wood handy (a paint stir stick or something similar) to lightly drag the apex on to insure any "micro-wire edge" is cleaned off.
 
bgentry said:
I don't claim to know exactly what's going on here... it's part of the reason I posted. :) I did two more days of minor testing on this blade. It's now gone through a total of around 40 feet of cardboard, and yesterday I opened a Hello Kitty flashlight in a blister pack. Some of these blister packs are made of surprisingly thick plastic, though this one was a more reasonable thickness. The 3 year old that owned the light was thrilled to have it in her hand BTW.

After all of this testing the results are very similar to after the first round: It only cuts phonebook paper very roughly and parts of the edge won't even catch the paper. Printer paper cuts mostly very cleanly, though it's "loud" indicating a rough edge. There are a few spots that catch a bit on printer or magazine paper, which is to be expected I think. Perhaps most importantly of all, that flat reflective edge has NOT reappeared. I'm sure it will eventually, but I hope only after a bunch more cutting.

This is much more like it. An edge that will clean slice printer paper for a very long time is very useful to me day to day. Now, what I would LOVE to have and I'd pay premium money for, is an edge that will go through this and more and hold a shaving edge. I don't think it would necessarily be very much more useful from printer paper slicing to shaving... but it would be really fun!

Did I have a very small burr? Frankly I kind of doubt it, but it's possible. If it's *my* technique that's causing this flat edge to appear after light use, I'd expect it to happen again eventually. If it does, I'll be honest and post about it here.

Brian.
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I strongly suspect that the answer for you is a different steel. Why put up with something finicky and (apparently) hard to heat treat when there are so many much better steels out there? Check out some listed on my first post, you'll never go back. Shoot, even CPM 3V, not at the top of the edge holding list, easily beats S30V by a substantial margin in edge holding and is much tougher. I've never had a stinker in that steel yet, and I find it very easy to sharpen. There are lots of others as well. Choice is good.
 
Try ” stropping” the edge across your finger finger nail. If there is a burr, you'll feel it, your nail will be scuffed and you will see a build up of nail dust on the edge behind the burr. Otherwise, it'll feel like glass
 
As of yesterday, the blade had cut around 50 feet of cardboard. It now has a VERY narrow reflection along most of the edge. This is no where near the width of the reflection from the original failed edge. It still cuts well, though not as finely as fresh, and of course won't shave hair at all. It still slices magazine and printer paper, though it's a little rough. It hangs and tears if you do it slow. Fast slices go right through though. I should mention that all of this cardboard cutting is just for testing. While I *do* open a good number of boxes, I almost always cut the taped seams, as opposed to cutting the actual cardboard. Still, opening boxes is hard on knives, probably because of the abrasion of the cardboard even if you aren't cutting it. I.E., the cardboard flaps pinching against the edge as you cut the tape holding them together.

I had decided yesterday that I wanted to sharpen it on DMT, but I didn't make time so... See next post.

Brian.
 
Today two pallets full of boxes showed up at work. Part of processing them was opening all of them and I hadn't sharpened my blade yet. With other blades, doing a task like this has made the blade go flat and lose cutting power half way through. I probably opened 50 to 60 boxes today, most of them big-ish.

I periodically looked at the edge and cut some magazine paper I had hanging around. It really didn't seem to change much. After I got home and cleaned the gunk off of the blade, I looked at the edge again: It still has a very narrow reflection. It's narrow enough that the lighting has to be right for you to even see it. In most indoor lighting you'd never see it.

Then I sliced some more magazine paper: Still performing as before. Rough, but slices cleanly if I do it fast.

I was going to sharpen this, but I think I'm going to wait and see for a bit. This kind of "working edge" is absolutely useful for me. I'd *really* like it to be more show off sharp, but it's getting the job done, so...

I'll report when I know more.

Brian.
 
I was cutting some cardboard with my S30V Rukus. After a while, it started to dull, so I switched to my K390 mule and continued cutting. That K390 edge just would not get dull, even after a lot of cardboard. I didn't even need to resharpen it afterwards. Just wonderful steel and blade geometry.
 
Since my last post, I've used the CPM-S30V Yojimbo 2 blade quite a bit, did a few SharpMaker sharpenings, and finally a full DMT sharpening. Honestly the edge holding hasn't changed since my 2nd session with the SharpMaker 4 to 6 weeks ago. It's still doing "ok" in that it can't hold a fine edge for long at all, but holds that slightly reflective "working" edge for a good while.

Yesterday I tried a "destress the edge" sharpening, where you cut the edge directly into a stone to remove any weak metal and then sharpen as usual. This is the sharpest I've been able to make the Yojimbo 2, but I don't expect it to hold it very long. We'll see. I honestly think that, as good as S30V is, it's not what I want. I want a steel that holds a fine edge for 10x as long as 8Cr13Mov. 5x as long would be good, but 10x is really what I want.

I guess I need to find a blade style I like in S90V or S110V then?

I'll report back if the edge holding has changed at all due to my latest sharpening.

Brian.
 
bgentry said:
Since my last post, I've used the CPM-S30V Yojimbo 2 blade quite a bit, did a few SharpMaker sharpenings, and finally a full DMT sharpening. Honestly the edge holding hasn't changed since my 2nd session with the SharpMaker 4 to 6 weeks ago. It's still doing "ok" in that it can't hold a fine edge for long at all, but holds that slightly reflective "working" edge for a good while.

Yesterday I tried a "destress the edge" sharpening, where you cut the edge directly into a stone to remove any weak metal and then sharpen as usual. This is the sharpest I've been able to make the Yojimbo 2, but I don't expect it to hold it very long. We'll see. I honestly think that, as good as S30V is, it's not what I want. I want a steel that holds a fine edge for 10x as long as 8Cr13Mov. 5x as long would be good, but 10x is really what I want.

I guess I need to find a blade style I like in S90V or S110V then?

I'll report back if the edge holding has changed at all due to my latest sharpening.

Brian.
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You would actually probably be looking for a steel with less vanadium, rather than more. Perhaps take a look at ZDP-189, CTS-XHP, or Aogami Super.
 
I think S30V should be sharpened with diamond .Don't press with diamond you'll pull out the carbides..It will cut anything ,let the diamond do the work. A micro serrated edge works best for me. Touch up rather than let it go very dull.600,800, 1200 ,grit , take your pick.
 
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HeavyHanded said:
I would definitely grind all the factory edge off and start over. Many edges from the factory have wasted steel along the cutting edge. I don't care if its a cheap kitchen knife, should be able to cut many feet of cardboard without failing as you describe.
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yeah i was going to suggest this . beat me to it
 
bgentry said:
HeavyHanded posted his suggestion more than 6 years ago. I followed it.

So you're right. But you're just a *little* bit late to the party. :)

Brian.
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So , do you still don t like S30V or you learn how to sharpen it :)
 
I can sharpen S30V pretty well. The last edge I tested scored under 150 BESS. That's from a 180 grit belt, deburred.

I still don't like the steel. It seems to lose it's fine edge faster than more pedestrian steels like 8Cr13MoV. It holds a "not very fine" edge for a long time. Then eventually becomes very dull. S30V overall edge holding is longer than lesser steels. But I don't like how it drops off SO FAST from nice and sharp to unimpressively sharp.

If I had my way, I would trade both of my S30V blades for something like 154CM.

Brian.
 
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