Edge Gremlins

ndeezl

ndeezl

Gold Member
Joined
Sep 18, 2008
Messages
2,037
Hi All,
Quick question for you. I received a new GEC #85 easy open and it had a decent edge. I popped it on the fine sharpmaker stones for 15-20 minutes and had it shaving hair. I wanted to take the edge a bit further so I decided to do some freehand work with a DMT fine (green) stone. I worked on the edge for another 15 20 minutes and when I inspected it, it appeared that a bunch of mini gremlins just chomped all along my edge (i.e. it looked like there were little chips all along the edge). So I put it back on the sharpmaker for another 15 minutes and had it back where I wanted (shaving hair). I was under the impression that the green DMT stone is a finer grit than the sharpmaker fine (white) stones. So what did I do wrong? Too much pressure on the diamonds? Inconsistent angle? I'm not a sharpening pro so I appreciate the help. Thanks.

Nathan
 
i had a member contact me with the same problem but on a knife i made. i told him not to use diamond to sharpen the knife because the edge will chip due to the high rc i put on my knives. when i got the knife to resharpen it, the edge looked like mini scallops the whole length. if you want to try something different and get your knives sharper, give the paper wheels a try.
 
This is the difference in cutting aggressiveness between diamond and aluminum oxide (ceramic). A 'fine' diamond grit will cut deeper, and leave heavier scratches, than a 'fine' ceramic. Two completely different grit standards. The diamond will definitely leave the edge more 'toothy' than the ceramic. The 'notches' ('gremlins') may not necessarily be chips, but just deeper furrows dug into the steel by the diamond. That's what it'll do, especially with simple carbon steel like 1095 (as GEC and many others use). The ceramic leaves a much more polished finish on steel, which is why you were able to get it back to shaving with it. The aluminum oxide abrasive in ceramics won't cut nearly as deep, so it leaves a finer finish. These two hones performed exactly like I'd expect them to, based on what you've described.

The green DMT is actually an 'Extra Fine' (9 micron particle size), by DMT's own definition. The 'Fine' DMT is the red one, at 25 micron particle size. The fact that you're seeing a coarser edge, even with the EF DMT, is testament to it's increased cutting aggressiveness.
 
knifenut1013 said:
You went down in grit.
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Meaning the DMT was coarser than the sharpmaker stone? Or are you just talking semantics?

Obsessed with Edges said:
This is the difference in cutting aggressiveness between diamond and aluminum oxide (ceramic). A 'fine' diamond grit will cut deeper, and leave heavier scratches, than a 'fine' ceramic. Two completely different grit standards. The diamond will definitely leave the edge more 'toothy' than the ceramic. The 'notches' ('gremlins') may not necessarily be chips, but just deeper furrows dug into the steel by the diamond. That's what it'll do, especially with simple carbon steel like 1095 (as GEC and many others use). The ceramic leaves a much more polished finish on steel, which is why you were able to get it back to shaving with it. The aluminum oxide abrasive in ceramics won't cut nearly as deep, so it leaves a finer finish. These two hones performed exactly like I'd expect them to, based on what you've described.

The green DMT is actually an 'Extra Fine' (9 micron particle size), by DMT's own definition. The 'Fine' DMT is the red one, at 25 micron particle size. The fact that you're seeing a coarser edge, even with the EF DMT, is testament to it's increased cutting aggressiveness.
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Thanks David. I've read in some of your posts before that you use different mediums for sharpening different steel types. The sharpmaker seems to work well with the 1095 so I'll probably just pick up some EF stones for now.

Thanks for the replies guys (from the three I was expecting replies from :))

Nathan
 
+1 on the paper wheels! Send all my sharpening needs to Richard and his edges are amazing with the paper wheels he uses!! Highly recommend him and the wheels!!!
 
ndeezl said:
Meaning the DMT was coarser than the sharpmaker stone? Or are you just talking semantics?



Thanks David. I've read in some of your posts before that you use different mediums for sharpening different steel types. The sharpmaker seems to work well with the 1095 so I'll probably just pick up some EF stones for now.

Thanks for the replies guys (from the three I was expecting replies from :))

Nathan
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The DMT is coarser in terms of cutting speed and finish left. That's all that really matters, when you get right down to it. I don't know if Spyderco has ever specifically stated actual particle size for their ceramics. So much also depends on how those are made & surface-finished, aside from the actual grit number of the abrasive itself.

And I do use different mediums for sharpening. That's just based on developing a familiarity with how each one performs (speed and finish left), and then using them to produce a finish that 'works' for me, on whichever blade I happen to be sharpening at the time. And even then, it's still somewhat experimental. I don't think I'll ever stop looking for an 'ideal' sequence that works universally. I'm not sure there is such a thing; it's so subjective to the individual preferences of the user.

I don't put much stock in grit size alone, UNLESS I'm sticking to one medium only, like all diamonds from start to finish, or all wet/dry sandpaper. Results are much more predictable that way. EDIT: And, by the way, the wet/dry sandpaper works excellently with 1095. I think that's my favorite method with 1095 or other basic, simple steels. Also excellent with 420HC, 440A and D2, for finishing to high polish (2000+ grit).
 
ndeezl said:
Meaning the DMT was coarser than the sharpmaker stone? Or are you just talking semantics?

Nathan
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DMT EF 1200 mesh, 9 microns
Spyderco fine ceramic, 6 microns

The ceramic abrasive also "cuts" the steel in a different way making a finer and more polished surface/scratch pattern compared to the deeper and more toothy pattern of a diamond.

I would also not recommend diamonds for any low alloy or carbon steel. The extreme hardness of diamond and its aggressive abrasive action is too much for these steels. Remember, diamond hones are intended for steels too tough to sharpen on regular stones.
 
Found this comment from Sal Glesser on Spyderco's own forum, regarding the grit numbers for their hones. What's interesting, is that they actually use the same exact abrasive size for each of the medium, fine and EF ceramics. The only difference is in how each is finished in their process. The bold highlight was added by me, to emphasize that part of his comment.
We've spent a great deal of time trying to determine grits for our stones. The manufacturer has also worked with us, to no avail. A guess seems to be best.

Most abrasives are measured by the grit size used in the matrix. Our ceramic doesn 't work that way. Grit size is constant.

We've tried to compare scratch patterns as Cliff mentioned and this is probably the closest, but nothing that we can say "This is blah blah". Then the Japanese water stones jump into the equation and suddenly there is whole new set of numbers.

So where we end up is:

Our diamonds are a 400 mesh (measureable). (600 on the Duckfoot)

Our gray stone is "medium". (Same material as fine but different carriers and heat treat).

Our fine stone is fine.

Our extra fine is a surface ground fine.



sal
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This is a great thread. I first noticed this when I got my XXF diamond bench hone (8000) and was surprised at how much coarser the finish it gave was in comparison with my 3000 and 6000 waterstones.

The business with Spyderco's ceramics differing only in finish rather than particle size can be understood by an analogy to saw blades. 10" tablesaw blades all have carbide teeth of about the same size. Larger open space (gullets) between adjacent teeth cause a freer and more aggressive cutting action. Fine finish blades don't have smaller teeth than the roughing blades; they have smaller gaps between the teeth.
 
I just want to apologize to the OP and the other members that have participated in this thread. While I thought I was providing helpful information by what works for me sharpening apparently was trolling? I received an infraction for trolling. Certainly was not my intention so please accept my apology!
 
No worries Striderco I just thought you were giving an opinion.

Thanks for that quote David that's pretty interesting info on the Spyderco stones.
 
Thats what I thought! I thought I was giving friendly advice on what I do to get my knives sharp?! But a moderator gave me an infraction for that post and gave me a 10 point fine! Find that a little extreme. If I tell you that I sometimes touch up my knives with a Spyderco ceramic tri angle sharpener, is that spamming?
 
Striderco said:
I just want to apologize to the OP and the other members that have participated in this thread. While I thought I was providing helpful information by what works for me sharpening apparently was trolling? I received an infraction for trolling. Certainly was not my intention so please accept my apology!
Click to expand...

I am puzzled about why you got an infraction also. Since an incident I had here a couple of years ago I tread lightly when posting or responding. I did not see any problem with your reply but I hope the moderator will clarify publicly to all of us for future reference.
 
I think this one mod just doesnt like me or something? I contacted Spark hopefully he can clarify things. Im thinking this moderator must be new.
 
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