I must admit failure!

R

Richard K

Joined
Dec 30, 2000
Messages
711
I've been able to get a razor sharp, hair popping edge on all my knives, Sebenzas, Benchmades, Spydercos, Fallknivens, TOPs, REKATs, etc. etc.
I've now met my match. I aquired an Emerson Mini CQC7A which to my horror came with a chisel grind edge (my first and last Emerson). I re-profiled the edge to 20 degrees with a 15 degree back bevel and cannot get an acceptable edge. I tried a 1" belt sander, Lanskey, Sharmaker with diamond, gray, gray and white stones, freehand, etc. Guess my skills aren't what I thought.
 
I would guess that you are having problems with the 154CM alloy not being stable at the low included angle of the edge. When you sharpen a chisel grind at 20 degrees that is your total included edge angle. When you sharpen a V-grind edge at 20 degrees per side your included angle is 40 degrees.

The only way I get good results with 154CM at low included angles is a diamond-only approach. All my edge finishing is done using diamond abrasives (it probably doesn't matter for the reprofiling--use a belt for that). I go from medium, to fine, to extra-fine hones then I finish by stropping (on a hard flat strop) using submicron diamond paste.
 
Dang CQC7A's have chisel grinds? If you figure out how to get that knife sharp it I bet it will be an awesome cutter. Are you flattening the back side real careful?
 
Japanese knives which has single bevel always have flat side slightly concave. Is it the way Emerson blade made? If not then sharpening entire flat side will be big pain.

However they do not make hunting or "tactical" knives like this single beveled, Japanese made them convex grind usually as more suitable for hunting job.

There is thread here about how to sharpen Sashimi hocho - you may check it out.

Thanks, Vassili.
 
Richard,

You can do it with either a Lansky or a Edgepro. I did a couple of chissell edges with them and they came out great. Forget freehand.

Regards
Frank
 
Just to keep the picture clear, the CQC-7A is a clip point, not a tanto, and it is not a full chisel grind, it only has a chisel secondary bevel.

As with any knife, if you're having a problem sharpening it, you might like to set it aside and try again another day.
 
Thanks Guys. To clarify, I used a 1" belt sander to take both sides of the blade down to 15 degrees (30 total). Then took diamond rods to bring the edge to 20 degrees (40 total) Next the Lansky
then gray rods and ending with white on my sharpmaker. It's sharp, just not as sharp as my acceptance level after carrying Sebenzas and Benchmades. It's going in the tackle box for extreme use like splitting wood and similar tasks.
 
So it looks like steel problem. ATS-34 can be sharpened to very good level - at least Buck888. I think you may call them and ask for replacement.

Thanks, Vassili.
 
how many times did you raise a burr? going from belt sander to sharpmaker to lansky to freehand, I would think you'd have to ensure you're getting to the edge every time you switch.
 
Hang your head in shame and send it to me. I will dispose of it properly for you.

Or raise a burr...
 
Reduce your reprofile to 10 degrees per side and then hone at 12 degrees per side using diamonds. If you are used to getting really sharp edges you will be disappointed with 154CM unless you finish with ultra-fine diamonds. The large grain structure will work of get rounded off if you finish with ceramic.
 
Well the Emerson is back among the living. Stubborn individual that I am, I took another whack at it. Following Jeff Clark's suggestion I took the edges down to 10 degrees on my 1" belt sander (deep bevel now). I then moved to the slack belt and put a convex edge on it then finished it off by stropping it with green rouge. It's now as sharp as most of the Benchmades you get from the factory. Still couldn't get it as sharp as my Sebenzas but it's acceptable.
Thanks for all the input!
 
Jeff Clark said:
If you are used to getting really sharp edges you will be disappointed with 154CM unless you finish with ultra-fine diamonds. The large grain structure will work of get rounded off if you finish with ceramic.
Click to expand...

Can you (or others) explain further how ceramics will round off 154CM? If I am understanding correctly, you are saying that a large-grain steel will not respond well to ceramic abrasives - I am curious why this is.

Would ceramics also be inferior on steels like S30V or ZDP-189 as well? Is large-grain the same as large-carbide?

Thanks for the help.
 
In the case of 154CM "large carbide" is what I meant to say (and usually what I am talking about if I say large grain structure). Sometimes I get in a hurry and get imprecise. The answer to your "why" question is "I don't know, it's just the results that I have gotten". I should probably stop now, but I'll do some ruminating on the issue.

Ceramic abrasives are fused in a furnace and don't have loose projecting grit like you find in most hones. They are less like a sandstone in texture and more like a very dense lava. In place of projecting grit you have more continuous solid with voids and soft spots in between. Anyway the ceramic doesn't cut extremely fast, but it provides a hard flat surface that you wouldn't expect to round off anything. I would guess that you could round off an edge filled with large carbides due to the large contact area of the ceramic honing surface. Instead of a finite number of sharp projecting grit points cutting material out of the edge the ceramic hone has broader and flatter grit that sort of tries to plane material off the edge. These microplanes are much broader than ultrafine diamond grit and catch and drag carbides out of the edge.

The proceeding may not be true, but it is true that I get better results with diamonds on 154CM.
 
Thanks for the info, Jeff. I generally finish with ceramics, and I have been happy with the results on most steels. I use VG-10, H-1, and SAKs the most and I have no complaints with ceramics on those.

However, I have not been happy with the results of ceramics on ZDP-189. Your description of 'rounding off' fits my experience with ZDP and ceramic. I will give diamonds a shot. I have a DMT fine and x-fine continuous diamond hone - based on what you are saying that may provide better results. It is worth a shot anyway!
 
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