How sharp with a DMT coarse?

J

Josh Perdue

Joined
Apr 18, 2017
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I’m wondering just how sharp everyone else can get there edc knife with just a dmt coarse stone? I’ve read of some being able to get hair popping edges with just this stone alone but I have been unable to obtain this degree of sharp with only the coarse stone. I can roughly cut hair on my arm and thick stock printer paper. I have no chance of cutting phone book paper.

When I progress from the dmt coarse to ceramics and then strop I get what I’d consider very good sharp edges that’s able to push cut phone book paper. It would be awesome to be able to obtain a sharper edge with this one stone.

Any tips or suggestions technique wise on improving my outcome.
 
I don't really try to get to 'hair popping' directly off the DMT coarse, not even really a goal for me as I don't view it as my final stone, but I'm sure that is possible and some here have probably done it.

I'm able to get to shaving arm hair, as you did, and doing push and draw cuts through thin newsprint or receipt paper. The basic things I do:

* Make sure you're starting with clean bevels at a good angle preferably 15dps or lower. If you aren't starting with this on your blade, you'll do better if you first go to an even coarser stone (I got to my 220 grit DMT, or my 120 grit Norton), and do some shaping work first to get your bevels in good shape. I've been shooting for about 12/13 dps on most of my folding knives.
* Alternate sides frequently and monitor the edge to minimize heavy burr formation. If necessary and a burr forms, take steps to reduce, such as a few passes at a slightly raised angle about +5 degrees over sharpening angle.
* Spending a fair amount of time on the coarse stone--this is where all the important work happens and you really establish your edge. All higher grits are merely refinement and icing on the cake, but if you don't get it right here, you never will. It takes some time, keep working that edge on the coarse stone for a while and testing it, I can eventually get it where I want it to be.
* Increasingly light passes to refine the apex and reduce the burr to as small as possible. By the time I finish, I'm doing alternating passes so light there's no pressure on the knife whatsoever, it is as light as I can possibly get it while still touching the stone.
 
Thanks for the informative reply. Just guessing I’d say I’m between 20-25 degrees with my bevel. I’ll try going down a little lower. I’ve been doing extremely light passes when finishing but haven’t been raising the angle any. I’m assuming you are saying to raise the bevel at the end a little for final burr removal with really light strokes.
 
Anything at/below 15° per side makes it easier. As for finishing, progressively lighter passes as you near apexing will minimize burring and keep them thin enough, that they'll remove easily. On a diamond hone, if you're getting heavy burrs at all, that's a sign pressure is still too heavy. The diamond abrasive will cut very cleanly with minimal burring; but, if pressure is heavy, the hard nickel & steel backing under the diamond is what makes heavy burring a problem. If the the touch is appropriately light, burrs will be essentially a non-issue when sharpening with diamonds. Finishing touches should just be 'skimming' the surface of the hone, as if brushing dust off the surface with the blade's edge. I personally don't raise the angle to de-burr, instead focusing on thinning any burrs at the set sharpening angle, to a degree they'll come off easily by most any means (see below).

Any burrs formed should be light & flimsy enough to remove with a few stropping passes on bare leather, wood, paper or denim - no compound needed. If they can't be removed as such, that's a sign the finishing work needs more attention on the hone itself. If fully apexed and appropriately thinned at the edge, the cutting of phonebook pages will be effortless, sounding & feeling somewhat 'zipper-like' with some vicious bite into the paper on first contact, coming off a Coarse DMT. It's a wicked feeling in cutting fine paper, when it's done right. And some hair-popping is possible as well, though it won't be comfortable against the skin for true shaving sharpness (remember that zipper-like 'bite'...).
 
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maximus83 said:
* Spending a fair amount of time on the coarse stone--this is where all the important work happens and you really establish your edge. All higher grits are merely refinement and icing on the cake, but if you don't get it right here, you never will. It takes some time, keep working that edge on the coarse stone for a while and testing it,
Click to expand...
Read this and give it some thought as you work. DM
 
Alright guys thanks for the help. I reprofiled my edge with an extra course dmt then followed by the coarse. I reprofiled to what I’d guess would be about 15 degrees. Spent a lot of time with the coarse diamond. I was able to cut the paper easier but still had that toothy bite.

I then progressed as follows
Coarse dmt/ kme coarse-medium ceramic/spyderco medium ceramic/ fine ceramic/ultrafine ceramic/ strop with compound= first true freehand hair whittling edge.

I think the keys were setting that initial bevel to what I’d guess to be 15 degrees as opposed to 20-25. Spending extra time on the coarse stone and very light stropping to finish. Seems like very small details but very important ones.
I’m pretty fired up thanks for the help guys.
 
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