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Playing with a really coarse grit belt
#1
The meanest, most gnarly and aggressive belt I have at the moment is a new 40 grit blue zirc belt.  It’s a very sharp beast indeed, and not something I would want to bump my knuckles into when it’s moving.  I was looking at the thing and thought, why not?
 
Using light pressure so I wouldn’t turn the blade into a toothpick, I sharpened it.  It only took two light passes on each side to raise a nice burr.  Then I did a quick job of deburring using a leather belt.  Really I was just playing around and did not expect too much from the edge, so my sharpening and deburring effort was minimal at best.
 
The bevel does not exactly have a mirror finish.  In fact, it has such deep scratches I actually used it as a fingernail file by sliding my fingernail along its length.  It worked well as a file, smoothing the end of my fingernail and visibly removing fingernail material. 
 
Here’s an image of the bevel.  Gnarly, eh?

   
 
The edge felt very sharp, so I took three sharpness readings.  To my surprise they were 90, 110 and 130 gf on the PT50B.  Of course it hangs on my fingernail and feels very sharp to my fairly educated sharp detection fingers.  It push cuts paper, melting through under its own weight.  It shaves the hair on my arm.  Melting through the skin of a ripe tomato is not a problem.  Using only the weight of the knife, it easily slices through folded paper towel and everything else I tried.  An interesting edge.  Here’s an image of the edge.

   
 
The fun thing about sharpening with a very coarse grit is that it is very, very quick and automagically produces a nice, toothy edge.  I noticed in Mr. Mark’s post, he was using a 60 grit Cubitron II at Sturgis.  It’s interesting to me that once you start down the road of using coarse grits, it’s hard to stop.  I have a couple 120 grit Cubitron II’s that I have not used yet, but now I think I’ll have to order a couple of those 60 gritters to play with too!
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#2
Yes Mr. Grepper, I'm definitely on board with toothy edges, but my experience at 60 grit left something to be desired. I cut the burr off instantly with the 140 Atoma. I didn't touch the other side of the blade. IMHO, that edge was actually just too coarse for clean cutting. It wasn't sharp enough to measure.

During the rally, I only used the 60 grit to profile the worst blades. I stuck to the 120 Blaze for sharpening.

I believe the biggest difference lies in the deburring. I don't think leather is in the picture for me unless I actually want a 1k finish, but I will revisit 40-60 grit CubeIIs and deburring on leather. I could be missing something.

Are you using a bare leather belt, Mr Grepper?
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#3
Mr. Mark, I think one of the reasons I get away with very coarse grit is because I use a very, very light touch when sharpening.  I had expected that when I tried the 40 grit zirc belt that I was going to have a chain saw like trashed edge, but to my surprise that was not the case.  That said, 40 grit was too coarse.  I won’t and would not recommend it for sharpening.  I doubt the uneven edge it produced would last very long.
 
The odd thing for me is that I didn’t see as much of change in the edge as I would have expected going from 80 grit to 40. Again I suspect it’s because I use such light pressure.  I’m using such light pressure that it does not remove that much steel.  I didn’t turn the blade into a toothpick.
 
Another reason I might be getting away with such coarse grits is because I’m deburring with the leather belt.  No matter how much I try there is smoothing of the toothy edge.  You can see that in some of the images that I have posted.
 
I got a new Surgi Sharp leather belt several months ago.  At that time I put a very small amount of Tormek honing compound it.  I have not applied any more since and it’s been used on a bunch of blades.  I suspect that the compound has mostly broken down by this point.  The Tormek compound is 1-3 micron, AO abrasive.
 
Tormek compound is abrasive in light oil.  I use the rough side of the belt, and when the belt was new it was so dusty I needed to do something so I used a very little compound.  I probably should have just used some light machine oil.
 
So, is it a bare belt?  No.  Do I think the compound is doing very much?  No. 
 
I wonder why after you did the 60 grit, it was not sharp enough to measure.  I would be most curious to see one of your blades after deburrig on the 140 Atoma under a microscope!
 
I take it you are free handing the deburring?
 
I’m very curious as to why you are not getting edges around 150 gf sharpness.  I’m really not at all trying to inflate my own balloon, really! Angel , but I get that sharpness almost every time without really trying. Whaasup  with that? I’m not doing anything special at all.  I just sharpen and deburr and that what happens.  Weird, huh!  The only thing I can think of is that I use an adjustable rest when sharpening so I maintain a consistent angle.  Other than that, I just raise as small a burr as I can on one side, turn the blade over and do the same again, then deburr the thing.  I just use one belt, not some series of grits.  Like I say, nothing special at all.  
 
Using the 120 grit belt and deburring with the Atoma, what sharpness reading do you usually get?
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