How thin before sharpening?

Richard338 said:
If you are doing hand shaping and polishing, you might want to try some EDM stones.
These are great before switching to paper for the final finish.
The ones from Congress tool are good.
Search item #EDM1201126 to get on the right page. After that you can select some different grits.
I use a lot more of the 120 grit than the higher ones. My last order was 6 of the 120, 2 at 220, and 2 at 320...
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How do you use these stones? Draw filing or like a pencil eraser? I ordered an assortment of the hard stones from falcon tool and was worried that I ordered the wrong kind, because others talk about using the softer mold maker stones. It seems like you're using the hard stones successfully though so maybe it's a matter of preference.
 
HSC /// said:
Slow your grinder speed down and use a sharp belt. The abrasive belt should not burn the edge. It should cut
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I followed your advice on M4 and I have no problem cutting it. I had always heard that ceramic belts wanted high pressure and high speed. I think that is true for some types of grinding but as knife makers much of what we do uses the initial edge of the grit. When cutting unhardened steel maybe that doesn't apply as much but once you get into very hard to grind steels they cut so much better with a slow belt and a fair bit of pressure. I thinned the blade on my M4 pocket knife and it was pulling so many shavings off with a 220 ceramic belt that I am now wondering how hard it is. I also tested it on some M4 that @Willie71 ran at 66Rc for me and it worked the same. I wish I could get back all of those 110 belts I used on his 66Rc Cru-Wear that I only got a few passes before they were gone. Thanks for the tip bud. Now if I could find a good 400 grit ceramic belt I would be doing awesome.
For most knives I use a sheet metal gauge. Once I am down to the thinest slot about 0.007 before I switch to finish grinding. For me that's also a great place to convex from. I have a leather platen that I really like for finish grinding. I either need to get a new flat platen arm or I find it best to batch up and do all the soft platen work.
 
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N.W. Gean said:
How do you use these stones? Draw filing or like a pencil eraser? I ordered an assortment of the hard stones from falcon tool and was worried that I ordered the wrong kind, because others talk about using the softer mold maker stones. It seems like you're using the hard stones successfully though so maybe it's a matter of preference.
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Mine are 6" x 1" x 1/2" so I hold them like a block. You can carefully polish the spine including a swedge or mune, holding precise angles. You can square up the ricasso on hardened steel (although they erode from square pretty quickly). You can remove coarse scratches or even shape the bevel slightly, such as convexing.
 
Storm W said:
I followed your advice on M4 and I have no problem cutting it. I had always heard that ceramic belts wanted high pressure and high speed. I think that is true for some types of grinding but as knife makers much of what we do uses the initial edge of the grit. When cutting unhardened steel maybe that doesn't apply as much but once you get into very hard to grind steels they cut so much better with a slow belt and a fair bit of pressure. I thinned the blade on my M4 pocket knife and it was pulling so many shavings off with a 220 ceramic belt that I am now wondering how hard it is. I also tested it on some M4 that @Willie71 ran at 66Rc for me and it worked the same. I wish I could get back all of those 110 belts I used on his 66Rc Cru-Wear that I only got a few passes before they were gone. Thanks for the tip bud. Now if I could find a good 400 grit ceramic belt I would be doing awesome.
For most knives I use a sheet metal gauge. Once I am down to the thinest slot about 0.007 before I switch to finish grinding. For me that's also a great place to convex from. I have a leather platen that I really like for finish grinding. I either need to get a new flat platen arm or I find it best to batch up and do all the soft platen work.
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On abrasion resistant steel, belts past 220 don’t really work. You would have to get a diamond abrasive belt to cut past 220
 
HSC /// said:
On abrasion resistant steel, belts past 220 don’t really work. You would have to get a diamond abrasive belt to cut past 220
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Sorry for the derail.

How did the diamonds work? Were the worth it and how high did you go? I'm in the middle of moving but once I get setup maybe I can send you a M4 test blade. @Willie71 and I are seeing how far we can push M4 and Z-Wear in search of the ultimate kitchen steel. He is running them all around 66Rc right now. Once I get get 220 power in my basement I can finally start heat treatment again. Are there any other steels in this sort of range you can get in France? One of these days having spare cash and finding thin V4E or 4V will line up. We are also trying the M2 since it cost a bit less and it's easier to find.
 
Storm W said:
Sorry for the derail.

How did the diamonds work? Were the worth it and how high did you go? I'm in the middle of moving but once I get setup maybe I can send you a M4 test blade. @Willie71 and I are seeing how far we can push M4 and Z-Wear in search of the ultimate kitchen steel. He is running them all around 66Rc right now. Once I get get 220 power in my basement I can finally start heat treatment again. Are there any other steels in this sort of range you can get in France? One of these days having spare cash and finding thin V4E or 4V will line up. We are also trying the M2 since it cost a bit less and it's easier to find.
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I don’t use diamond belts I use diamond micro finishing film for hand sanding when I offer that finish. Or when and if the customer wants to pay for it

it is absolutely worth it if you value your time. I’ve only had one customer take me up on the highly polished finish and I think it was 15 µm diamond or 9 µm I can’t recall.

i’m not really seeing the point of chasing extreme high hardness I think at some point you have to be concerned about toughness and brittleness for the customer.

i’ve been back in Arizona since December 18
 
As a caveat to this discussion, I just got @Larrin's book and the first chapter talks about bevel geometry. Amazing stuff!
 
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