Factory sharp

K

klattman

Joined
May 5, 2004
Messages
1,055
Hello all,
I have always polished my blades to shaving sharp or better, but after acquiring some spydercos I see that their factory edge is sharp, but not polished. It has even vertical scratches, which are nice and agressive, but can still shave. I suppose this is done on a belt sander, but I'd like to know any techniques to reproduce it.

For example, one could rough it up with a coarser stone, but vertical strokes would tend to make the edge grind uneven...
 
It sounds like it is done with a very fine, very even, very sharp, very open abrasive. A high quality, slightly worn, ultra-fine sanding belt might do that. A well broken in fine diamond hone is another candidate. You might also get a similar edge with around a 3,000 grit japanese water stone. All of these would have a fine sharp grit and leave an even finish. After you honed you could do some light stropping with a bare leather strop (to allign and slightly debur the edge without polishing). The work would require a well practiced hand or a mechanical fixture to maintain the edge uniformity.
 
My guess would be that in most cases the factory edge is put on by a belt grinder, and then possibly a leather wheel in a buffer as GarageBoy said. Polished doesn't necissarily mean sharp, a knife is sharp when the two edge bevels meet at an appropriate angle. A polished edge is a lot of extra work, with very little return for most uses, and as far as I know only more expensive knives have a polished edge. Anyway unless the initial grind is done well a pretty looking polished edge won't cut, but that rough looking edge will cut like a dream.

If I sharpen an knife on my belt sander I finish off with a 400 or 600 grit belt, and it will show grind marks like those you are talking about. Finishing the edge on a Sharpmaker will polish them off and leave a sharp edge.
 
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