convex edge w/ sandpaper for sharpening

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wam03

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May 7, 2000
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I read a nice article on sharpening convex edges using a mouse pad covered with initially 1000 grit wet dry sandpaper and finishing the polishing with 2000 grit paper. I have never seen anything finer thatn super fine 600 grit wet dry. Was this a typo or what paper grit do you use to strop an edge back on a convex grind. See article below:

http://www.mhcable.com/~yocraft/sosak/convex.htm
 
Hardware stores rarely carry above 600 grit. But as mention above Pep Boys will carry it, so will any auto supply shop for finishing car paints, etc.
wam03, In your link I see where he says he uses 600 grit then finishes with 2000, that makes much more sense than 1000 to 2000 since you will be sanding for VERY LONG time with grits so high!!!!!! In fact if you are trying to put a convex on instead of restorring one ,you should start with much lower grit, 220 or even lower. For finishing- 2000 may be unnecessary esp. on "user knife" I think 1000 is suficient, even 800. Higher grit = more effort. Try and see what you like.
One more thing- your article link, it says putting on a convex edge can scar your blade finish, this is true because you will "trail up "the face of the blade as you draw it across the sandpaper. You can minimize this by placing heavy duty tape on your blade above the edge area you want to make convex, usualy 1cm is good, it depends on the edge angle you begin with. Again, try and see what works for you. Good luck!
Martin
 
Anything above 600 grit is really just polishing the edge. I.e., taking it to a level that might shave hair more cleanly or slice leather more cleanly, but generally, past those kind of tasks, you may not find the polished edge to offer much performance-wise. I find a coarser finish to cut other stuff more aggressively so I typically stop at 400 or 600 grit.

There are some good threads on this forum also ... search on "convex" and "mouse pad" and "Strop" and "sandpaper", etc.
 
I understand the principle well and tried it several times, but I can still get a better edge with bench stones or a Sharpmaker than can with the mousepad/ fine sandpaper setup. I also tried using leather as a base material and had no better luck there (tried a couple different types of leather with different densities as well). I guess I just don't have the touch for this technique.

Call me traditional, but I do my best work on old style stones. I will admit to using the Sharpmaker for general maintainance these days because of the convienience, but if a blade needs real attention, it's off to the bench.

jmx
 
I bought one of Handamerican's sytems and am very happy with the results for convex edges. It's basically a base, a kind of soft cotton pillow that rests on the base, and the sandpaper which goes over the pillow. Or, in other words, a fancy version of sandpaper-over-mousepad -- although handamerican's cotton pillow thingie is definitely softer than a mousepad and thus the sandpaper curves around the edge a bit more. As I said, I"m very happy with the results.

Joe
 
You can just buy belts for sanders and use them without the sander, these can be found in very fine grits. Lee Valley also sells sandpaper up to 0.5 micron which is finer than any hone (8000 grit waterstone is several time more coarse).

-Cliff
 
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