faking a convex grind with a sharpmaker?

singularity35

singularity35

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Mar 1, 2010
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This occurred to me while sharpening on my SM. What if I stroked on the 30 degrees inclusive angle with a rubber band across the top of the two rods? this would in effect close up the angle. after stroking on the corners of the brown and white with rubber bands, I would then stroke still on the corners of both without the rubber bands opening up the angle somewhat. I would then shift to the 40 degrees angle with rubber bands. then finally i would do the 4 steps on the 40 degrees without the rubber bands(the widest angle).

will this technique fake a convex grind? the rationale is having three back bevels but am I right in assuming this? need the feedbacks of the sharpening guys here. thanks.
 
It sounds like that's going to give you secondary, tertiary, quady-ary, etc. bevels rather than a smooth convex bevel. It's like the integral: if you want to approximate the area, use a few rectangles that go as high as your function and then take the area of each and add them up. If you want the exact area, you have to use an infinite number of infinitely skinny rectangles. Or to get a circle, you can start with a square, make it a pentagon, hexagon, octagon... and you'll have something "close" to a circle. But to get an exact circle, you have to have infinite sides.

I guess your method would give you a "somewhat" convex grind, but I suggest you use the classic mouse pad and sandpaper.
 
Sandpaper on a mousepad is very forgiving, even if you have a hard time freehanding on stones. If you want convex, give it a try. It's not an expensive learning process, and can get really wicked sharp edges.
 
It's really simple. You get different grits of wet-dry sandpaper. I use 220(only for re-profiling), 400, 600, and 1500. You get a mousepad and put it on a table or board, and put the sandpaper on the mousepad. I cut mine into narrower strips. You then use an edge trailing or "stropping" stroke to sharpen the blade. You can use pretty firm pressure at first, but lighten it up as you progress through the grits. Work up a burr along the edge on both sides befor changing grit. The burr will get smaller and smaller. After the sandpaper, strop with loaded leather to completely remove the burr, and polish the edge. Super sharp edges.
 
Its not guided so its convex anyways, even if you don't use rubber bands.
 
You won't get better at freehand sharpening unless you practice. Start with some cheap kitchen knives. Read a couple of tutorials and just go.
 
I would completely avoid your above idea. sounds like it will be a mess when it is done i.e. too many angles. Just get yourself sandpaper wet/dry 220-2000 and a mousepad. Do this with a few beers and then polish the edge either by stropping or you can use metal polish and then what i have done in the past for quick touchups is run this over the sharpmaker white rods at a 40 degree edge setting 5 times on each side. this gets my knives scary sharp if i am in a hurry for touchups.
 
Women can fake orgasms, men can fake the entire relationship, but you can't fake a convex. It either is, or it isn't.

As suggested any freehand method is convexed to some degree because it is impossible to hold a steady angle without a jig.

Set yourself up with the mousepad sandpaper method. It is inexpensive and very easy to learn.:thumbup:

Kevin
 
I already tried it. i seem to have made a bit of progress. i got my endura sharper than i ever did on the SM. sure hope this isn't a fluke. :)
 
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