reliable convex edge measurement & creation?

hardheart

hardheart

Joined
Sep 19, 2001
Messages
8,968
Measuring angles and thicknesses of v-ground edges is simple, but how can a convex grind be measured? One v-ground edge can easily outperform another, and we can see why by measuring the differences between them. They are also simple to replicate or adjust with relative accuracy.

How do we compare convex edges, or a convex edge to a comparable v-ground edge? Is there a simple way to calculate the curvature and repeat it on another blade? Something that would be relevant in sharpening by hand? Or something that would work with the deflection of a sanding belt?
 
Well, for measuring, take measurements of widths at set heights and compare them. Lacking micrometer/caliper, one could take modeling clay or another material that is soft but holds its form and press the edge in. Then, with just a ruler, width at different heights could be measured.

If the edge is close to following a parabola perfectly, assuming I'm remembering my geometry correctly, four measurements should be all it takes to produce an equation representing the curve.

edit: I should mention that's just off the top of my head, not something I've tried.
 
Well, i would be tempted to say a set of radius gauges could check it, but the problem would be that the actual bevel would be very small and hard to match a radius too, and pretty much all convex grind radii will probably be much larger than what you find on most gauges. I suppose it's worth a shot though.
 
effer, I do remember that thread now, and it must have been in the back of my mind the whole time, because that was the only thing I could think of doing before starting this thread - molding something around the edge, and then measuring a picture of it on the computer with a graphics program.

I may resort to it for testing and evaluation purposes; though something faster would be nice.
 
You must log in or register to reply here.
Back
Top