Rounding the Edge?

B

BladesB4Firearms

Joined
Oct 13, 2013
Messages
182
I've already read the stropping sticky, but I need some things clarified.

What does "rounding the apex" mean? I know what an apex of an edge is, I'm not sure I understand how it can be "rounded". This apparently happens to me from time to time (about 25%) with my leather belt on my sander I strop with.

The edge will be silky smooth and cut well through certain things (cardboard especially) but won't tree-top hair like it normally would off my strop, or even shave it off my arm. Could it be my micro-bevel or simply too much pressure with the strop? I do not set the micro-bevel with a strop.

I set the primary bevel at 5-10 degrees and my micro bevel at 15-20 degrees (not inclusive).
 
The apex is the intersection of two (presumably) flat bevels. Ideally, those flat bevels will intersect in as small and sharp a point (in cross-section) as possible, assuming angle is perfectly controlled. In 'rounding' the apex, this happens when the angle isn't perfectly controlled; variation up/down in angle will create curvature near and into the apex, which makes the intersection of the bevels 'rounder' (again, in cross-section).

In stropping on a conformable (soft) surface like leather, both inconsistently-held angle and the pressure used can create rounding of the apex. If pressure is too heavy on a softish surface, the surface will conform itself around the apex while abrading/polishing it, which causes the apex to gradually become rounder & wider/thicker (in cross-section).


David
 
Thanks. I just tried again with less pressure and it worked like a charm. So when the apex is rounded it becomes more of a "U" than a "V". I see now
 
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