Thread: Grit issues, does any one else see a problem here

Come on now. The scratch pattern affects the edge. This is simple trigonometry. Doubly so as there are two bevels meeting at the apex. Just think about it - if you have a scratch of x depth on both bevels on a razor with a 17° bevel that coincide with each other at the apex, you're looking at a dip in the bevel of around 16*x. A scratch on a single bevel and you're looking at 8*x recession into the edge.

There's no need to obsess over scratch patterns, merely try to minimize scratch depth. The man asked us to analyze his problem, and again, this is not a razor, it's a knife. There's no shaving going on here.

Originally Posted by eKretz

Come on now. The scratch pattern affects the edge. This is simple trigonometry. Doubly so as there are two bevels meeting at the apex. Just think about it - if you have a scratch of x depth on both bevels on a razor with a 17° bevel that coincide with each other at the apex, you're looking at a dip in the bevel of around 16*x. A scratch on a single bevel and you're looking at 8*x recession into the edge.

There's no need to obsess over scratch patterns, merely try to minimize scratch depth. The man asked us to analyze his problem, and again, this is not a razor, it's a knife. There's no shaving going on here.

Ok agree on that point and bow to superior knowledge, geometry was never my strong point! Thinking about this some more as I've just been hand sanding a blade, I totally see your point as if the scratches aren't smoothed out I'd never get the metal smooth enough to get that mirror shine on the blade. Maybe I'll pay more attention to the edge patterns when I next hone a razor from bevel to finisher then compare the edge to another razor where I've not been as fussy. You see that's what I love about this site you're always learning and it makes you think. Thanks

I've been PM'ed by a member who was doing the math, and just wanted to add that the numbers above were done with quick mental arithmetic - I have since rechecked and the actual difference is 3.5*x for a single scratch of depth "x," 7*x for double coincident scratches of depth "x." Quick working sketch below with a theoretical example showing scratch depth of .001" for the sake of easy comparison. (I made a boo-boo here in my original mental calculation, the 7*x is for the double scratch as it's calculated to centerline).