Bevel finish on knife

[Natlek]

Following this topic https://www.bladeforums.com/threads/sharpness-chart.1535016/page-4 and reading on this site https://scienceofsharp.wordpress.com I start to thinking that bevel finish has also much impact on cutting capability of knife ??
If edge look like this immediately after honing on 3micron diamond film.......................

I wonder how look both bevel side finished with 800 grit for example ??? Maybe like Sierra Nevada Mountains ??
What do you guys think about that ?

 

[FortyTwoBlades]

Coarser scratch patterns slice more aggressively but are worse at push-cutting as the micro-serrations are more prone to folding over in such work. More polished edges are better at push-cutting but very rapidly lose their slicing aggression. As such, one may tailor their degree of edge refinement to the range of work they expect the knife to be doing. I typically stop at 22.5µ with a light brush on a sintered ceramic stone to crisp up the apex without erasing the scratch pattern. It strikes a nice balance between slicing and push-cutting.

 

[Natlek]

I mind on main bevel , not on secondary bevel/edge bevel/ ....if I choose right words for both ?

 

[FortyTwoBlades]

Finish on the primary grind can have some impact on cutting performance, but only on cuts in materials that want to squeeze back on the blade, and the geometry has many more times of an impact than the surface finish does in those cases.

 

[Natlek]

600 grit diamond stone is 25 micron and if this applies on sandpaper too , we have Sierra Nevada primary bevel It will affect cutting in any direction ?

 

[FortyTwoBlades]

Not significantly on the primary grind. Only on the edge. Yes, there'll technically be some increased friction vs. a finer polish to the blade, but not very much. The edge is a thicker angle than the primary grind is, and so causes deflection away from the blade. Only materials that flow back into contact with the primary will even be affected at all, and then, not much. 25µ is still a fairly smooth finish. Don't let the SEM imaging spook you.

 

[HeavyHanded]

These pics are from 800 grit wet/dry, same edge and same approx location, at 1000x magnification - not as close as the SEM pic, but look at the scale on the pics and consider a single red blood cell is about 8 micron...

Second pic is with the blade at 45°, no easy task with oil immersion lens. Something I concluded a long time ago, ALL "sharp" edges are submicron.This exact edge would easily shave armhair and crosscut newsprint, and still could shave some armhair after 200+ carving passes across red oak on the endgrain, laid in with many lbs of pressure per pass. Steel is some incredibly tough stuff.

And then absolutely, friction and pressure profiles along with geometry determine how well an edge will cut whatever material with a given amount of force and a given amount of edgewise motion.