So I got a ken onion work sharp and love it. I can put a mirror edge on all my knives. But i noticed something weird, it can’t shave hair and doesn't FEEL sharp. But it S cuts paper like its a razor. It slices through cardboard better than some of my hand sharpened knives that can whittle hair. Can someone explain this to me?
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Convex edge
- Thread starter ZtCubster
- Start date
evilgreg
Why so serious?
- Joined
- Dec 25, 2012
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- 4,092
Polished ultra perfect hair-whittling edges never seem to perform well in real life for me. Even if they're blazing sharp they seem to lose that critical sharpness very quickly, much more so than an edge created by sharpening with a more abrasive stone.
I tried comparing this a few years ago with two Spyderco Southards. I used my Edge Pro Apex and ran through six or seven grits until I was up into the ludicrously fine range and achieved a mirror polish. Using the same angles and grits I sharpened another Southard but quit a few stones into the process, so the edge was sharp but much rougher.
Immediately after sharpening both, the mirror polished edge was sharper, though both shaved arm hair pretty casually, but overall the knife that stopped at 400 grit ended up cutting better and longer than the knife that went to 2000 grit. The mirror polished knife needed to be resharpened much sooner. I don't know why that is, but practical experience since has generally matched that pattern, with knives sharpened to lower final grits working better in use. I've seen some here say that it's because the rougher edge is essentially serrated, comparatively, at a microscopic level. Whatever the reason, it does seem to be true.
I've been using the bottom of a coffee mug and a loaded strop as my only sharpening tools for a few months and I'm quite pleased with the results I'm seeing. A lot of times I just use the mug, I keep the strop by end of the couch where I whittle and have mostly just been using it to touch up my carving knives while I work. I don't know what grit the random coffee mug I've been using equates to, but it raises a burr on highly wear resistant steels pretty quickly, so I assume it's pretty aggressive.
I tried comparing this a few years ago with two Spyderco Southards. I used my Edge Pro Apex and ran through six or seven grits until I was up into the ludicrously fine range and achieved a mirror polish. Using the same angles and grits I sharpened another Southard but quit a few stones into the process, so the edge was sharp but much rougher.
Immediately after sharpening both, the mirror polished edge was sharper, though both shaved arm hair pretty casually, but overall the knife that stopped at 400 grit ended up cutting better and longer than the knife that went to 2000 grit. The mirror polished knife needed to be resharpened much sooner. I don't know why that is, but practical experience since has generally matched that pattern, with knives sharpened to lower final grits working better in use. I've seen some here say that it's because the rougher edge is essentially serrated, comparatively, at a microscopic level. Whatever the reason, it does seem to be true.
I've been using the bottom of a coffee mug and a loaded strop as my only sharpening tools for a few months and I'm quite pleased with the results I'm seeing. A lot of times I just use the mug, I keep the strop by end of the couch where I whittle and have mostly just been using it to touch up my carving knives while I work. I don't know what grit the random coffee mug I've been using equates to, but it raises a burr on highly wear resistant steels pretty quickly, so I assume it's pretty aggressive.
When you use the bottom of a coffee mug, do you use 'pushing' (or slicing) strokes, or pulling-away strokes?
Jim
(heresy). Generally, (perhaps not with a convex) extremely sharp means a thinner edge which will not hold up as well as sharp enough but not as thin at the edge. I think. 
evilgreg
Why so serious?
- Joined
- Dec 25, 2012
- Messages
- 4,092
I've done both, and both ways work as long as you keep a consistent angle.
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How thick is the blade? On one of 4mm or thicker, a convex is super strong and sharp but I find it harder to shave with due to edge geometry.
Put one on a thin Opinel and it's a different issue .
Put one on a thin Opinel and it's a different issue .
A rougher edge has "micro serrations" and a polished edge is just an acute wedge. Push cutting is better with a polished edge, but slicing works better with a rougher finish. I'm not the end all expert, but I don't think it's necessary to mirror finish every knife.
That is the reason ............serrated
This saw on picture will cut even when tooth are dull .Will slow down BUT will still cut wood , right ?Can we cut in same manner with spine of that saw , even if we sharpen it to razor level ? NO !
Personally I sharpen all my knife with max.400 grit . I wish I could do that with 40 grit
