BluntCut MetalWorks
Knifemaker / Craftsman / Service Provider
- Joined
- Apr 28, 2012
- Messages
- 3,462
Facts:
1. thin apex radius (keenness) = ease of fracturing/splitting material.
2. high % damages to apex due to lateral force (initial and eventual).
*ignoring edge upward/away flex variable
Micro bevel of 22.5+º dps (45+º inclusive) strengthen apex 2x or more against lateral forces. e.g. if cut entry is at 23º (barely planed into material), lateral force is normal/perpendicular to entry force, hence there is tiny bit more than 2x steel above. Basically, ensuring more steel above the lateral/repelling of contact. In perspective of lateral, this micro bevel serves act as a scraping tool with 90º edge start out thin but thicken very rapidly.
=== Example of an apex with radius/thickness around 0.5um ===
Apex1 - 15º V
A2 - 20º V
A3 - 15º V with 25º 50um wide micro
If tasks are cutting 100 times at hard material such as very hardwood; bone; etc.. Performance wise(energy efficiency and clean cuts) - A3 will be best since its working edge will stays much thinner than A1 & A2.
===
Geometry is more important than finished grit - as long as grit can shape smallest geometry in setup.
IME - I found rolled edges have drastic reduction in slicing performance (well, no fun to cut with more/less a small round wire - has at least 2.5x initial apex radius - for an edge).
As for wedging from a micro bevel - the magnitude can be adjust by micro bevel width, while sufficient to support apex per intended tasks. I think, high keenness apex yields much greater performance gain than downside of wedging. Blend/convexing micro bevel also helpful in reduce cutting motion chatter/sputter.
1. thin apex radius (keenness) = ease of fracturing/splitting material.
2. high % damages to apex due to lateral force (initial and eventual).
*ignoring edge upward/away flex variable
Micro bevel of 22.5+º dps (45+º inclusive) strengthen apex 2x or more against lateral forces. e.g. if cut entry is at 23º (barely planed into material), lateral force is normal/perpendicular to entry force, hence there is tiny bit more than 2x steel above. Basically, ensuring more steel above the lateral/repelling of contact. In perspective of lateral, this micro bevel serves act as a scraping tool with 90º edge start out thin but thicken very rapidly.
=== Example of an apex with radius/thickness around 0.5um ===
Apex1 - 15º V
A2 - 20º V
A3 - 15º V with 25º 50um wide micro
If tasks are cutting 100 times at hard material such as very hardwood; bone; etc.. Performance wise(energy efficiency and clean cuts) - A3 will be best since its working edge will stays much thinner than A1 & A2.
===
Geometry is more important than finished grit - as long as grit can shape smallest geometry in setup.
IME - I found rolled edges have drastic reduction in slicing performance (well, no fun to cut with more/less a small round wire - has at least 2.5x initial apex radius - for an edge).
As for wedging from a micro bevel - the magnitude can be adjust by micro bevel width, while sufficient to support apex per intended tasks. I think, high keenness apex yields much greater performance gain than downside of wedging. Blend/convexing micro bevel also helpful in reduce cutting motion chatter/sputter.
I carefully follow all of what you're doing and I think that with hardness you achieve in steel , convex grind is probably best ........................... 
). 