Steels and edge angles

[Mephtyrm]

We've all heard of steels and edge retention, but I've always wondered if anyone every recorded what steels perform better with a certain edge angle.
For example, does 154CM hold an edge better at 30 degrees or 40 degrees? What edge angle would generally get the best edge retention out of 440A?
I know the edge retention depends on the individual knife and its grind and heat treatment.

 

[me2]

The edge angle a knife needs depends on what its cutting. Thinner is better, until the edge is too thin to hold it. I have knives at very low angles that will do kitchen work for a long time. However, if I take them outside for yars work, they get damaged quickly.

 

[Jason B.]

The edge angle a knife needs depends on what its cutting. Thinner is better, until the edge is too thin to hold it. I have knives at very low angles that will do kitchen work for a long time. However, if I take them outside for yars work, they get damaged quickly.

+1

You go as thin as possible for the task of the knife. How thin is greatly dependant on material hardness, regardless of alloy type.

 

[Jastab]

To the op, That's a very interesting point. I'd like to see cut counts on steels with different angles.

 

[Jason B.]

This chart shows CATRA info on a few different steels. It does not give the edge angles, or behind the bevel thickness which are also very important. IMO you would rarely see TCC (total cards cut) levels that high in a production knife.

 

[Mephtyrm]

The reason I asked that is because my new Benchmade 746's 154CM seems to despise cardboard, 325 and 750 grit diamond edges on that have the toothiness go away after just a few cuts and be unable to slice printer paper after a decent amount of cardboard while a 1000 grit just dulls right off the bat.
I tried 3 different grits so I assumed it was the edge angle because it doesn't really seem to perform very different from my Kershaw Crown's 8Cr13MoV.

 

[Jason B.]

Grit finished to makes a small difference overall, edge angle is king. Going thinner might actually help you.

Cardboard is a known edge killer, your results sound typical.

And its been my long standing opinion that BM 154 cm is ran rather soft.

 

[HeavyHanded]

The reason I asked that is because my new Benchmade 746's 154CM seems to despise cardboard, 325 and 750 grit diamond edges on that have the toothiness go away after just a few cuts and be unable to slice printer paper after a decent amount of cardboard while a 1000 grit just dulls right off the bat.
I tried 3 different grits so I assumed it was the edge angle because it doesn't really seem to perform very different from my Kershaw Crown's 8Cr13MoV.

Do you know what the inclusive angle is on your edge? In my experience BM puts an overly broad angle on most of their knives - 40* or greater with relatively thick back bevels. That really effects cutting performance - none of my Benchmades in 154cm performed well from the factory. Thinned down to 25-30 inclusive it should perform much better on cardboard, even/especially with a finer finish. Not all cardboard is created equal either...

 

[Obsessed with Edges]

The reason I asked that is because my new Benchmade 746's 154CM seems to despise cardboard, 325 and 750 grit diamond edges on that have the toothiness go away after just a few cuts and be unable to slice printer paper after a decent amount of cardboard while a 1000 grit just dulls right off the bat.
I tried 3 different grits so I assumed it was the edge angle because it doesn't really seem to perform very different from my Kershaw Crown's 8Cr13MoV.

Try:

• Thinner edge angle and/or blade profile (cross-section)
• Convex
• Higher polish (~2000+ grit)

Any one of these traits, or all of them in tandem, have worked well for me on cardboard. When taking advantage of all three in one edge, it makes for laser-beam cutting.

In particular, polishing the shoulders of a convex makes a huge difference in cardboard. Anything that reduces the friction of steel against the cardboard helps; otherwise it tends to bind more. Friction comes from a coarser finish, or from the hard-edged shoulders of a V-bevel, or even from a 'toothy' edge if it's not done well, or as the 'teeth' begin to dull (which is a much bigger issue with softer steels; teeth go away fast). All tend to grab & bind in tougher cardboards.


David