How do you measure "thickness behind the edge"?

[Steel_Drake]

You can standardize the thickness behind the edge measurement by stating how far back from the apex the transition occurs. I tend to run much lower than stock edge bevel angles (typically around 7.5 degrees per side on my EDC knives) and I will always measure the distance to the apex at which the transition from blade bevel to edge bevel occurs.

You can even use an online triangle calculator to use those measurements to compute what the thickness would be at a standard distance behind the apex (I typically use 1/32"). Most production folding knives, in my experience, are ~0.025-0.035" thick at 1/32" behind the apex (as measured with micrometer calipers). By contrast, I run my EDC knives at about ~0.010" thick at 1/32" behind the apex.

[paladin]

Just a few quick measurements that I took with my Micrometer to put things into perspective. :)

20 LB Printer paper - .0035"

Phone Book Paper - .002"

Double edged razor blade - .003"

Sal can cut things WITH a piece of Printer paper... :spyder:

[Cliff Stamp]

do you have any good sources or papers on the cutting force approximation you described?

Its a first order hook's law approximation, most materials tend to obey it, especially in small displacements. Beyond that it gets very material and cutting specific. "Modeling of cutting by means of fracture mechanics", Jovorek et. al. . shows the current approach to the modeling and "Cutting properties of hemp fibre", Kakitis, et. al., discusses more the direct experimental approach.

[Evil D]

You can standardize the thickness behind the edge measurement by stating how far back from the apex the transition occurs. I tend to run much lower than stock edge bevel angles (typically around 7.5 degrees per side on my EDC knives) and I will always measure the distance to the apex at which the transition from blade bevel to edge bevel occurs.

You can even use an online triangle calculator to use those measurements to compute what the thickness would be at a standard distance behind the apex (I typically use 1/32"). Most production folding knives, in my experience, are ~0.025-0.035" thick at 1/32" behind the apex (as measured with micrometer calipers). By contrast, I run my EDC knives at about ~0.010" thick at 1/32" behind the apex.

Wouldn't this still bring up the same issues as measuring at the shoulder of the bevel? Seems like the exact same thing actually, just worded differently. Unless you mean just having a standard distance from the apex that you measure, but again if you simply run a lower angle edge bevel then you can alter the behind the edge number simply by narrowing the bevel.

[Steel_Drake]

Evil D,

The important point is to specify how far back from the apex the thickness measurement is taken, because then math can be used to determine the thickness at the SAME distance behind the edge as any other knife for which you have the same data. Foe example, if knife A is 0.020" thick at the shoulder, and that shoulder is 1/32" behind the apex, and knife B is 0.020" thick, but at 1/16" back from the apex, then you can use math to determine that knife B is approximately 0.010" thick at 1/32" behind the apex (i.e. the same distance back as knife A).