On 8 mei, 05:45, "Del Cecchi" wrote:
"Mitchell Jones" wrote in message

***{That's right, and the reason is due to the variations in the force
required to slide the sides of the blade past the material. All we are
really concerned with is the force required to get the edge to slice
through the surface of the material. The deeper it is embedded into
whatever is being cut, the larger the adhesive/frictional force that
must be overcome, because that is proportional to the areas that are in
contact, and is clearly not relevant to the issue of sharpness.

Why isn't it relevant? Many cutting tasks involve things of non
negligible thickness.

Because you're measuring blade sharpness, not sharpness + some other
factors involving friction and target geometry. While we rec.knives
types are all about practicality, if you want to measure and quantify
things scientifically you have to isolate factors as much as
possible.

Ultimately, a blade's utility is down to several things; sharpness,
geometry, rigidity, the target material... there's a mental tendency
to lump this all in to "sharpness", because that's a handy word to use
for how easily a knife cuts through something, but it's not accurate.

***{It would be very difficult to ensure that the slicing motion was
the
same in all cases, so I would not recommend that method.

So it is not a valid alternative because it is hard? Better give up the
particle accelerators then.

Particle accelerators make it *easy* to reproduce conditions, that's
why they cost so much. Put practically, it could be a very expensive
process to create a repeatable and standardised slicing motion.

Cheers
Rich