"Mitchell Jones" wrote in message
...
wrote:
can you imagine if the conventional wisdom for judging size-tolerance
of fabricated-materials was along the lines of, "how does it feel when
i shave hairs on my arm?"
I want to _measure_ knife sharpness. In a repeatible, scientific
way. And preferably, non-destructive to the sharpened edge!
the floor is open for discussion.
***{You want to cut a homogeneous material that will not take the edge
off of your blade. Use paraffin.
You want the conditions to always be the same, so that you can compare
results. Clamp the blade to be tested so that it forms the horizontal
member of an isosceles triangle, the equal sides of which point
downward. Hang a platform in the "V" and add weights until the blades
cuts smoothly through the paraffin. The less weight required, the
sharper the blade. Always use identical blocks of paraffin.
The weight required, then, is the measure of dullness; its reciprocal is
your measure of sharpness. Always include the weight of the "V" and the
blade in the data you record.
That should work.
As can be seen from experiments on shaving blades, the sharpness
is somewhat a function of the chemistry of the thing to be cut,
so perhaps it would be best to have the blade cut the material
involved.
If this is a non-destructive, production test, and speed is required,
you extrude the material to be cut through a small hole,
and slice the material using a tiny edge of the production item,
using a photo-optical device to determine when the material was cut.
You could use increasing air pressure
or move a mass along a balance beam
to apply force to the blades.
If the blades are the same mass,
and the test is go/no go,
you could drop the blades on the material,
and have the blades that don't cut through
stick to the material and be carried away
or deflected away from the "good" blades.
--
Tom Potter
*** Time Magazine Person of the Year 2006 ***
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