On Apr 12, 1:39 am, 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.


the problem with SHARPNESS is it is not a good measure of the
effectiveness of a cutting tool. so even quantifiabbly measuring
sharpmess means nothing in itself. Sharpness will be like Watts in car
stereos or Horsepower in motors and compressors

The reason i say that is that the Cutting tool is dependent on the
material being cut for its effectiveness.
by knife standards a SAW is a thick flat edge with 0 sharpness but its
very effective at cutting trees.


If i use trees as an example try cutting a tree down with a splitting
maul and you will be into one of the most frustrating experiences of
your life. Just a little less so than splitting wood with a felling
axe

the felling axe is sharp and is made for cutting the splitting axe is
meant for prying wood apart sharpness is not very useful to a
splitting maul since it is serving as a LEVER not a blade

Food

Sharpness is a DETRIMENT to effectively slicing soft or airy foods.
Take a loaf of bread, a tomato, and an appleas examples

a Bread knife has a serrated edge and cuts with a sawing type motion
because Bread is mostly air with fibres of bread itself tham move
easily, its impossible to no have then crush someonwhat under an
unfirm blade so a sharp sawing motion catches it

A tomato is similar loose fibers in mostly water a knife with some
roughness on the edge slices it BETTER that a purely sharp edge to
avoid

an apple is MUCH more firmly put together and a purely sharp edge cuts
it better than the earlier two


There are as many different ways to sharpen a blade as there are ways
to prepare lathe toolbits.

EVERY material does better with certain angles or feed types or feed
speeds

Sharp isnt everything but SOMETIMES sharpest is best other times it
isnt

But dont confuse a worn edge with an edge that is not sharp.

I keep my pocket knife edge very fresh but at an angle to deal with
anything i might come across (I dont measure it but it is likely about
a 30 degree angle based on how i hold my hand while sharpening. It
needs to still be in decent shape if i need to cut copper wires or
strip coating or chop off plastic tiewraps i wont be using it for fine
detailed cutting. But a filleting knife i would have sharpened to a
FAR steeper angle for a far finer cut and so that it might wear down
FAR faster if it was cutting anything firmer than a fish

I can chop through copper cable with my pocketknife if i need to and
then need to resharpen it at the end of the day. my kitchen knifes or
chisels would have their edge ruined doing that immediately.

Sorry for the long Post but the overall point of it is Sharpness is
not a direct measure of effectiveness

Brent

Ottawa Canada