Re: piezo problem

Lump:
I always start with over wide stock.
Adhesive back 3m paper stuck to a flat
piece of 5/16 thick iron welding stock,
then run the bone stock over the sandpaper.
Stop before it is "almost" the right thickness
and allow the polishing to bring it down the
additional .001 or so.

Tony:
Sounds good. Do use a fairly big piece
of steel flat to hold the bone? (I think
that would make it easier to keep the removal
uniform.) Or just enough to use as a handle?

The flat steel lies flat on the table top. My piece
is 4" by 12". The sandpaper sticks to that, abrasive
side facing UP. Then I rub the bone blank on that
by holding it down against the abrasive.

To hold it down, I sometimes use an eraser.
A regular, pink, school type eraser meant for pencil
marks. The rubber "sticks" just enough to be able to
move the bone blank and it keeps my fingers and acrylic
nails out of the way of the abrasive paper.

Typically I don't even use that, just my fingers.
Flip the blank 180 degrees frequently, mark some
pencil witness marks and I find I can get it very
even thickness. I check it from time to time during
sanding with a digital micrometer. If I find it's
a little thick in the middle, I'll apply more pressure
there during sanding. I find that I can easily get
within .005 inch just with finger pressure.

There is a jig that will hold the blank in that
attitude too, but I don't have one. It's a spring loaded
thing that pushes the blank down to the surface of
the abrasive.

I guy that was a Navy machinist taught me about
measuring .001s of an inch. He would put two
feeler blades down on a formica counter top.
One maybe .005 the other .008. Then he'd say
"feel the edge and tell me which one is thicker".
If you do it enough you get to where you can
tell not only which one is thicker, but you can
have someone blindly put down a blade and you
can tell how thick it is. The Navy guy could do
it every time to the thousandth. He'd been doing
it for a gazillion years.


Lumpy

How come you didn't star on Star Trek?
Because Clint Howard beat me for the part of Balok.

www.lumpyvoice.org





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