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Re: Japanese punch drill (sharpening)

           See The Exhibition Online, And Order Your Catalog.

We sell a hole drill made by Maun in England. It sounds like it follows the
same principle as the Japanese Hole Drill everyone is referring to, expect
that it does not have the automatic twist mechanism; you must twist your
wrist back and forth while applying pressure.

In any case, the bits for this unit are sharpened with the bevel on the
inside, and unless you only intend to punch a few sheets at a time, it is
imperative to continue to sharpen them that way.
If you bevel the outside of the cutter, instead of cutting a clean hole of
the right size, the cutter will cut an undersize hole, then stretch it as
the bevelled end passes into the hole.

This has two drawbacks:
1) The punch will jam in the hole when you try to punch anything more than a
trivial amount of paper.
2) The hole edges will be crushed and the hole stretched, leaving a raised
edge on the hole or a dished area in the sheet around the hole.

For sharpening this type of bit, you need a cone-shaped mounted sharpening
stone (like you would use in a dremel), but the cone must have the correct
angle for the cutter. I would expect that you would want a fine grit to
minimize the metal removal, and keep the dremel speed low to prevent
overheating the metal. These bits appear to be regular carbon steel, so they
are *very* susceptible to loss of temper while sharpening. If the metal
loses its temper, it will only stay sharp for a few cuts.

Another choice would be a tapered wood arbor which is coated with a slurry
of grit in oil and spun in an electric drill.

Also because they are carbon steel, these bits are prone to rust.
-Kevin Martin
 the Papertrail

>-----Original Message-----
>From: Book_Arts-L: READ THE FAQ at http://www.philobiblon.com
[mailto:BOOK_ARTS-L@LISTSERV.SYR.EDU]On Behalf Of William Minter
>I have sharpened the outside of the tips with very-fine wet-dry emery, and
>Crocus Cloth. A DREMEL would also help for some inside touchup, if needed.
>Bill Minter

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