On Thu, 17 Mar 2005 01:44:40 GMT, Jaggy Taggy
wrote:
Several discussions here pointed out to me the importance of proper bit
sharpening for lathe work.
I should start getting a proper bench grinder, but what would people here
recommend as a grinder which would solely be used to sharpen bits??
TIA
Uwe
==============================================
Suggest that you take a long hard look at disk/belt sander.
Typically one with a 4 X 36 inch belt and 6-inch diameter disk.

You can get zirconium oxide [blue norbide type ] belts from Enco
in a number of grits, and can pick up adhesive back silicon
carbide disks in finer grits at most auto parts stores.
Zirconium oxide belts seem to grind very rapidly and much cooler
than the aluminum oxide belts. Use the belt for roughing and the
disk for finishing. You can get a mirror finish if you wish.

The angles that you can set with a "miter" gage that comes with
the typical belt sander (or grinder) are not accurate so I
suggest fabricating a block on which you can clamp the tool and
set with a machinist's protractor.

Fabricate an angle-setting block that you can use to accurately
set the table angles and use to set the "miter" gage
perpendicular to the disk/belt. You can also use this to set the
table [slot] parallel to the face of the wheel, disk or belt.

By using the angle-setting gage for the table and setting the
tool angles with a machinist's protractor, you can get repeatable
results. Otherwise, you will grind a tool, it won't cut right,
you will grind some more, etc. and will never be sure what works
and why.

If you go with a grinder, buy a diamond dresser, and fabricate a
holder so you can "drag" the diamond across the wheel at the
correct angles using the "miter" gage while maintaining it
parallel to the guide slot. A sharp wheel makes all the
difference in the world.

A useful hint is to use an abrasive bristle brush to remove the
burrs from your newly ground bits and give the hand-honed effect
in a few seconds. I bought the one I use at ACE hardware. It is
about 5 inches in diameter, has a 1/4-inch shaft, with medium
grit nylon bristles.

Another tip is to keep a spray bottle [old Windex type bottles
work fine] filled with water and lightly spray the grinding wheel
while grinding. This keeps the tool much cooler as the water
evaporates and avoids thermal shock when you dip the tool. This
can be very hard on carbide. You can add a small amount of
water-soluble oil [water pump lube @ 99cents a can] to avoid
rusting.

Avoid oil on the table/slot as this will attract and hold grit.
I like Teflon spray. It is dry and very slick. It also seems to
protect against rust.

It would be helpful I can post pictures of the tool holder block
and replacement miter gage to the dropbox.