Sharpening
AlCarruth@aol.com
Tue, 25 Jun 1996 21:49:21 -0400
There are several things that can be done to keep a grinding wheel from
burning. The most important is to keep it clean and sharp, which is easily
accomplished with a tool called a 'star wheel'. It looks like an
old-fashioned spur with a handle. In use you hold the 'rowels' of it against
the spinning grindstone. The points dig in a little, and knock off all the
glaze and built up metal in the surface of the wheel that was causing it to
burn. I stupidly went without one for years, and had all kinds of trouble.
Never again!
A coarse wheel will burn less than a fine one, and cut faster. Since you
are not going for a final edge here, use as coarse a wheel as you can. The
white or pink wheels run a lot cooler than gray ones. The green ones are
intended for carbide. Never grind aluminum, brass, or any other copper alloy
on your wheel. It will just load it up. Most high-speed wheels should not be
used with a water bath. They will tend to soak up water on one side when they
are not running and get out of balance, which can cause them to explode.
Dipping most steel alloys in water between cuts on the wheel will help
keep them cool. I understand that some types of high-speed tool steel are
hurt by this, but I try to stick with carbon steel for cutting tools, as I
like the edge I get.
If you do want to use a sander to sharpen tools, remember that, unlike a
wheel, the belt should be moving AWAY from you as you sharpen. If you try it
the other way, the tool can dig in and tear the belt, and you as well. You
really need all of those fingers for playing!
Wet/dry sandpaper can be used for sharpening too, in a pinch. Lay it on
something flat, like a piece of glass, and wet it down. Move the tool in a
figure-eight pattern to keep the bevel flat. Most woodworking stores carry
only up to #600 grit, if you are lucky, but the auto body shops use grits up
to #2000 and finer, which should put a commendable edge on anything.
Gosh, how these 'short notes' get away from one!