Lots of old wive's [or old machinist's] tales about this. Some
of these are even true in a production environment, which won't
apply to low volume, lack of time pressure hobby or home shop
machining.

General rule is that you don't want any combination of tool and
material which will "react." For example, iron is known to
dissolve carbon when it is hot/molten. Thus you want to avoid
green [silicone carbide] or diamond wheels on steel. This holds
true for cutting tools as well. Diamond tools don't work too
well/long machining steel. Ceramic [aluminium oxide] tools don't
seem to last too well on aluminum.

Having said that, with the light use a typical grinder gets in
the home machine shop you most likely won't see much difference.

Biggest single tip is to keep your wheels "dressed" so they will
cut rather than rub. If you use aluminium oxide [white] wheels
the silicone carbide blocks, typically 1" X 1" X 6" will do a
fine job. If you use the green rocks, I suggest buying a
inexpensive diamond dresser [ 10$] and fabricating a holder out
of a square or rectangular piece of steel. Normally the diamond
dressers are round and tend to get away from you. Remember to
rotate the diamond in the holder block to avoid grinding flats on
it and it will last you a lifetime.

Take a look at my website in the craft machining section to see
the tool grinding fixtures we made as a class project.
see: http://www.mcduffee-associates.us/machining/thfnce.htm
and http://www.mcduffee-associates.us/ma...g/tabanggg.htm
With these and a machinists protractor, even the first term
students were able to grind a "line-out" acme thread tool. It
won't make that much difference if the HSS gets hot (see how hot
it gets when you are cutting), but try to keep any carbide tools
cool and never dunk hot carbide in water as this will cause
microcracking and it will quickly fail in use although it may
look fine.

One trick is to use a 5 or 6 inch diameter abrasive loaded nylon
brush in a drill press at medium speed. These are commonly
available in hardware stores and have blue bristles with a 1/4
inch shank. Use on the your new ground tool to give the effect
of hand honing in removing the wire edge. Also works well on
resharpened drill bits.

If you have not done so I suggest you buy the South Bend and
Sheldon lathe book reprints from Lindsay. These give a good
explication of the terms and have lots of pictures.
see http://www.lindsaybks.com/bks/lathebk/index.html

Just don't get discourages when the right hand tool your were
grinding turns out to be left handed. It has happened to
everyone.

Uncle George



On Fri, 02 Dec 2005 01:14:17 GMT, "Dick"
wrote:

I've got a H/F lathe tool grinder, a copy of a Balder or something. Any
way I have read that the green wheels are for carbide but that you shouldn't
sharpen tool steel on a green wheel. I'm thinking about getting a diamond
wheel to put on this and was wondering if tool steel can be sharpened on the
diamond wheel? Also, which diamond wheel would you get if you could only get
one, coarse, medium or fine? As always, thanks in advance for your comments.
This is by far my favorite forum.
Dick