"Sunworshiper" wrote in message
...
On Sat, 31 Jan 2004 22:24:38 -0800, "Harold & Susan Vordos"
wrote:
snip---

Grinding parting and grooving tools ??? What is that? Thin disks?
What size of HSS are you using?

Not thin disks. Narrow tools, just like a commercial parting tool, but
made from various sizes of HSS tool steel. I grind them from 3/8" and 1/2"
square mostly. 1/4" X 1/2" saves a lot of grinding time but limits your
ability to place the tool where you might like it in your tool block. I
prefer the square ones. When you grind the tools, they are usually right
handed, so they cut near the chuck. That's especially important for parting
tools. Grooving tools are generally ground to specification, for such
things as O ring grooves, or snap rings. Piece of cake with a good running
wheel and no work rest.

I should just get my SG going and not
worry about it.

You can get in trouble with very thin tools, including on a surface grinder.
Tool steel has incredible tensile strength, but breaks easily when shocked,
so you have to be careful, especially if you're grinding a long, narrow
tool. As long as you use the right wheel and keep it sharp, though, you
can expect pretty good results on a surface grinder. The only hard part is
getting precisely the angle you desire. That is usually determined by the
holding fixtures. One that is commonly found in shops is a 60 degree one
for sharpening threading tools. That's likely one of the most desirable
fixtures to have if you are fortunate to own a surface grinder.

Good thread. BTW, how do you know diamond dressed
wheels are "dull" and have to be fixed?

If you're making reference to them being dull from dressing with a diamond
instead of a dressing stick where hand grinding is concerned, I know it from
experience, having dressed wheels by every conceivable method aside from
crush rolling. The only way you'll understand the difference between a
wheel that is roughed up with a dressing stick as compared to one that is
diamond dressed is to A-B the wheel. Dress one with a diamond then grind
with it. Touch it up with a dressing stick and repeat. You tell me which
one cuts the best. All that goes out the window on a precision grinder,
though. Diamond dressing is the only way, but conditions are not the same.

If you meant a wheel that is dull from use, then my response is:

It's from experience, and something that may not be real apparent to the
novice. There are signs you can look for, though. One of them is a shiny
surface on the wheel. If a grinding wheel takes on a glaze from use, it's
not breaking down anywhere nearly fast enough. As the grains get dull, the
surface begins to shine and the wheel cuts poorly. It will make a hell of
a lot of heat, but will remove very little material. At that point you
have to decide if you're using the wrong abrasive, or if the wheel is too
hard. There are certain absolutes that are known, so you can make good
decisions about your particular problem. For one, if you're using a
silicon carbide wheel and you're grinding steel of any kind, it's the wrong
selection and the wheel will display the condition I mentioned, and quickly.
Frequent dressing doesn't help.

Another sign of a wheel needing dressing is if it is loaded. That's pretty
easy to see, especially if you're grinding with white aluminum oxide wheels.
The surface of the wheel takes on a black appearance and gets packed off
with swarf. Simple. Dress the wheel. It doesn't take very much, either.
A few thou will get the wheel back to good condition.

I've stood in front of huge
grinding wheels for many hours. I need to work on my very cheap
grinder present , but figured if I was going to get it from one it
would have been long ago. I use to think of such things when starting
them up in the morning and wondering if some idiot hit it with
anything. ) Put a steel plate over the top so it won't knock you
out (head injury) , you can always bleed slowly , maybe.

That theory might work on small wheels, but if you're running large wheels,
say on a crank grinder, if the wheel goes and you're in line with it, pretty
good odds there's going to be a funeral. I'm sure some have survived
exploding wheels, but I wouldn't bank on it. Wheels of that size would
likely move the steel and get you anyway. Lots of energy there.

The biggest I
worked with was "about" 3.5' Dia. X 3". I was trained in three weeks
from completely broke and asking gas station patrons if they wanted to
buy this redwood waterbed that I built out of 3.5" X 13" laminated
beams. The guy was curious and asked me my background and told him
that I understood linear and rotational geometry and he was like do
you want my job I'll train you ...? I just bought machines and
figured it out may years later about cutting instead of grinding.
I have no real guards or rests , should!

I'd love to have someone
show me something I don't know or could "see".
I get lost in printed descriptions. I just tense up and do it with a
very and hopefully non debated form 3 dimensionally in my mind and
do it. Like grinding the top ? If you put in a chip breaker then you
really have to grind a lot for the next when it wears out. Don't ask
me. The others know more.

Depending on the nature of the chip breaker, you can often just grind it
slightly deeper and push it farther back towards the opposite edge of the
tool. The net effect is to lower the cutting point of the tool, but you
can get considerable mileage from the tool that way.

The best part of chip breakers is that when you understand them and can
apply them properly, you can take cuts that you otherwise would not be able.
Boring is a great example. By winding the chips tight enough to break them,
you not only can take a better cut (thanks to the positive rake developed by
the chip breaker), it is also much safer because you don't generate long
strings that can pull you in when they get wound up in the chuck.

Harold