Harold & Susan Vordos wrote:

"George E. Cawthon" wrote in message
...


Harold & Susan Vordos wrote:

"Statics" wrote in message
news:5Fzub.461$b64.76@okepread02...
I bought several packages of their diamond cutoff wheels, they last a
while
as long as they are not overheated. Bought two or three blister cards
of
5
over a year ago when they were on sale, I am only on my second disc
(light
use only or where I need
the thinnest kerf possible, otherwise I use a bigger tool). I killed
the
edge of
first disc working too hard at cutting a hardened parting tool. For
the
price, I am impressed.

I have my doubts about the other ones, several of the diamond sets I
have
inspected had visibly eccentric tips or were worm shaped.

StaticsJason

Diamond tools run at elevated speeds should not be used on anything
containing iron. You'll find that these tools will hold up quite well
cutting things like rock, but not well at all on steel of pretty much
any
kind. Reason? Diamonds are, of course, carbon, and iron has an
affinity
for carbon, so at elevated temperatures the diamonds tend to dissolve
into
the steel you're trying to cut. That dulls the diamonds rapidly,
leading
to higher temperatures, and, of course, faster dissolution of the
diamond.

Harold

Most of what you said as an explanation is not true.

Perhpas you can tell all of us what is true, then!

I have
no idea what a dissolute diamond is but many dissolute
people seem to be attracted to diamonds.

With that, I would likely agree.

Likely I have egg on my face regards a word chosen to describe a diamond
being dissolved into steel (my mom told me I should have gone to college),
but the principle is one well known by anyone that works with diamond
grinding wheels. The information is well documented by the grinding
industry. Diamonds are not recommended for use in grinding steels, and for
the exact reason mentioned. The dulling of the diamonds lead to other
problems as well, they are not limited to just further dulling. Pulling
the dull diamond from the bonding matrix is one more of the problems.
Diamond wheels experience very short life spans when used improperly.

It's the same with silicon carbide grinding wheels on steel, which, like
diamond, dissolves into the steel being ground. If you've ever run any
kind or grinder and had poor results, you'll now understand why an aluminum
oxide wheel, in spite of being a lot softer (the abrasive, not the bond)
than a silicon carbide wheel, cuts steel exceedingly well, while the silicon
wheel dulls up instantly and creates lots of heat but does little grinding.
That characteristic is very obvious on a surface grinder, where the wheel
behaves as if it's loaded shortly after being dressed.

Did I use a selection of words that please you this time? If not, learn
something from the message, and replace the improper words with those of
your choosing.

Harold

Not my job to tell you what is true, but diamonds don't
dissolve and they certainly don't dissolve into steel. The
diamonds in a wheel can shatter (break), they can be pulled
out of the wheel matrix, and they can be smeared with either
the wheel matrix or the material being ground. The latter
is what happens when you say it loads up. Loading depends
on a lot of things but highly important are the coarseness
of the abrasive, the bond of the abrasive, and the speed of
the wheel.

If silicon carbide is so bad on steel, how come most small
bench grinders come with silicon carbide wheels? Granted
that not every abrasive is suitable for every material.
However, you can cut and polish just about everything with
the correct grades of diamond. As another person stated,
diamonds work quite well on steel.

Diamonds don't work well at the high speeds used in many
industrial tools and they certainly won't last long without
a cooling/lubricating fluid. However, speed is often much
more important that cost, but that's no reason to not
understand the physical process. Let me say one last time,
there is no dissolving of diamonds or silicon carbide in the
grinding process.