Hi Harold,

I followed your thread regarding diamond vs. silicon wheels. One point of
confusion. Steel should not be ground on diamond. How come the Drill
Doctor and my el-cheepo knife sharpener use diamond impregnated wheels? Is
it simply a matter of short life time and I buy a replacement wheel? Or
there alternative cutters for consumer quality products?

Thanks,

Your Jazz listening buddy from Oregon
Ivan Vegvary

"Ivan Vegvary" wrote in message
news:MmRcj.2734$si6.1329@trndny08...
Hi Harold,

I followed your thread regarding diamond vs. silicon wheels. One point of
confusion. Steel should not be ground on diamond. How come the Drill
Doctor and my el-cheepo knife sharpener use diamond impregnated wheels?
Is it simply a matter of short life time and I buy a replacement wheel?
Or there alternative cutters for consumer quality products?

Thanks,

Your Jazz listening buddy from Oregon
Ivan Vegvary


I think you'll notice that the surface speed of these devices is well below
a critical threshold.
Where the problems begin is at red heat. If diamond is run on steel at
low surface speed, such that it doesn't get hot----no problem. Once up to
the heat of ignition, however, carbon begins transferring to iron, which has
an affinity for carbon. This process rapidly dulls diamond. If you touch
the base metal of brazed carbide tools to the diamond wheel (it happens
occasionally), there is an almost instant change in grinding
characteristics. It can be attributed to some loading of the wheel, but
the diamond is also dulled in the process. The wheel often requires
dressing to restore its qualities.

Regards the expected life of the wheels you have now---it all depends on the
nature of the wheel. High quality diamond wheels are a layer of matrix
(there are various bonds---metallic, resinoid, and more), filled to various
degrees, with diamond. The layer thickness and degree of concentration
dictate useful life. Needless to say, a 100% concentration that is 1/8"
thick will outlast (and out-perform) a wheel that has 25% concentration and
is 1/16" thick. It stands to reason that the higher the concentration,
the less the matrix is abraded, and the faster the wheel will cut.
The wheel of choice for grinding (brazed carbide) toolbits is a resinoid
bond, but it should not be applied freehand. A rest is a definite
advantage, and steady coolant is required. Drip can cause more damage than
none at all, due to thermal fracturing.

Damned shame about the loss of Oscar Peterson. What a treasure he was.

Harold

Harold and Susan Vordos wrote:

Where the problems begin is at red heat. Â* Â* Â* If diamond is run on steel
at low surface speed, such that it doesn't get hot----no problem.

Thanks for that explanation. Despite I didn't ask. ;-)

And a happy new year!

Nick
--
The lowcost-DRO:
http://www.yadro.de

"Harold and Susan Vordos" wrote in message
. net...

"Ivan Vegvary" wrote in message
news:MmRcj.2734$si6.1329@trndny08...
Hi Harold,

I followed your thread regarding diamond vs. silicon wheels. One point
of confusion. Steel should not be ground on diamond. How come the Drill
Doctor and my el-cheepo knife sharpener use diamond impregnated wheels?
Is it simply a matter of short life time and I buy a replacement wheel?
Or there alternative cutters for consumer quality products?

Thanks,

Your Jazz listening buddy from Oregon
Ivan Vegvary


I think you'll notice that the surface speed of these devices is well
below a critical threshold.
Where the problems begin is at red heat. If diamond is run on steel
at low surface speed, such that it doesn't get hot----no problem. Once
up to the heat of ignition, however, carbon begins transferring to iron,
which has an affinity for carbon. This process rapidly dulls diamond.
If you touch the base metal of brazed carbide tools to the diamond wheel
(it happens occasionally), there is an almost instant change in grinding
characteristics. It can be attributed to some loading of the wheel, but
the diamond is also dulled in the process. The wheel often requires
dressing to restore its qualities.

How do you dress diamond wheels? I wasn't aware they could be dressed, but
I've never had much to do with them, except for some old castoffs I
salvaged.

--
Ed Huntress

"Harold and Susan Vordos" wrote:

I think you'll notice that the surface speed of these devices is well below
a critical threshold.
Where the problems begin is at red heat. If diamond is run on steel at
low surface speed, such that it doesn't get hot----no problem.


I've also ment to ask about steel and diamond. Do you have an idea on what
surface speed is acceptable?

Wes

"Wes" wrote in message
...
"Harold and Susan Vordos" wrote:

I think you'll notice that the surface speed of these devices is well
below
a critical threshold.
Where the problems begin is at red heat. If diamond is run on steel
at
low surface speed, such that it doesn't get hot----no problem.


I've also ment to ask about steel and diamond. Do you have an idea on
what
surface speed is acceptable?

Wes

Sorry, Wes, I can only guess. Carbon combusts at something like 1,100° F,
so I'm inclined to think that it starts to occur at that temperature.

Norton did research on this subject back in the 50's, although I've never
read any of the reports. Could be you could learn more on their web site.
I've never bothered to look, so I have no clue.

Harold

On 2007-12-27, Ivan Vegvary wrote:
Hi Harold,

I followed your thread regarding diamond vs. silicon wheels. One point of
confusion. Steel should not be ground on diamond. How come the Drill
Doctor and my el-cheepo knife sharpener use diamond impregnated wheels? Is
it simply a matter of short life time and I buy a replacement wheel? Or
there alternative cutters for consumer quality products?

Hmm ... aside from the matter of speed which Harold covered (and
I think that the Drill Doctor is still pretty fast -- I could measure it
with a StroboTac, but it is also pretty small in diameter -- less than
an inch I think) -- but the Drill Doctor is *also* sold for carbide
masonry bits -- thus making the diamond necessary for that. Otherwise,
I would have prefered something like CBN. (Hmm ... how does that do in
sharpening carbide?

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

Ed Huntress wrote:

How do you dress diamond wheels? I wasn't aware they could be dressed, but
I've never had much to do with them, except for some old castoffs I
salvaged.
With a single-point diamond dresser. Same as you use for
carbide wheels. These are surprisingly cheap, for 1/4 carat
or so.

Jon