From the "interesting bit of metalwork" thread came a discussion of
how to make diamond points. Years ago I used the method Ed described
after reading it in either Moore's book or Machinery's Handook. When I
did this cheap diamond was not available. I lucked out when I was
given some diamond grit that I then graded. It was already pretty well
crushed into many different particle sizes. Now I use the diamond
paste that comes in plastic syringes. It is cheap and cuts pretty well
and is already graded. For making the points I use brass or cast iron
that I turn to the desired size and shape. Then I squeeze some diamond
paste onto a hardened steel plate and thin it with some kerosene. I
then use another piece of hardened steel to press against the point as
the point is rolled along the bottom plate. The pressure doesn't need
to be that high. I just lean hard onto the top plate as I push it
along and the point rolls between the plates. I do this a few times
because the thinned diamond paste squeezes out of the way when the
point is rolled across it. It seems to me that if I use the paste
without thinning it doesn't charge as well into the point. If you do
this you will need to experiment a little to see what works best. I
also make cast iron lapping plates for my slow speed carbide grinder.
To charge them I lay the plate on the bench, apply the diamond paste,
and roll a ball bearing across the plate. I put a shaft through the
bearing and press down pretty hard. The hardened outer race of the
bearing does a pretty good job of forcing the diamond into the surface
of the plate. When the plate starts to cut too slowly I charge it
again. The plates themselves do not wear because the work never
touches the cast iron if the plates are used properly. I make all
sorts of different form tools for turning or milling. When grinding on
high speed steel I keep the revs down on the point so that the diamond
lasts longer. Kerosene or WD40 make good cutting lubricants for this.
When I use care when charging the points with diamond they last a long
time. If you don't crowd the point when grinding, if you let it cut at
the rate it wants to cut at, it will last a long time.
Eric

On Sun, 08 Feb 2015 17:31:19 -0800, wrote:

From the "interesting bit of metalwork" thread came a discussion of
how to make diamond points. Years ago I used the method Ed described
after reading it in either Moore's book or Machinery's Handook. When I
did this cheap diamond was not available. I lucked out when I was
given some diamond grit that I then graded. It was already pretty well
crushed into many different particle sizes. Now I use the diamond
paste that comes in plastic syringes. It is cheap and cuts pretty well
and is already graded. For making the points I use brass or cast iron
that I turn to the desired size and shape. Then I squeeze some diamond
paste onto a hardened steel plate and thin it with some kerosene. I
then use another piece of hardened steel to press against the point as
the point is rolled along the bottom plate. The pressure doesn't need
to be that high. I just lean hard onto the top plate as I push it
along and the point rolls between the plates. I do this a few times
because the thinned diamond paste squeezes out of the way when the
point is rolled across it. It seems to me that if I use the paste
without thinning it doesn't charge as well into the point. If you do
this you will need to experiment a little to see what works best. I
also make cast iron lapping plates for my slow speed carbide grinder.
To charge them I lay the plate on the bench, apply the diamond paste,
and roll a ball bearing across the plate. I put a shaft through the
bearing and press down pretty hard. The hardened outer race of the
bearing does a pretty good job of forcing the diamond into the surface
of the plate. When the plate starts to cut too slowly I charge it
again. The plates themselves do not wear because the work never
touches the cast iron if the plates are used properly. I make all
sorts of different form tools for turning or milling. When grinding on
high speed steel I keep the revs down on the point so that the diamond
lasts longer. Kerosene or WD40 make good cutting lubricants for this.
When I use care when charging the points with diamond they last a long
time. If you don't crowd the point when grinding, if you let it cut at
the rate it wants to cut at, it will last a long time.
Eric

How do you determine when the diamond point is cutting? Do you do it
by sound? The lack of sparks makes it a little tricky. I could hear a
slight "rushing" sound when I just got them cutting.

--
Ed Huntress

On Mon, 09 Feb 2015 00:13:18 -0500, Ed Huntress
wrote:

On Sun, 08 Feb 2015 17:31:19 -0800, wrote:

From the "interesting bit of metalwork" thread came a discussion of
how to make diamond points. Years ago I used the method Ed described
after reading it in either Moore's book or Machinery's Handook. When I
did this cheap diamond was not available. I lucked out when I was
given some diamond grit that I then graded. It was already pretty well
crushed into many different particle sizes. Now I use the diamond
paste that comes in plastic syringes. It is cheap and cuts pretty well
and is already graded. For making the points I use brass or cast iron
that I turn to the desired size and shape. Then I squeeze some diamond
paste onto a hardened steel plate and thin it with some kerosene. I
then use another piece of hardened steel to press against the point as
the point is rolled along the bottom plate. The pressure doesn't need
to be that high. I just lean hard onto the top plate as I push it
along and the point rolls between the plates. I do this a few times
because the thinned diamond paste squeezes out of the way when the
point is rolled across it. It seems to me that if I use the paste
without thinning it doesn't charge as well into the point. If you do
this you will need to experiment a little to see what works best. I
also make cast iron lapping plates for my slow speed carbide grinder.
To charge them I lay the plate on the bench, apply the diamond paste,
and roll a ball bearing across the plate. I put a shaft through the
bearing and press down pretty hard. The hardened outer race of the
bearing does a pretty good job of forcing the diamond into the surface
of the plate. When the plate starts to cut too slowly I charge it
again. The plates themselves do not wear because the work never
touches the cast iron if the plates are used properly. I make all
sorts of different form tools for turning or milling. When grinding on
high speed steel I keep the revs down on the point so that the diamond
lasts longer. Kerosene or WD40 make good cutting lubricants for this.
When I use care when charging the points with diamond they last a long
time. If you don't crowd the point when grinding, if you let it cut at
the rate it wants to cut at, it will last a long time.
Eric

How do you determine when the diamond point is cutting? Do you do it
by sound? The lack of sparks makes it a little tricky. I could hear a
slight "rushing" sound when I just got them cutting.
Since I am either holding the work or the motor that spins the point I
can tell by feel. On the rare occasions when I have used a homemade
point in a machine and fed either the point into the work or the work
into the point I just go real slow, slower than the point cuts. It is
amazing how much feel a person can develop for delicate work with not
too much practice. Even after suffering some pretty major nerve damage
in both hands I was still able to regain much of my tool grinding
skill.
Eric