The Diamond Tool Holder

As always, Clive is right on the money.

I have a Bison QCTP (Dickson clone with 19 holders) that is on my lathe 96% of the time. I have the original 4 way tool post that is used 1% of the time and a home made lantern tool post sans rocker holding an Armstrong holder for those awkward lack-of-space jobs or one-off tool bits for the other 3%.

As you can see, i find the lantern/Armstrong far more useful than the 4 way.

Has anyone tried using the tangential tool with a brazed carbide on a square tool shank ? I have a couple of these tool holders from eccentric but rarely use them as I use carbide insert tooling for the most part but have always wondered if a chunk of carbide brazed onto the end of a piece of square stock then ground the same as the tool steel bit would work .

In this thread **LINK** a few years back I gave details on how to work out the angles to get different clearances. Thanks to Michael Gilligan I can now find old posts!

Not sure, it might work. Someone gave me several broken 1/4” solid carbide end mills so I tried one of those once ground in the Eccentric tool and it works great on hard stuff. I turned some HSS with it the other week.

I silver soldered this 1/8 inch carbide shank into a suitable size square piece,the edge is milled out about half the diameter and the piece soldered in ,it seems to work best if left as a round shank.The round piece fits neatly between the clamp.

The one on the left is ground to conform the the square shank ,because carbide chips easily when ground to the acute angles of the diamond tool a shallower angle is needed at the top and both the sides need a little grinding for clearance.

Useful for harder materials and maybe cast iron.

John

I have made a carbide tool bit to use in a tangential tool holder. I have used it on hard plastics. I have not used it on steel yet.

With that high rake angle I bet it cuts very well in the beginning but will not last long. Sharp points like that on carbide are prone to chipping.

Hi John Pace.

GMTA I made the same toolbit using the carbide shank from a PCB drill, PCB drills are so tiny to hold up they are made from very fine grain carbide. Tough too.

I milled a piece of key steel of the correct size and silver soldered in place.

Been using it for a couple of years. The ten degree angle you normally use for the Diamond tool can be reduced to around 5 deg by angling the template. More robust for heavier work. However it will work fine as standard.

Regards
John

Posted by John McNamara 7/01/2019 13:23:07

Hi John Pace.

GMTA I made the same toolbit using the carbide shank from a
PCB drill, PCB drills are so tiny to hold up they are made from
very fine grain carbide. Tough too.

I milled a piece of key steel of the correct size and silver
soldered in place. Been using it for a couple of years. The ten
degree angle you normally use for the Diamond tool can be reduced
to around 5 deg by angling the template. More robust for heavier work.
However it will work fine as standard.

Regards
John

Hi John,

I don't use the supplied fixture to sharpen the toolbits,some while ago
I bought 10 off 1/4 square toolbits from J&l supplies they were on offer
at about 80p each 10% cobalt.
Both ends are sharpened as can be seen in the photo .I had this process
scribbled out on a piece of paper and have tidied if up here for use
on the Quorn grinder or tool grinders with similar axis. This may be useful
for others wishing to do this.The self centering 2 inch four jaw chuck is
from Chronos and makes this much easier to do.

Having 20 ground ends if one is dulled it goes in the grind box and
a fresh one fitted.

The carbide tips that are ground similar to a CCMT shape only need regrinding
on the top until the are worn down enough that the sides need doing again.
Grinding the carbide is best done towards the cutting edge to avoid chipping.
These days the tangental toolholder gets the most use.

John