Mystery TC inserts.

I have this box of tungsten carbide inserts which I bought several years at a car boot sale. I am wanting to make some holders for them but am unsure as to the size of the fixing hole. It is too loose for 2mm and not big enough for 2.5mm. An 8 BA bolt fits but is still a bit loose. I just wondered if anyone can suggest what size screw/thread is used with these.

The inserts are 10mm on a side and 3mm thick.

Edited By Anthony Knights on 08/06/2020 15:30:42

Normally a torx screw but no tapered hole in the picture shown. Probably of the style that lets the hole locate on a round peg and then uses a top clamp over the chip breaker groove.

I have seen insert holders that have a pin that goes through the hole. A hex cap screw underneath pusherd the pin base and levers the insert into its pocket.

I'll have a look see if I have one somewhere.

Martin C

Anthony

Try these people for advise. **LINK**

Pin is 1.95mm diameter. The pin is eccentric and has a hex socket on the back. Rotating the pin releases or clamps the insert.

Martin C

Edited By Martin Connelly on 08/06/2020 16:38:34

Are they single of double sided? Are the sides square, or sloping? A 3-48 UNC screw comes in between 2 and 2.5mm sizes. Those inserts are as old as the hills, all I can say about then is that they are right handed.

I believe the H13A denotes suitable for aluminium.

Emgee

Thanks for that. A bit complicated for my intended use. I think I will use the KISS principal and use the nearest size screw I have, possibly backed up with a clamping arrangement.

I will report back with my success/failure in due course. Thank you all who responded.

Don't invest too much time and effort in to it. The correct part is not so expensive. Anyway this is the sort of tool you need to design and make.

PTGNR holder

Martin C

I've learned something today, that there is a TNMG 11 size insert. I have TCGT 11 and TCMT 11 for a boring bar. That PTGNR type of holder is by far the most difficult to make and would be far beyond the average person. The body is hollow and a rocking clamp is used.

Just thought I'd update you as to use of the inserts. I made a double ended tool, which seems to work quite well. I tried it on a piece of rebar which is a pig to get a decent finish on, even using a freshly ground and honed HSS tool with cutting oil. The tips were held in place with 8BA screws.

I then moved on to the item I originally intended using the tips on. This was in the May edition MEW and has been in my project file since.

When I first tried it it was absolutely awful. I had obviously got the cutting edge too high. Put the main block in the 4 jaw and took a light skim. When re-assembled and checked against the height gauge (just a metal cylinder of the correct height), it looked spot on, but a check with the finger nail showed it to be just a gnats below centre height. Tried a test cut and it worked well. Most of my turning is done with tangential tools, but this will come in where they aren't suitable. It joins my growing selection of specialist tool posts.