Hi Karl,

Welcome to the forum. Carbide tooling needs a rigid lathe, high speed and a certain depth of cut, usually at least the nose rasius of the carbide insert. I often use carbide for the roughing cuts and finish ith a newly honed HSS tool.

Thor

Most carbide inserts are relatively blunt compared to a well sharpened piece of HSS so need a decent depth of cut to work well. Going for a small cut will probably result in the tool randomly going between rubbing and cutting and so produce a terrible looking result. A carbide insert sharpened and polished for use on aluminium is a much better option for small cuts than the standard inserts. They are also good for use on other materials if you have a rigid lathe, I have used them to machine stainless steel and HSS.

So the issues you are having are probably due to the type of insert you have has a relatively blunt cutting edge and the lathe is not rigid enough to resist the forces that result from this bluntness.

Martin C

Agree totally with the reponses so far. A Light machine like the Sherline is not optomised for tools like this in my opinion. Good HSS bits will give much more consistent results. Cutting titanium on such a machine is probably pushing things, I'm sure it is possible, but never going to be easy.

regards Mike

Yes, and IIRC, Sumitomo do titanium carbide inserts which claim to be suitable for small DOC.

The rated power of your motor is I think 90 w and that is very small to consider any form of carbide tooling. If you are successful with HSS, you should stick with it

Grinding HSS tools is very easy with a grinder and fine wheel I’ll add photos of my setup later simple to build it uses the radius of the wheel to provide front and side clearance when the holder is on the sliding platform. Although I have a tool and cutter grinder, this set up is used for all but very critical grinds as it’s so quick to use. One of these days I’ll make a metal base fir it as the sliding part tends to stick a bit removing some sensitivity.

The critical dimension is the platform top should be 10 mm below the wheel centre the slider with the adjustable angle is 6 thick, and the tool holder is 8 mm thick . Note the tool is located by a 6 mm square riveted to the base , and is sized so the tool is able to be located on the front or side Springs push the top plate up to release it when the wing nuts are loosened.

I also have holders for small round shanked preformed boring bars and other round tool bits

Jason, yes I agree about some can work well with carbide with this lathe, but I was echoing earlier posts about the lack of power, its lack of rigidity and the op had success with HSS

Edited By Zan on 12/09/2022 13:30:32

With a smaller lathe, the inserts designed for aluminium used with small depth of cut would be my choice, I use them for finishing cuts on steel and have also used them on titanium aircraft parts, we have plenty of spare bits waiting to be made into something else at the museum.

If your inserts are identifiable, you can get certain types in pairs rather than boxes of ten from APT, which is a good way to experiment.

Edited By old mart on 12/09/2022 14:22:43

That is a ANSI code for a DCMT insert which are the "blunter" types, The one I linked to earlier will be a direct replacement and is one specifically for Titanium alloys. It has a smaller tip radius and is also meant for fine finishing which will be ideal of the Sherline

As a half way house you could get away with a similar general DCGT that is not specifically for titanium such as this which can be had in packs of two

What part of the world are you in? as that will affect availability of what is suggested

Edited By JasonB on 12/09/2022 14:58:15

The APT ones will do you then, It's just that the titanium specific ones you will probably have to get a box of 10

The ones for aluminium, non ferrous and Stainless will also work well on steels too and I would suggest using them for all your turning and they may well do for the titanium too. Worth a try to just buy two of those. This is one taking a 1thou (0.025mm) depth of cut on steel

Edited By JasonB on 12/09/2022 15:13:46

The last two numbers should be the radius, I believe it’s thickness then radius, but could be wrong.