Lathe jam

I have a problem that I’m hoping someone has an answer or suggestion, on my Myford 10 while using the Rocketronics els when my tool bit gets to a shoulder it jams, EG for example say I have a length of 25mm mild bright steel that I want to turn down to 10mm say over a length of 40mm, in the control I I input-40mm for Z and - 7.5mm for X , using a eccentric engineering tool the first few cuts are fine although I can hear the extra cutting up against the shoulder and with each cut the extra cut seems to get louder and the last 1mm or so before the shoulder is very rough and a Matt finish but it’s when the part is getting towards the 10mm it jams , I have checked to make sure the tool is square to headstock .
Thanks in advance Dell.

This is what I was making.

It sounds like it's shoving itself into the corner and the flanks need more relieving

Whats the angle your using?

When I did the same sort of work I needed a very pointy tool, for some reason a common sense 10-15 degrees just didn't do it

Edited By Ady1 on 11/07/2023 17:05:44

This is the tool setup.

I presume you have a digital readout on the lathe or control, watch to see what position it is going to at each cut, that will give you a good idea what is going on, also speak to Rocketronics? You tool also needs sharpening

Tony

The readout goes to 40mm every time that tool bit has a radius corner so should I use a sharp corner ?

you are putting a high load on the length of the left hand edge of the tool if it is at 90deg to the lathe bed, you could try 89deg then when last long cut is taken, take a cut at the 40 mm dim from the outside edge to the diameter turned.

Maybe the technique is to set the X to 39.5 mm, and as a finishing cut, to face the shoulder to length, so that the tool is moving at 90 degrees to the lathe axis, but only removing a small quantity of material down to the required diameter.

Howard

What happens if you feed by hand. I'd have the angle twixt cutting face and material slightly more than 90 so that it doesn't try to cut full depth right at the left hand end

I find having the shank of the Diamond tool set exactly perpendicular to the lathe axis gives the correct clearances for both longitudinal and facing cuts. And it does look like you need to sharpen it.

Rob

Depends how old the diamond holder is, mine is fairly old and has to be set quite a way off. This was some compromise to do with screw cutting. It's also a d*mned nuisance

Thanks for all the replies and suggestions,The tool holder is less than 6 months old and I put the finished part in to chuck so I could take a picture of it with tool up against the shoulder and I can see I have more clearance one side and not much near the shoulder.

Dell

Dell, looks to me like there is enough clearance on the shoulder side.

Tony