Advice for turning on mini lathe, pls

[Prizen]

Hi all.

For those with experience of the small metal lathe, looking for your advice on turning AL round bar stock, 25mm dia and 120mm long. The stock tends to be displaced in the 4 jaw from the cutting forces. I'm generally only taking a small amount off in each pass, and the tooling is good quality carbide inserts.

I've tried and tried to ensure tool tip is on centre line. But, still have this issue .

Any thoughts? Thanks

 

[Robbo3]

Are you using the tailstock to support the work? If not, you should.

 

[novocaine]

as already said, try with the tail stock (rule I was taught was 3 times the diameter but on smaller stuff it's more like 2 from experience) but also:
1. What type of aluminium is it?
2. Is your insert tooling suitable for cutting it? (hint, most aren't but will do it in a pinch, they have the wrong geometry and chip breaker).
3. have you tried HSS with the correct geometry?
4. what feeds and speeds are you trying at? (another hint, look up whats correct for grade of material)

 

[AES]

Another +1 for the tailstock once the job comes out of the chuck more than about a couple of inches.

Also:
Another +1 for use of HSS rather than tipped tooling. Tipped tooling is intended for lathes with more rigidity than common on mini lathes (see below).

Also:
Very basic I know, but are you sure both the job and especially the chuck jaws are perfectly clean and swarf-free before chucking the job?

Finally, these little mini lathes are IMO very useful (I have one myself) but they are SMALL, which means they lack rigidity. That means you cannot take as deep a cut as you would with even a "little but proper" lathe like, say, a Myford 7. But at least 10 thou off ali should be perfectly do-able. That's AFTER you've adjusted ALL the gibs to ensure that there's no "float" on any of the screw handles (e.g. I've got mine set so that that they're quite stiff to turn).

What chuck are you using?

HTH