[Icehole]

Hi i wonder if anyone has any special knowledge on turning aluminium .
I have a haas SL10 i am not a machine shop i just use it for prototyping and i use cadcam to generate all my programes so all my feeds and spped are done by software.
The problem i am having is stringing when turning as i get towards the centre IE: i start turning at 32mm it chips fine until i get to around 18mm the it strings like crazy . what i want to know is there a general rule of thumb when turning alluminium .
I am wondering if maybe the aluminiuim is getting softer towards the centre and thats whats causing the problem.

[Geof]

Are you using constant surface speed? G96 on the lathe. Going fast with a good depth of cut and feed can make chips break better. Also using a tool with a chip breaker that tightly curls the chips.

But sometimes it is practically impossible no matter what techniques are tried, and in these cases I resort to the G74 and G75 canned cycles to program short retract moves to create small chips.

[thething84]

problem sounds like that is isn't on constant surface speed as mentioned, there for the surface speed at 32mm is fine, but as you get towards the centre of the material the surface speed actually gets slower. therefore the feed per rotation decreases.