Parting off aluminium in the lathe can be nerve racking and especially if you’ve got it wrong in the past and either the work piece has come out of the chuck or the tool has broken. Aluminium has the tendency to snag and stop the lathe dead.
Based on this I’ve noted down some simple rules:
- tool height is exactly on centre
- cutting angle = 35° for aluminium
- ensure the holder is tight with just enough overhang to make the cut
- use plenty of cutting fluid
- Lock the saddle
- Low speed – 150rpm or less
- Use parting blades that are at least 12mm deep
- Check alignment, then check again
- Hone the tool on a diamond abrasive
The result is the tool is at the correct height, everything is as stiff as possible (blade depth, overhang reduced and unused motion locked) and the cutting speed is low along with cutting fluid to ease the cut.