Thread: Hercus 9" parallel turning accuracy

Chris,

Don't see any reason why you couldn't use Aluminium for the test provided the diameter of the bar was increased. The overhang for the test (assuming it's no more than say 100mm or 4") isn't enough to cause any concerns about deflection provided you take very light cuts. Heavy cuts will push the bar away from centre and give you readings where you'll begin chasing your tail.

The ToT recommends using 1" (25mm) "soft steel" - which means annealed or normalised plain carbon. Assuming you're planning on using 20mm steel bar for the test, you'd need to go to about 30mm for Aluminium in order to give you the same stiffness, which means the same amount of deflection due to machining in each case. Hope this makes sense - if not PM me.

David