[asuratman]

Hi,
Please let me know how to enlarge internal diameter, say from 2.25" to 2.312" in long tube (3'). The OD of tube is 3.5". How long maximum toolholder and diameter can be used for lathe machining for this tube. Up until now, I enlarge from one side and then go to another side. It takes long time to set on CNC machine. Thanks. Aristo.

[WhiteTiger]

That sort of job is typically done with a piloted reamer. If internal finish is important, use a right hand cut, left hand helix reamer with a ported pilot and supply air or coolant at the far end of the tube to flush chips from the reamer flutes.


Tiger

[MarkT]

I have done similar on manual and CNC lathes with a good quality carbide devibe bar, positive rake configuration, machining in halves, with steady rest if possible. Depending on finish quality, removing all material in one pass.
Hope this helps!
Mark T.