On 12/12/2011 12:46 PM, Lloyd E. Sponenburgh wrote:

I made a really beefy (3" steel tube) boring bar, and found only that the
flex in my compound/cross slide is still too much to keep the bit from
singing excessively.
Yup, that was my worry. Only an insanely HUGE lathe would be stiff
enough to handle a boring bar with 15" overhang. I have a 3500-Lb
Sheldon 15" lathe, and I really doubt it could handle such a nasty
job properly.

Jon