O.K. How long is "short" compared to the diameter of the
workpiece? If there is more than 4 times the diameter sticking out of
the chuck, you will have deflection -- to an amount dependent on the
cutting forces involved.

Where does this "4 times" rule of thumb come from? I am querying this
because deflection is much more sensitive to diameter than length. e.g.
comparing 1" diameter bar of 4" length to a .5" bar of 2" length, both
loaded with 100 lbs at the free end, the deflection is _twice_ as great
for the smaller bar. This is even worse if the deflection in proportion
to the diameter is considered.

BeamOut''(30E6,I_tube 1 .5)Beam 0 (4 100)
pos'n pt. couples shear bend. slope def'l
force stress stress
0 -100 -400 -169.8 4074 0 0
4 100 0 0 0 0.0005432 0.001449

BeamOut''(30E6,I_tube .5 .25)Beam 0 (2 100)
pos'n pt. couples shear bend. slope def'l
force stress stress
0 -100 -200 -679.1 16300 0 0
2 100 0 0 0 0.002173 0.002897

Ted