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Lloyd E. Sponenburgh[_3_]

fired this volley in
:

The reason I suggested a slightly undersized mandrel is because the ID
of the tubing will shrink some. But the other important feature of the
setup I suggested is that it limits the deformation because only one
cutter is used. This is because the tubing is supported right at the
pressure point. If more than one cutting wheel is used the tubing will
not be supported at every pressure point and so will shrink.

Eric, if the mandrel is a very close (nay, 'snug') fit in the tubing,
you'll get no noticable distortion of the diameter, regardless of how
many wheels are on the cutter.

If the mandrel fits well, only one is required, ever.

Lloyd