15 years ago
(over ASTM A500 or A513)? I am looking at using a 4.5"x4.5"x0.25"x13'
steel tube to mount a profile rail. One side of the tube has to be
machined to be flat to within 0.040". The less twist the better,
otherwise I must specify excessively thick walls to leave enough
material for machining. I am using the ASTM A500 twist specification
of 0.087" per 3 feet of length.
Also, does the drawing process create surface tension in the tube that
will relax when one face is milled (causing the tube to become
Am I better off using something other than DOM tube? Low twist is
more important than strength in this application.