I am attempting to make tubing from flat CNC perforated and parted blanks. My material thickness range is prolific - from 0.025" to 0.125" across a small amount of cold rolled steel, but significant population of stainless steels (301, 304, 17 - 7 PH) and a significant population of aluminum (3003 h-14, 2024 0 and T 3 / 4 temper, 6061 0 and T -6 and 7075)

While I am being some what succesful in the cold rolled and the 3003 h-14, I am experiencing ovality (roundness) issues on the stainless and tougher aluminums.

I am initially creating a Butt Seam tube. The butt seam is held to a 0.0" to 0.005" allowable gap.  This does not seem to be as hard to acheive as originally thought. Later on it will be welded.  However, for now I must be succesful at getting the best roundness possible.

Does anyone have any experience in this domain.  I am using old practices to make "U" & "O" formed tubes. However, I have created a machine to do it more efficently, automatically with transfer automation.  My diameter range is as prolific as my materials. I work from minimum O D. of 0.317" to max. O. D. of 3.740" in lengthss as short as 0.800" to 13.0"