This demonstration walks through how to straighten square tubing automatically, where the goal is not just overall curvature but control of the two diagonals, corner twist and face flatness. The square tube is indexed through profiled rollers and guided supports that contact the flats rather than the corners, avoiding corner deformation while bending moments are applied plane by plane.
The CNC measures deflection across multiple sections — short pieces use 2–3 measurement points while long square tubes use 5 or more — and corrects each plane in a 20–90 second cycle. Square tubing from small furniture sections up to heavy structural sizes — anything in the Ø5–600 mm capacity range and up to 12 m long — comes off the machine within 0.10–0.30 mm/m, with tighter 0.02–0.05 mm results for automotive and precision frames.
Straight square tubing is essential for trailer frames, racking, greenhouses, gym equipment and steel furniture, where twisted sections prevent welding and cause assembly gaps. The footage also shows how fixture changes handle rectangular sections on the same machine.
For more setup detail, see our guide to how automatic straightening works, view our full Bar & Tube Straightening Machines catalogue, then contact our engineering team with your square tube sizes for a trial-run proposal.
Plane-by-plane correction controls curvature, twist and diagonal mismatch
Profiled rollers contact the flats to protect square corners
2–3 measurement points on short sections, 5+ on long tubes
Handles square and rectangular sections with quick fixture change
380–480V three-phase industrial power for fabricator floors
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