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XYZ to YBC Converter for Tube Bending

Convert tube centerline XYZ points to YBC (LRA) bend data for a CNC tube bender, or YBC back to XYZ, with cut length and arc length.

XYZ to YBC

Enter the intersection points of the tube centerline, from start to end.

XYZ
Feed YRotate BBend C
Cut length (centerline)–
Total arc length–

YBC to XYZ

Enter feed, rotation and bend angle for each bend, then the final straight. The first point starts at the origin, feeding along +X.

Feed YRotate B, °Bend C, °
XYZ

Feed is the straight between tangent points. Results are theoretical at the centerline and do not include springback, elongation or machine-specific offsets such as clamp length; check against a test bend.

How XYZ to YBC conversion works

A bent tube can be described by the XYZ intersection points of its centerline, as on most part prints and CAD models, or by the YBC (also called LRA) bend data a CNC bender runs: Y is the feed length of each straight, B is the rotation of the tube between bends and C is the bend angle.

  • Bend angle C is the angle between two straight segments.
  • Feed Y is the segment length minus the tangent distance R × tan(C ÷ 2) at each end.
  • Rotation B is the signed angle between the plane of one bend and the next, measured about the tube axis.

Machines use different sign conventions for rotation, so use the setting above to match your bender. For 3D tube design and bend programming, ask us about BendFlow tube CAD software. Check developed length and tooling in the tube bending calculator.

Frequently Asked Questions

What is YBC in tube bending?

YBC is the bend data format used by CNC tube benders. Y is the feed (straight length), B is the rotation of the tube before the bend and C is the bend angle. It is also called LRA: length, rotation, angle.

Why are my feed lengths negative?

A negative feed means the bends overlap at that radius: the straight between two intersection points is shorter than the two tangent lengths. Use a smaller centerline radius or move the points apart.

Is the cut length the same as the developed length?

The cut length shown is the theoretical centerline length: all straights plus all arc lengths. In practice the tube stretches slightly during bending, so confirm the cut length with a test bend and add any clamp or trim allowance your machine needs.

Why does the first bend have zero rotation?

The first bend sets the reference plane, so its rotation is zero. Each rotation after that is measured from the plane of the previous bend.

Programming bends by hand?

A CNC tube bender with 3D programming converts your CAD to bend data automatically. Talk to us about VLB and SOCO CNC benders.

See CNC tube benders