KEVOS® MAKEOS · Fabrication
Tube Bend Developed Length
What centreline length follows from these straights and bends?
Sum straight tangent lengths and centreline arc lengths for repeated equal-radius tube bends.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Centreline bend radius | mm | Radius to tube centreline, not inside radius or die outside diameter. |
| Direction change per bend | ° | Direction change per bend; 90° is a right-angle turn and 0° is straight. |
| Number of identical bends | bends | Bends sharing the same radius and direction change. |
| Total straight tangent length | mm | Sum of straight centreline lengths between tangencies and ends, not theoretical sharp intersections. |
Method and formulas
- One arc = radius × angle × π/180. Total = total straights + bend count × one arc.
- Example: two 90° bends at 50 mm centreline radius add 157.079633 mm to 400 mm straights, giving 557.079633 mm.
- For different radii, calculate each arc group separately and add each contribution once to the common straight total.
Limitations
- Centreline geometry excludes stretching, thinning, ovality, springback, clamp allowance and trim.
- No minimum bend radius or forming feasibility is established.
- Bend intersections and three-dimensional collisions are not checked.
- Default values are worked examples, not recommended settings or material properties.
Typical uses
- tube development
- centreline arc
- bend allowance
Who it is for
- Tube fabricators
- Mechanical designers
- Estimators
What you get
- Arc per bend
- Total arc length
- Geometric developed length
Interpreting the result
- Confirm tangent locations on the drawing or CAD model.
- Use process trials and the machine method to release the production cutting length.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 1382–1383. Topic reference; implementation and examples are original, and no source tables are reproduced.
- Method: circular arc length in radians plus straight centreline lengths.
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