Segment bend calculator for large radius bends
Enter the total angle, the number of bends and the centre-line radius. You get the angle per bend, the spacing between marks and the developed length of the sweep.
Enter your measurements
Angle per bend
9.00°
Exact geometry
- Mark spacing
- In the app
- Developed length
- In the app
Every result is in Truemark
The free web version shows the main result and the drawing. Truemark gives you every mark and measurement, and exports a cut sheet. It is free to download.
How to lay it out
Choose the radius and the count
Decide the centre-line radius of the sweep and how many small bends it will take. More bends give a smoother curve.
Mark the spacing
Starting at the first bend, mark the pipe at the mark spacing for every bend in the sweep and wrap each mark.
Bend every mark the same
Bend each mark to the angle per bend, every bend the same way and in the same plane.
Check the finished sweep
Check the total angle with a protractor or against the layout before you cut anything off.
Good to know
- FabLayout runs the same code as Truemark; the result is exact geometry.
- Source: Plane trigonometry; same calculation as the Truemark app
Method and formula
A segment bend makes a large-radius sweep out of many small bends, for when a hand bender's shoe is too tight or a factory sweep does not fit. The total angle is shared equally, and the marks are spaced along the chord of the arc.
- Angle per bend = total angle ÷ number of bends.
- Mark spacing = 2 × R × sin(angle per bend ÷ 2), the chord of each segment on a centre-line radius R.
- Developed length = R × total angle in radians, the length of pipe along the centre of the sweep.
Worked example
The page defaults: a 90° sweep with 10 bends on a 36″ centre-line radius. Each bend is 90 ÷ 10 = 9°. The marks are 2 × 36 × sin 4.5° = 5.6491″ apart. The developed length of the sweep is 36 × π ÷ 2 = 56.5487″.
Questions
How many bends should I use?
Enough that each bend is small. Many small bends give a smoother sweep and kink the pipe less than a few large ones, at the cost of more marks.
Why is the mark spacing shorter than the arc divided by the count?
The marks are spaced on the chord of each segment, a straight line between two points on the arc. A chord is always slightly shorter than the arc it spans.
What is the centre-line radius?
The radius of the sweep measured to the centre of the conduit, not to its inside or outside face.
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