Segmented 90 Calculator
By Andrew ·
Quick answer
A segmented 90 builds a wide sweep from several small bends, called shots. Each shot = total angle ÷ shots, and the marks are sweep length ÷ shots apart, with sweep length = radius × π ÷ 2 for a 90. A 30" radius sweep in 5 shots is 18° per shot with the marks 9 7/16" apart.
Calculator
- Results
- Between the shots’ marks
- 7 9/16" (7.54")
- Angle of each shot
- 18°
- Conduit used by the sweep
- 37 11/16" (37.7")
Worked out the textbook way, from the bend angle alone. BendMate also uses your bender’s radius, deduct and shoe.
Turning a curve into short bends
A hand bender cannot make a gentle curve in one pull, because its shoe has a fixed small radius. A segmented 90 gets round the problem by taking the corner in several light bends, spaced along a curve of the radius you want.
degrees per shot = total angle ÷ shotssweep length = radius × (π ÷ 2)Worked example: a 30" radius in 5 shots
- Sweep radius
- 30"
- Total angle
- 90°
- Shots
- 5
- Each shot
- 18°
- Sweep length
- 30" × π ÷ 2 = 47 1/8"
- Marks apart
- 47 1/8" ÷ 5 = 9 7/16"
- Mark every shot along the conduit from the stub end, the marks the same distance apart.
- Put each mark on the arrow in turn, hook toward the stub end, and bend it to the shot angle.
- Make every shot the same way and in the same plane.
- Check the stub with a level when the last shot is done.
More shots, smoother sweep
| Shots | Degrees each | Marks apart |
|---|---|---|
| 3 | 30° | 15 11/16" |
| 4 | 22.5° | 11 3/4" |
| 5 | 18° | 9 7/16" |
| 6 | 15° | 7 7/8" |
| 8 | 11.25° | 5 7/8" |
Few shots make a blocky corner and a conduit that finishes slightly low, because a chain of short straights sits just inside the circle it stands in for. More shots track the curve more closely, but each needs its own mark and its own pull.
Where segmented bends go wrong
- Letting the conduit twist between shots, so the bends are not all in one plane.
- Using a radius too tight for the number of shots, which puts the marks too close for the shoe to grip.
- Measuring from the wrong end. Every mark is measured from the stub end.
- Pulling the shots by eye to different angles. The total only comes out at 90° if they are equal.
Shots, shoe and bender
The spacing above is for the sweep. The shoe decides how close two shots can sit and the first mark’s position. In BendMate the same math accounts for your bender’s radius and deduct, and flags shots too close to bend.
Get the marks for your bender
BendMate works this out from your bender’s radius and deduct, flags a bend that won’t work, and shows you every mark.
Common questions
What is a segmented 90?
A segmented 90 is a large-radius bend made of several small bends, called shots, spaced evenly along the curve. It is used to sweep around another 90 or a big obstruction.
How many degrees per shot?
Divide the total angle by the number of shots. For a 90° bend, 5 shots is 18° each and 6 shots is 15° each.
How far apart are the marks on a segmented 90?
The sweep length divided by the number of shots. A 30" radius sweep is 47 1/8" long, so 5 shots are 9 7/16" apart.
How many shots should I use?
There is no fixed number. More shots give a smoother sweep that finishes truer, at the cost of more marks and pulls; fewer give a blockier corner. Use enough that each shot is a modest bend, and keep them far enough apart for the shoe to grip.