Bending a four-point saddle
A four-point saddle crosses something too wide for a three-point saddle, like a beam or a duct. One offset takes the conduit up, it runs level across the top, and a second offset, the mirror image of the first, brings it back down to its line.
What to measure
- Obstruction height: how far the conduit has to rise to clear it.
- Angle: all four bends are bent to it.
- Obstruction width (optional): how far it runs along the conduit. With it you get all four marks; without it, only the first offset’s.
- Distance to obstruction (optional): from the end of the conduit to the near side of the obstruction.
How to bend it
- Bend the first offset from marks 1 and 2 just like an offset, with the hook facing the end. Its second bend finishes at the near side of the obstruction.
- Turn the bender round so the hook faces away from the end for marks 3 and 4, as the marks list shows.
- Put mark 3 on the arrow and bend it the same way as bend 2, then mark 4 the same way as bend 1, so the conduit comes back down to its original line.
- Sight along it: the top should be level and all four bends in one plane.
Where the numbers come from
Each half is the Offset screen’s offset. The straight across the top is exactly the obstruction width, so bend 2 finishes at the near side and bend 3 starts at the far side. Across the top runs from mark 2 to mark 3. With marks for the arrow it is more than the width, because those two marks sit on the outer sides of their bends; on Bend center it is the center-to-center distance, 14 3/16" in the example.
shrink = 2 × (height × tan(angle/2) − 2·g(angle))- Obstruction height
- 6"
- Angle
- 30°
- Obstruction width
- 12"
- Distance to obstruction
- 40"
- Between bends
- 11 15/16" (12" by multiplier)
- Across the top
- 17 5/16"
- Shrink
- 3" (3 3/16" by multiplier)
- Marks from the end
- 26 7/8", 38 7/8", 56 3/16", 68 1/8"
If it turns orange or red
The same as an offset: red if the two bends of an offset would run into each other, orange if there is too little straight between them for the shoe. Use a smaller angle. Red also shows when a mark would fall before the end of the conduit.