FabLayout

3 point saddle calculator

Enter the obstacle height and the distance to its centre. You get the centre mark with the shrink added and the two side marks for a 45° and 22½° saddle.

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The PDF cut sheet with this drawing and your marks is made in Truemark. It works offline on site and keeps your jobs.

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221133SpreadSpread1010″″ShrinkShrink3388″″
Scale drawing

Centre mark from the end

36 3/8in

Exact geometry

First mark
In the app
Last mark
In the app
Side marks from centre
In the app
Shrink
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.

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  • Bend 45° at the centre mark and 22½° at both side marks.

How to lay it out

  1. Measure the obstacle

    Measure the height of the obstacle the conduit has to cross and the distance from the pipe end to the centre of the obstacle.

  2. Mark the centre

    Measure the centre mark from the end. It is the distance to the obstacle plus the shrink, so the hump lands over the middle of the obstacle.

  3. Mark both sides

    Measure the side mark distance back from the centre mark and forward from it, and wrap both marks.

  4. Bend the centre first

    Put the rim notch (saddle notch) on the centre mark and bend to 45°. If your bender's guide uses the star for saddles, use that.

  5. Bend the two outer marks

    Bend each outer mark to 22½°, both the opposite way to the centre bend, keeping all three bends in one plane.

Good to know

  • Bend 45° at the centre mark and 22½° at both side marks.
  • FabLayout runs the same code as Truemark; the result is exact geometry.
  • Source: Greenlee Textron, Site-Rite Hand Bender Instruction Manual, IM 1071 Rev 4, three-point saddle instructions, with trade training material: centre 45°, outer 22½°, outer marks 2.5 × height, shrink 3/16″ per inch, bend order centre then outers

Method and formula

A 3-point saddle lifts the conduit over a pipe or other round obstacle with three bends: 45° in the middle and 22½° at each side. Three numbers come from the obstacle height.

  • Shrink = obstacle height × 3/16″ per inch of height.
  • Centre mark = distance to the obstacle centre + shrink.
  • Side marks = obstacle height × 2.5, measured each way from the centre mark.

These are the published field constants for this saddle, not exact trigonometry: centre 45°, outer 22½°, outer marks at 2.5 × the height and 3/16″ of shrink for every inch of height. Bend order matters. The centre bend goes first and the two outer bends follow; done the other way round, the outer bends move the centre and the saddle will not sit over the obstacle.

Worked example

The page defaults: a 2″ obstacle with its centre 36″ from the end. The shrink is 2 × 3/16 = ⅜″, so the centre mark is at 36⅜″. The side marks are 2 × 2.5 = 5″ each way, at 31⅜″ and 41⅜″. Bend 45° at 36⅜″, then 22½° at both outer marks.

Questions

Why is the shrink added to the centre mark?

The saddle takes up length as it rises over the obstacle. Adding the shrink to your measurement puts the top of the saddle over the centre of the obstacle instead of short of it.

Can I use other angles for a 3-point saddle?

This calculator uses the 45° and 22½° saddle, which is the one with published multipliers. For other heights or wide obstacles, a 4-point saddle built from two offsets gives you control over the angle.

Which notch do I use for the centre bend?

Most hand benders have a rim notch or teardrop for the centre of a saddle. Some guides use the star instead. Follow the marking on your own bender.

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