Glossaire du cintrage
Every conduit bending term — shrink, gain, take-up, multiplier, springback, developed length and the rest — defined plainly, the way you use it at the bender. Most of them are just names for a length or an angle in the same handful of triangles — once the terms are clear, the formulas read like sentences. If every word here is new, the six lessons on Bending, from zero introduce them in the order you meet them at the bender.
The six looked up most
- Hauteur
- The height an offset lifts the run — how far it steps up or over. The rise, with the angle, sets the distance between the marks and the shrink.
- Déport
- Two equal bends that step a run over an obstruction and level it out again, so it carries on parallel to where it started.
- Multiplier
- The number you multiply the rise by to get the distance between the two offset marks. It is 1 ÷ sin of the bend angle and depends on nothing else — 30° is always ×2.
- Raccourcissement
- The length an offset takes out of the run, because the sloped pipe between the bends is longer than the flat ground it replaces. You add shrink to your measurement before the first mark, or the far end lands short.
- Reprise
- The length a 90° bend consumes as the pipe sweeps through the corner. It is stamped on the bender per pipe size and varies by tool — never a universal figure. The stub mark is the finished height less the take-up.
- Deduct (deduction)
- Another name some benders use for take-up on a 90 — the amount you deduct from the finished height to find the mark. Same idea, same number.
- Gain
- On a 90, the length you SAVE because the pipe rounds the corner on a radius instead of turning a sharp square. It is why the two legs of a 90 add up to more than the pipe you use. Watch the word on a concentric bend: there "gain per run" is the opposite sign — the EXTRA pipe each run further out needs to get round the same corner on a bigger radius. Same word, two trades' worth of habit; on a 90 you subtract it, on a concentric rack you add it.
- Longueur développée
- The length of pipe a curve actually uses along its arc — radius times the angle in radians. It tells you how much conduit a sweep or a large-radius bend consumes end to end.
- Retour élastique
- The small amount a bend relaxes open after you release the pressure, because the metal is partly elastic. You slightly over-bend to land on the angle you want; how much depends on the pipe and the bender.
- Selle
- A set of bends that carries a run over an obstruction rather than around it. A three-point saddle peaks over something round; a four-point saddle crosses a flat top with two offsets.
- Stub
- A single 90° bend to a set height, the leg standing up from the run. The mark is the finished height minus the take-up, measured from the end of the pipe.
- Kick
- A single bend that lifts or angles a run — one leg of an offset without the second bend to level it out. A kick 90 pairs a kick with a 90° stub.
- Roll
- How far a run moves sideways while it also rises. When both happen at once the jog is a rolled offset, and the true offset is the hypotenuse of the rise and the roll.
- Roll angle
- On a rolled offset, how far to rotate the pipe off vertical before bending, so the tilted jog points where it needs to. It is the arctangent of the roll over the rise.
- Arrow
- The reference mark on the bender you line up with your layout mark for a stub or the leading bend of an offset. The other main reference is the back-of-bend mark.
- Back-of-bend
- A second reference on the bender — often a star or a notch — that sits at the heel of a finished 90. You bend the second 90 of a back-to-back off this mark so the distance between the backs comes out true.
- Trade size
- The name of a pipe size — 1/2" EMT, 3/4" rigid, 2" PVC — not a measurement of anything on the pipe. It stays the same name whether you lay the bends out in inches or millimetres.
- Coude segmenté
- A large-radius sweep faked with many small equal bends spaced evenly along the pipe, because a hand bender cannot pull a wide radius in one go.
- Coudes concentriques
- Several conduits turned around one corner on shared centres, each on a larger radius than the last, so the group stays parallel and evenly spaced through the turn.
Where the terms are used
The how-to guide puts these in the order you meet them at the bender, and every calculator on the site shows the term it works with beside the result. Shrink and the multiplier turn up on the offset calculator; take-up on the stub-up and take-up pages.