Bending a rack

A rack is a run of conduits side by side, on strut or a trapeze, that has to stay together through its bends. The rack builder works out every conduit at once, each on its own shoe, so a rack can mix sizes: a 1" beside two 1/2", say.

Which way the rack bends

Square to the rack: the bends go up or down out of the rack, like a rack on the ceiling dropping under a duct, or a row of stub-ups. The conduits sit side by side through the bends and are all bent alike, with their bends lined up across the rack.
In the rack’s plane: the rack bends sideways, one conduit inside the next, like a rack turning a corner along a wall. Each conduit’s bends then move to keep the spacing. Conduit 1 is always the one on the inside of the first bend, so list the conduits from that side.
A kick is always in the rack’s plane: the conduits lie side by side and their 90s stand up out of the rack, against a wall square to the run. Saddles are only made square to the rack.

What to measure

The bend’s own measurements, as on its screen, for conduit 1.
Conduits: each one’s size, from conduit 1 outward. The sizes come from the bender you have chosen.
Spacing: between neighbors, inside to inside (the gap you would measure with a tape) or center to center (the spacing of the clamps).

How to bend it

Mark each conduit from its own list. With a distance or a stub, the marks are from each conduit’s end, so line the ends up; with no distance, they are from conduit 1’s first mark, so lay the conduits side by side and mark across them.
Bend each conduit on the shoe for its size, as on the single screen for that bend.
For a rack bent in its plane, keep the conduits in order: conduit 1 on the inside of the first bend.

Where the numbers come from

Square to the rack, every conduit gets the same bend, with its corners lined up across the rack. In the rack’s plane, the conduits are parallel lines a set distance apart, center to center, and each bend moves to keep them so.

offset: bends further along = centers from conduit 1 × tan(angle/2)

The same for any bender, as on the Parallel offset screen. With a distance to an obstruction, the conduit that finishes last finishes at it.

90: stub and leg grow by centers from conduit 1 + (OD − conduit 1’s OD) ÷ 2

Both ends line up, and each outer conduit goes round the one inside it. A segmented 90 is also made concentric: its sweep radius grows by the same center distance.

kick: each kick = conduit 1’s kick − centers × (1 ÷ cos(angle) − 1)

As on the Parallel kick forward screen: the outer conduits kick less, and their 90s stand centers ÷ cos(angle) along the wall from conduit 1’s.

Three 1/2" EMT, 1" apart inside to inside, offset 6" at 30° in the rack’s plane, finished 40" from the end, on a 1/2" EMT hand bender

Offset height: 6"
Angle: 30°
Distance to obstruction: 40"
Spacing, inside to inside: 1"
Conduit 1: 26", 37 15/16"
Conduit 2: 26 7/16", 38 3/8" (7/16" further along)
Conduit 3: 26 7/8", 38 7/8" (15/16" further along)

1/2", 3/4" and 1" EMT, 1" apart, turning a 90 in the rack’s plane with a 12" stub and 30" leg

Stub length: 12"
Other leg: 30"
Spacing, inside to inside: 1"
1/2": stub 12", mark 7", cut 39 1/2"
3/4": stub 13 15/16", mark 7 15/16", cut 42 3/4"
1": stub 16 1/16", mark 8 1/16", cut 46 3/16"

If it turns orange or red

Each conduit is colored on its own, and the rack takes the worst of them. A kick turns red when an outer conduit would have to kick less than nothing: the rack is too wide for that kick at that angle. A conduit with no shoe on the chosen bender says so and holds up the rest.

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