How to measure a cable reel

What you need

A 25-foot tape measure does nearly all of it. A straightedge or a spare board helps on large reels, where the tape has to bridge from one flange to the other. A flexible sewing-style tape, or a length of string you can lay against the tape afterwards, makes the drum easy when the flanges are in the way. A phone camera records the reel stencil and the measurements in one go.

Measure on level ground with the reel standing on both flanges. Anixter's handbook says reels should be stored that way anyway, apart from small ones under two feet and 200 pounds. Never climb on a reel to reach across it, and never stand in the path it would roll.

The five measurements, step by step

1. 01

   Flange diameter

   Hook the tape on the rim and run it straight across the face of one flange through the arbor hole to the far rim. Take the largest reading. Check the second flange; if the two differ, note both.

2. 02

   Traverse

   Measure the inside distance between the two flanges, at the drum, from inner face to inner face. Take it at two or three points around the drum; a leaning flange gives different readings.

3. 03

   Drum diameter

   Wrap a flexible tape or string around the bare barrel to get its circumference, then divide by 3.1416. Or use the depth method below.

4. 04

   Out-to-out width

   Measure across the outside faces of both flanges, including any arbor plates or bolt heads that stand proud.

5. 05

   Arbor hole

   Measure the hole's diameter straight across, then turn the tape 90 degrees and measure again. Two different readings mean a hole worn oval.

Two ways to get the drum when you can't reach it

The drum is the awkward one, because the flanges stop you laying a tape across it. The circumference method works on any empty reel: wrap a tape around the staves, read the length, divide by π. Make sure the tape sits on the staves, not on a strip of leftover cable, old tape or a raised board.

The depth method works when you can't get a tape round the barrel, for instance on a reel standing close to a wall. Lay a straightedge across the flange rims, measure straight down to the drum, and you have the flange depth. Drum diameter is then the flange diameter minus twice that depth. A 48-inch flange with 12 inches of depth to the drum has a 24-inch drum. The method also tells you the usable depth for the capacity formula directly.

Traverse and out-to-out are not the same number

The traverse is the second number in the size and the width the cable winds across. The out-to-out is the overall width, which adds the thickness of both flanges. People mix them up all the time, and it matters: the capacity formula wants traverse, while a stand, cart or trailer cares about out-to-out.

Published maker tables show the gap. Okonite lists a 24x12x10 at 15 inches overall, a 36x24x17 at 28.5 inches and a heavy-build 72x36x36 at 44 inches. Subtract the traverse and halve it, and those flanges come out at about 1.5, 2.25 and 4 inches thick. Southwire gives a maximum overall width of 32 inches for its 48x28x24 nailed reel. A thick multi-ply flange on a big reel can add 8 inches or more to the traverse.

Flange thickness here is our arithmetic from the published overall widths, not a figure the makers print.

Reading the stencil, and when to trust it

Most reels carry their size on a flange. Okonite describes the marking as flange x inside traverse x drum, along with the cable supplier, the reel class, a rolling direction arrow, the reel maker and the assembly date; reels under 40 inches often show only the size, maker and date. If the stencil is legible, photograph it first. It saves time and it tells a buyer who built the reel.

Then measure anyway, at least on one reel per size in a lot. Repaired, re-staved and weathered reels drift from their stencil. Rims wear from rolling, wood shrinks and swells, and a replaced flange may not match the original. When the numbers disagree, the tape wins.

Arbor holes, drive holes and the details that decide fit

Arbor holes are not all the same size. Southwire's wooden reels use 3.125 inches and its small plywood spools 2 inches. Okonite lists 3 inches for its common reusable reels. Anixter's small plywood reels run 1 1/2 inches on 12 to 16 inch flanges and 2 inches on 24 to 30 inch ones. Measure yours and compare it with the shaft, spindle or pipe it has to take.

If the reel will be turned by a powered stand, measure the drive hole too: its diameter and its distance from the arbor center. Note whether there is a steel plate or hub around the arbor, because it adds to the out-to-out and changes how the reel sits on a shaft.

Measuring a reel that still has cable on it

Sometimes the reel is not empty yet: a part reel in a warehouse, or leftover feeder you want to sell the reel from once it is used. You can still get flange and out-to-out directly. For the drum, read the stencil or use the reel maker's table for that size, because the barrel is buried. Then measure from the rim straight down to the top layer of cable. That gap, subtracted from the full flange depth, tells you how deep the remaining cable sits, and the capacity formula run on that depth estimates the footage left.

It is rough, since leftover cable is rarely wound evenly, but it beats guessing. If the jacket has sequential footage marks, compare the outer mark with the inner end's mark, which on many reels can be read through a start hole or slot near the drum. The difference is the length still on the reel.

Weighing, and why empty weight is worth knowing

Weight is not part of the size, but freight, forklifts and payoff stands all care about it. Published tables give a feel for the range. Okonite lists a 24x12x10 at 23 pounds, a 36x24x17 at 77 pounds and a 72x36x36 at either 335 or 559 pounds depending on build. Superior Essex lists its 96x42x48 fiber reel at 1,100 pounds. Moisture adds more: a reel that has stood through a wet winter can be noticeably heavier than its stencil weight.

A platform scale, a forklift with a load cell or a crane scale gives a true figure. For a lot, weigh one reel of each size and multiply by the count. That total, plus the size and count, lets us choose between a van and a flatbed before anyone books a truck.

How to send us the numbers

For a lot of reels, measure one of each size and count the rest by matching them up. Write each size as flange x traverse x drum, then the count, then the arbor hole, then anything worth knowing, such as a few with torn tie-off holes. A line like 18 pcs, 36x24x17, 3-inch arbor, most stencils legible is exactly what we need.

Add three photos: one stencil, one of the stack, and one of the worst reel. Stand the reels on their flanges if you can, so the count is easy to check from a picture. Send it to info@cablereelsforsale.com or put it in the form, and we will quote the lot either way.

• Flange, traverse and drum for each size, in inches
• Count of each size
• Arbor hole diameter
• Out-to-out width if fit matters to you
• Photos: stencil, stack, worst reel
• Where the reels are and what loading equipment is on site