The first light bars for trucks were roll bars or grill guards that off-road race teams used to mount lights for night racing. Today, the truck accessory market is flooded with manufactured light bars that adapt to almost any make of domestic or import trucks. The roll bar-type accommodates a spread of lights above the truck cab, while the grill guard-type has lights closer to road level. Making a bar using steel tubing requires special equipment to bend the tubing. You can build a light bar using steel channel and steel plate. The only requirements are shop tools and apprentice-level welding experience.

Instructions

.          1

Measure the width of the truck bed. Measure the height from the bed rails to the top of the cab. Cut one piece of 3-inch-by-3-inch steel channel as the top of the bar that spans the width of the bed. Cut two pieces to the height measurement as uprights at each end of the bar. Cut the steel channel using a mitre saw with a metal cutting blade.

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.          2

Position the pieces of channel on edge with the channel recesses facing in. This gives you a protected channel to run the light wires. Align an upright perpendicular at each end of the top bar. Square the corners using a framing square and weld the uprights to the top bar.

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.          3

Cut two pieces of 3/16-inch-by-2 1/2-inch steel plate 24 inches long as base plates that bolt to the top of the bed rails. Use a drill press and a steel drill bit to drill three holes, evenly spaced in the flat surface of the bar for bolts. Typical attachments are made with 3/16-inch carriage bolts.

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.          4

Position the base plates flat, and parallel at the width of the light bar. Stand the three-sided roll bar atop the plates and align the uprights with the end of the plates. Weld the uprights to the base plates.

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.          5

Measure and cut two additional pieces of 3-inch-by-3-inch steel channel as diagonal braces for the light bar. The braces span from the top corners of the bar to the end of the corresponding base plate.

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.          6

Position the diagonal braces with the flat side of the channel facing up. Weld the braces at each end of the top bar and the corresponding ends of the base plates.

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.          7

Cut pieces of the 3/6-inch-by-2 1/2-inch steel plate 6 inches long as mounts for the lights. Cut as many pieces as needed to accommodate a particular spread of lights. Drill 1/2-inch holes in the centre of each mount.

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.          8

Make layout marks at the top bar for the spread of lights using a bolt or metal file. Stand one of the mounts atop the top bar at a layout mark with the flat sides of the mount facing forward and back. Weld the base of the mount to the top of the bar.