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Burning Blue: How To Build A Roll Cage

Posted in How To: Body Chassis on August 1, 2011
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Buy a truck for off-roading and the next thing you know you’ll want to build custom stuff for it. You can beg or pay someone to weld your upgrades, or learn to do it yourself. And if you choose the latter, you ought to check out this new welder from Miller. The Millermatic 211 Autoset MIG welder is the perfect first welder. It offers a variety of settings and controls that allow the guy behind the mask to grow and hone his skills.

The Millermatic 211 can run on either 120 or 230 volts, meaning you can buy it when you are starting out and renting a room in an old shanty with your buddies and have only a dirt driveway to work in, then keep using it as you grow into your own place with a full 5,000-square-foot shop on some property up on the hill with more electric power when you make it big. (Don’t forget us when you make it big.)

To test out this machine, we put a cage in BluFerd, our ’79 F-150, with the crew from Fabworx Off-Road. Fabworx specializes in welding and building all variety of trucks, and its sister company builds architectural steel railings and gates, so they have plenty of welding experience and gave the 211 a thorough workout.

The first stop on any welding project is the steel yard. We went to the local Industrial Metal Supply (IMS) to load up on tubing for BluFerd. IMS sells tubing in mild steel or chromoly in various sizes and thicknesses. We went for a mixture of 2-inch for strong main tubes and 13⁄4-inch for cross braces and floor tubes. In the end we used about 80 feet total.

The Millermatic has this handy material thickness gauge that helps in setting up the welder. All the tubing we used had a wall thickness of 0.120 (roughly 1⁄8) inch.

The welder can be tuned manually to various voltages and wire speeds, or put on Autoset and then set to various material thicknesses. We chose to do the entire cage in Autoset and worked with the crew from Fabworx Off-Road, who specialize in custom fabrication, to get a professional’s review of the welder.

The Millermatic can run either 0.030- to 0.045-inch flux core wire or 0.023- to 0.035-inch solid welding wire. Flux core will require the serrated wire roller on the left, whereas solid wire uses the smoother roller. Flux core wire is substantially more expensive to purchase than solid wire; however, both can produce strong welds.

If you use solid welding wire you often get a cleaner weld, but you will need a shielding gas plumbed into the welder to cover the weld to protect it from atmospheric contaminations and porosity. We used a gas mix of 75 percent argon and 25 percent CO2 at about 30 psi when welding. To ensure a tight fit at the regulator, spray some soapy water and watch for bubbles seeping out.

You switch the 211 machine from 120V to 230V by unscrewing the end of the cord. There is no need to change settings in the machine. However, on 120V it is only rated up to 90 amps for a 20 percent duty cycle and 24-gauge to 3⁄16-inch material. On 230V it can run 150 amps for a 30 percent duty cycle and 24-guage to 3⁄8-inch material.

As for the cage in Bluferd, we concentrated on simplicity with a rear hoop, front and side drop pillars, and top and bottom windshield bars. The main uprights are all 2-inch; the dash bar and the shoulder harness bars are out of smaller 13⁄4-inch.

Dave Williams cut holes in the floor to drop the cage down through allowing him easier access to the tops of all tube joints for complete welding.

To secure the cage, Billy McCully and Williams built rock sliders that weld to the frame and attach to plates at the body. The plates cover the holes drilled prior. Bushings could be used for less noise transmission, but welding the cage, plates, sliders, and frame solid is fine for an off-road truck.

Once installed, the 13⁄4-inch chromoly rock sliders offer superb rocker panel protection while not hanging excessively low. They can also be used at lifter points with a Hi-Lift if need be.

Inside there are floor tubes tying the front-to-rear downbars. These are also 13⁄4-inch to reduce tripping when getting out of the truck. They just clear the factory bench seat and can be built off of if we ever upgrade to fancy desert-style racing seats in BluFerd, our Ranch Raptor.


Miller Electric
Appleton, WI 54912
Industrial Metal Supply
Irvine, CA 92606
Fabworx Offroad
n/a, CA

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