The Perfect Welder - Melting Metal

The time that the welder can produce the rated output is represented by a duty-cycle figure, which is given as a percentage (example: 30 percent for a Handler 187). The duty cycle is how long (in minutes) the welder can produce the rated output in a 10-minute period. A welder rated for a 30 percent duty cycle can produce full-rated load for three continuous minutes and then it must cool for seven continuous minutes. The welder can produce a higher output than the rated output, just for a shorter period of time than the rated duty cycle. While smaller and cheaper machines can tackle big projects, you may spend more time waiting than actually welding if you exceed the machine's duty cycle.

Another number presented to the user is the maximum amperage-probably the most abused number. Providers of high-quality, industrial-grade welders represent this number as the maximum welding current that produces a quality welding arc. However, there are manufacturers that will state a number, regardless of whether the machine will actually be able to weld well at that level or not. This can easily confuse the user.

One major factor that influences the rating is the construction of the magnetics. A poorly designed transformer will have a significant droop characteristic as the machine heats up, resulting in a drop in weld voltage output as it is being used. This results in inconsistent welds-not something you want when repairing a frame, attaching a steering-box mount, or building a custom suspension

What size welder is right for you? Each of the big three's Web sites offers comparison and welder selection recommendations to help you choose. Perhaps the easiest way of classifying and comparing welders is by how much amperage they generate at a given duty cycle. Think of amperage like heat: thin metals take less heat to melt, and thicker metals require more. For example, MIG-welding 18-gauge (0.050-inch) steel in a single pass takes roughly 70 amps, whereas welding 1/4-inch steel in a single pass requires roughly 180 amps. The single pass term is important because you can weld thicker material by beveling the edges and making multiple passes to fill the joint. You may have heard of the multiple-pass technique called "laying stringer beads" by someone who has welded thick steel beams or pipe. Multiple pass means the user must prepare the weldment for welding (usually by beveling the material), and then lay several weld beads on top of each other. Ultimately, there is nothing on a Jeep that should require a multiple pass. You shouldn't purchase a welder planning on using the multi-pass technique on your Jeep. You'll likely be disappointed when you unexpectedly find out your welder wasn't powerful enough. The damage that a ripped-off suspension bracket or steering box can cause will surely be more costly than the additional price of a more powerful welder. Always buy more welder than you think you will need.

When welding on thick material like axle housings (1/4-inch and thicker), welders that are powered by 230-volt service are usually required to achieve full penetration with a single pass. Welders that are powered from 115 volts are limited to the current-carrying capability of the 115-volt service. Also, on 115-volt-powered welders, manufacturers will rate the top-end metal thickness capability with flux-cored wire. If solid wire and gas shielding are used, the thickness rating decreases. And sometimes to enhance metal-thickness capability, some manufacturers will rate the small, 115-volt-powered welders for thicker steel, then attach asterisks to direct the user to a footnote in the ratings that qualifies it as multiple pass. It's kind of sneaky.