DIY MIG Welders

Turn on the MIG welding machine, then open the valve at the top of the shielding gas cylinder to allow the shielding gas into the welding nozzle. The gas will not release from the welding nozzle until you pull the trigger.

Align the metal parts that you wish to weld together. Remember that you will not be able to adjust the parts once the welding process has begun, so be careful to place them exactly where their permanent position will be.

Set the voltage and wire speed on the welder for the material you are welding. In general, thin sheet metal calls for low voltage and low wire speed, materials between 1/16 inch and 1/4 inch call for medium voltage and medium wire speed, and larger, thicker workpieces require high voltage and medium-high wire speed. If you are in doubt, most MIG welders have a chart either on the machine or in the owner's manual.

Lower your welding helmet, then align the nozzle of the welder where the welding wire protrudes from its tip up with the part that you are welding. Hold the welding tip at a 45-degree angle to the work piece, then pull the trigger. As the electrode touches the surface of the metal, you will see a weld puddle form.

Move the welding tip in small circles, enlarging the weld pool until it is approximately 1/4 inch wide, then begin pushing the weld pool along the seam to be welded. This is done by continuing to pull the trigger of the welding gun, moving in circles, and moving the welder along the seam. Pushing the weld puddle results in good surface weld penetration. Pulling the weld puddle results in beads of welding material not adhering to the material surface and thus a poor-quality weld.

Scrub the surface of the weld with a wire brush to determine its cohesiveness. A solid weld will show a scorched mark on the back side of the metal being welded as well as nicely rounded lumps where you applied the weld material.