How to MIG Weld Vertically

There are two directions of travel when MIG welding vertically, each direction requiring practice to perform a correct vertical weld.

Uphill and downhill are two directions of travel when welding vertically with a MIG welder. The direction of travel you use while MIG welding varies depending on the thickness of the metal you are welding. When you are welding metal 1/4 inch or thicker, you would weld uphill to increase weld penetration, as the fast travel of downhill welding does not allow for a structurally sound weld in thicker metal. Downhill welding welds thinner metals with ease and is often used in place of flat position welding for light-gauged sheet metal.

Things You'll Need

• 2 pieces of metal, 12-inch-square
• Welding table
• MIG welder
• Welding hood
• Safety glasses
• Welding gloves

Instructions

Preparing the Weld Piece

1. Set one 12-inch-square piece of metal flat on the surface of the welding table.

2. Connect the grounding clamp of the MIG welder to the welding table. Turn on the welding machine and set the voltage and wire speed per the welding guide sheet on the MIG (metal inert gas) welder. The welding guide sheet will be in a protected compartment of the MIG welder and will show the settings required for the thickness of the metal you will be welding.

3. Put on your welding hood, safety glasses and welding gloves.

4. Stand the second 12-inch-square of metal vertically in the center of the metal lying flat on the welding table to form a T.

5. Align the wire extending from the tip of the MIG gun with the area where the two squares of metal meet. Lower your welding hood, pull the trigger of the MIG gun and hold the arc for 2 seconds to tack weld the metal pieces together. Repeat this step to place a second tack weld on the weld joint. The tack welds should be near each end of the weld joint.

6. Raise your welding hood and stand the tack-welded pieces of metal vertically on the welding table with both inner weld joints of the T facing you. Tack weld the metal T to the welding table as described in Step 5, but align the wire from the MIG gun where the metal T meets the surface of the welding table.

Welding Uphill

1. Place the tip of the MIG gun at the bottom of one side of the metal T, lower your welding hood and pull the trigger of the MIG gun. Move the arc in a straight line across the weld joint, then in a 3/16-inch diagonal line toward the center of the weld joint and back down 1/8 inch to form a triangle with the center of the weld joint used as the tip of the triangle.

2. Continue with the triangle pattern until you reach the top of the weld joint to finish welding the metal uphill.

3. Allow the weld joint to cool before welding the weld joint on the other side of the T.

Welding Downhill

1. Align the wire exiting the tip of the MIG gun with the top of the unwelded joint sitting at a 5- to 15-degree angle pointing toward the surface of the welding table.

2. Lower your welding hood and pull the trigger of the MIG gun to start the welding arc.

3. Follow the front of the weld bead down the weld joint while making a small circle with the MIG gun every 1/8 inch until you reach the bottom of the weld joint.

4. Allow the welded metal to cool to room temperature before handling the metal, as the two welds will have made the metal hot enough to cause severe burns, even through welding gloves.

References

• Miller Welds: Making a Sound MIG Weld
• Welding Tips and Tricks: MIG Welding Uphill Technique