One of artist Kevin’s favorite and easier solutions is to use heavy clamps to keep the metal from moving. The key is to clamp the metal to a thick surface like his 1″ thick welding table.
If you possible, clamp the pieces of metal holding down the metal you are welding the entire length of your work.
You can also simply tack the metal you are welding right to your workbench. Later you can cut it off the bench and grind the area smooth.
To demonstrate a variation of clamping to stop warping, artist Kevin has clamped down two lengths of 1″ metal box tubing with his two pieces of 1/8″ mild steel under them. Clamp down the metal as close as you can to the weld while making sure you can still get the torch to the joint.
Kevin fires up his Everlast PowerTIG 255EXT, sets it to 124 amps, and uses an E3 1/8″ tungsten and some 16-gauge filler wire. He tacks both ends of the two pieces of metal he is welding and runs a bead between them.
When he releases the clamps and flips off the square tubing, the metal is completely flat.
And dont miss the outtake at the end from a video you will never see!