Make: Projects

Welding a Jig

Make an invaluable tool for right-angle metal work.

Welding a Jig

A joint that is not clean and tight will end up having an ugly, weak weld. Let’s make a jig, an invaluable tool that holds two chunks of metal at right angles while allowing ample room to weld tacks in the corner.


Step #1: Lay out and clamp.

Welding a Jig
  • Lay out the angle iron on the inside of the square and measure 1” from the inside corner. Clamp the cross bar behind it at about the 3” point.
  • Don’t use your granddaddy’s favorite square. Anything could happen!
  • When welded, the diagonal cross bar will hold the angle iron at 90 degrees until California falls in the ocean.

Step #2: Flip it and weld.

Welding a JigWelding a JigWelding a Jig
  • Make sure the clamps are right and flip it over. Weld tacks at points 1, 2, 3, and 4. Tack weld a nice, hot tack at each of the points.
  • Try G-4 for about 1 second at each point. The tack welds don’t have to be gigantic, since they are just holding it together so you can remove the clamps and weld a bead. Re-trim the wire stick-out to 3/8” after each weld.

Step #3: Examine the tacks.

Welding a Jig

A pair of not great-looking tacks, but it will hold. The left tack is particularly puny and I should have continued welding for another half second.

Step #4: Weld beads and tack the clamp.

Welding a Jig
  • As with the sample beads, start on the left and drag across to the right.
  • With a 3/8” stick-out, touch the wire joint between the angle and flat bar, pull the trigger, and keep at a 45° angle.
  • Like laying a bead of caulk, just fill the joint with metal!
  • Before tacking the clamp, make sure to remove any paint from the clamp edges that will be welded. Then, tack it like you tacked the angle iron. Repeat both sides, both clamps.


This project first appeared in MAKE Volume 03.

Mister Jalopy

Mister Jalopy

Mister Jalopy breaks the unbroken, repairs the irreparable, and explores the mechanical world at

  • popawdon

    This will be my first project/welding tool. I welded years ago and know how useful this will be. Thanks for making this available!

  • Elder James

    muito bom esta ideia vou fazer…..

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    What Purpus Make Copper Tube Welding Jig

  • Jean-Paul Emilien

    We always learn when we go to the tomb we stop learn

  • Jean-Paul Emilien

    Very interesting super