Practical MIG welding - Jigs

Jigs come in all shapes and sizes. Generally you'll need them when bits of metal need to be precisely aligned - anything from suspension mountings to a couple of bits of bar than need to be straight.

I thought I'd make a page with some pictures of jigs i've used in the past, hopefully they'll give you some ideas for your own jig.

Rear Suspension Jig

I made this jig to line up some new suspension mountings on my Renault 4. It's constructed from 4 steel plates welded to a scaffolding pole. The dimensions were calculated from hole co-ordinates in the factory workshop manual.

The rear suspension was bolted to each chassis member using 3 bolts. Problem with the Renault 4 is if one of the holes is out by more than 1mm the car will sit to one side.

I had to weld in some completely new suspension mountings (the old ones had fallen off) so the only way to get things close was to use a jig.

Rear suspension jig

Simple Rear Suspension Jig

This jig is much more simple. It's job was to set the height of the lower suspension mounting on an Aston Martin and is constructed from a couple of bits of tube and a bit of square bar.

It's a 4 link suspension. There's redundancy in there as you only need 3 links to hold everything in the right place. Therefore the fore-aft position is controlled by the suspension on the other side of the car and I only need to take care of the vertical positioning.

The work was completed with the suspension still attached to the car so I could check wheel alignment before welding.

Simple suspensiomn jig

Body Jig (for Sill Welding)

Staying with the Aston here's a body jig. The intention was to hold the gap between the A pillar and B pillar while the sills were removed.

Normally a simple steel bar welded between the pillars would be enough, but in this case the gap started off too wide. I made the jig adjustable and made the jig in two pieces with bolt between them which I could tighten to reduce the gap. Once the gap was correct I welded the two parts of the jig together.

Door brace
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