How to MIG weld seams in mild steel

Make strong and beautiful joins in different thicknesses of metal

There’s MIG welding… and there’s MIG welding. Books the size of doorsteps have been written on every niche area of the subject, not to mention the underlying metallurgy. Pub bores, internet forums and Youtube videos offer a morass of information. It’s not necessarily wrong – but it’s not necessarily relevant to your needs, either.

Welding the airframe of a helicopter, the core of a nuclear reactor and the wing of a Morris Marina call for very different approaches. The basic principle of good MIG welding, however, is the same for all disciplines: the careful manipulation of weld penetration. If you’re new to welding classic car bodywork, our advice is to take a ‘less conversation, more action’ approach. Don’t let yourself become overloaded with unnecessary information. Get your welder set up correctly, get your head round a few simple techniques and start practising.

In the August issue of Practical Classics we talked you through how to get your welder perfectly set up and ‘tuned in’. This time, we’re demonstrating the basic techniques you’ll need to weld seams in thick and thin mild steel. Welding strong and neat seams in thin steel – ie, the panels of a car – is easier to master than welding thicker stuff. Once you’ve absorbed the rudiments, you’ll get good results in no time.