BODYWORK RESTORATION PART 5
So you know how a car is put together, how to cut out rust, how to shape some replacement sections and, following Simon’s piece last month, you know how to use a MIG welder to join pieces together. Now, at last, we can move on to some actual car work. Don’t forget to disconnect the battery and unplug the alternator first though – electric welding can cause damage to both…
MIND THE GAP!
Welding is a process which joins metal by melting it so that two or more pieces become one, with the welding rod helping the process along. However, and this is a common misconception, the rod does not stick metal together, rather its metal mixes and merges with the pieces of metal that are being joined. It therefore follows that all types of welding need somewhere for the welding rod’s metal to go. With plug-welding this is straightforward – the weld plugs the hole. With lap welding the weld goes between the sheets so to speak and into the lap.
However, when you’re inserting new metal into an existing panel in place of rust and want the join to be totally invisible, you need to provide a gap between the two panels for the weld to flow into. This needs to be as consistent as possible and about 1-2mm wide. As you can see in the photos, Andy – like most body restorers
