|The MGA With An Attitude
PANEL JOINING, Spot and Plug Welding - RT-221
On 27 September 2005 at 04:35:28 UK time Frank Graham wrote:
The easiest way for the DIY restorer to attach these panels is by plug welding with a MIG setup. You punch 3/8" holes every few inches on the flange of the panel, clamp it in place and fill the hole with weld. Of course this assumes that the old metal that you are welding it to is sound and intact.
Drilling out the old spot welds can leave you with Swiss cheese for a working surface, that is why I invested in a pneumatic spot weld mill to remove the welds first and leave a smooth intact surface to work with.
I have a whole series of photos and descriptions on my Sebring MGA web site. Just scroll to the bottom of the home page and click on 'sill repair'. I wanted the panels to look original so after plug welding I ground down the plug welds and went over the panel with a Lenco spot welder every 1/2" (OK I admit to being anal about originality). I had found that the spot welder worked very well when joining two pieces of fresh metal but produced unreliable welds when attaching new metal to old. Sometimes the spot weld would pop, sometimes burn through and sometimes hold well, all with the same setting. OTOH, the plug welds were consistently good and solid.