MIG welding .080 5052 aluminum sheet

[Jack D Davis]

In working out details prior to beginning my canoe project, I tried welding .080 aluminum sheet with my MIG. Weld were successful, but difficult. Determined to weld .080 to save weight, I tried backing the seam with 3/8" round 6061. This worked very well. I also designed a clamp that will eliminate tack welds along the seam. Place as many of these clamps as necessary to hold the seam in place. Weld between the clamps. Remove the clamps and finish welding the seam, filling the screw holes. Since the finished weld completely fuses all three components, I see absolutely no need to weld the inside of the seam. Bend test tends to show this.

Pictures following are first the joint detail and clamp. Materials used for this test are 5052 x .080", 3/8" round 6061 and .030 MIG wire. Clamp is made from 3/4 pipe and a drywall screw in #25 hole through the 3/8" round. The gap between the plates is about 3/16".

First the clamp/joint detail then the test welds.

[mmd]

Looks like a good process. I've specified the plate/bar arrangement in a couple of the alum designs I've done, but the clamp system is news. What is the maximum distance between clamps? How much time does it add (if any) to set up for the weld? Do you pre-drill the rod or drill and clamp en situ for each clamp?

[Jack D Davis]

Still experimenting with the clamp. All I can say is it holds very well. Spaced as many as needed to hold the plates in contact with the round bar. I envision drilling the bar in place as needed. I'm guessing it will save a lot of time over tacking and then cleaning out the tacks to make a nice weld. Welding only one side is also a big time saver. This test is all I've tried, so far. A #25 hole and a bugle head drywall screw seems to work. Screws in easily and holds tight. I made several clamps today in about 30 minutes with a plasma cutter to slot the pipe and a cutoff saw to cut to length (about 1-1/2"). Deburring and drilling finishes it off.