MIG welding .080 5052 aluminum sheet

Discussion in 'Metal Boat Building' started by Jack D Davis, Sep 26, 2005.

  1. Jack D Davis
    Joined: Feb 2005
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    Location: Elmira, OR

    Jack D Davis Junior Member

    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.
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  2. mmd
    Joined: Mar 2002
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    Location: Bridgewater NS Canada

    mmd Senior Member

    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?
     
  3. Jack D Davis
    Joined: Feb 2005
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    Location: Elmira, OR

    Jack D Davis Junior Member

    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.
     

  4. Bob La Londe
    Joined: Jan 2018
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    Location: Yuma, Az

    Bob La Londe New Member

    I am aware this is an ancient thread.

    I originally bought a Miller 212 to build boats and found that .080 was about the minimum I could weld with it. It takes some practice, but it can be done. Never have built any boats, but I have repaired a couple. Two boats I've had were damaged from power loading, and the bow was caved in and cracked from bumping the winch tower repeatedly. Another came partway off the trailer, and I had to cut out all the damaged material and slap on a bandaid. Fortunately all of them were made out of .080. I have mig welded thinner, but the simple fact of the matter is with a regular MIG I just can't move the gun fast enough. A pulse mig might be much better, but at more than twice the price... Now I know why so many guys go with AC TIG for thinner aluminum welding. Its self cleaning and it can be used a little slower.

    Using an integrated backer is an innovative solution. Using an overlap joint also works, but it creates an area to trap moisture which can lead to corrosion failure over time. Probably not an issue for a boat that is stored indoors in a "dry" place and is only used a few times per year.

    I was quite surprised at the choice of .080 for a canoe. I'll have to go out and measure mine, but I am pretty sure the hull is much thinner. With .080 I am curious how heavy the finished canoe is. I imagine it is quite heavy duty. Given the age of this thread I am sure there is quite a lot of insight you could offer about your canoe and your construction method if you happen to see this message.
     
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