Just Starting Out

After doing a lot of looking at production boats and not liking what I see, I have started thinking about building one on my own (with the features I want) I would like to build a 17-19' hunting boat at some point but I think I'm going to start a bit smaller. To be exact I want to build a Alumacraft Ducker (kind of a fat and decked canoe) 12x4 w/ pointed bow and stern.

My question is, I do not want to make it out of .19 Alumimum plate due to the weight. I would rather use .1 or .125. I have a small MIG welder (110v) that I use for sheet metal repair on old cars. Would I be able to weld this thin of aluminum with it? The book that came with the welder says it can be done but all the books and info I see say that you can't weld less than 3/16 with MIG however I see a lot of welded production Jon boats (.125 or less)

Thanks for your inputs

 

testing your skills

H20fwler, the answer will result from a test of your skills combined with that particular MIG system.

I'd acquire as series of strips about 12 to 20" long of 0.060", .080" 0.100" and 0.125"; say a few dozen of each. If you can find them scrap then use them, if you can't then see if you can find off-cuts, waste or other scrap and have them sheered into 1 1/2" strips.

Two of these strips will simulate tacking up, and welding out a chine, keel or sheer seam as well as give an idea what you'll face.

There are two separate scenarios you'll test. First is the unsupported or non-heat sink joint and the Second is WITH a heat sink or support.

In all cases the test is of an outside corner which has the two strips inside edge to inside edge where the thickness of the material froms a V joint OUTSIDE of the test coupon.

I'm assuming a hardchine design, but this test will tell you plenty about what you can expect in other joints too.

The sheering process will give a nice clean straight edge but will curl the lenght of each strip. Tack one edge together at about 90 degrees, and the tacking settings will tell you about the open circuit voltage and instanteous power available to your power supply. This is critical to boat building even if you use a building jig.

Next, after you've adjusted up and down heat, wire speed and cover gas, you'd begin the weld test. I'd use a down hand drag bead leading at 15 degrees and looking under the gas cup to see the puddle.

If you can't get the thinnest material to weld in any setting combo (and there a plenty of various combinations of amperage/voltage wire speed; coupled with travel speed and parent metal section) then ADD a 1/8" or 3/16" aluminum angle or bar extrusion to the BACK of the weld zone. This will support the molten puddle and act as a chill bar freezing the puddle more rapidly and allow higher power settings which will vaporize the wire while not melting the parent metal beyond the HAZ zone.

Conduct this test of the thicknesses mentioned and with both cases of weld, in various heat settings and you will discover what your MIG system will do.

If you aren't experienced with ALUM MIG its often the case you will travel WAY , WAY WAYYYY to slowly and melt the parent metal which will slump or drop through wihtout a color indication like steel.

The reason for these tests is that they will create a table (if recorded responsibly) that will show you what you've asked in CONTEXT of your system coupled with your skills.

Some MIG welders would use 0.045" wire at 250 A to weld 0.080" 5052 at rates that others might find physically impossible. I might suggest that this material is more in reach for most people with 0.035" wire at 130 amps! The spread is determined by experimentation NOT recommendation.

The info you seek is most likely too relative to lend itself to a hard rule of thumb. I've suggested a self applied testing routine to learn how you could handle various materials. If yo need the seam support and chill bar then you'd end up making provision for that fixture as part of your build procedure.

Hope I've been on-point replying to your inquiry?

Cheers,
kmorin

 

Great input!! thanks. I was planning on getting some scrap to work on before I start on the real thing. I'm just glad to here that it can be done.

Many more questions to come.

Thanks again

 

MIGHT be done

H20fwler, I hope you are aware that I've no knowledge of your MIG system and was giving you a "system test", not trying to say the system will work for your preferred material thicknesses.

If the system will produce welds then: cut the 90 deg strips into 3" long sections transversely. Bend them backwards until they fail and observe which alloy, wire diameter, heat settings and weld procedure gives the "best" (most angle of bend before failure) combination of final weld.

Then repeat the procedure with a back weld inside the test strips, and back bend; now you have some reliable info about what you and your MIG system can do on a boat.

Cheers,
kmorin

Cheers,
kmorin