welding sheet metal to 1" square tube frame

[kennyrayandersen]

Spot welding won't work well (HF has a cheap spot welder which I looked at for my build) because it is mostly used where you can get to the front and backside of the seam. With a square tube frame you'll never get to the backside. The suggestion of drilling a hole will probably be your best bet and won't be too hard to pull off. Just use something like a 1/4 metal bit. It will eat into the tube a bit but you should be fine. My dad did this with a stick welder but a mig will do it much easier. Just use a small wire gauge and keep the amperage and feed speed down. If you get it down it will be a hell of a lot quicker than anything else you could do, even screws or adhesive. Shouldn't take more than a second or two for each plug.

Good luck,
Tom

Your probably right about the spot weld -- especially if the spot welder is a cheap one. If you were going to weld it then, why wouldn't you just weld it at the edge, which would let you cover with trim and you wouldn't have to drill all the holes?

[Larwyn]

Spot welding won't work well (HF has a cheap spot welder which I looked at for my build) because it is mostly used where you can get to the front and backside of the seam. With a square tube frame you'll never get to the backside. The suggestion of drilling a hole will probably be your best bet and won't be too hard to pull off. Just use something like a 1/4 metal bit. It will eat into the tube a bit but you should be fine. My dad did this with a stick welder but a mig will do it much easier. Just use a small wire gauge and keep the amperage and feed speed down. If you get it down it will be a hell of a lot quicker than anything else you could do, even screws or adhesive. Shouldn't take more than a second or two for each plug.

Good luck,
Tom

Your probably right about the spot weld -- especially if the spot welder is a cheap one. If you were going to weld it then, why wouldn't you just weld it at the edge, which would let you cover with trim and you wouldn't have to drill all the holes?

A combination of butt and fillet welds where the panels meet on a frame member would be good. The plug welds I mentioned would be to attach the sheet to the fame where the frame member is not on the edge of the panel. I think the plug welds would deform the panel less than a fillet weld on the inside of the sheet. Also plug welds are easier for me on a vertical surface. But that is just the way I would do it, I am not a professional welder....

[chorizon]

We do have "professional-style" spot-welders at work. Their throat depth is 18". On a big panel (usually much smaller than the size of a TD side), we have to use 2 people to weld something. One person to help stabilize the piece and watch one level on the material, and another person to help stabilize and watch another level and step on the pedal.

A plug-weld would be a good idea, as a filllet on the backside would definitely dimple the material on the front. Just have to make sure you get good penetration from the front into the base material. Then its just a matter of using a "speedy", aka right-angle grinder to smooth the plug-weld out.

[kennyrayandersen]

Spot welding won't work well (HF has a cheap spot welder which I looked at for my build) because it is mostly used where you can get to the front and backside of the seam. With a square tube frame you'll never get to the backside. The suggestion of drilling a hole will probably be your best bet and won't be too hard to pull off. Just use something like a 1/4 metal bit. It will eat into the tube a bit but you should be fine. My dad did this with a stick welder but a mig will do it much easier. Just use a small wire gauge and keep the amperage and feed speed down. If you get it down it will be a hell of a lot quicker than anything else you could do, even screws or adhesive. Shouldn't take more than a second or two for each plug.

Good luck,
Tom

Your probably right about the spot weld -- especially if the spot welder is a cheap one. If you were going to weld it then, why wouldn't you just weld it at the edge, which would let you cover with trim and you wouldn't have to drill all the holes?

A combination of butt and fillet welds where the panels meet on a frame member would be good. The plug welds I mentioned would be to attach the sheet to the fame where the frame member is not on the edge of the panel. I think the plug welds would deform the panel less than a fillet weld on the inside of the sheet. Also plug welds are easier for me on a vertical surface. But that is just the way I would do it, I am not a professional welder....

yeah -- not suggesting a fillet weld, but letting the sheet(s) run all the way to the outside corner and welded there -- any distortion would be covered by the trim angle. I see what you mean on the interior (window etc.) frame members which would probably have to be done with the hole and plug weld, though for me I would have no problem letting the rivets show as it gives it a real mechanical/industrial look (kind of steampunk), which I like, and it avoids all of the warping issues, and you could always flush them, though that hardly seems worth the effort.

[Billy Onions]

I am building mine from 1" x 1" box section.

Just had it back from the galvanizers and to give you an idea of the weight they weighed it at 120kg / 264pounds. This was for the sub/chassis frame with the shell on top. No hatch and no doors (as these will be electro galvanized later).



I plan on sheeting with 18swg ally on the sides. I am also sat here now at this moment waiting for a call from 3m UK to put me in the direction of a distributer for this stuff

http://multimedia.mmm.com/mws/mediawebs ... r3COrrrrQ-


I decided to go for the tape for a couple of reasons which were pointed out to me by a couple of the ever helpful members of this forum. The first being the risk of elecrolytic corrosion. I am hoping the tape will act as a barrier between the ally and the steel.

The second being thermal expansion. The different rate of expansion if fastened by mechanical means can cause unsightly distortion and eventually the damage of fasteners.

Of course if you are using steel against steel neither of these points really matter to you. However the weight I would expect to be considerably more, bearing in mind what my 8 x 4 build of similar construction came in at.

Another thing to consider if you do eventually decide to go down the welding route is what ever you do lay a bead along the box section of something to stop it rattling. I used to use silicon sealer but only because I had a lot lying around.

Good luck with the build.

[angib]

VHB tape is simply wonderful stuff, like most 3M products. And, like most 3M products, you want to be sitting down the first time they tell you the price.

It would be worth finding a local industrial tape/adhesive merchant/distributor to see if they can offer you a cheaper product that can do the job. I was looking at half the price for a non-3M tape a couple of years ago - the alternative might not be quite so good, but I don't think a teardrop body is a particularly difficult application.

Andrew

[Billy Onions]

Andrew,
you're not wrong about the price of 3M VHB tape.

The commercial vehicle tape I posted a link to above isn't available in the UK I was told by the 3M rep. What he did tell me was that basically it is the same as 4943F but marketed in the US under CV45/63F to specifically target the CV / RV market.

http://www.directa.co.uk/site/scripts/p ... t_id=17214

The above link for 33m is £102.90 + VAT = £118.34 about $200 A box of 500 rivets is around a tenner $17

The data sheet does cause some concern in my case

http://www.directa.co.uk/product_datasheets/4943.pdf

Galvanized surfaces are potential problems and should be carefully evaluated

As you can see from the photo mine has quite a shiny finish to it. Normally if I was going to have something galvanized then painted I would have asked the galvanizers not to quench the job which would leave a dull finish.

Ideally I think I should apply some T wash / mordent solution prior to bonding or even some kind of acid etching primer as if it were to be painted.

[Big DE]

I made mine out of 1 x 1 square tube and bought several different kinds of adhesives like auto adhesive ans sign adhesive. The auto adhesive needed a 120V caulk gun to dispense it as I didn't have one I tried to do it by hand and as the adhesive mixes in the long tip it gets very difficult to squeeze out especially when it starts to setup. Also the $35.00 a tube price kind of hurt.
So I went to a sign supply and bought a aluminum to steel adhesive. It needs a special kind of caulk gun. Being determined not to waste another $38.00 tube of adhesive I bought the caulk gun for $97.00. Once I started using the adhesive it went on the first piece very well, the second piece was a little harder and by the time I got to the third piece the adhesive had dried up in the tip making the rest of the tube (just about half) useless. So in my frustration I went to Home Depot and bought 15 tubes of construction liquid nail. I was able to use one part of the sign glue on the one seem that would catch most of the wind, I didnt screw or weld any of the edges except where the corner trim went on and I haven't had any problems.

On my next trailer I will use the 1 x 1 square tube but I will cover it in 1/4" luan as to have more gluing area and to help stiffen the aluminum.
Pat take a look at my album you will see what I mean.

Big DE

[Ugly Truck Nut]

What about this from The Eastwood Company.





http://www.eastwood.com/metal-fabrication/welding/spot-weld-gun-w-2-electrodes.html

[kennyrayandersen]

What about this from The Eastwood Company.





http://www.eastwood.com/metal-fabrication/welding/spot-weld-gun-w-2-electrodes.html

I'm thinking that would work -- especially if you used it near the outer edge (corner). Then I'd use rivets for the internal skin attachments. Someone posted a picture of a shinny TTT the other day that I noticed they did this on and it looked really sharp.

[Pat's 49]

Thanks for all the info, I think I will check into the spot welder from eastwood. I did finish bending the tube for the side walls and they match!

[Erik-the-red]

No on the spot welder. Plug welding is the way to go. That is how I secured the sheet metal to my 1 x 1-inch tube frame. A Dewalt grinder makes short work of the metal plug to bring it flush to the sheet metal. Then, automotive bondo will make the plugs invisible once you paint it.