Welding sheet metal to frames


Old 03-02-05, 04:42 AM
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Welding sheet metal to frames

I am trying to build a trailer which involves welding 1.6mm sheet metal to square tube frames to form sides roof and doors.

I tack the sheet to the frame and then run a continuous bead along the edge of the sheet, with an arc welder, to fix the sheet and create a seal. After tacking the sheet is nice and flat, but after running the bead either the sheet stretches or the frame shrinks and the sheet forms bulges which can be pushed in or out of the plane of the frame. Any suggestion how I can keep the sheet flat?
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Old 03-02-05, 05:53 AM
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The reason the sheet is buckling is because you are not staggering the welds.
For what you are trying to do a series of short tacks are needed where you alternate the location of the welds.
Also, if you are saying stick welder rather than mig then the high heat is also causing problems.
Welding thin sheet to framing is difficult because of the difference in thickness.

I will say though that I have built many trailers and your method of attaching the sheeting is not what I am familiar with.
It is customary to rivet, screw or bolt the panels.

Got a picture of your project and a place to host it?
Old 03-02-05, 05:54 AM
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Well, MIG would be easier/better. What size rods you using? Even with MIG I would recommend using smaller rods (wire if MIG), do smaller runs and move around more (ie start on one end of the trailer, go to the middle, then the other end, etc... I wouldn't know what else to try if you're already doing that as I don't do much sheet metal but that's what I would try. I don't think you'll be able to do it in a single run. It will generate too much heat.
Old 03-02-05, 08:05 AM
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Thanks. Will try to move around more. No pic as yet.
Old 03-02-05, 08:24 AM
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Commercial process emulation

Enclosing a trailer is done commercially. Examine a unit similar to what you are
building. Go and do likewise. Rivets and sealant are probably what you will find.
Plus, riveted assembly will make repair SO much simpler.
Old 03-03-05, 03:36 AM
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Another way to cope with the sheet movement is to put some very light folds into it, which absorb (or control, really) the expansion/contraction. These faint ridges can make the sheet stronger too.

But I agree rivets and sealant the normal way.
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