Thread: Can these 2mm thick pieces be wielded without adding to their thickness?

Here is what I want to weld up to keep a piece of plywood from warping. Could the join be welded & grinded back mostly so it doesnt add anymore to the thickness?
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Was wondering if the draper expert 130A 230V gasless MIG would do this?

Thickness will be the last of your worries - stopping it from twisting into a pretzel will be more of a problem.
What's it for?
You might find it easier to have it plasma cut out of some 2 mm plate.

Originally Posted by BobL

Thickness will be the last of your worries - stopping it from twisting into a pretzel will be more of a problem.
What's it for?
You might find it easier to have it plasma cut out of some 2 mm plate.

Might try finding someone to cut the plate then. It is to keep a square piece of Plywood from warping. Thinness is important. Maybe those automotive epoxy glues will do?

Originally Posted by Tegmark

Might try finding someone to cut the plate then. It is to keep a square piece of Plywood from warping. Thinness is important. Maybe those automotive epoxy glues will do?

How thick is the ply and what sort of forces are on it? And more importantly what are you ultimately trying to achive? We might be able to propose an alternate solution.

Short answer,yes it could be welded up as you desire and ground back and kept flat and true. If you were going to get it cut from a sheet, then laser cutting would be your best option, I would not guarantee plasma cutting would provide an unwarped component. This would be costly for a one off component.
However unless I am mistaken in your intent I doubt it will achieve much at all as far as strengthening your plywood. As BobL said, some more information would be good.

Like the others have said - no problem welding and grinding flat but no use straightening I'd imagine. I use flat bar sometimes for various things and carrying a long length of flat bar around is a PITA primarily because it just flops like limp spaghetti. A better idea would be angle or RHS/SHS. The smallest you could get would be 20mm SHS. How thick is the ply? Can you route a rebate into it and recess a thicker metal frame into that? Or can you laminate another product to the ply, like a sheet of glass each side or carbon fibre would stiffen it considerably with very little thickness added.

I, too, assumed that the flat bar would do nothing for warping, but provided the bar is solidly glued to the ply (i.e. laminated), the bar will resist the contraction and expansion caused by the ply trying to go convex or concave, so it may actually work.

I doubt whether it would have any stiffening effect given that 2mm FMS is easily bent by hand. I can't see how it would resist any warping by plywood.

Originally Posted by Gavin Newman

I can't see how it would resist any warping by plywood.

Because, as I mentioned, if glued to the plywood, the steel will resist expansion and contraction. The end result is that the assembly won't be that stiff, but I can see why it might resist warping.