My problem is welding 20x5mm flat bar on edge around perimeter of 600x600x5mm plate and started with a tack at the center, welding to ends using 10mm tacks 50mm apart with the plate clamped bent to counteract pull from the bar. Not working, even tried over bending...That then stayed over bent!? Is it better with these problems to tack weld from one end to the other? Seems that my technique of starting in the middle and going to each way is not correct. I'm using bits of stout angle as supports.
I should have added, TIG and steel.
For clarity, is the 20x5mm installed on its edge and split the thickness of the plate? Essentially a "frame" around the plate?
If so, I would spot tack 2 opposing sides numerous times, say every 75mm on both sides of the 20x5. (Again, if I understand correctly the orientation of the 20x5). I would then weld install the opposing ends and repeat the tacking.
When it comes time to weld, one fillet on each opposing side, opposite ends of their length. Think of starting top left, then bottom right, then top right of the opposite end, the bottom left of the opposing end...Then flip the part and weld the other side in the same manner (if you need 2 sided welds). You want to work in short lengths to prevent too much heat along any edge, or along any length. By swapping sides, top and bottom, with short runs, you should equalize the push/pull. Go slowly and let the welds cool. If I can feel heat in the plate say 50mm from the edge with my hand, I pause until it cools. It takes longer, but controlling distortion is all about heat and time management.
Clamping tightly while tacking works, but while welding, it is my experience that I get better results by going slowly and allowing the part to "flex". If you have it bound up while welding, when you release the clamps, that stored energy has to go somewhere, and your part will taco!
If so, I would spot tack 2 opposing sides numerous times, say every 75mm on both sides of the 20x5. (Again, if I understand correctly the orientation of the 20x5). I would then weld install the opposing ends and repeat the tacking.
When it comes time to weld, one fillet on each opposing side, opposite ends of their length. Think of starting top left, then bottom right, then top right of the opposite end, the bottom left of the opposing end...Then flip the part and weld the other side in the same manner (if you need 2 sided welds). You want to work in short lengths to prevent too much heat along any edge, or along any length. By swapping sides, top and bottom, with short runs, you should equalize the push/pull. Go slowly and let the welds cool. If I can feel heat in the plate say 50mm from the edge with my hand, I pause until it cools. It takes longer, but controlling distortion is all about heat and time management.
Clamping tightly while tacking works, but while welding, it is my experience that I get better results by going slowly and allowing the part to "flex". If you have it bound up while welding, when you release the clamps, that stored energy has to go somewhere, and your part will taco!
On edge but flush with outside edge of the plate, so forming an angle around perimeter.cj737 wrote:For clarity, is the 20x5mm installed on its edge and split the thickness of the plate? Essentially a "frame" around the plate?
The distortion I'm getting is the plate bending along it's edge, so convex bowing against the edge strip and not across the whole face of the plate.cj737 wrote:If so, I would spot tack 2 opposing sides numerous times, say every 75mm on both sides of the 20x5. (Again, if I understand correctly the orientation of the 20x5). I would then weld install the opposing ends and repeat the tacking.
I think making the tacks too large and too frequent was part of the problem. I'm not usually doing this heavier material so was a bit casual in my attitude, also because the job itself is fairly rudimentary and is to be galvanized, but certainly couldn't accept it bowed around the edge.
The last edge worked. I welded from one end to the other using smaller, less frequent tacks Now to cut and re-tack the 2 that didn't go well.
I also now appreciate the idea of just holding with a hand and then getting 1 or 2 tacks to start things off because clamping everything at first is a pain.
Thanks.