If you do not provide the correct clearance between the 2 plates and leave them touching each other, when you tack any one place it will bend the plate off of 90 degrees with more force than the magnets will hold. That gap is often done with welding wire, and when you tack a wire spaced gap the contraction of the tack will trap the wire. When plates are positioned apart with magnets they will simply slide down the gap by slipping on face of magnetic angle positioner, maintaining exactly 90 degrees. You NEVER **** 2 pieces together with no gap unless you are prepared to deal with the resulting distortion and tolerate the stress you are building into the joint. Also, as plate thickness goes up, the gap is needed to allow full penetration of weld bead(s).
Or a stub end of an electrode (Welding Rod)
It doesn't expand. It contracts when it cools. If you want to see it in action, run a good bead across one side of a piece of square tubing. Let it cool, then set it on something flat
what you put there depends on the thickness of the materials you are welding and if you need a full penetration root - and of course if your welder has the power to penetrate half way through the plate with gap. For no other weld prep, I like to be almost 1/2 material thickness - so if you are doing 1/4 plate as was suggested above you might want 3/32 or even 1/8. Once you get over 1/4" unless you are hitting it with BIG power time to start doing some bevelling to prep the weld to reach full root depth.
I'm not trusting any welds in 3/4" steel don't with a 125A mig no matter how many passes unless they preheated it to red hot and held it there while running beads
Yes
So what you're saying is if the project being welded is big enough, and if there's enough tacks in place, everything should stay square; correct?
yes, the best chance of keeping stuff from moving is not getting the metal too hot. But by no means am I an expert on welding, so take it fro what it's worth
makes sense. I get it . 1/8" is going to get real hot real fast .
I'm going to continue using clamps for tacking and forget about the magnets. I find that I can stay pretty square if I clamp the runner to a piece of square bar stock and then use a 2nd clamp on the runner holding the whole assembly against the table for the tacks.I guess the only thing I can say is, they will know that the metal is going to move on you. they are probably looking for the weld quality , not the alignment of the pcs, maybe you're overthinking the fact of trying to keep it square?
I get why you want it to look right.
A bunch of little tack welds is a good way to not pass this "test". If you do that in structural stuff, you run a good chance of not getting any penetration. 1/8" hot enough, it'll probably be sound, but it'll won't get you a job.
