Welding Tips and Tricks

I am finishing up a plasma table build and need some advice on how to minimize distortion. I need to weld in a vertical 11 GA 3 X 3 tube for some shelving (see attached photo), but I don't want to distort the horizontal tubing. How can I minimize or eliminate the distortion?

Thanks in advance,

Mike

The vertical one towards the right of the picture nearly right above the caster area? Make sure the gap is nearly zero, the less weld metal you deposit the better you can minimize the heat input. Make sure it's clean, clean, clean, clean. The cleaner it is the less heat you need to make the puddle wet-out, which again helps to minimize heat input. I would tack the middle of the tube and not the corners, because heat tends to accumulate in the corners. The quicker you can wrap the corner, the better IMO. Short beads, in order to allow for cooling.

Lastly, if you really want to wick out the heat, take some 1" wide tinned (or not) copper braid, and wrap tightly around the horizontal tube on both sides, as close as you can to the weld area, but while still having some space to accomplish the weld. Wrap it around the vertical tube as well. I used this trick on Titanium with a regular TIG cup and it worked awesome.

If it's just for shelving, don't fully weld it. Just put a few 1/2" tacks and call it good. It'll be strong as for shelving and minimise heat input.

I'd concentrate on getting a real good fit up. Tight enough so you have to tap it in place with a mallet. Doing so will leave no (or at least very very little) room for the horizontal bar to pull down.

Thanks for all the great advice everyone. I ended up with about 4 decent tacks on each end.

The reason I was asking is during my construction of the frame I had tacked the top of the frame together and found on one corner, one edge to be a little higher than other. Unfortunately I had tacked it up pretty well and had to remove some material to adjust the fit. The missing material caused that bar to contract and it wound up being 1/8" out of square. Well within tolerance, but annoying. Also, I installed two center support bars that were fit up really well, but they expanded and caused the top bar to bow up about 1/16. After grinding for about an hour to get the bars flat, I figured I'd better learn how to avoid distorting my work. The table hardware is complete, hope to be up and running later this week.

Mike

Journeyman grinder, apprentice fabricator.