Advice on 48" x 24" door frame -- material/warping...

[tom86951]

I am planning to make a panel that's about 48" by 24". I'm planning to use square tube of some kind with 45 degree mitered corners to make a rectangular frame, and then rivet or tack on a sheet metal skin. It's for an artsy thing...kind of like a metal painting canvas. Very much like the frame in this video.



Anywho, the size of the box tubing isn't mission critical, nor is the type of metal. I have a Fireball Tools mega square on the way, so am feeling ok about getting it squared up initially, but my concern is is warping as I finish off the corner welds. I'll follow the video's advice on weld sequences, etc., but my question is about material selection and what is most/least likely to warp?

aluminum or mild steel?
.065 wall or 1/8"
1/2" box; 3/4"; 1"? Bigger?

All things equal, I'd probably use 1" aluminum box tubing with .065" walls, but am totally open to steel, bigger/smaller box and wall size. Advice?

[Mac's Crew]

Aluminum moves more and differently than steel, so if you cannot hold it flat and square i would use steel. Just my 2 cents of free advice.

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[Louie1961]

It's not just weld sequencing that you need to worry about. Have you seen this other video from fireball tools?
It's kind of a how-to on using your mega square to get things flat and in one plane.

Using the techniques in both of these videos, I have been very successful at making flat frames out of 1 inch steel square tube up to 3 inch square tube. I don't like to use aluminum much because of the cost difference

[walker]

Steel, .065, 1”. Clamp everything as true as you can. It is fairly easy in these sizes to bend back to flat after welding and grinding. After it is flat and square use VHB tape on the frame. Put one row of 1/2” around the perimeter. Before laying the sheet on peel the backing off about an inch and fold it of to the outside. Lay the sheet on and square everything up, then grab the tag of backing that you left hanging out and pull it off, then do the opposite side, and then the other sides. Use a hair dryer or heat gun and warm the perimeter where the tape is to make the adhesive very sticky.

[wb4rt]

To be clear, lots of differences between steel and aluminum- both in technique and machine requirements. I expect you know that but not knowing your equipment and experience, your post sounds like more of a new welder. Give us more details to help you make the project well.

[jwmelvin]

Some advice I was given on here was to limit which joints I weld if strength wasn’t required, to limit distortion. I used this approach recently on a frame I made of 2” x .25” wall 6061 and didn’t get much distortion at all. It was not critical, however, as the frame does not mate to another surface, like a door will.

Welded only of the faces:

[Shootr]

But, just in case, here is the video Sam posted on straightening a warped frame.

[tapwelder]

I like the dont overweld advice. For what it is...dont get hypnotized perfecting welds on every joint in this project.

[jwmelvin]

But it’s so easy to get carried away when having fun under the hood (for a novice like me, at least)!

Like I did here:

[Bob]

A flat table and lots of tacks and you shouldn't have any problems. I have built a lot of tables lately and I build the whole project with tacks before welding it out and never even have one rock, even a little bit and they are all made of 1 1/4" x 14 ga. sq. tube.

[tom86951]

I was planning to use my Diversion 165 TIG welder. I have a fair bit of experience making small car brackets/parts, including with aluminum, but still very much a weekend hack. See examples below. Never did a big frame like this, so figured I'd ask. Strength is not critical, so will definitely follow the advice about not over-welding it... I ordered 1" square tube mild steel with .065" walls...