Welding Tips and Tricks

I'm in the process of creating a cart for my Primeweld and had a couple questions in regard to how you folks fabricate a mitered corner using tube for tig welding.

I will first say, dayyyyuuuuuuuuummm, it's getting hot here, last week was cool and I told my wife it's usually hot for Memorial Day traditionally...the weather G*Ds sure didn't let us down.

So, my question is this. I am building some frames to form this cart. I'm using 1x2 square tube, .090" wall thickness. I've made a few mobile bases for machine tools and a cart I keep at my yard, and what I find is that I tend to bevel the miters, but don't touch the outside corner seam leaving both edges sharp and run the torch down with no filler and just close up the seam.

In the past I leave the inside lap seam un-welded, for a couple reasons. The first is that if you close everything up on tube you need to drill a hole to allow the air/gas to escape, then fill that hole after it cools. With the inside seam left unwelded it seem to allow the gas/air to escape without the need to do so. Doesn't look too bad on the ones I've done as long as they seam is close. Maybe I'm overthinking that piece.

Also, it seems that welding the miter on top/bottom provides plenty of strength for a frame welded out of tube.

I'm getting a bit better with my skills and I've seen where people flatten the outside edge to have more area to weld on and use filler on that edge seam. My edge beads are still not as good as I'd like to get a really good looking bead and I don't want to grind it. I'd like to leave the welds un-ground if possible, otherwise why tig? I like to use cold blue on the metal, I like that look. I use Brownell's Oxpho-Blue which has it's pros and cons...pro being it's easy to use, con being that it's never as consistent as I would like but that has a lot to do with prep.

Any comments on the miter corners and how you folks approach that? Would love to hear your approach and how it compares to what I have been doing for both outside corner and inside corner. My lap is getting better and I may try welding the inside, not entirely sure yet. For now I've just been prepping the material.

Here's an example of the type of frame I'm talking about, this was for my Wilton bandsaw.



Here is what it looks like with cold blue on it.

Definitely flatten out the corners, but not so much that you end up creating a gap. Just knock off about 1/16" or so. I'd try using pulse on the machine, or you can manually pulse with the pedal. That will help TIG'ing vertically. Or go real slow one separate puddle at a time, letting each previous puddle cool. No worries about over-heating the corner that way. And remember that outside corners split the shielding gas flow, so keep the stickout and arc length short with +2/3CFM. Or just use a large cup and a lot of argon flow.

And you think it's hot there? It's worse here, lol.

In this case thickness of filler makes the difference.
Run off some s-6 mig wire and twist two strands together with one end in a vice and a battery drill the other. Tig your joints up with that and enjoy the pretty.

I always weld the inside corner too but be warned, this is where the frame can pull out of square easy. Wise to offset a little here or maybe clamp down hard on a table.

Guys, I added a couple pics in the OP.

Oscar wrote:Definitely flatten out the corners, but not so much that you end up creating a gap.

Ok, maybe I'll try that on this one. That bandsaw base was one of my early tig projects. Not that I have done a lot of them, but have done a few.

Oscar wrote:I'd try using pulse on the machine, or you can manually pulse with the pedal.

I've thought about that and in the past have manually pulsed with the pedal, but hadn't really thought of that this time...

Good idea on the corner/pulse to keep heat down.

Oscar wrote:And you think it's hot there? It's worse here, lol.

Yeah, I shouldn't complain... but my garage is hot today...

Coldman wrote:In this case thickness of filler makes the difference.

Ah, another good point. I have some 1/16" but think that might be the smallest...I'm not sure I have any .045, but will check. Was planning to use 1/16". Definitely no mig wire, I tend to get my snap crackle pop with stick welding... :laugh:

Coldman wrote:I always weld the inside corner too but be warned, this is where the frame can pull out of square easy. Wise to offset a little here or maybe clamp down hard on a table.

Yes, a good point indeed. I try to weld from inside of corner out to try and keep it in square, and try to clamp as best I can. :laugh:

oh, and when I said pulse, I meant high-speed pulse if using the machine's pulser. Use Jody's rule of 33, or just slightly under, with the machine set to about 1A/0.001". Won't need much more heat than that on an outside corner, as it should puddle quickly. I think 1/16" filler should be fine. Of course, always practice on scrap first.

Oscar wrote:Of course, always practice on scrap first.

Yes, I like to do that.