Thread: Welding thin rectangular tube

Tiger
More info,
Ok its 1mm thick but you have not provided any other information to help us help you.

What size rectangle ?

Painted or coated? What colour ? Color of blue would probably indicate SHS or RHS.

If painted did you grind the paint off to enable a good earth? No good earth, no arc. Observe the form and colour of sparks if grinding .Are the sparks the same as other bits of steel that you were are able to weld?

Cheers
Grahame

Hi Grahame,

Size is approx 50 x 19 mm. Colour is grey, the metal is light, it may have been a leg from some furniture. I did grind the paint away where I tried to weld, clamp was earthed to welding bench where I normally weld. I tried a 2.5 mm electrode.

Hi Tiger,
Have you tried clamping the the earth directly onto the tube (a clean unpainted section of course) that you are trying to weld?

With the earth clamp connected to the bench, and paint on the tube, it may not be making a good contact.

Just a thought,
Cheers Turpy

If the clamp was earthed to your bench, I'd say it wasn't completing the circuit as the paint or coating was isolating it, the earth clamp for ideal welding conditions should be attached directly to the bare metal on the job.

One of the problems with using the clamp via the bench is it doesn't allow a full 100% complete circuit and whet eventually happens is that the leads run hotter which then causes the connections to start breaking down.

Had another thought too, when you ground the paint off the tube, did you get sparks from it? If you didn't or only a very small amount, it may be some sort of alloy that has a small amount of steel in that isn't weldable.

Thanks guys you were right. The metal had some sort of powdercoating on it and I didn't grind enough of it to get a decent earth.

So, after getting the metal ready, the real work started. The metal is so thin that I created holes but I found that if I moved fast and kept the arc slightly longer than normal that I manaaged to get some welding in. Still, it was difficult and would be interested on what is the best approach to use with this type of metal.

Try to arc on the thicker parts of the material.

If you have a butt join the rolled edge will be a bit thicker than the cut off end.
Run the arc along the thicker part, rolling the weld across to the cutoff end edge.
If you are lucky the molten metal will join without creating holes.

Easiest way I find is to give up.
Although, I have a new welder which I am still in the fros of getting used to.

PS.. powder coat and the like can produce really bad types of fumes.
Do all the safe stuff !!
Try to position yourself so you aren't crouched over the welds sucking the fumes in.

And if it looks like cocky s*&$t, you've created a dinky die Ozzie weld.

Try running verticle down while aiming to the thicker piece. Its a bit tricky. You'll master it on the last run! I use S/S rods sometimes as you can run them at lower amps. Cheers, Col.

I'm planning on doing a heap of welding of 25mm SHS, mostly 1.6mm and some 2mm, and I'm very much a newbie. From doing lots of research, I've gotten the impression that a DC inverter welder would make it be easier to weld thin stuff (apart from using techniques elsewhere on this forum e.g. tack it up and do it in short sections).

Advice please?

Originally Posted by quickstep

I'm planning on doing a heap of welding of 25mm SHS, mostly 1.6mm and some 2mm, and I'm very much a newbie. From doing lots of research, I've gotten the impression that a DC inverter welder would make it be easier to weld thin stuff (apart from using techniques elsewhere on this forum e.g. tack it up and do it in short sections).

I am about to start making some shelves using 30x30x1.6mm shs with my unimig 160 DC inverter arc welder. I have some gemini 6013 2mm rods, hopefully for another noob like myself this should work ok and not blow to many holes in the steel. I'll let you know how it goes when I get started, which will hopefully be Mondayish.

Matt.

Originally Posted by Matty5700

... with my unimig 160 DC inverter ...

Oops. I should have been more clear, I meant to ask:

Is it easier to weld thin section with a DC inverter stick welder (compared to using an AC stick welder)?

Originally Posted by quickstep

Oops. I should have been more clear, I meant to ask:

Is it easier to weld thin section with a DC inverter stick welder (compared to using an AC stick welder)?

Well I also have a Lincoln AC225 AC 3 phase arc welder, I might do a welding comparison if you want.

ok, just been welding up my new shelving units made from 30x30x1.6mm using my Unimig 160amp DC Inverter and the Lincoln 225AC welder with Gemini E6013 2mm rods and the difference is chalk and cheese. I had the Lincoln at 40 amps and it was still to much, although the unit might not be working properly is a possibility here. Whereas the unimig runs on 80-90 amps and it does beautiful welds.

I hope this helps although its not the post scientific test. The 2mm Gemini rods are very very nice for this work, I never even got close to blowing a hole in the material when the gaps were done properly (ie I tacked both sides properly to stop one side moving away)

Matt.

Slight update, it turns out that I am actually welding 30x30x2mm. I purchased 1.6mm but they gave me 2mm and I only just found out when I started using it. That said the 2mm Gemini rods are very good.