What are the limitations of Arc on thin steel

[rich r]

I've welded a cracked garden spade, which was about 2mm using 1.6mm 6013 rods on an Aldi buzzbox (the 160A fan one, not the newer one) at about 55A. The crack ran the full width of the blade about halfway down. Weld's still holding despite using the spade to dig holes in soil.

As said above - a heat sink behind and not being too bothered about the repair being neat. Definitely practice on scrap first though to get an idea of just how quickly 1.6mm rods burn down -it's all slag and barely any metal. I've used 2.0mm rods too on 3mm steel with far less bother though. I don't think 1.2mm is worth even trying - that's firmly in Mig/Tig territory.

I certainly wouldn't do it on anything that it'd matter if the weld failed on. A dodgy repair to a garden spade so I can finish putting some shrubs in until I can get a new one is fine though

 

[Kent]

I did a very thin wheel barrow bucket four years back
Dunno how thin but the boss of another fabrication firm said it was too thin ( he was doing some digger work for me at the time)
I did it and it's likely the strongest connection on it
Like I say run down hill and snap right out one you see things start to get to warm. A millisecond delay and your stuffed with a hole

 

[awemawson]

I did replace the front suspension brackets / towers on my Hillman Imp years ago using 1.6 mm electrodes and my home made transformer arc welder It wasn't at all easy, nor was it very pretty but it passed it's MOT

 

[cumbriasteve]

Was in the workshop this morning and among my steel pile lo and behold I had some 1.2mm sheet, could not resist it so decided to have a go.

Now I am not an professional arc welder but I have had many many years of burning rods and can hold my own against most.

Using an R-Tech inverter with 2mm rods (had nothing less), with the sheet clamped tight down to a heavy lump of angle to hopefully pull away some of the heat I welded the sheets together, very difficult indeed and a very untidy weld but it held when I did a destruct test.

I still however say if the person is not experienced then arc on 1.2mm is a no and if they are experienced then arc should only be considered if it is a 'nothing else available' situation.

 

[cumbriasteve]

Pics

hmmm, I may recover it from the bin tomorrow if I am not too ashamed

 

[rich r]

I hid my spade repair under a lot of primer and Hammerite, it was so shockingly messy. But it's still holding up OK. Think all those 'this is my first go at welding - how does it look?' posts, but actually with plenty of penetration (occasionally penetrating right through to the other side and having to be filled in later with a little circle of weld).

 

[mfletch]

The secret in welding very thin metal is to do small like spot welds once done you go over it again putting down a normal weld

 

[PTvor]

The secret in welding very thin metal is to do small like spot welds once done you go over it again putting down a normal weld

But even so there's a limit somewhere. It's 1.5mm in my opinion and that's dodgy for stick. I'm sure someone, somewhere can weld 0.5mm with stick, but it's so much easier with other processes. Maybe anyone can do it with practice, but I don't want that much practice.

I'm sure most of the DIY MIG sets are mainly used for car bodywork. The duty cycles don't allow much at their top end. There are reasons why MIG is so popular, and there's a MIG welding forum and 1.6mm arc rods are becoming an endangered species. Actually, my local welding supplier says that as far as consumables go, he sells relatively few arc rods these days and it's mainly MIG wire.

 

[Kent]

The secret in welding very thin metal is to do small like spot welds once done you go over it again putting down a normal weld

Blobbing in is what I call those spots and you can create quite a nice looking single pass weld via it but you must clean and take your time

 

[Bill Edwards]

surprised someone hasn't said they can do it with 3.2mm rods and 130amps

Probably at half the amps, but I have welded the thicknesses discussed with a 3.2mm rod. Oh, and using a buzzbox.
The machine is still in heavy use today (crop sprayer booms) and not long ago I went round them welding up additional cracks (with gas this time, thankfully) and none of my previous welds needed attention, the bits I did were in completely different areas - the booms as a little thin and weak IMO (I know they're trying to be lightweight, but they're like paper).
I left the odd hole where I'd had enough and wasn't prepared to go on and get it filled, but it works. It was a bit of a nightmare though, the 3.2mm rods were used because they were all I had and I can't get the sprayer opened out in the workshop where the oil cooled welder reaches it so had to drag the little buzzbox round.

It's not impossible, but I certainly would not recommend it - given the choice of any other process I know which I'd use.

 

[Kent]

As bill puts it " given the choice " nobody in their right mind would stick weld thin sheet if another option was available to hand

 

[Wendelspanswick]

I did replace the front suspension brackets / towers on my Hillman Imp years ago using 1.6 mm electrodes and my home made transformer arc welder It wasn't at all easy, nor was it very pretty but it passed it's MOT

Years ago a pop rivet repair would pass!!!

 

[Kent]

Years ago a pop rivet repair would pass!!!

Until they allow a good poke with a Screwdriver or hammer fools and profiteers will still get cars through with a hood stuffing of newspaper body filler and underseal on structural parts

 

[Richard.]

I think it really depends on the job. To answer your question on the whole 1.2mm plate is easily joined with mma process.
There are people on here who would put my mma to shame yet ive just easily performed a butt joint with a 2.5mm 6013 70 amps DC+ on 1.2mm sheet.
As jim mentioned the crucial part which is if it is fitted tight to a heat sink With tight fit up it's not difficult at all.
Below is exactly that joint. Not the tidiest granted because I raced it down but I had it fixed tight to a thick bench top. I would even dare to say a 1mm would be doable also. If it was without a backing or bad fit up then the possible thickness is higher.

 

[Richard.]

To my suprise most of it peeled off its self considering it was red hot.

 

[Kent]

It peeled because of the thermal movement lol its like a banana

Speed which you note here as key to this is why I say go downhill the Weldpool will fairly chase you down and with limited penetration not great if your welding on a snatch hook to a 4x4 but great for handling thin stuff

 

[Richard.]

Bent like a banana it is but its welded and strong. Speed is key but to have the most successful joint a heat sink even more so. Take as much of the heat away as possible and it's not a difficult task. As you know Tig is far my strongest suit so if a wally like me can do it most people here I'm sure can.

 

[Kent]

The bend was inevitable and it was only a test for the crack after all
I was just trying to point out peelers are not indicative of a good weld or a bad one to those not acquainted with the why curving a 6013 weld into an arc should always lift the Slag off

 

[Bill Edwards]

I think, from Richard's post, that as that's done at 70 amps DC+ there must be plenty of scope for thinner. Just think, a 2mm rod with less amps and DC- would get you onto thinner stuff.

 

[rich r]

It was definitely the use of a decent chunk of metal clamped to the back of the spade that enabled me to do that weld. If you can stop the thin metal from melting and running away by having something to suck the heat out once the weld pool has moved on, then you're most of the way there.