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View Full Version : How To Stick Weld 2mm onto 4mm ?



abrogard
04-26-2011, 08:44 PM
I'm a mug welder...

Latest task is to weld 2mm thick 24mm OD gal pipe onto 4mm thick 36mm OD gal pipe.

The job is laying flat on the bench. It's legs and crosspieces for a table.

Do I go 130A (my welder's max - they say for 3.2mm, that's the theoretical max I can weld I suppose, but the job's gotta be done with it) for the 4mm or 55A for the 2mm or something in between?

And use what technique? Run a bead or tack weld? Bead on the thick pipe and flow onto the thin? Or bead on the thin, flow onto the thick? Or bead on both at once?

I am, of course, trying to find the way myself but with so many variables I just keep getting inconclusive results and probably the best thing to do is just ask someone who knows.

:)

toolsrule
04-27-2011, 02:09 AM
i would use rated amp/voltages for think to thin as best make two passes of differnt amp/voltages

applejiya
04-27-2011, 02:25 AM
hey i recently learnt how to stick weld but sometimes when i strike it the rod sticks to the metal is there a way to stop this?

toolsrule
04-27-2011, 02:34 AM
hey i recently learnt how to stick weld but sometimes when i strike it the rod sticks to the metal is there a way to stop this?

drag the arc...(drag your rod against the metal) as it lights to a strong arc pull away and began welding

abrogard
04-27-2011, 06:25 AM
Well I've been getting some results that look okay and feel okay... but how good they really are I don't know without an x-ray.

What I've done is use max Amps on my machine which gives me 130A, enough for 3.2mm metal, it says.

And I try to stay on the thicker pipe and let the weld pool flow onto the thinner one.

sometimes it works good and sometimes not so good.

When it is not so good the weld pool either doesn't reach the thinner pipe at all or seems to flow over it and solidify leaving a 'crease' or whatever you'd call it underneath. Like the bottom of a car tire down where it meets the road.

I assume that's because the weld pool wasn't hot enough to melt into the thinner pipe.

So then I make another pass right along that 'crease' but quickly enough so's I won't blow through the thin stuff. That melts the old weld and puts a new one with some penetration of the thin stuff and I finish with what looks like a nice flat bead. As many extra passes as necessary. Chip off the slag first, of course, then quick brush.

Another thing I did was change my sticks. I was using 2.5mm 6013 general purpose sticks and I stayed with the same type but got a thinner stick - 2mm - and it seems easier to use.

It seems like the difference between a needle and blunt stick. I have more control over where it goes and I can simply see more, too.

These are horizontal welds on pipe. Like two pipes, one butted up against another, both laying flat on the table, forming a 'T'. The thinner pipe has actually been hammered down a little on each side to make it flatter - take the circle shape out of it, make it oval, so's it contacts the bigger pipe a bit better.

But it still often doesn't touch it.

I found then it was difficult to weld together without blowing away the edge of the smaller pipe.

So now I either build up bead on the thick pipe with a number of passes until it is higher than the thin one and then lay a final bead that bridges the (now very small) gap and does the job - or lay a piece of welding rod (minus flux) in there and weld it in.

So that's my technique. I invite comments and criticism.


I'm such a beginner I shouldn't be telling anyone anything about welding at all. But when I see one guy is only 17 and another guy is asking about his rod sticking I think it might not hurt if I try to help?

In my (limited) experience the rod sticks mainly when there's not enough amps. Crank up the amps.

Or the metal is greasy or dirty, or the earth connection is not good. Clean the job and put the earth on bright metal and close to the weld area.

A cold rod is a different thing, too. My work is home stuff that can be rough and ready, so I can brush my rod along the job causing sparking (and leaving little tracks of spatter and whatnot) and warm up the rod before I start in on where I want to weld. I find this helps. Just a couple of quick sweeps, about six inches along the job... That's quick sweeps that're sparking, arcing, crackling a bit - a hundred sweeps wouldn't do any good if nothing is happening. I guess if I had a fancy work job that needed to be kept clean I'd clamp a piece of rubbish metal onto it just for that purpose, I use it so often.

And after stopping sometimes it is hard to strike an arc again. I find tapping the rod quite briskly against the job (or anything else) hard enough to knock off some of the flux on the end helps it strike a fresh arc easier.


If I'm completely wrong with all I've said hopefully we'll all get put right by someone who really knows his onions.

:)

toolsrule
04-28-2011, 01:41 AM
well i shouldn't have put my age for this problem... i have been welding for 14 years and strong machining for 5 working for 4 and as all welding processes penetration and concentration is key! if your rod sticks there is two main causes to less of amps on too think of rod or the way you strike it.. !"the book is not always right"! get the feel of what you like not how the right way to do it





ps: moral dont judge a book by its cover