Welding 1mm to 3mm

[Mouse]

I need to weld some 1mm plate to repair the floor in my Disco but i need to weld it to some 3mm box along one edge.
The problem is that i am not able to join the two sucsefully and could do with some advice because if i have the power high enough to get a weld on the 3mm the 1mm burns away but if i have the power low enough to get a good weld on the 1mm it does not "stick" to the 3mm.
the welder is a clark 100en turbo with .6 wire and argoshild lite gas, by the way i am only a "hobby" welder so no realy techinal answers please.
Thanks
Mouse.

 

[pedrobedro]

You need to weld to suit the 3mm and just catch the edge of the thinner material, practise is the only answer.

 

[keith19]

Hi Mouse, are you using the Thin Metal Technique (TMT), to start with?
(See the thin metal technique video in the tutorials).
A series of tacks at first to join the metal together, then more tacks to add to the tacks already there. We are talking short tacks here, maybe only 1 to 3 seconds in duration.

This is a very useful technique for joining different thicknesses of metal which might otherwise prove difficult.
The tacks should be short, and started off on the thicker metal, then move across to the thinner metal and release trigger. The aim is to use a power setting the thicker metal is happy with, then move the pool across to the thinner stuff sufficiently to melt into it, then release before you blow through.

Need plenty of practice at this, as Pedro says.

Another thing which might help is to have something like a copper or alloy plate under the thinner metal where you are welding if possible - this will help disperse some of the heat.

 

[chunkolini]

Three pieces of advice.
Practice
Practice
Practice.
Get some off cuts, check your settings and try changing them and keep notes, change one thing at a time.
Thin to thick is one of the hardest welds to get the hang of.
Try getting a stable arc on the three mm, then gently weaving onto the 1mm, so that the edge of the weld pool just touches it, then move away. You can develop a slow weaving motion that just keeps the edge of the thin metal melting. The weaving movment is tiny, maybe a couple of mm.
Watch the weld pool, I have never seen this in any books, but you can see a 'shiny' edge develop as the metal starts to melt, like a crescent. Keep an eye on this and move away as it develops.
Hard to describe, easy to do once it has clicked.
Last thought, a 100amp welder might struggle to get a decent weld onto the 3mm base metal.
Keep at it, and keep us posted.

 

[Lawnmowerboy]

a month or so ago at work we made some small boxes for some cctv cameras welding 2mm zintec to 15mm square ans instead of welding the edge weld 3mm in like on the top of the "square" and it melts in to it
with full penetration

 

[Wozzaaah]

I need to weld some 1mm plate to repair the floor in my Disco but i need to weld it to some 3mm box along one edge.
The problem is that i am not able to join the two sucsefully and could do with some advice because if i have the power high enough to get a weld on the 3mm the 1mm burns away but if i have the power low enough to get a good weld on the 1mm it does not "stick" to the 3mm.
the welder is a clark 100en turbo with .6 wire and argoshild lite gas, by the way i am only a "hobby" welder so no realy techinal answers please.
Thanks
Mouse.

As Chunko says, for 3mm box you should be using a considerable bigger welder and 0.8mm wire if you want it to stay joined.
No point in advising on techniques if the equipment is the main problem, which in this case it is.
Sorry if that's not what you wanted to hear but for a Disco you need something more than a 100 amp welder.

 

[Drains]

As Chunko says, for 3mm box you should be using a considerable bigger welder and 0.8mm wire if you want it to stay joined.
No point in advising on techniques if the equipment is the main problem, which in this case it is.
Sorry if that's not what you wanted to hear but for a Disco you need something more than a 100 amp welder.

Not sure I'd agree Warren. 3mm might be at the top end, but for weld fusion, that welder should do it. I say that in a "been there done that" kind of way. I certainly don't agree that 0.8 wire is necessary either - on the contrary, if the welder is struggling, putting thicker wire in will just make things more difficult as the thing will need more power to melt the wire before it even gets a look at the parent metal.

I really think this is a technique issue. Turn up the volts, aim for the 3mm, wash the edge of the weld pool to the 1mm stuff.

 

[brightspark]

a question someone can answer. on stick welding u can run a bead along on the thinner metal and build the thickness up then weld the pair together no problem without burn through why cant u with mig ??

 

[stuvy]

cut some thin strips, like 5 to 10mm (the length of the boot floor) out of your 1mm sheet then tack weld them onto the panel you want to stick in the boot and youl have two 3mm pieces to weld together, job done! or do like they used to on the old Range Rover classics and rivet the piece in!

 

[Mouse]

Thank you for all your replys.
Spent quite a bit of time practicing with a spare bit of box and some 1mm plate and used the wash idea and used loads of tack welds and joined them all together.
I also found that if i drilled a small "dent" in the 3mm that the weld penertrated into it better and that i was not able to hammer the two bits apart without the 1mm tearing away but still leaving the weld still there so it seems to have enough strength.
So once again thanks
Mouse.