Lap welds with dissimilar sized metal?

[JMS1972]

I'm lashing up a crud collector for my T&C grinder out if bits of metal I have lying around.

The two parts I'm welding are 1mm and 2mm mild steel

I'm using 1.6mm Tungstens and filler rods and 55Amps with 2second post flow.

Tack welds are going okay starting from the 2mm side.

Seam welds as you'd expect I'm tending to burn back the 1mm.

Obviously I need a lot more practice (generally) any tips on welding different sized stuff?

It's starting to take shape note stack of dipped Tungstens that need sharpening.

thanks.

 

[AndersK]

For this kind of non structural work, try without filler and use low freq pulse. You can pulse manually if your machine doesn't have pulse but increase down slope then.

If using filler, go down in size to 1,2mm or use mig wire. 2x0,8mm twisted is still less than one 1,2 mm. To thick filler and you spend too long time melting it.

Always help to focus arc on thickest part and then wiggle against the thinner as pool establish.

Make sure you can rest against metal to easier keep arc length consistent and that you can slide without effort. A paper towel between glove and steel works great. If it's too hot take a piece of fire blanket, folded to a few layers instead.

Also make sure theres no gap between layers. If they start to separate, tap them down again

 

[tom2207]

bung in a backer and clamp to it too , if you can.

 

[JMS1972]

For this kind of non structural work, try without filler and use low freq pulse. You can pulse manually if your machine doesn't have pulse but increase down slope then.

If using filler, go down in size to 1,2mm or use mig wire. 2x0,8mm twisted is still less than one 1,2 mm. To thick filler and you spend too long time melting it.

Always help to focus arc on thickest part and then wiggle against the thinner as pool establish.

Make sure you can rest against metal to easier keep arc length consistent and that you can slide without effort. A paper towel between glove and steel works great. If it's too hot take a piece of fire blanket, folded to a few layers instead.

Also make sure theres no gap between layers. If they start to separate, tap them down again

Thanks for that my TIG does do pulse so I can try that. I was trying to favour the thicker steel but don't quite have the skills yet

Getting a comfortable position was difficult as it's an odd shape. I'll work on it.

 

[AKN]

It's starting to take shape note stack of dipped Tungstens that need sharpening.

Thank you for sharing, I’m relieved I’m not the only one who spend more time sharpening tungsten’s than welding I was getting a bit of a complex about it! Try puting something under the bottom edge so the bit you are welding is horizontal so you can rest your torch hand On it.

 

[Barking Mat]

Bloody big copper heat sink is my advice.

Clamped underneath.

The autogenous or mig wire makes sense, but I'm a tig amateur too.

And... How low do you go / try , amp wise.

 

[pedrobedro]

Use a thin wire and lay it in the join just melting it into place, you could try your pulse function on it as well.

 

[addjunkie]

I aint no expert, and have on occasion produced lumps rather than dimes as the yanks say. But comfort and speed are key with thin stuff.
if you are not comfortable you will never produce quality. And go as quick as you can, so your not lingering and getting burn back

 

[Brad93]

Your amps are too low. Because you're waiting around for a puddle to form the heat is soaking into the thin material at the top edge and that is then melting back.

Up your amps a good 15%, keep a tight arc and direct the tungsten at the thicker piece of work. Get the thick bit puddled and then drag the puddle onto the thin bit and start throwing the rod in.

1.6mm rod is fine for that joint.

If you go down a filler wire size and you're not quick at feeding the rod in there you'll end up in a mess.

Remember addition of filler is a great way of chilling the pool and controlling your heat.

 

[Munkul]

what he said ^
Long wandering arc does that - It just takes practice to keep a tight arc and then you have control over the puddle, without dipping tungstens every minute or so.

I'd probably try a pulse as well, either 2-3 hz or 60-120hz, and see how it goes, but I don't think it will benefit you unless you get better arc length control first.

 

[Brad93]

Get the basics right before adding pulse to the mix would be my honest recommendation.

 

[Kram]

When I tried similar thin stuff I found pulse annoying and it was better to use the trigger/downslope when I needed it.

As Brad said filler is a good way of chilling the weld, I found it easier with 2.4mm filler to stick 0.8mm and 2mm sheet.

If you can, clamp a bit of aluminium as a heatsink. If you cant get a clamp in there, tack weld a temporary clamping bracket to hold it?

If I were doing it again, I probably wouldnt tig and save the gas, instead Id use 1.6mm arc rods. That doesnt help my tig skills but I found they work very well.

 

[JMS1972]

So I've tried higher current - 64A and a chunk of ally as a backer. I was already trying to move from thick to thin but made a bit more effort to get a stable weld pool before moving.

Stuck with 1.6mm electrodes and made a bigger effort with ergonomics and added a bit of lighting too. I did move my filter up to a 10 from 9 (Aldi helmet with flames!)
I'm pretty pleased with the improvement.

Previously tacked.

Backer random chunk of ally

Better results.

Thanks for your help everyone. Obviously still need to work on it but feel it's a step forward.

 

[Munkul]

How long an arc length have you got?
Amps probably would be right without the ally heatsink, but it still looks cold. Unless you're trying to travel too fast? Are you watching the arc instead of the puddle?

You're losing the puddle and soldiering on without going back to catch it again. You need to bring the puddle with you. This means slight push angle with the torch, and enough amps/travel speed to "push" the puddle between the two bits of metal along. You can manipulate the arc in a small weave if it helps, but really you should be able to do that in a straight push.

 

[JMS1972]

Another go 70amps with backer. And slowed down a lot. Focussed more on the weld pool. Felt a lot more in control.

Decent penetration.

 

[Brad93]

Still too long an arc

 

[Munkul]

Massive improvement in that last pic.

Tell you what is a good exercise: every time you make a tack, try to make it as small and delicate as possible. This means a stab of amps (probably 70-80) a tiny arc length, and a tiny dab of filler to bridge the two pieces together. If the edges curl back before you get them joined, you're doing something wrong.

Then you have to try to hold that tiny arc length whilst welding seams also

 

[JMS1972]

I've been trying to shorten arc length tidying up the previous pigeon poo. Not worth showing but I'll continue to work on arc length.

Thanks everyone for your input it's helped a lot

 

[tom2207]

dont try to melt the filler with the arc , use the puddle that will let you keep the arc length down too.

 

[JMS1972]

dont try to melt the filler with the arc , use the puddle that will let you keep the arc length down too.

I only do that when the filler gets stuck