Puddle problems with thin steel

[scotto75]

Hi all,

I'm practicing my TIG welding at home so that I can take on more jobs at work, if I feel confident enough to stick my head out and volunteer myself! But I've been struggling recently to get a good puddle formed when working with various joints in 1.5mm and thinner steel box and tubing. I find it a lot harder with the thin stuff to start an even puddle quickly.

For example, I will try to start a puddle on a fillet joint on some 1.2mm box section. I'll point the tungsten at a 45 towards the corner, but it will refuse to pool in the middle or root of the joint and usually blow a hole in the top piece due to hanging around too long.

Once I have a puddle formed I'm usually pushing the puddle and feeding filler. I have loads more confidence and experience with some thicker stuff above 2mm, but the thinner stuff will be the majority of the TIG jobs at my work.

I have an R-tech 160, set at around 60A for 1.5mm or 40A for 1.2mm. I'm using a 1.6mm tungsten sharpened to a long point at 15 degrees or so. I have CK gas saver pyrex #6 lens and gas flow at 7lpm.

What I want to do this week is not to do any long runs, but just practice initiating an arc and forming a puddle. Just repeating that over to get to point where I can get a puddle going quickly and in the right place.

I would appreciate any advice on the following....

1 - Tungsten grind angle. Is there any benefit making a shallower angle of 30-35 degrees when doing fillet joints in thin stuff, to help direct the arc to the centre of the join?

2 - Electrode/torch angle. I usually push with a 10/15 degree movement, but I'm not sure what is the best angle to aim the arc into the joint - for example, on a lap or fillet, should i be pointing the arc towards the bottom piece to give it more heat, or is it better to aim it at a 45 straight at the centre?

3 - Material temperature. I don't have any heating in my workshop so it's as cold as a polar bear's knackers. I tack the metal to get some heat into it but is it worth me preheating the metal to an even temperature to help the puddle form at all?

Any advice or help in just initiating an arc and forming a puddle on a fillet joint in thin steel would be greatly appreciated.
Thanks.

 

[GrahamGKD]

I'm no expert but to me it suggests your arc length isn’t tight enough? Hopefully someone with more experience will be along at some stage.

 

[mike os]

assuming your fit up is nice and tight, try a little more stick out on the tungsten, so you can get right into the root, keep the arc short and I would probably go at about 45A to start then go up a little if you need to and as you get the technique

thin is always more difficult.

tungsten size and exact point wont make much difference as long as it is sharp.

cold would actually help as it will loose heat slightly faster... but no enough to notice.

as most things tig... tight arc is usually the answer

 

[Munkul]

thin box section is fiddly to get neat, unless your fit-up is perfect. The top edge just wants to melt back all the time, so your goal is to weld it before that happens. Once it's joined, the top piece can dissipate heat into the bottom. If that makes sense. So whacking the filler in ASAP can help.

It does sound like you need to tighten up your arc length, it needs to be so that you're close enough to dip. Sharp tungsten point, and 30-35 degrees is good for most things, I wouldn't go much more either way personally but some people like a sharper angle.
Push angle of 10-15 degrees, 45 deg into the joint, if you need to then pull the arc slightly away from the top edge. IMO it's easier to aim for a single set of angles for everything, and just move your torch slightly if you need to favour one side or another.
Pre heat won't help IMO, it will hinder if anything.

TBH it probably comes down to practice more than anything I do a lot of stainless TIG box section on 3mm and I struggle with 1.5mm the odd time i do use some, it's never as neat as the bigger stuff.

 

[scotto75]

Thanks for the replies. That’s really helpful. Didn’t end up getting any practice in tonight, but tomorrow at work I’ve got a couple of brackets to make in 16swg, so will remember this advice.

I do try and keep the arc tight, but I find I risk dipping the tungsten more when ground to a very long fine point. The times I have had less of an angle I can get the tip closer to the piece or puddle without dipping.

assuming your fit up is nice and tight, try a little more stick out on the tungsten, so you can get right into the root.

thin box section is fiddly to get neat, unless your fit-up is perfect. The top edge just wants to melt back all the time, so your goal is to weld it before that happens. Once it's joined, the top piece can dissipate heat into the bottom. If that makes sense. So whacking the filler in ASAP can help.

Thanks for the tips. This is great advice and I’ll experiment with what you’ve said trying to get a good fit up, tight arc, and use of filler.

I may change cup size so it fits a bit better and I can get closer to the joint.

TBH it probably comes down to practice more than anything

I enjoy it so practicing isn’t a problem (cost of gas is though). I’m one for just repeating things, so going to practice just starting up over and over again on various joints in thin scrap I can find at work, until I get it dialed.