First attempt at tig, lots of help needed

[Norm]

Hi Guys had a first attempt at tig using a dc inverter tig set, and it's not going well, although I'm ashamed to post these you've got to start somewhere and the only way to learn is to seek some advise, I wasn't going to try before I got some proper gear together, steel, tungstens, filler rods etc but being without a car until tomorrow I thought I would have a go and have had to make use with what was at hand. Steel is some old 2mm RHS, tungsten is a grey tipped 1.6 and the filler rod was 2.6mm copper coated for steel I believe but can't be certain, gas pure argon set to about 10lpm.

I can get the puddle to form ok, but it doesn't appear to want to move or flow forward as easily as the one in the tutorial video and the resultant bead when I get one has a coating of slag, It's rough looking and not clean and shiny. The steel was cleaned with a flap disc and was really shiny before I started, definitely getting gas out of the torch and pretty sure the torch angles where as per the tutorial.


Obviously I am not doing this correctly so where should I start to improve matters I am thinking that matching the tungsten and filler sizes would help and getting some new clean steel or possibly cleaning the steel with acetone before welding? I really want to crack this and appreciate that it's not a easy process or something you can learn in 5 minutes. I am going to see if there are any night school courses available but would appreciate any help or advice in the meantime.

I appreciate the amperage was way too high on some of these but I was adjusting amps and speed to find a starting point,

P.S go easy please, I have had a bad enough weekend with the car breaking down as it is

Thanks Norm

 

[Paul.]

Firstly, you would be better with a smaller filler rod, 1.6mm is much easier to melt and will make a world of difference, a big rod will make you move slower and overheat the job, your metal is very small anyway which wont help,
Make sure they are tig rods, you need A18 or A15 which contain deoxidisers, Copper coated mild steel rods for Oxy acetylene welding will give some or the symptoms you have there, IE sluggish pool, oxidation, slag floating on the pool and blowholes,

Cleaning the top surface of the material is only part of the battle, if the pool is hot enough to penetrate through the material thickness you will drag dirt from the back of the material up into the pool,

When you are dipping the rod make sure the hot end stays in the gas shield, if not the hot end oxidises in the air then you shove the oxidation straight back into the pool.

You don't say what size cup (ceramic) you are using but I wouldn't use any thing smaller than a 7 for what you are doing there, gas flow is too high, 4 or 5 LPM is more than enough, any more is just a waste unless you are outside in the wind.

Check that your torch is correctly assembled and is not drawing in air, it may sound obvious but I've seen it many times

 

[Norm]

Thanks paul, cup is a size 5 which is the only one I have at the moment and I have a concern about the torch assembly the rear part blacK pointy end (sorry don't know the correct terminology doesn't screw right up to the white ring although the rubber o ring goes into the body ?
Norm

 

[Norm]

heres a picture of the torch

 

[Paul.]

Have a look at how to assemble the torch, http://www.mig-welding.co.uk/wiki/The_Basic_TIG_Torch.
This is a basic weldcraft style, there are others but this is probably the most common.

Then to test your set up try this:
Here is a simple set up test illustrated and what you should expect to see from it
this is just an offcut of 2mm thick mild steel box section cleaned with a flap disk, set up your welder with a post gas flow of about 3 or 4 seconds after the arc stops,
Hold the torch vertical with a minimal arc gap, this is about 2mm with a 1.6 electrode, welder was set at 50 amps, with a flow of 6lpm


Strike the arc and hold the torch still until you see a molten pool, then trigger off and hold position till the gas flow stops, if your gas flow is correct and uncontaminated it should look something like this, ignore the pinhole in the middle, remember this is without filler, you can clearly see the circular area protected by the shield, surrounded by the unprotected tinted area outside the cup, a bigger cup or a gas lens would probably have almost eliminated the blued area.


Just to show the effect of the post flow, on this one on the right I moved the torch away immediately the arc stopped

 

[Norm]

Thanks Paul, really appreciate your help,
Norm

 

[Welderpaul]

Paul, that's a neat trick to test gas coverage.
When i am tigging, its generally into tightish corners, glass lugs, handrail brackets etc. I tend to go for a small lens to give me a bit more room for manouvre, but am i better going for as big as possible then?

 

[Norm]

Welderpaul, I'm no expert as you can tell, but I have watched a fair few tutorial videos on Tig welding over the past couple of nights and that very topic was covered in one of them, the chap reckoned that in tight fillets the gas was contained in the corner so you can use a smaller cup without problems if you needed to get into tight spots, I'm not experienced enough to say if that is correct but that's what was said.
Regards Norm

 

[Paul.]

Paul, that's a neat trick to test gas coverage.
When i am tigging, its generally into tightish corners, glass lugs, handrail brackets etc. I tend to go for a small lens to give me a bit more room for manouvre, but am i better going for as big as possible then?

I find for most joints On Mild and stainless a 7 is ok, big enough for decent coverage, and small enough for fillets, maybe just extend the stickout a bit, for awkward corners I drop down to a 4, aluminium needs a a bit better coverage so would increase the gas flow a tad and stick and 8 or 10 on and probably set up a lens too, rule of thumb is to have your ceramic at least 3 times bigger than the electrode and the stickout no more than the dia of the ceramic, but if you have to get in a corner the fillet will help to contain your gas and you can bend or break rules of thumb.