TIG amps question

[Legion]

The inside corner had spatterings of filler here and there. Less than a millimetre, not fusing through, just enough to tell it had tried to in places. Not being a box builder I've always thought you want it to perfectly fuse square with filler exactly at the join but not gushing through (for e.g. sanitary stainless boxes or whatever). I was also concerned with the sharp edge like you commented though. It does look like a failure start point.

[WelderMick]

Just another thing... try and plan it so that you don't have to do that third pass - in the situation you describe it sounds like if you got your second pass done nicely (nipping the edges religiously and filling low spots on the fly) you really didn't need to run over it again. Doing that extra pass means that the job has got yet another opportunity to distort due to heating/cooling - so best avoided if possible. Just heating a job repeatedly on one side without adding any filler at all can cause distortion.

Avoiding over-welding is particularly important with aluminium too - which can lose its temper with too much heat input - you end up with the whole area in the vicinity of the weld being weak and floppy.

[Legion]

Thanks. Yeah, I just did the third pass to go overboard and make sure I ate right into the edges. I generally am scared of multi pass for the reasons you said. Two would have been fine. With that in mind I would like to test with more amps, bigger filler and one pass before I do more "thick" stuff. Also work on penetration through the root, as you said. So much to learn!

Speaking of distortion I spent quite some time today fixing distortion from a stupid mistake yesterday ...

[WelderMick]

I still get caught be distortion despite looking out for it all the time... after the fact it's obvious to see what happened, but not always so easy to predict in 3D space.

[Karl Robbers]

Thanks. Yeah, I just did the third pass to go overboard and make sure I ate right into the edges. I generally am scared of multi pass for the reasons you said. Two would have been fine. With that in mind I would like to test with more amps, bigger filler and one pass before I do more "thick" stuff. Also work on penetration through the root, as you said. So much to learn!

Speaking of distortion I spent quite some time today fixing distortion from a stupid mistake yesterday ...

I wouldn't suggest trying a 6mm weld in one pass. That is quite a bit of molten metal to be trying to control and you run a very real risk of lack of fusion if the puddle gets ahead of you, maintaining a penetration key hole and laying that amount of metal down will be near impossible. Visually, a large single pass weld will not stack up as well as a multipass either.
At 6mm thicknesses, you don't see TIG used all that often for general welding for a variety of reasons, certainly not to say you cannot though. Generally when TIG does get used at such thicknesses it is because there is a definite reason such as improved control, material type or to gain the absolute best quality weld for pressure type work. All these situations typically demand multipass techniques.
Multipass welding does bring a greater potential degree of distortion, naturally when pressure pipe welding, this is controlled at least to some degree by the shape of the pipe, but plate work will require consideration of welding sequence, pre setting, strong backs or simply dealing with the distortion post weld - boilermakers didn't become known for the size of their hammers for nothing .

[Legion]

Thanks Karl. More good info to file away in my slowly expanding bank of knowledge.

[Karl Robbers]

Not a problem.
That's what this whole fabrication/welding game is about. There are general rules and procedures, but the rest is tailoring our approach to the individual job.
At the end of the day, as long as a weld is produced that is structurally sound - both in the short and long term, free from defects that compromise whole of life performance and visually acceptable for the application, then all requirements have been met.
I was thinking to myself that you would almost be feeling the need to step up to a water cooled torch, (or do you already run one?), with the work you are doing, that torch must be getting pretty warm.
Tig welding is very therapeutic isn't it.

[Legion]

I run a CK FL150 torch, rated to 100% duty cycle at 150A. I've had the machine up to 160A straight and 170A pulsed but you're right - long runs at reasonable amps can make it hot. In fact, I've just ordered a CK TL210 torch, which is lighter and therefore might become my preferred torch anyway. It's rated 100% duty at 200A. I have found the flex-loc head very useful on occasion though.

I would like a water cooler and occasionally check for bargains on the internet. My trolley has room. I might end up making one though. I did burn my finger to the point of blistering through the glove a few weeks back, doing a long run where I felt the heat but didn't want to stop and thought I could handle it. I like to hold the torch right up at the head. I also like paper thin gloves. That was only at about 120A. Maybe I need to start wearing a stick glove on my torch hand because sometimes the radiant heat alone gets pretty hot, let alone the torch through the glove.