I'm James and have been doing engineering for around eight years now but mostly welding mig and stick with quite a lot of structural steel work. I have now come across some new opportunities to get more involved with tig welding for odd jobs and especially with stainless steel material.
I've been having a go at 1.5mm tube and are starting to improve after several hours of practice and have been reading on the forums here and studying the different videos as well. "Thanks to Jody Collier for the Tig Finger and his vast welding Knowledge and also to the other highly experienced welders here on the forums much appreciated!!
I've got a couple of questions I have asked in another thread but decided to do my own and a little introduction as well since I have just joined the forum.
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Is it more common to wiggle the cup while resting it slightly or alternatively weld freehand around the pipe?
How can I pickup the technique easier for uniform looking welds should pulse be used ideally for this as I'm trying to keep to size down to 3-4mm runs?
I admit to only doing limited stainless tube work & that's usually handrails - but it's largely the same - there will be other replies from more experienced guys I'm sure that do sanitary welds all the time.
" walking the cup " as it is referred to generally is done usually only on a V groove weld or fillet - your type weld will usually have no prep as it's an autogenous weld so walking the cup is not viable - also on alot of stainless tube work you cannot leave the marks that doing this leaves - ceramic cups feel smooth to the touch but leave marks behind like a grinder !
Much of this kind of weld is just experience - it's all about judging heat / travel speed / arc length /torch angle - my best advice is to use a small diameter good quality tungsten - keep a needle point on it even if you spend more time sharpening it than welding ! - hold the shortest possible arc - try to get in a comfortable position so you don't dip the tungsten too often - try to travel fast with enough amps - don't try slow / minimum amps as this will heat soak the piece & give you hell - pulse is a help if your machine has it - I never tried Jodie's " rule of 33 " as the cheap end welders don't go up that high on pulse - but if he says it works - then trust him ! even if yours does'nt go that high it's worth experimenting - I don't think those figures are set in stone - it was likely just a convenient to remember set of parameters close enough to what he found by experimenting.
You can't do all welds this way - but I found keeping the torch stationary while propped & rolling the tube works really well - it takes some of the variables out of the equation so you can concentrate on speed / heat balance.
I've found so far that it's quite comfortable going around this pipe if you just rest the cup slightly on the material and extend out the electrode a little bit to compensate as this seems to work quite well with out scratching it, otherwise like you have said going around the pipe freehand is more industry standard for this application.
I agree with the idea of rolling the pipe as well although have not tried that one so far.
My machine has different pulse settings built into it but you can't adjust the background current etc only the pulse time.
So far 125pps is quite nice for welding and leaves a reasonable pattern on the pipe.
