Stainless tube will not tack?

[Noods]

Hi All..

Things of late tig wise have improved of late thanks to you Guys.. A lot cleaner welds etc.. Next issue.. I'm trying to tig 160 esab weld a 90 degree angle in SS .. But, using the same method as I would in steel, I can't get it to tack together... I'm using 1mm SS tube, cut to 45 degree angle with pure argon varied the amps but it just won't tack.. I'm not dipping any filler in just trying to get it to tack before filler use.. Anything obvious I'm doing wrong?

Many thanks

 

[wheresmejumper]

Gap has to be super tight
Arc length super short
Hit it with loads of amps for a short burst.like twice amps that you would weld it

 

[Paul.]

Just wont tack is a bit vague, is it refusing to melt, is it breaking after you join it, are the edges burning back, do you have a good joint fit up, a bit of filler is advisable on very thin material, tungsten prep, arc length, current, filler rod size, are all factors that will affect the outcome.
See the tutorial for a tacking technique.
http://www.mig-welding.co.uk/tig-butt-weld.htm

 

[jimmyspeed]

dont aim directly at the gap, try and get a puddle on one side and transfer it across the gap

 

[Noods]

I'm getting both edges burning away.. Have tried heating one side and moving the pool across but it just doesn't seem to want to take! If I turn up the amps it creates a wider gap.. Initially I had a really tight gap but now it's burnt away .. So start again time.. I have a fine tip on my tungsten and all is very clean...

 

[Richard.]

Both edges burning away can be a result of current to low for too long a time, arc length too long and fit up not tight enough. Exactly as WMJ said in the first resonce.
If you cannot achieve this then as Paul said add a dab of filler to make life easier.

 

[Ami]

I think Jimmy got it, thats how I do it and it never fails. If you can aim your arc downwards it's ideal. If you're working with a pedal start low, slightly melt one side then floor the pedal for half a second.

 

[norlander]

What are you setting up on before tacking? can you post a picture of your set up before tacking?

 

[AndyStobbs]

Get filler in quick style, as soon as there is heat there. You can neaten the pool afterwards.

 

[roofman]

Try marking where the other piece lies and putting a high spot of filler..then offer the other piece up and run the spot of filler onto it to tack. Prety much what Andy has said really