arc flickering while tig welding

[Phil G]

Well. I'm still involved in the continouing effort to learn the art of TIG !! On my last session of running beads(with filler) I have had a little trouble with my arc flickering. The problem usually starts after I've carried a bead for an inch or two. The arc will stert to flicker and at times it will pretty much disappear. the first time it occurred, I tried to duplicate the problem thinking that I might have extended the arc too much, but when I raised the torch the arc just got brighter. I am pretty sure that it is an operator problem, so I am hoping that someone can point me in the right direction!!
I was welding on clean mild steel, .043 thick, tungsten was 1.5 MM ceriated sharpened to a point(happened using a thoriated tungsten also), using a No 6 cup with about 1/8 inch stickout. Im using a 200 amp inverter welder set at 41 amps, using a foot pedal and around 7 lpm argon flow.
Any hints, pointers or ideas will be greatly appreciated!!!!

 

[GrahamGKD]

Hi Phil,
It wouldn't be a bad earth would it? The only time I generally notice my arc changing is when I have contaminated the tungsten by touching it down or touching it with the filler?

 

[^neo^]

Probably more down to power supply if it starts ok then gradually dies. Are you plugged straight into the socket or running off a lead?

 

[pedrobedro]

What make is the machine and how are the controls set up? The pedal can be set sensitive so the slightest movement may be affecting your arc without you realising you have moved.

 

[GrahamGKD]

The pedal can be set sensitive so the slightest movement may be affecting your arc without you realising you have moved.

Phil,
You could always try a run or two on the button with the pedal disconnected to rule out any possible issues with pedal movement or a bad connection to/in the pedal?

 

[malcolm]

Is it an inverter welder? They often have a function that turns the power right down if you dip the tungsten in the weld pool (helps stop the tungsten from becoming contaminated). Way around is to just dip the filler into the very front edge of the weld pool and don't force it in unless the job needs a lot of filler.