Advice on tig set up needed

[oggy]

Hi all. I have been aluminium brazing for about 12 years now at work. Now they have new work but it involves aluminium tig welding which they want me to do.
They borrowed a tig welding set for me to practice with & i got decent results.
most of the work involves 2 to 3mm stuff & i was using about 70 amps & gas flow was set at 8lpm tungston & rods were both 2.4.
Now my problems start. we now have a transtig 252. using the same size rods etc & gas flow the same as before it seems to be so much hotter even right down to 25 amps. ac balance at 70%.
Being new to all this im lost. I did notice that the regulator on the kit we borrowed had 2 gauges & the one we have now only has one which says how mucn is left.
would a double gauged reg be better for controlling the pressure or would the gas flow metre do that.
sorry for the long post
cheers
trev

 

[pedrobedro]

A flow meter would do the regulating more accurately than a twin gauge in my opinion. Which bit is hotter, is it melting the metal easier or is it melting the tungsten, have you experimented with the AC frequency and balance ?

 

[oggy]

Its the metal that seems to melt quicker. I have played with the balance but hot the frequency. To be honest im not sure how to adjust it as i cant see anything to do it with. or am i missing something ?
thanks for the help

 

[hotrodder]

There is no AC frequency adjustment on a Transtig 252 as they're a big ol' transformer machine. All machines vary some, if the borrowed kit was a little inverter then they can be quite different to traditional transformer kit with regards to ally

If you're experimenting/practicing with small offcuts then it'll make life difficult due to the nature of ally- needs lots o' amps initially due to it's conductivity but small bits quickly become heatsoaked i.e. large changes to amperage (or travel speed) are needed. Are you actually blowing holes at 25A or is it more a case of the weldpool being larger/wider than with the borrowed kit (what was it)?

As said a flowmeter is typically more accurate than a 2 gauge reg that has the second gauge calibrated to show flow. The single gauge regs are a fixed output type and designed to be used with a flowmeter

 

[oggy]

The borrowed welder was an inverter & i seemed to have more control over the weld pool . The transtig seems to get a weld pool straight the way. Im not blowing holes in the metal but seem to be getting very close to it with alot more penertration than with the inverter. or is that how its meant to be ?
cheers for your help

 

[hotrodder]

Generalising i'd say with an inverter the AC arc typically appears more constricted/focused which can obviously make the weldpool a bit easier to control. At the same time i'd say inverters have a 'harsher' arc which can make things happen faster but a lot depends how the inverter was set up.

Are you using a footpedal? Been a few years since i've used a Transtig but from memory the pedals had a far narrower range (or a coarser resolution) than is common with inverters. Could that be it?

 

[oggy]

yes im using a foot pedal. It maybe just me needing to get used to the transtig. The welds im doing do look clean so i cant be far off id say ?. I welded some filler necks onto some radiators the other day with great results but that metal was alot thicker & i was using 150 amps. Maybe i just need real low amps on the thinner stuff? & move abit quicker ?
cheers again