tig alu tb302 experiment....

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got my TB302 set up for DC tig so far.Today a friend asked if i could weld a small aluminum part.I said bring it down and i'll see what happens.With the CFH @ 30 got a scrap bit of Alu and tried AC tig with no freak box.....nothing.Couldn't even get it to spark up, thought it was something to do with a suspected slipring problem (nother thread). Messed around with everything. got life with DC, but nothing in AC tig mode, so i tried it in AC stick mode thinking that it should be the same thing.  I got plenty of life, but not something i could weld with.Why cant i get an arc on AC Tig? ....i know i need a freak box...but why?I looked into getting Helium and welding on DC, but that process looks like its only for heavier parts, not sub 3/16" parts.....is this correct?Well thanks for reading, just thought i'd share an experience, and hopefully solve some of my puzzles.G
Reply:I have a TB302 and tried the same thing with pretty much the same results. I ended up having to weld it with DC and helium.The lift arc and helium don't got together well either,the arc was a real pain to get started and even harder to kep going as the auto-stop kept kicking in even though there was only a very small amout of movement in arc lenth. I recently got a 251hd hi-freq box and got it set up and have now ran both some more AC and DC alum. with it. It worked out pretty good but the AC just acted a little weird I guess from being ran of the generator not nearly as smooth as my syncrowave for sure.And i think in a pinch you could weld some thin alum. with DC and helium but your gonna have to be real easy on the heat and would be best off using a foot pedal to have quicker adjustments to your heat. And it probably ain't gona look the greatest either.Syncrowave 250Millermatic251Trailblazer302Thermal Dynamics cutmaster52
Reply:I can't remember exactly, but there was something about the AC TIG output being tied into the 14 pin or something like that. Without all the pieces in place, she no workee.QamuIs Heg qaq law' lorvIs yInqaq puS
Reply:Thanks for the reassurance.So did yours not arc on AC tig liftarc without the HF box also?I'm debating a dynasty 200dx which would cure all problems.Then i wouldnt need a freak box and id have a plug in welder in the shop, but still waiting on the 2800$$Might get a freakbox if i get a deal on epray, but i'd be better putting that towards the DY!!G
Reply:In AC, every time the current changes direction, which is 120 times per second (60Hz), the arc is extinguished as the wave crosses the zero amplitude mark.  That is why you can't start and maintain an arc in AC without the high frequency.  The high frequency keeps the arc going with a amall background current while the main current is changing direction.   With a non-inverter power source, you need continuous high frequency tig in AC.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:Edit:Sorry, this word-  'amall' was supposed to read 'small'By the way, its not a box for FREAKS.... it's a freq (aka frequency)  box  MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:Originally Posted by DesertRider33In AC, every time the current changes direction, which is 120 times per second (60Hz), the arc is extinguished as the wave crosses the zero amplitude mark.  That is why you can't start and maintain an arc in AC without the high frequency.  The high frequency keeps the arc going with a amall background current while the main current is changing direction.   With a non-inverter power source, you need continuous high frequency tig in AC.
Reply:Thanks Craig, I will use it next time.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:tb302?? Don't know what you are referrring to. Brand? Inverter?Just use argon for welding aluminum.You need AC high frequency continous.AWS certified welding inspectorAWS certified welder
Reply:Originally Posted by DesertRider33Thanks Craig, I will use it next time.