Newbie Lincoln Squarewave TIG 175 Problem

BigJim1976 · Tue Jun 18, 2019 2:17 am

Newbie Greetings from Bonnie Scotland,
I just picked up a Lincoln Square wave 175 TIG and having problems on AC welding aluminium.
Everything is good on DC welding steel but on AC the Arc is unstable and leaving black deposits.
The electrode seems to be overheating almost straight away and tripping the breaker.

I'm using pure argon gas, green electrodes, aluminium is clean, rods are clean, tried increasing gas/amps

Any suggestions before I take it to the repair shop.
Many Thanks
Jim

Tue Jun 18, 2019 4:32 am

i don't know that machine. is that a transformer machine?
is there any balance adjustment on it?

what thickness aluminum are you trying to weld ?
what filler?
what breaker size do you have?

BigJim1976 · Tue Jun 18, 2019 5:32 am

Hi, thanks for the reply,

4043 rod
32a breaker on 240 volt UK
Transformer welder,

Its like the arc on AC is all over the place, coming from inside the cup?

New to TIG so im not sure what is normal.
DC- is working great, DC+ stick is great.
Its pecking away aluminium but not melting it?

The welder is dual voltage 400/240, the person I bought it off was using it on 400v 3 phase, DC only.
I changed it to 240v as per the manual, I wonder if that actually effects the ac?
Cheers
Jim

BigJim1976 · Tue Jun 18, 2019 5:33 am

And only thin aluminium 6mm

LtBadd · Tue Jun 18, 2019 6:26 am

The problem is most likely the type and diameter of your tungsten vs the amperage your using. The green (pure tungsten) will not stand up to a lot of amps.

Tell us what diameter tungsten and what your amps are.

Coldman · Tue Jun 18, 2019 8:30 am

Loose the green electrodes and get some blue 2% lanth. Set to 70% EN or higher and crank up the amps. 6mm is probably too much for your 175 power source. If you're tripping your circuit breaker, get a bigger circuit or go 3 phase.

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aeroplain · Tue Jun 18, 2019 8:39 am

If it's a used machine, it might be the points for the high freq. start need cleaning and re-gapping.
Same thing happens with my Syncro 250 I've welded with with for years.
Quick search shows .15 for your machine.

BigJim1976 · Tue Jun 18, 2019 10:21 am

Thanks for all the info,
Lincoln service tech here in UK says to change the gas bottle first and go from there.
Seems that pure argon here in the UK can get contaminated?

If thats not the problem then I will start with setting the gap and go from there.
Thanks Again
Cheers
Jim

LtBadd · Tue Jun 18, 2019 12:22 pm

Jim, can you post a few photo's?

Coldman · Tue Jun 18, 2019 4:25 pm

Contaminated gas is a real possibility, but if it were your mild steel welds would be a problem too right?

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Tue Jun 18, 2019 6:13 pm

BigJim1976 wrote:Hi, thanks for the reply,

4043 rod
32a breaker on 240 volt UK
Transformer welder,

Its like the arc on AC is all over the place, coming from inside the cup?

New to TIG so im not sure what is normal.
DC- is working great, DC+ stick is great.
Its pecking away aluminium but not melting it?

And only thin aluminium 6mm

The welder is dual voltage 400/240, the person I bought it off was using it on 400v 3 phase, DC only.
I changed it to 240v as per the manual, I wonder if that actually effects the ac?
Cheers
Jim

firstly no way it should be tripping a 32a breaker. unless its one of the really sensitive type.
check your wiring setup.

6mm is far to big, try 3mm or smaller. 175 is fairly low for doing aluminum and you will be wasting some of that due to the balance.

if its transformer it may not have any balance adjustment and it would pay to go up a size in tungsten. i suggest a 3.2mm tungsten.