Welding was going good, then not so good...

[chugchug]

Hello there, I recently purchased a Tig welder (R-tech 201 AC/DC) I initially set the welder up and everything was fine and I was happily practicing laying some beads on some aluminium box section. I had to pack the welder away and disconnect the gas bottle etc due to the garage being used for a party. When I had re-assembled the welder and sat down to practice the following things happened:

The arc would not 'hold' and instead of producing a silver dot type weld puddle, it cratered the aluminium (see picture)

The tungsten rapidly broke down and became grey (oxidized)?

It was very puzzling as the settings had not been changed since the last session. I was thinking possibly an Argon supply fault but I seemed to be getting a healthy burst of through the torch when depressing the foot pedal. I am a relative novice so I imagine it's something pretty basic. I have included all settings being used at the time below:

r-tech 201 AC/DC with foot pedal, set on AC mode, 125 Amps ,Tig torch to negative, earth lead to positive,Adams bottle pure Argon, 7 lpm on flow meter, 8 seconds post flow, 1.6 mm white tipped tungsten, 1.6 alloy filler rod

All help much appreciated!

 

[FranV8]

At that current I'd try the 3.2 tungsten you got with the machine.

Have you got the tungsten too far out of the torch?

 

[chugchug]

Hi there, sorry I meant to say the larger tungsten supplied with the welder (3.2mm if that's the case). I had it about 4mm out from the shroud. Also when I switched back to DC to try on some mild steel (using red tipped tungsten) I had the same problem with the arc not holding and cutting out at about 2 seconds (thermal overload perhaps)?

 

[Hitch]

Have you got the torch and earth round the wrong way?

Torch in the -
Earth in the +

Double check it....

 

[chugchug]

The welder is packed away again now but I am sure I remember looking at the set-up pictures in the manual and checking each terminal. Do the craters in the picture look like the result of reverse polarity?

 

[Delgado]

Are there any warning lights coming on? Are you trying to start the arc in AC mode with a big ball on the end of the tungsten, if so the HF will most likely just dance around and not establish an arc, although the fact that it doesn't work in DC mode seems strange (unless you're not grinding the tungsten). Try what's already been said, sharpen your tungsten corectly (It'll be different for AC and DC, see the Forum TIG Tutorial), and try again. If that don't work then contact R-tech.

PS. 8 secs post flow is way too much for what you're doing.

 

[chugchug]

No warning lights, tungsten prepared as per tutorials....I shall set it up again at the weekend and see if it happens again. It's just strange that the settings were exactly the same and the only connections that had to be made again were to the bottle. Could air be getting in the lines somewhere causing the cratering? (Although I could not detect any leaks.) Thanks for the advice on post flow btw.

 

[malcolm]

Are you talking about the 4 black welds around the silver one? That's no gas at all getting to the weld. Check the gas is continuous after pressing the torch button and ideally measure it with a peashooter at the torch. That'll let some gas through which should purge the line (important after first assembling the gas).

 

[tigroddave]

I would definatly check the leads were on the right way . i have done it myself and caused much confusion

 

[chugchug]

Hypothetically, would a small leak allowing air into the gas lines cause the black cratering in the photos - would it 'displace' the argon? I say this because I was defanitly getting a 'burst' of gas when depressing the foot pedal through to post flow

 

[malcolm]

Was the burst of gas definitely coming from the torch? Not from some other place like a pipe fallen off inside the welder? These dudes come in handy: http://www.weldequip.com/gas-flow-tester.htm

Can't see polarity making a lot of difference on AC, and it's hella-black.

 

[hotrodder]

A leak that allows a little air to be drawn in can be enough to cause a mess and would trash the tungsten too. As said pic looks more like there the argon was switched off. As Malcolm could be a gas line come adrift after the solenoid, could be a sticking solenoid (occasionally see this when the cylinder is almost empty)

If the leads were connected round the wrong way you'd have vaporised the tip of the tungsten when you tryed it in DC

 

[chugchug]

The gas was definitely coming from the torch, I could feel it when I put the gun to my face (so to speak!)I was also using a flow meter (although not a pea shooter.)

It seems to be that the general consensus when looking at the picture is that there is a lack of/no argon. The cylinder was half full when I started and around a quarter full when I stopped (in frustration) so the argon was definitely going somewhere....just not seemingly to the weld, in which case I wonder what was coming out of the torch?

 

[hotrodder]

If gas is flowing from the torch then start looking for leaks. Leaks in the system can draw air in and cause a mess. IIRC there's a thread or two about somewhere discussing the accuracy (or lack of!) of the regulators that come with Rtech kit- something about them reading waaaay low and flowing getting on for double the setting. Higher flow rates can exaggerate the problem

 

[Engineer]

Too much argon will in some cases cause similar problems to not enough. If you are using small type bottles, it makes a lot of sense reducing the flow to as low as possible, and this will save quite a lot of gas.

 

[chugchug]

I think my plan of action for the weekend is to set the welder back up (double checking terminal connections) and check for leaks using some leak detection spray. I will aim for a flow rate of around 4/lpm on the flowmeter (possibly 2/lpm on the r-tech regulator) to make sure that there is not too much argon coming through and report back. Thank you all for your help and advice so far.

 

[Engineer]

Also worth checking all is ok with the tungsten..........not sure what sort of torch the Chinese sets use, but make sure everything is tight and the tungsten is making good contact.

 

[dannyp]

the R tech regulator is crap

it took my reg back to ESC where i bought my 251 tig from and said i thought it was duff.

they swapped it straight away for a parwled regulator that is much much better also bought a flow meter and to be fair to the parweld reg the flow meter reads what the reg is set to

 

[NTwoO]

Further check for cracks in the Bakelite back cap on the torch. This cracks easily. Also check the O ring on the torch and the join between the cup and the torch. The flow of gas can easily suck in air at any of these points. Maybe some of the veterans on the forum can help with diagnosing this without getting an HF jolt. Maybe stuff the cup with a cork or something and check for leaks upstream?

 

[chugchug]

UPDATE:

Sooooo today I set the welder up again, going thoroughly through each procedure, especially looking at all the gas connections. I checked every connection for leaks and all was well. Looking at the advice given (thank-you hotrodder, NtwoO especially) I decided to check the torch for any possible leaks. I dis-assembled the torch and using the guide on this forum, reassembled the torch. It was at this point that I noticed this:

For the eagle-eyed among you, that is a picture of a collet stuck the wrong way round in a collet body. I share the welder with my dad so one of us must have accidently put it on the wrong way and screwed it up whilst changing tungstens or some such (I vote him!)
I ended putting the smaller (1.6) collet/collet body on the torch (the right way!) And all is well.
Thank you to everyone who gave advice and if this could act as a lesson to other fellow novices to: 'CHECK THE BASICS,THEN CHECK THEM AGAIN' then my adventure would not have been in vain! I'm am sure that I will be back with another 'issue' in the near future. Cheers.