Welding Tips and Tricks

Any advice would be greatly appreciated here. I have a Miller Syncrowave 250 TIG welder (old pre-LED model 903056) that I purchased new around 30 years ago. It always served me well, but for about a year now I just can't get a descent weld, it is like all my welds are contaminated and pitted like a complete novice. It may be a wrong observation, but it seems like the heat is only attacking the very top surface of the metal, and when I press harder on the footpedal to increase the amperage it does melt the steel deeper but violently bubbles & oxidizes immediately.

I replaced the Argon cylinder about 3 months ago hoping it was somehow bad gas, but that didn't help. A few weeks ago I opened the welder case and blew out the dust, and I wiggled all connectors just to be sure everything was making good contact, that didn't help. The last thing I did was replace the torch hose/cable and that didn't help either.

FYI, I use .020", .040", and 1/16" tungsten (mostly .040"), I use 50-75amps, and i usually weld small pieces of steel or sheetmetal.

Do these welders truly wear out? Anyone have suggestions for me?

Check the internal gas hose and fittings. Over time, they age and crack and leak argon. It sounds more like to me you have a shielding gas issue than a mechanical issue with the box. You could also check your torch, they don't last forever either.

You don't mention if the problem is on AC, DC or both.

Have you checked with a flow gauge ; https://www.arc-zone.com/shield-gas-flow-tester-50020 to ensure the solenoid / internal gas hose is OK.

Edit: CJ beat me to it !

As others have said it sounds like a gas issue but hard to tell over the net, what about the hose from your flowmeter to the machine?
Do a bubble test on the flowmeter for leaks, if inside the machine the gas line is a hose as opposed to stainless tubing then maybe it has degraded and needs replaced

Hi Tigger,,,,as others have stated, it appears to be shielding gas issue. Kiwi suggests to get a flow meter to test the gas flow right at the torch cup. And Richard is suggesting that it may be internal hoses degrading internally which you will not see and that will cause flow issues. Also while you're going to be inside the machine, you might want to check for dust in any of the control knobs. You said that when you push on the pedal looking for more amps, you get a violent reaction...is that all of a sudden or just as the amps come up to max? How about the pedal itself,,,does it feel smooth ? But check gas flow for sure.
gramps

Thank you guys for ideas, but my welder does not have any internal hoses. It only has one hose from the bottle to the servo, and one from the servo to the torch (I just replaced that hose). I can feel the argon coming out when I press the footpedal, so even though I don't have a flow meter to test the actual flow, I "think" I am getting good enough flow.

To answer the questions, I only use DC for steel. When I depress the footpedal I get a gradual increase in amps, it is nothing stuck or "spiky", and nothing obvious. My feeling (being ignorant on how a TIG actually works) is that I am not getting a deep enough frequency? Or is that just an ignorant statement? I still feel like the Argon is doing nothing, but what are the odds of getting bad gas 2x over 6 months apart? (I buy from AirGas)

2 things: check the “red” hose in your picture from the fitting to the bottle with soapy water. It is very possible you have a split or crack along its length that is not apparent until pressure (flow from the regulator is active).

If your pedal is behaving properly, it is highly probable the potentiometer switch is faulty. This could be due to debris, age, corrosion on contacts. You could use a multimeter and check the resistance across the contacts, put that’s not always a perfect sign. The cord from pedal to machine could also have internal damage causing a short in the amperage values being delivered.

oldtiger wrote:Thank you guys for ideas, but my welder does not have any internal hoses. It only has one hose from the bottle to the servo, and one from the servo to the torch (I just replaced that hose). I can feel the argon coming out when I press the footpedal, so even though I don't have a flow meter to test the actual flow, I "think" I am getting good enough flow.

To answer the questions, I only use DC for steel. When I depress the footpedal I get a gradual increase in amps, it is nothing stuck or "spiky", and nothing obvious. My feeling (being ignorant on how a TIG actually works) is that I am not getting a deep enough frequency? Or is that just an ignorant statement? I still feel like the Argon is doing nothing, but what are the odds of getting bad gas 2x over 6 months apart? (I buy from AirGas)

I saw this on the Miller forum and replied there as well, but you've added some more info here. A slight step back in terminology. The red hose is connected to your flow meter or regulator at the bottle, and to the gas valve/solenoid on the machine. You're saying you replaced the black and white hose that goes from the gas valve to your torch?

Regardless, you need to check the fitting where the regulator attaches to the bottle, the fitting where the hose attaches to the regulator, where the hose attaches to the gas valve, and where the other hose attaches to the gas valve....you can't have leaks any of those places..

Totally separate question, but is the torch power lead attached to the lug on the left or the right?

sounds like the gas solenoid isn't working. I would try bypassing it and running gas from the regulator directly to the torch connection and just let the gas flow constantly for the purposes of the test. Assuming the torch isn't somehow damaged, that will likely address the problem. There is no "frequency" on DC, and there is nothing inside the unit that could cause this other than lack of gas flow.

I had already tested for Argon leaks as best as I could with a squirt bottle with soap water, but as we all know, gauges can leak and it may not bubble up. The red hose is all good. I do not own a flow meter, but I will look into buying one just to test the unit. I can feel a fairly strong flow coming out of the torch when I depress the foot pedal when on, so even if I have a leak, I feel Argon (or contaminated air if my Argon is bad) is flowing. The solenoid is working, but I can't know how much it is opening, only that it is being activated and opening.

Yes, I just replaced the black/white hose/cable, and the torch power is on the right side of my photo.

The more & more I read all replies, it is really just making me feel like my first thoughts of bad Argon is most likely.
Is there any way to test or determine if my Argon is good or bad? I have my Argon running at 20cfh, is that correct?

Internal photos attached, just FYI.

Bad argon is hard to test...I've had two tanks that were contaminated and the only way I could prove it was to compare with a known good tank.

It sure sounds like you're getting enough gas at the torch end. 20CFH could be on the high side depending upon the cup size....normally you want about twice the cup size, so a #6 cup you'd want something like 12CFH, etc. Unless you're running a really small cup I suspect 20CFH wouldn't cause a problem.

Is there any way you can borrow another flow meter/regulator? If that has an internal leak it could be letting air in and then you'd have plenty of flow at the torch, but it would be contaminated.

I'd go through and check or replace all the torch parts as well....make sure the seal on the back cap is in good shape, new collet, collet body, etc. It's really a process of elimination thing.