Struggling with low current starts on 255EXT 2015

[windscreen]

I've been playing with and learning welding on my 255 for the last three months, and watching a ton of YouTube videos. Yes, it probably sounds like I'm a welding hack, but I think I'm doing pretty good. I can make nice looking, and strong welds between 1/8" aluminum sheet, and have sectioned, polished, and etched to verify the quality of the AC welds. A few days ago, to see if it could be done and to test the low end of the machine, I made a lap weld on a pair of 0.015" steel sheets, using an 0.040" tungsten and 0.035" MIG wire as the filler rod (this is on DC, obviously). It worked great!

One issue I've had, when working on light gauge aluminum, is when terminating a weld and throttling back on the pedal, when I get to low currents, the arc will stop and the machine's HF start will kick back in. If you hold the pedal position, you get a pop-pop-pop, as the machine tries to reestablish the arc, and the tungsten (1/16" 2% lanth, here) is immediately balled to over its full diameter. In trying to learn what I'm doing wrong, I came across this video from Everlast:
https://www.youtube.com/watch?v=KN-aYQWW7a4
The first 3:30 of this video is very interesting to me, as I cannot get anywhere near this performance out of my machine.

The narrator states the following settings: Balance at 35%, 120 Hz, starting at 20 A, minimum start amps set to 5 A. (I find the last two settings contradictory, and confusing.) Also, listening to the video and comparing to a tone generator, the frequency was set at 230 Hz, not the stated 120 Hz. The cup looks like a #5 to me. At 1:41 he says "we are lowering the main amperage to 5 A, so the unit is forced to start and cover at 5 A." I take this to mean it was set with 5 A start, and 5 A welding.

There is no way I can get my 255 to start at 5 A, like in the video. If I just push the pedal far enough to get the initial click, and start the welder at minimum weld current, I'll get a pop-pop-pop, and the tungsten point is balled to over the full diameter (1/16" diameter, as in the video, but in my case 2% lanthinated). I assume the pops are the HF circuit getting an arc established, handing the arc off to the weld circuitry, at which point the arc goes out, and the HF start comes back in. I was initially doing this with the stock water cooled torch, to which I put on a gas lens collet holder and was using a #5 gas lens. I tried argon flow rates of 5, 10, 15 and 20 CFH. FYI - If I turn up the welding amps to 20 A, and smash the pedal, I'll get a single, clean start, every time.

Then, to better match the video, I put on my air cooled torch, with a #5 cup, and tried again, with the same results. Next, I tried adjusting the points gap (my machine must be an early one, without the solid state start circuit). As delivered, it was about 0.030". I tried 0.045", 0.055", 0.060" and 0.025", and then put it back to 0.030", as I could not detect any difference between settings. I cannot remember what my gas flow rate was for these tests. At this point, I gave up and put the water cooled torch back on.

For all my tests, I had about 1/4" of stick out, with a sharpened tungsten. I called tech support yesterday, and was told my problem was way too much stick out and that my gas flow was wrong. The recommended parameters were 3/32" stickout (!!) and 8 CFH of argon. I'm not quite sure how one welds with 3/32" of stickout, as it's awfully hard to see the arc, much less tip the torch and get in a filler rod. In the Everlast video, he clearly has more than 1/4" of stickout, maybe even close to 1/2".

So, after that long winded explanation as to what I've tried, what's going on? Am I doing some thing wrong, or does my machine have an issue at low current on AC?

Thanks,
-Steve

[performance]

I think that there may have been some wires crossed in communication. You should have a standoff height of less than 3/32" of an inch. In actuality, the factory recommendation is .9-1.0 mm, which translates to .035-.045" stanoff height while starting and welding. You have to have good motor control. It's not something that everyone can do, quite honestly. It takes practice and a good comfortable position. Anyway, no you won't be able to see the arc much even with a 1/4" stickout, but you just have to lean over and look. That's the life of a TIG welder. In the video, it says "Start and Hover at 5 amps".. not cover.

I don't know what a tone generator does to compare, but if the video said 120Hz, it was right around 120 Hz. Different welders produce different pitch sounds depending upon wave form designs.

When I said ...20 amps with start amps set to 5 amps, that means welding amps were set to 20 and start amps were set to 5.

Keep in mind when you are welding with extremely low amperage, the resolution changes so it does make the foot pedal more sensitive to starting as it has to move more and the feel is different. The SSC pedal is better at it with its shorter throw. But one of the things you might want to check is the calibration on your panel. The potentiometer may not be zeroed out when you hear the click.

The way to check this and work with this at low amperage (and the best way to weld at low amperage) is with the torch switch. Use that first to compare. IMHO, the point gap units are not as soft on the starts as the other type...and if the unit senses you have dropped off the face of the earth with the amperage it will try to restart the arc...and that is where you will get the cycling. I don't think the solid state ones do it the same way. But I don't have a point gap one to personally test and compare.

[performance]

You neglected to mention what type of tungsten you were using. This test was done IIRC with thoriated 2%. Not all tungstens are equal on starting. Especially if they are contaminated or poor quality.

[windscreen]

You neglected to mention what type of tungsten you were using. This test was done IIRC with thoriated 2%. Not all tungstens are equal on starting. Especially if they are contaminated or poor quality.

First of all, thanks so much for the quick reply, Mark!

I'm using 2% Lanthinated, from Weldcraft. I think it's pretty decent quality. The video shows text stating 1.5% Lanthinated was used (at 1:21).

I have checked the calibration of the pot in my foot pedal, and it seems spot on, from the click through to full on. I did this by propping the torch handle on a piece of material with the tungsten about 1/8" off some aluminum stock. Full pedal corresponded exactly to my weld amps setting, and at the click, or minimum pedal, the display showed 5 A (for the very brief moment I was able to get a 5 A arc).

FWIW, I did try the torch switch, and got the same results (no low current stable arc). I also tried lift to get the HF circuit out of the mix, and the unstable arc result was similar. With 15 A start and 5 A weld with 0.5 sec upslope, I could occasionally get an arc struck, but it would immediately become unstable and go out. If I wire brushed the heck out of the aluminum sheet, the 5 A arc might hang on for a second, but it is very unstable. Not even in the same ballpark to how smooth the arc sounded in your video.

-Steve

[performance]

First of all, thanks so much for the quick reply, Mark!

I'm using 2% Lanthinated, from Weldcraft. I think it's pretty decent quality. The video shows text stating 1.5% Lanthinated was used (at 1:21).

I have checked the calibration of the pot in my foot pedal, and it seems spot on, from the click through to full on. I did this by propping the torch handle on a piece of material with the tungsten about 1/8" off some aluminum stock. Full pedal corresponded exactly to my weld amps setting, and at the click, or minimum pedal, the display showed 5 A (for the very brief moment I was able to get a 5 A arc).

FWIW, I did try the torch switch, and got the same results (no low current stable arc). I also tried lift to get the HF circuit out of the mix, and the unstable arc result was similar. With 15 A start and 5 A weld with 0.5 sec upslope, I could occasionally get an arc struck, but it would immediately become unstable and go out. If I wire brushed the heck out of the aluminum sheet, the 5 A arc might hang on for a second, but it is very unstable. Not even in the same ballpark to how smooth the arc sounded in your video.

-Steve

You should have 0 upslope with the pedal and for the torch switch upslope is a moot point at low amps...What is it upsloping from?

With the pedal...At the click the unit starts at 5 amps, but if you do not go down further on the pedal the amps will drop to 2 or 3 amps immediately. If the arc has not been fully established it will go out if you do not give it enough pedal to satisfy the maximum amps.

Again, standoff is the key in this by and large.

[performance]

I should add that the amps dropping are a result of the low amp setting. Higher amps, the welder does not notice the difference as much and it's much smoother.

[windscreen]

Also, is it possible to swap out a points gap HF start board with a solid state/gas discharge tube one? It's something I'd be willing to pay for, if the cost isn't too bad.

Thanks,
-Steve

[windscreen]

Just to show I'm not a complete hack with no clue, I just went down to our weld lab at work and hopped on a Dynasty 300DX and laid a 5356 bead on a Coke can.


Pedal control from 5 to 15 amps, 15 cfh argon, #5 conventional cup with 1/16" tungsten. It was actually pretty easy, and could hold a 5 A arc at 15 volts, all day long. There is NO way I can do this on my 255 ext right now.

[windscreen]

The tungsten melts back because the arc isn't stable, terminates, and the high frequency start comes back in and hits it hard (for lack of a better term). Arc fails again, HF start hits it again, and the cycle continues. After 5 or so of those hits, the tungsten builds enough heat and melts.

If I set welding amps to 20 ish or more, I can hit the pedal hard on arc start and get to a stable arc, and the tungsten stays pointed. However, try that on light material, and you have a hole.

And I don't want to turn this into Everlast vs Miller vs what ever. My point was just to show I have at least a mild handle on how to do this stuff, and it just might be my machine.

-Steve

[performance]

Well there are a couple of things. I am willing to admit your unit may have a slight issue if we resolve all possible problems...but the problem more often than not lies in the welding environment, or user and not the machine, especially this one issue with balling you've brought up. Just the other day, I went through this with a customer (I think on a forum...can't remember if here or where or maybe email) and he kept assuring me of all the things that were RIGHT. I kept thinking it was gas contamination. Tungsten was burning back (at low amps I think). I didn't hear from him right away and he comes back to inform me that he had been opening his garage door to weld lately. When he closed it and all things were fine. Drafts and breezes can do this...and cause the arc to destabilize, wander or otherwise just plain out quit. At 5 amps, the arc has a tendency to destabilize easily by a draft from about anything, even your breath or the fan from the welder.... magnetism...tungsten contamination...slight gas contamination etc. Make sure you welder is well out of the way and not on your table where you are working. No fans, air conditioners, cross drafts or anything on or remotely near you. Also try a gas lens. That might help. 1) Make sure you are in the negative connector on your unit with the torch. Had this the other day with a customer as well...similar symptoms 2) Your current has to flow from your work clamp to your torch. Any interruption along the way will cause an issue. The unit has a sensor to sense current flow and if it does not sense it, it shuts the inverter output off. Your clamp should be attached directly to the metal. Aluminum oxide is a barrier to current carrying. If you are relying on a ground that is indirect or you have not removed the oxide under the ground it will create trouble with the flow of electrons. Same for steel. When I did the video on the can the work clamp was just inches away and I had to work on positioning the can so that it made good contact with the table. The knife/razor blade was the same condition. Make sure the clamp is secure and the CABLE in the DINSE connector is securely tight. As far as swapping out the boards...I don't know if I am the right person to answer that one. That is a tech support issue. Likely it can be, but it might require a new top board as well to work with it. Whatever the problem, it isn't a major one with the unit that signals impending failure. At worst it could be the sensor isn't getting the signal or isn't sensitive enough or something isn't sensing that current is flowing. I don't know whether there is an adjustment or it is in the programming, (or a bad hall sensor...though that would be the first I heard of one) or even if that really is the issue, but sounds like it to me. Are you having the issue on both DC steel and AC aluminum?

It's possible that the unit is trying to start in positive polarity and hence the arc instability, (and some units do, and the original test unit programming did do that for certain things) There are reasons that some manufacturers do start in EP for AC. But if it does it in both AC and DC, then it is a gas issue or contamination issue...

[windscreen]

Hi Mark,

First of all, thanks for the after hours reply. That means a lot.

I'm not necessarily trying to force the issue that there is an issue with my welder. I just want to figure out whether the problem is with it, with me, or both, and get myself to that robust 5 amp AC arc you had in that video. Thanks for all the attention, so far. The stability issue is only in AC. This machine is very awesome in DC mode. A few days ago I used some 0.040" tungsten along with 0.035" MIG wire as a filler rod to do a nice lap joint on some 0.015" thick steel. It was very controlled, and my biggest problem was getting the shade on my mask low enough to see the arc.


Environment
My shop is completely enclosed, doors shut, and windows shut. It's finally warm enough that the heater isn't running anymore. I'd say the air is dead still. The welder is on a cart, about 3' from the table.



Setup
Other than when I swapped out my usual water cooled torch to see if the gas cooled was any better, I've been using a #5 gas lens. All Weldcraft parts on the torch body that came with the welder. I checked for gas leaks tonight by pushing the tungsten up inside the lens, snugging down the back cap, then plugged the lens with my finger and turned on the purge. There was a leak past the back cap o-ring (which seals to fairly non-firm rubber of the torch body, but that's a whole 'nuther issue). I fixed the leak by going to a thicker o-ring I had in an o-ring set.

I normally run indirect grounding via a single star ground point on the welding table (3 cables: TIG, MIG, and an extension cable with a clamp for off-table work. All with crimped on ring terminals and 1/0 cable). Per your request, I did the tests below with the ground clamp directly to the material. I used the factory supplied cable and clamp for this. The ground clamp is connected to the machine + and the torch to -, as it should be for TIG welding.

I made sure the aluminum stock for this test had very clean surfaces for ground and striking the arc. I cleaned up all the surfaces with a 180 grit flap wheel in my 4.5" grinder. Subjectively, free-handing, this did seem to yield a bit more stable arc, but the change was small, and still no go when I tried starts at 5 and 10 amps.


Tests
Without further ado, here are links to video files I took to better describe what I'm seeing.

test 1 - 5A start, 5A welding, 0 sec up and down slope, 120 Hz, 35% AC balance. 0.5 sec pre-flow, 9 sec post flow. (warning, 131 MB movie file)
movie 1

test 2 - same as test 1, but with starting and welding amps upped to 35 A each to achieve a stable arc (even then, you can hear it crackle a bit)
movie 2

Thanks,
-Steve

[performance]

I think you have some sort of coating on that and not getting through it with your wire brush. Is it anondized? You should not be getting that black around it unless there is some contamination of gas, tungsten or metal.

[windscreen]

The material was 6061 plate, and I hit it pretty hard with a 180 grit flap disk. I just ran outside and tried it again on some 1/8" 6061 sheet, and I'm seeing the same black, sooty edges. The tungsten was freshly sharpened on a grinder I have reserved for tungsten sharpening only.

Contamination of the shield gas would make a lot of sense. I've noticed that my welds on stainless (304 sheet with 308L filler) don't have that shiny, rainbow look that I often see in other's welds. I assumed it was my technique, and lack of experience. My stainless welds, when done, look much more like a regular carbon steel weld...dull and grey. Maybe this would explain that too.

I've still got about 400 psi left in the argon cylinder, but I'll try to get over to the welding store and exchange it today. I'm fairly excited to have a potential solution in sight.

Do you ever sleep, Mark?

Thanks,
-Steve

[rick9345]

Why does that bad gas show up on new welders?
Never have had a bad tank in over 20 yrs, just lucky.?
My friend, his new welder, same LWS, bad 2 nd tank.
Having said that I suppose my next will be bad.
Nice that you found problem.

[slzboy]

Hi Steve, i know this post is a couple months old i'm having the same problem on my two week old 255 ext on ac on low amps the arc is all over the place no where near stable like the video, works good at higher amps i am running the ssc pedal but it welds horrible. The arc flears up and jumps all over the work then once its starts to weld good and you hit the pedal to reduce heat then it jumps and stutters ,wonders again i think its the welder. i started welding at night but not last night LOL.

[slzboy]

There is no way you can weld a soda can with this welder the arc to to unstable at the low amps or is a problem with the machine

[Rambozo]

Have you tried a new bottle of argon? As you can see from this thread, that fixed Steve's problem.

[slzboy]

No i will try it see what happens thanks

[rick9345]

some people don't/won't/can't assimilate the info at hand.
others TROLL
ON my 250EX, problems have been operator error induced RTM (then reread)

[slzboy]

I have read the RTM over and over i started welding at night but not last night but this is my first CHINESE WELDER . Operator error can not cause the arc to wonder and flutter and not start then blast like a blow torch then let off the pedal then the arc is barely there and its only on AC don't matter what the amps are the ARC SUCKS.