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Tungsten Arc Stability
Posted: Sun Jan 31, 2021 1:37 pm
by bap_
I've been welding some sheet metal art with 24ga stainless.
I set my machine around 25 amps (dial type machine), and just use the foot pedal to watch the puddle.
What I've noticed:
- Purple tungsten (generic branch from LWS), arc starts sputter all over the place sometimes. Once stable it welds fine.
- 2% Lanth (CK branch), clean low amp arc start, stable and controllable.
It had me thinking on the differences. Is it my grind that makes this difference, maybe previous contamination from dipping, the actual type of tungsten? I grind on a dedicated bench grinding wheel and just use my hand to spin it and point the electrode down.
I was thinking back on previous podcast episodes from WT&T and Jody and Roy discussing aircraft parts where arc starts are required to be perfect basically.
Re: Tungsten Arc Stability
Posted: Sun Jan 31, 2021 3:24 pm
by cj737
If our are welding a great deal of work at those amperages, I’d be using a 1/16 with a 60* taper.
Re: Tungsten Arc Stability
Posted: Sun Jan 31, 2021 4:13 pm
by bap_
I've been using 3/32 since its all I have. I'll have to pick up some 1/16.
Re: Tungsten Arc Stability
Posted: Sun Jan 31, 2021 5:05 pm
by Louie1961
Don't bother. If you put a fine enough point on your 3/32 it will go as low as you want. Jody has a few videos on that issue and I have seen some similar stuff from Mike Zanconato. There's almost no need to waste your money on 1/16th electrodes. I definitely prefer the 2% lanthanated for an all purpose electrode, but 2% thoriated is probably slightly better on steels.
Re: Tungsten Arc Stability
Posted: Sun Jan 31, 2021 5:59 pm
by Spartan
I like the CK layzr tungsten for really thin metal. Has the smoothest arc starts for me at low amperage on my machines. I use 2% lanth for everything else, and 3/32" usually 99% of the time, but I have layzr tungsten in 1/16" and 0.040".
I've also found that using the smallest cup size and lowest argon flow possible (like a #4 with only 6 or so CFH) helps quite a bit to get the smoothest arc starts possible for delicate work using small tungstens. Seems it has less turbulence at the start that way. It can also help to give yourself a solid 1 second preflow to further reduce the effect of turbulence on arc starts for delicate work.
Re: Tungsten Arc Stability
Posted: Sun Jan 31, 2021 11:34 pm
by G-ManBart
I actually like 1/16" electrodes better than super sharp 3/32 for low amperage work, but mostly from a convenience and economy standpoint.
I can take a 1/16" tungsten and give it a quick pass over the dedicated grinder and be ready to go quickly. With 3/32 I have to sit there for a while to get it sharp and all that's doing is grinding away material you paid for.
I generally buy Midwest Tungsten Service tungstens off eBay, and they get $8.99 for a 10-pack of 1/16 2% lanthanated where the 3/32 are $19.98. Why grind away $10 when it's so cheap to keep a pack of 1/16" on hand?
Re: Tungsten Arc Stability
Posted: Thu Feb 11, 2021 7:51 pm
by sbaker56
The type of tungsten definitely makes a difference, I've never really done a back to back comparison with amperage that low before however 2% lanthanated does everything well in my experience, some 2% thoriated is way better than others in my experience, I have a piece of Sylvania 2% thoriated that works every bit as well as 2% lanthanated on DC and I've had thoriated that sucked in comparison.
For your application though, ceriated tungsten would definitely be what I'd recommend testing before any other kind as it's intended specifically for stability at low amps
Re: Tungsten Arc Stability
Posted: Fri Feb 12, 2021 12:06 pm
by BugHunter
Most of what I do doesn't require tons of attention to the grind. I do that stuff on a belt sander in the shop that's not dedicated to tungsten.
However, when it's something delicate where I need all the help I can get with the weld quality, there is no question that a perfect grind is needed. No sanding off the ball of gunk that went 3/8" up the tungsten when the filler touched it, no marks on the tungsten, and NO contamination whatsoever.
For that I use 4 wheels. First, I have a dedicated grinder with 2 wheels, coarse and fine. I use the coarse the wrong direction, tungsten sideways and set the shape. Then on the fine wheel I go the correct direction inline with the tungsten. Then off to the dedicated rubber diamond wheel where the finish is made as nice as a 180 diamond wheel can make it. Then to the fiber wheel where I polish the ground area to a mirror finish (which the diamond almost had it to already). At this point, there's not so much as a molecule of foreign matter on that tungsten, not so much as a color change anywhere. That baby will strike and arc at 2A if I want to, and it will penetrate to a root like no other grind.
I'm not advocating doing that all the time, but everyone should be aware of the tradeoffs of a less well prepared tungsten.
Re: Tungsten Arc Stability
Posted: Sat Feb 13, 2021 12:51 pm
by walz10
There’s some good advice here I think. Being that I’ve only been Tig welding for a few months I’ve never polished a piece of tungsten to know what would happen. I do have the ability to dip my electrode faster than I can dip chips in salsa though.[emoji23][emoji1787] Considering how often I’m grinding contamination off my electrodes I just go over the grinder that also grinds everything else in the shop and get with it. I do use a drill to spin the piece though.
Re: Tungsten Arc Stability
Posted: Sat Feb 13, 2021 1:07 pm
by bap_
I normally just hand grind it on a bench grinder, and don't even pay attention to which wheel hah. The wheel is dedicated to grinding tungsten though so I have that going for me.
I think for what I do/plan to do, picking up some 1/16th is a good idea.
In welding school one of the guys had a sharpie. When he was certifying for pipe he just let me borrow it in my booth. The thing was awesome, just a quick zap and perfect tungsten all day long. Pretty pricey but if I was a professional I'd probably pony up for it. I've also had people tell me once I dip esp on AL, to just snap off the contaminated part. Personally I just grind all that crap off, so I'm sure there's contaminants in all my electrodes.
Re: Tungsten Arc Stability
Posted: Sun Feb 14, 2021 12:28 am
by BugHunter
I have one of these on a Baldor grinder. Now you wouldn't need the two inch by 12 inch version necessarily, but any one of these wheels is awesome for all sorts of deburring and polishing of Steel, stainless or aluminum or anything for that matter. Mine at work has been on the grinder for a decade and could be on there for three decades if I hadn't done stupid things to it.
https://www.mcmaster.com/4628A72
Then I buy diamond wheels on eBay, I wish I could find those fiber wheels on eBay! LOL
150x12x32x4x150# is what I have. Anything narrower than 12 mm isn't easy to keep a part steady on. I sorta wish I'd bought the 80 grit... is more money though. For grinding carbide the 80 grit is definitely faster and nicer.
https://www.ebay.com/itm/6-150mm-Straig ... 1510301541