Welding Tips and Tricks

I'm gonna rehash this again. I posted once before on this and now I am seriously thinking of buying one of these little dudes. For those of us that live in scratch start land this could be a neat little gizmo.

www.arcpig.com

Looking for input from Jody as well as from all of our TIG gurus here.

Hey,

Off you tube,

http://www.youtube.com/user/ArcPigHF

Mick

Looks kinda cool but for a couple hundred more you can step into an inverter with a whole lot more bells and whistles. JMHO

Rake that is true but I need to be able to run off of a 1975 SA200 as well as a Trailblazer 301G. I don't have any "wall" machines so whatever I do has to be completely compatible with my engine drives and this seems to fit the bill better than anything else I have run across yet. Just where I'm coming from. No biggie. Thanks for the input.

Damn Nick, I recently sold a Miller HF 20 that would have done you well and I let it go for $100 + S&H

Wow no kidding. I'd run about anything at this point I just can't spend thousands of dollars on anything right now and I'd like to get set up for tigging aluminum.

Nick,

The Arc Pig will NOT give you continuous HF for welding aluminum. It is strictly an HF-Start device.

It will work on an AC rig, but you'll still be at the machine's 60Hz once the arc is established.

Steve S

OK so I'm stupid on this one. Do you NEED continuous HF for aluminum tig or is it just the start that you need the HF for? According to the website the arcpig turns it on and off as needed too but still it classifies it as a starter.

Most aluminum TIG requires AC, and usually at 90hz? or better. Someone will correct me here if I'm wrong, Im sure.

I won't say it can't be done at 60 hz... When it was "heli-arc" that's really all there was.

Lincoln machines made me LOVE 400Hz.


Steve S

I see so if I want to tig aluminum off my truck I might not get away from the 220 plug on the front of the trailblazer versus being able to use the welding posts. Man I wish it could be done another way, and make a quality weld anyway.

It's possible to weld aluminum on DC, but it requires exeptionally clean metal, which you won't find in the field. I don't know enough about it to even say what alloys it can be done with. I would say there's no harm in experimenting with 60Hz AC, just to see if you can get a passable weld. The one thing I know for sure, is when I weld aluminum, I set the machine to "HF continuous", and the buzz the Synchrowave makes sounds like 120Hz or more. It, too, operates on a "tesla-coil" with a spark-gap, but is regulated for a controlled frequency, where the arc pig sounds like it produces low start currents in the KHz to Mhz range.

Steve S

Hi guys...

Disclosure: I designed the Arc Pig.

Just chiming in here to let you know it *does* do continuous fire.

Gordon Hanka

Arc Pig wrote:Hi guys...

Disclosure: I designed the Arc Pig.

Just chiming in here to let you know it *does* do continuous fire.

Gordon Hanka

Thanks for commenting, Gordon,

By "continuous fire", are you suggesting the capability of AC welding on aluminum? It's my understanding that the Arc Pig operates in the high KHz range to ionize air or shield gas for initiating the arc, then when the resistance at the arc falls near zero the Tesla coil disengages (as it is no longer the path of least resistance).

I'll be interested to hear more.

Steve S

I did end up getting one of these and I do like it. I tried it with aluminum with mixed results but I'm sure if I kept playing with it I could have figured it out. I works well though for what it was designed to do. Very interesting stick welding with high frequency but I don't actually use it for that. I was just trying things.

Hi Steve...

Yes, the Pig fires to ignite the arc (actually it fires in the low MHz.) After the arc is ignited (that is, while weld current is flowing) no HF igniter will do anything. The HF spark has paltry power (a few watts) so it is lost among the kilowatts already crossing the weld gap. But with aluminum you might leave the HF ignition on anyway ("continuous fire") to be sure your arc ignites every single half-cycle. Sometimes the arc fails to ignite on the EP half of the AC cycle ("Rectification") so you don't get adequate cleaning. Continuous fire HF ignition can help with that.

There may be confusion on this point, because of the other, completely different definition of "high frequency." A high-end TIG box will let you crank up its frequency (that is, the frequency of AC weld-current polarity changes) beyond 60 Hertz, to tighten up the arc. For example, when TIG-welding aluminum, you might set the frequency to 200 Hertz. This is "high frequency", but is completely different from HF ignition.

Gordon

Arc Pig wrote:Hi Steve...

Yes, the Pig fires to ignite the arc (actually it fires in the low MHz.) After the arc is ignited (that is, while weld current is flowing) no HF igniter will do anything. The HF spark has paltry power (a few watts) so it is lost among the kilowatts already crossing the weld gap. But with aluminum you might leave the HF ignition on anyway ("continuous fire") to be sure your arc ignites every single half-cycle. Sometimes the arc fails to ignite on the EP half of the AC cycle ("Rectification") so you don't get adequate cleaning. Continuous fire HF ignition can help with that.

There may be confusion on this point, because of the other, completely different definition of "high frequency." A high-end TIG box will let you crank up its frequency (that is, the frequency of AC weld-current polarity changes) beyond 60 Hertz, to tighten up the arc. For example, when TIG-welding aluminum, you might set the frequency to 200 Hertz. This is "high frequency", but is completely different from HF ignition.

Gordon

That's an excellent explanation. It seems, then, that the Arc Pig would make AC welding on a simple transformer 60 Hz machine more practical, since arc-drop in the phase transition is the big problem with using a simple AC transformer for AC TIG.

Steve S

Thanks Steve.

That was a good way to say it, HF ignition makes aluminum a little more practical with a 60-Hz transformer box. Personally I use it for stick welding, because low-power scratch starts make me swear in front of the kids.

Of course, in a perfect world we only use a $3,000, 400-Hz square-wave inverter with built-in HF and on-torch heat control.

gordon

Gordon,

I've had the advantage of the $3k machines for many years, so it took a minute to put this all in perspective.

Have you considered contacting Jody? (Jody Collier, the founder of this forum.) He often reviews products, making videos of his attempts and results. He's a master craftsman, but has done videos of testing a homemade DC welder using a rectifier array scavenged (I think) from microwave ovens...

He'd likely do a review on a loaned unit, if you were interested. There's been interest in and discussion of the "Arc Pig" on this forum previously. While the forum is a small group, Jody's YouTube channel gets traffic in the hundreds of thousands...

Just a thought...

Steve S

Otto Nobedder wrote:Gordon,

I've had the advantage of the $3k machines for many years, so it took a minute to put this all in perspective.

Have you considered contacting Jody? (Jody Collier, the founder of this forum.) He often reviews products, making videos of his attempts and results. He's a master craftsman, but has done videos of testing a homemade DC welder using a rectifier array scavenged (I think) from microwave ovens...

He'd likely do a review on a loaned unit, if you were interested. There's been interest in and discussion of the "Arc Pig" on this forum previously. While the forum is a small group, Jody's YouTube channel gets traffic in the hundreds of thousands...

Just a thought...

Steve S

I too would love to see a "Jody" review.

Its the best thing you can do to a welding product.

Good idea guys. I will pursue the review idea.

gordon

Not exactly sure how the arc pig is setup, but the only downside I see with trying to use it for tig welding aluminum is most machines this will be used on would be sine wave by nature. Possibly could compensate some by running slightly higher amperage.
Unless it smoothes the voltage/ current to resemble something closer to square wave.

Regarding sine wave versus square wave versus HF, the theory is that a square wave can substitute for continuous-fire HF. Either will help prevent arc extinction (or rectification, which is just extinction of the electrode-positive half-cycles.)

Note that weld current flows through a conductive path of ionized air. The weld current maintains its own ionized path by stripping electrons out of air molecules. When the weld current shuts off, the ionized air dissipates quickly. In fact it dissipates so quickly that the voltage required to re-establish the arc will double in a time on the order of a hundred microseconds (a tenth of a millisecond.) This is why it is so hard to weld in the wind; your conductive path is constantly drifting out of the weld gap.

The problem is worse with a sine wave, because each half-cycle of a sine wave ramps up slowly.

AC current is a series of half-cycles: a heating half-cycle (EN) followed by a cleaning half-cycle (EP), repeat forever. Each half-cycle of a sine wave ramps up slowly, so the arc is "off" for several milliseconds, more than long enough for its conductive path to dissipate. This problem is worse for the cleaning (EP) half of the cycle, I think because it is harder for electrons to jump off a flat surface (the workpiece.) Cleaning cycles are particularly important with aluminum, so aluminum has a particular problem with rectification (extinction of the cleaning cycles.)

Extinction/rectification is less a problem with a square wave, because square-wave voltage ramps up quickly, so the arc is "off" for less time between half-cycles, giving less time for the conductive path to dissipate.

This has been a bit long-winded, but here is the punchline: A continuous-fire HF box like the Arc Pig substitutes for a square wave. Every half-cycle, the Pig watches weld voltage ramp up, and if the voltage gets close to its maximum (Ie., if voltage approaches your welder's OCV) without re-establishing the arc, the Pig fires a flurry of high-voltage sparks to ionize the air and re-establish the conductive path.

Other continuous-fire HF boxes like the Miller HF251 do the same thing, except that the HF251 in continuous-fire mode does not monitor weld voltage, it just fires periodically on the up and down slopes of mains voltage.

Of course even with a square wave you might still want HF for no-touch ignition. Especially if your welder starts hot and melts your tungsten.

gordon

after reading last night I tried holding down the ignition button on my pig. I noticed the weld puddle to be more distinct and was actually able to add filler metal. without holding it, it did nothing more than etch the surface.