Re: Mig polarity and other stuff...long...sigh


"Gunner Asch" <gunner@xxxxxxxxxxxxxx> wrote in message
news:5h13h1t662q92j2ffc6f4619buvt913uev@xxxxxxxxxx
> Some time ago, I traded into an absolutly MINT Arco PulseArc 350 mig
> welder. Only problem was..I made the deal before looking at it closely
> and when I got it home, discovered it was 3 phase. Sigh... So I loaned
> it to a friend who I guess never used it.
>
> I got it back a couple weeks ago, and tonight I decided to try to see
> if it would run on 1phase 220. I could get the fan and controls to
> work..but no arc, by supplying 220 to two of the three leads. I didnt
> try to put power on 1 and tie 2 together. Shrug.
>
> So I put a longer power cord on it, and plugged it into my 5 hp 3phase
> rotary converter, which brought it to life. I had to futz with the
> drive rollers, and play around with wire speed and amps before it
> would actually start to run a bead with that frying bacon noise..and
> not ratsnest the wire in the wire drive. I noticed I was getting burn
> back, and while the beads looked great..I had nearly no penetration.
> It worked and sounded wierd. That machine has some sort of pulse
> mechanism in the arc, so wrote it off as that. Until it hit me....I
> was using straight wire, no fluxcore with 75/25..and so I checked.
> Sure as ***..the machine was hooked up electrode negative. (sound of
> Gunner slapping his head..hard)
>
> A quick change over..and voila..it runs a great bead, with good flow
> of the glassy smooth puddle with a hell of a lot less amps, and I can
> see good burn into the parent metals. Still has a wierd sound to the
> arc though and is picky about wire speed and amps adjustments, even
> with a consistant stickout distance. I was even able to weld a couple
> pieces of .060 *** metal together..which surprised the *** out of
> me as Im using .035 wire. And for me..thats damned good cause Ive
> never claimed to be anything more than a low grade dauber. And no back
> plate either. <G>
>
> Anyone have one of these? Any hints on setting it up? The amp dial
> goes from 0-35, which has no corresponding marks, but there is are amp
> and voltage dials..which are of some use.
>
> Another question...Ive got at least 3 BIG rolls of .045 Dual Shield
> and the proper contact tips. Since this stuff is flux core, to be used
> with shielding gas..do I leave things electrode positive, or do I swap
> it over for normal flux core polarity..electrode negative?
>
> Im also having a small issue with something that I cant quite
> understand, and it may be related to having the thing running off a
> RPC. Or maybe its just being a newbie without a clue...
>
> At low currents, like the *** metal above..it tends to sputz out a
> bit of wire before the arc gets really well established and starts to
> melt. About an inch or so, Now Ive never used pulsed mig before, and
> as I understand it..this is spray transfer(?) and the wire never is
> supposed to be in the puddle? This welds far differently than my old
> Dan Mig, even the arc is differnt, not counting the sound with that
> hum in the arc. Im used to nearly dragging the wire in the puddle and
> this has the melting zone a fair amount above the puddle..which is
> strange to me (but then..I wake up in a strange new world every day
> <G>) This bit of wire is not melted into the puddle. It may stand
> proud sticking out of the bead at the first, or coil up a bit. Its
> really disconcerting and it may be the result of too little amps set
> at the output via the amp dial ? Do I need to crank up the amps and
> live with a hotter arc than I think there should be? Or am I being
> fooled by the sound/sight of the pulsed arc and am thinking Im really
> cranking out the power where Im actually not?
>
> And lastly....the amp control goes from 0-35. It seems that with the
> .035 wire Im using, it gives me a good arc at around 22-25 with a very
> fast wire feed. The amp gauge shows around 100-125 amps. and about 25
> or so volts. If the welder is 350 amps..shouldnt that be a lot higher
> amps? Or is there some relationship between the wire size and what
> the arc actually "draws" and if I left the amp setting at the same
> place, but ran .45 wire..the arc would "consume" more amps and the amp
> gauge would read higher?
>
> What am I looking for when I both first start an arc, and when I run
> it, visa vis arc length, sound and so forth? Pulse is totally new to
> me and is quite different than short circuit type mig.
>
> Thanks
>
> Gunner
>
There are a few sites that relate wire speed, size and voltage to current.
www.weldreality.com has some decent explanations and a forum run by the
cranky but knowledgeable Ed Craig. You are correct that larger wire will
result in more amps given the same wire speed and voltage. The size of the
welder is really not relevant until you get to the maximum output, ie the
same wire size, voltage and speed will run the same amps on a 250 as a 350.
I would try the unit without the pulsed feature and get the spray settings
down first. With regular spray transfer you should have more argon in your
mix- 92/8 will get you into spray mode at lower wire size/speed. You need at
least 85% argon to achieve spray transfer at reasonable current levels. I
don't have a fancy pulse welder but I think the same would be true for
pulse.


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