[dkmc]

Thought weak HF was the problem.
I got the new caps for the HiFreq. installed...
Less spectacular improvements than I was hoping for.
HiFreq is 'somewhat' stronger, but on Alu. it still does weird things.
It acts 'cold' even on high range.
There is not an abundance of cleaning action, and the puddle is sooty.
Makes no difference if I clean everything rabidly, or not.

Then there's the ever present weirdness where the puddle seems to 'vibrate'
or hop up and down about .040 or so, plus the arc has that buzzing sound that
goes along with the vibrating. When it's doing that, it acts real cold, sooty and
hard to get the puddle to even get shiny.

3 things I suspect:

1.Torch is sucking air, or bad bottle of Argon.
2. My aluminum service wire is not delivering enough amps, or somehow primary
voltage is dropping off.
3. Internal problems.......other caps, or ????

Also weird that some days it will act quite hot with a smooth sounding arc,
then other days......what I described above.
I have an old air cooled Linde torch around someplace, I will try that just for chance.

Any ideas what the problem could be?
Appreciate any ideas.

[bobhdus]

Could be one of your ideas above. Tungsten issues, dirty aluminum etc... Does it have AC balance or any other controls? Usually, with an older welder, the first few welds are kinda "smutty", then as it all gets hotter it smooths out. These newer Welders with their inverters have so many features built into them that it makes Aluminum welding look so easy. It's not that it's hard on an old welder, you just don't have as many controls to adjust. I don't know what your welding but you may also need to be sure the aluminum your welding is weldable. I come across automotive parts I'm supposed to weld and it turns out to be similar to "pot metal" cast of some sort, zemack or even magnesium.... Try welding on some aluminum strips to see if that changes anything.

[dirtmidget33]

I seriously doubt you will ever get good results trying to weld aluminum on a.c. with it. The biggest reason I see is getting a true square sine wave. You need to have it jump from positive to negative almost instantly. A regular a.c. volt sine wave is curved as it ramps up and ramps down. Square wave goes from a full positive to full negative with very little ramping. Its typically drawn straight down but there is some time that passes as it moves from negative to positive. If it doesn't jump to full positive as a regular sine wave you start to add more heat to tungsten and etch the base metal, it hits peak of the wave and tungsten cools as etching tapers off. Now you enter negative cycle as base metal starts to heat up till it's peak then starts to cool as it goes back to zero before heading to positive. Most of your sine wave is ramping up and down with very little peak time. With square wave you get full positive etching then instantly switches to full heat in the part.

You will get a buzzing sound with a.c. the higher the frequency (hertz) the more pronounced sound it makes as it cycles back and forth.

[Braehill]

dkmc,
Does your welder stick weld on all three polarity settings? Clean the contacts on your polarity selector. Make sure all the taps on the transformer are in good condition. All connections tight. Sounds like you may only be getting one or your DC legs while set to AC.

Len

[dirtmidget33]

I should add I thought you where modding a welder that never had a.c. or high frequency. I have no experience with airco welders as for what they came with originally.

[dkmc]

Here's the "Mile Long" part number of this machine:
AIRCO AC/DC Heliwelder Model 2A/DDR-224HPA/B-D
Same or very similar to a MILLER 300A/BP

Bobdhus:
I am playing with 6061 1/4" plate.

dirtmidget33:
What is square sign wave??
It's one or the other, but not both.
Do you realize how many thnigs were welded with great welds for 75+ years with this type
welder before the fancy controls came on the scene?
The way it's working at present would never be acceptable in industry.
It simply has a problem.

Braehill:
It does weld in all 3 settings DC+ AC DC-
After I try a different torch I will take the top off and check connections

Please clarify----when you say

Sounds like you may only be getting one or your DC legs while set to AC.

I am not understanding what you mean

Thanks guys!
DK

[MinnesotaDave]

I seriously doubt you will ever get good results trying to weld aluminum on a.c. with it.

You serious? I use my Airco (miller 330 abp) on aluminum - does a great job
It will even weld pop cans together.

[dirtmidget33]

You serious? I use my Airco (miller 330 abp) on aluminum - does a great job
It will even weld pop cans together.

I addressed that because when I first read post I thought he was converting some old stick welder to do AC TIG. Converting say a tombstone for instance to do aluminium is like shooting yourself in foot not worth the hassle. That was my fault for misreading it and not realizing he is just repairing a tig/stick welder

I should add I thought you where modding a welder that never had a.c. or high frequency. I have no experience with airco welders as for what they came with originally.

Here is a quick overview of sqarewave though to help you understand it. modern AC and I believe yours too use it. MinnesotaDave would know. Changing this wave form is what gives us some fine adjustments making welding aluminum easier. There is newer wave forms coming out like trangular and such on inverters like the dynasty. Knowing how this works makes it easier to adjust balance and frequancy settings.

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drew up in phone old guy trying something new on new phone hope it works

[GreinTime]

For the record Wallace, Square wave is not a sine wave, and is created by giving a "mechanical push" to get the switch from positive and negative as short as possible. It's not truly a square wave either as it isn't instantaneous, but it's close enough by most people's standards!!! It's like using a hall effect sensor on your crank versus a reluctor wheel and a mag pulse generator to generate a signal. Both accomplish the same thing, one has just been around way longer than the other.

On newer machines, they accomplish it using semi conductors (transistorized circuits, either MOSFET or IGBT, although everyone is switching to Internally Gated Bridge Transistors if they haven't already done so. They last quite a bit longer than their counterpart) to provide "instantaneous" switching from positive to negative. Because a microprocessor controls it, they have features like amplitude control and all of the other stuff because they are using pulse width to control the amplitude of the waveform as well as the frequency in a cycle that it stays at one end or the other.

Sent from my SM-G900V using Tapatalk

[dirtmidget33]

Hey Sam this is from my first post

Square wave goes from a full positive to full negative with very little ramping. Its typically drawn straight down but there is some time that passes as it moves from negative to positive.

And while not a true sine wave easiest way to describe it since he didn't know square wave was and will appear Oscilloscope like shown.

Dann can't type on this new phone worth a crap, miss the keyboard got one of the biggest damn screens before going into tablet type phone to make it easier. Plus some how posted things twice several times..... Okay end of my rant.

[dkmc]

I'm sorry, who didn't know what square wave was?
I know what square wave is......and I know there's no such thing as sinesquare wave as well.
I even own a couple O'scopes, and know how to use them.
Still trying to figure out how my first post sounded like I was 'converting' an old welder to TIG....

I read thru the tech manuals and I may have come up with something.
I'm looking inside the case......will report back.

[dkmc]

MinnesotaDave......

I found something interesting in the Miller 330 Tech manual.
Page 5 (which is the PDF page 9)
Section 2-9. Full Wave / Half Wave Balance.
The 4 problems they list with Full Wave seems exactly the same as the problems I am having.
1. Poor cleaning action
2. Porosity
3. Fluctuation in the arc
4. Uneven weld penetration.

I opened up the right side cover on my Airco.....no terminal strip TE3, and no bolted connections either.
Any idea if there's a way to connect up the Airco model 2A in Half Wave configuration?

[MinnesotaDave]

That's a good question - I've not tried that with mine but have often wondered about it.

One thing I've noticed that mimics what you describe is not using enough amps and staying in one place too long waiting for the puddle to form - causes arc rectification.

Are you using enough amps to make a puddle and start moving in 3 seconds or less?

Is this a new problem for this machine?

Is your high freq intensity knob turned all the way up? I have mine maxed.

[dkmc]

HF is def. maxed....it's dismal at best like all these machines were.
When it's acting up I can floor the pedal and that oscillating of the arc/puddle begins.
Sadly, it's been an intermittent problem for years. But when it's good, it welds great
which is the frustrating part. And it stick welds just fine as well.
ALMOST makes me wonder if the times it works well, I'm switching it on at the "right" part of the sine wave
cycle....and just catching it lucky? Or something weird like that.
Does your machine TIG Alu. well? Nice shiny puddle and fillet?

Man I wonder if there's anyone alive on earth that would know if the half wave connections
are possible on this machine, and how to make that happen.
Wish I had the bux to upgrade but work is very slow and that's not going to happen till things
pick up.

[MinnesotaDave]

My machine tig welds aluminum very well - nice clear puddle and lots of power.
I will even use a 5/32" tungsten if cranked up high on aluminum - plus lots of control on the low end with 1/16" tungsten.

Only real problem I have is an intermittent post flow timer.
Some times it doesn't post flow - but a new timer is cheap, just have not gotten around to it yet.

I guess I would check other stuff first before the machine - they are pretty durable. Mine is a 1963 model.

Sounds like you've got a real puzzle on your hands.

[dkmc]

Next I'm trying a different (used) torch.
I think mine is an early '70's model but not sure.

[MinnesotaDave]

I forgot to ask, is the Balancing Resistor Knife Switch in the open position?

As I recall, reading different year machines had the knife switch reversed as far as "up" or "down" position.

But it boiled down to "open" for tig, "closed" for stick.

[MinnesotaDave]

MinnesotaDave......

I found something interesting in the Miller 330 Tech manual.
Page 5 (which is the PDF page 9)
Section 2-9. Full Wave / Half Wave Balance.
The 4 problems they list with Full Wave seems exactly the same as the problems I am having.
1. Poor cleaning action
2. Porosity
3. Fluctuation in the arc
4. Uneven weld penetration.

I opened up the right side cover on my Airco.....no terminal strip TE3, and no bolted connections either.
Any idea if there's a way to connect up the Airco model 2A in Half Wave configuration?

Terminal strip TE3 should be under the left side cover by my book.

You will just be unhooking the three wires and swapping their positions around.

half wave conversion.GIF (49.55 KiB) Viewed 2070 times

[dkmc]

I misspoke, there is nothing like that under my -left- side cover.
No numbered wires either.
It's never seemed to make any difference which position the knife switch is in,
I've tried it both ways with equal results.

[MinnesotaDave]

I misspoke, there is nothing like that under my -left- side cover.
No numbered wires either.
It's never seemed to make any difference which position the knife switch is in,
I've tried it both ways with equal results.

I looked up the half wave / full wave stuff and it appears to have started in early 1971 for the Miller abp.

I'm wondering if it didn't start in the Airco version until later than that since my manual says my 1963 Airco should not have it.

I'll pop the cover when I get home and look.

[dkmc]

Maybe it's on the right side??
If you could, maybe check the right side as well......or look thru?
The DIY cart mine is on has support straps on the sides making it a huge pain to
open the side covers. I had to cut the left one with a cutoff wheel to open the left cover
Plus its buried between an old large MIG on the right and a Milling machine
on the left.....close quarters to work in.

[MinnesotaDave]

Me and the kiddo popped the side off.

Mine is too old of a model to have it - I guess 1963 is getting a bit "long in the tooth."

[dkmc]

Thanks for that effort Dave!
I appreciate it.
Now if I could only find my other torches....