Setting up Voltage / Wire Speed

[Spainman]

Hi,

I'm new to Mig Welding apart from a traineeship decades ago. I have an old and rugged Union Carbide 160A Welder. The machine has a single dial on the front panel to set the amperage (scaled 30A-180A for CO2, continous, no steps) and an additional adjustment for the wire speed under the "hood" (0-100%). The wire speed and voltage change simultaneously when altering the amperage dial.

Now how do I find the correct wire speed setting?

I tried setting the amperage dial to 80A and tuned the wire speed adjuster so that I get a ws of 4m/min with 0,8mm wire (18% on the ws dial). From there I tried to tune the wire speed adjustment to get a friendly, consistent crackling sound but it is not possible.

I either get a pretty loud low frequency nearly popping sound (just a bit over 4m/min) or a fierce crackling with increasing spatter and no loud popping. The welds look good when choosing the low frequent popping setting range and the arc seems stable, no excessive spatter either and the sound is consistent. Still it does not sound like in the numerous mig welding videos. It is much harder. Lowering the ws way below 4m/min is no option. The loud popping sound persists till the wire speed is too low (burn back / visible drops on the wire).

Is it possible that the harsh popping sound is normal to my machine because of the stepless voltage setting (phase angle control?) or whatever type of choke it uses?

Any hints on how to set up the machine differently to find a correct "default" wire speed setting? Are the 4m/min with 0.8mm wire ok for something around the 80A or am I way off? Got the value from some formula I found somewhere in the www.

Another thing is that the dial is scaled "30-180A CO2". Now what I'm using is an Argon/ 18% Co2 mix. So what does that mean for the scaling? Do I need to choose a lower amperage on the "Co2 dial" to get the same amperare on mixed gas?

I know... lot's of questions and text. I'm sorry. I've consumed every source I've found regarding mig welding stuff but I still don't have the feeling that the ws/voltage are in the correct correlation. The crackling is so rough. No bacon and eggs...

Cheers,
Ruben

PS: The torch and ground cable are new (including a new ground socket and wiring inside the machine). Fresh grounded, shiny scrap metal (2mm) for the tests. New expensive ground clamp with massive copper jaws. So most likely no problem with a bad ground. Even tried a different clamp and cable from the Tig welder.

 

[shenion]

My Miller is a similar design with a continuous voltage control (1979 vintage). Howerver, it is scaled in voltage not current.

Try increasing the voltage. On mine, I find below a certain point I get similar results. You should get a bit higher current with an argon mix.

Is there any inductance settings (mine had 7 different values.) Usually either two different work lead terminals or jumpers within the machine.

Welcome to the forums

 

[Spainman]

Will try with a higher voltage. Thanks for the fast reply.

The machine has only one ground socket and no jumpers on the outside so I assume it has only one inductance setting.

From what I remember when I had the machine open (cleaning and replacing rotted ground and power cord) it consists of two control boards (voltage control + wire feed control with spot welding timer), the transformer, an additional aluminum coil where the ground cable is connected and something that looks like a heavy heatsink which I assumed that it was the rectifier. I've only theoretical knowledge about this stuff, but if the machine had different inductance setting I would expect a series of coils inside with different pickups. Correct?

So is it possible that the popping sound is simply because of a steep amperage slope during the shortcut phase and by design (low inductance) of my machine? So nothing to worry as long as there is no spatter and the welds look good?

The identification plate on the machine says that the off-load voltage is 15-37V and the working voltage is 15,5V at 35A to 21V at 160A. Any Idea how the off-load voltage and the working voltage correlate so that I could measure off-load voltage and generate an according load voltage scale?

I would love to have a voltage scale so that I could use the numerous guideline tables that are available to choose an initial voltage and ws for the application. The amperage scale is somehow useless without any mig experience.

Btw. I don't see how everybody says MIG welding is easy. Cold start points with low penetration or towering weld to get hot enough. End craters and sagging joints at the end that are really difficult to avoid on small joints because everything gets hot and hotter. Feeling somehow out of control. Really difficult to make welds look beautiful.

Cheers,
Ruben

PS: I'm no native english speaker (writer) so bear with me if my wording seems strange.

 

[shenion]

Mine is 3-phase and has 3-coils to set the current slope:

It performs poorly on short-arc mode as the inductance is too low. Later models added a separate reactor. I'm wondering if yours might be similar.

I fought mine and then tried wrapping about 10 turns of the work lead around an old crankshaft. It made a world of difference. I since have removed the slope coils and wired them as a reactor (basically moved from before the rectifiers to after.)

Yes, MIG has cold starts but you can alleviate that a bit by starting with the torch real close. Speaking of torch length, how long a gap between the work and torch are you using. I find mine like a short length unless I crank the voltage up.

I find it odd that yours is calibrated in amps. Sounds like an arc welder which would not work well at low currents. My Airco (TIG/ARC source) came with a wire feeder and was useless below 150 amps.

Have seen several Line/Union Carbide/Airco/A. O Smith welders. All are very similar as most were made by Miller or ESAB. Post some picts of it and maybe we can find more info on it.

 

[Drains]

Ruben, what size wire are you using? It can make a difference to how easy it is to get a smooth arc.
Sorry - I've read your post properly - 0.8mm.

80A would probably be a fairly low current for that sized wire, although I'm guessing as (as Scott says) Mig sets are normally graduated in volts. It might be worth trying 0.6mm wire.

 

[Spainman]

Will take some pictures of the inside and outside of the machine next time I'm in the shop.

It is a pure MIG machine, 3 phase, around 60Kg of weight, integrated wirefeeder in the upper half of the machine (cast iron, huge motor, could be good enough for a cable winch ;-) ). The actual welding seems to work ok (although I have no comparision). It's just the harsh sound and not being able to adjust it to the typical gentle crackling sound what made me scream for help

Regarding my "mig welding technique" ...
As soon as the arc lights I reduce the stickout to around 3-5mm to add some heat in the beginning and try to do the rest of the weld with around 8-10mm distance. At the end of the weld I increase the stickout to 15-20mm for a second to lower the amps/heat input while backing up a few mm to fill the crater. Sometimes it even works. A matter of practice I think. The bigger the weld and thicker the material the easier it seems. On short welds (e.g. construction made of 20x20x1,5mm profile steel) it seems to me real difficult to get proper penetration at the start while not sagging or even burning through at the end.

What's the difference in having the choke before or after the rectifiers related to it's effect on the actual welding?

Thanks for the support!

Cheers,
Ruben

 

[Spainman]

Ruben, what size wire are you using? It can make a difference to how easy it is to get a smooth arc.

It is 0,8mm.

I tried some welding on the maximum setting (180A) on a thick plate. The loud popping sound was similar. The feeder roll does not accept 0.6mm wire anyway (0,8 or 1mm grooves). So trying another wire isn't too easy right now.

Cheers
Ruben

 

[Spainman]

Have been too busy working on other things, so had no time to open the welder and take proper pictures of the whole machine yet. In the meantime there is enough snow here that I can't even get into the shop. I attached a picture I made previously while replacing some rotten wiring. It shows just the last component in the ground line so this should be the choke/reactor. The wire exits to the ground socket.

Meanwhile I'm wondering if the problem might be a missing phase? Maybe the contactor does not close the circuit properly. The whole machine was full of dust and I even had to disassemble the 2/4 way selector switch to clean it up inside and make it work.

Could a missing phase produce the described symptoms or would it be worse and make the machine "much more unusable"?

Ruben