Rectifier vs inverter?

[Munkul]

I wouldn't worry too much about the low end amps, the voltage range is more important!

 

[DennisCA]

I see, well in that case the ESAB had a minimum of 50A/15V
a Kempomat 180 starts at 30A/15.5V
a Kemponat 250 goes as los as 30A/15V so slightly better
My dads wallius starts from 30A/15V

The Kemppi RA230 apparently has a range of 11-33 volts despite the minimum current being 40A, that's way bigger than any of the other machines. The marking plate is different and lists amperes and voltages separately. The voltage refers to "no load voltage", not sure if that is the same as what is referred to in the other machines.

 

[Munkul]

At the lowest setting, there will be a minimum surge of current... it makes the difference between a nice sizzle and a nasty hissing burnback. BUT, the current surge will be determined by the voltage.

Some machines go by load voltage, some go by no-load. There will be a degree of voltage drop on-load, but it depends on the machine.

a 15v no-load voltage might well correspond to another machine's 11v on-load voltage... worst case, though. It really depends on the machine.

 

[DennisCA]

Well if the Kemppi RA230 list 11V as a no load voltage, that means it drops even lower under load.

 

[Munkul]

Well if the Kemppi RA230 list 11V as a no load voltage, that means it drops even lower under load.

correct but how much it will drop by depends on the machine's design and how much wirespeed you're running through it. The higher the amperage draw, the more the load voltage will drop, to a point. It should be a "constant voltage" process, but in reality it isn't quite, especially for a transformer.

At sensible wirespeed and wire size, I wouldn't it expect to drop too much. There's not much MIG work you can do at 11 volts, anyways

 

[DennisCA]

Well I think the best is just to look for something like the kempomat, Wallius or similar which specifies something in the 30A/15V range and that I know are machines known to be good with thin and thick materials both.

There is a new kemppi mig for sale locally now, 200A welder, pretty old looking a Migomat 160 CD and only down to 60A/15V. Maybe I shouldn't stare myself blind at the amperage but it's twice as high as the other machines on my wanted list.

EDIT: Pictures here, think it comes with an empty co2 bottle
https://www.findit.fi/sv/1544391.htm

 

[DennisCA]

I found a manual (finnish only) for it and it says it's meant for the auto and repair work. So that sounds like it ought to be suited to bodywork despite a high lower setting. Google translation of the manual.

The MIGOMAT-160 gas arc welding equipment is as well designed for auto repair shops as for the lightweight industry needs.

Especially the simplicity of processing, welding values the choice of just one 5-position switch makes the MIGOMAT-160 a versatile welding machine that gives quick results even to the untrained user.

Automatic periodic welding capability ensures perfect operation even when the quality and fit of the sheet to be welded is undesirable.

The possibility of spot welding completes the application.

 

[DennisCA]

If I am reading this correctly, the machine has some kind of primitive pulse function as well.

6.2. Automatic cycle welding

In automatic cycle welding (Pat. No. 46465), the welding wire feed is not continuous but pulse-free. The length of the welding cycle is controlled by the adjustment knob (A) on the front wall or by the cycle time remote control, which is connected to terminal G.

Selection is made with switch B. During a fixed pause, the melt solidifies and the continuously flowing gas promotes the cooling of the weld melt. This method can effectively prevent puncture of ultra-thin sheets (less than 1 mm) and control welding even in butt joints with variable air gaps. The method typically uses welding power selector switches (D)

 

[Memmeddu]

If I am reading this correctly, the machine has some kind of primitive pulse function as well.

Might be just a timing circuit for tack welding

 

[DennisCA]

Started getting some answers to my ad now.

Some guy sent me an SMS with this, wants me to offer him a price. Kempomig 3500... 350A mig welder. I can barely run this on my 16A 3ph outlets I believe as long as I don't run it full throttle, then it wants 20A fuse. Is that a euro torch? No idea what to bid, don't like it when people do that.

And someone offere a Wallius 240A welder too.

 

[Munkul]

It certainly looks like a euro torch.

You might find that it trips a 16amp breaker occasionally on startup, but it should run up to 300 amps relatively happily.

I'd lowball him, it could be a fantastic machine if all in good condition etc, but you never know til you see it in person...

 

[DennisCA]

I offered 400€ for it, I can test the machine too. He said he would get back to me, but 400 is my max offer.

Though I am honestly not sure if it's a machine for me. Such a massive machine might not be that good on sheet metal, it's probably meant for heavy construction. Unlike the Kempomat range of welders it lacks the pseudo-pulse function which is said to be great for thin sheet metal.

I have been talking to kempomat owners who says it's great, correctly adjusted you can use a higher voltage than conventional welding and it makes the weld flow out almost flush on the sheet metal and removes a lot of the need for grinding. It sounds pretty good.

Someone offered me a Kempomat 320 but wantted 750€ for it, thats just more than I am willing to pay, though it would probably be an ideal machine for thin sheet metal to heavy construction. I said I could stretch to 550 for it but no more. But it's assuming everything works.

 

[eddie49]

From this front panel, it looks like the Kempomig 3500S has all the options:
Sold by Dutch auction site www.onlineveilingmeester.nl for 451 Euro.

 

[DennisCA]

That's a lot of features yeah. Would be nice to have pulsing, as it seems to have that. Looks like it's a modular setup.

 

[DennisCA]

That guy with the kempomig started talking about 1000€ and I just stopped bothering there and then. No reply on the kempomat 320 that would be ideal machine. Still now another Kempomig 160 came out from another seller and 280€ with gas bottle and regulator. Looks in better shape and with a gun.

 

[Munkul]

3 phase and only 160 amps?

 

[DennisCA]

It's 200A, despite being called the 160. I think maybe it's the "sweet spot" or something for that machine, maybe. I would like a bit more, but still it seemed interesting.

 

[DennisCA]

Oh I found an important tidbit. It's a 160A welder, only in spot welding mode is 200A accessible. that's why it's called a 160. Think I'll pass then.

 

[DennisCA]

I stopped looking actively during the summer, but now I am back looking and I offered 700€ for this. Kempomat 2500 with euro adapter. It's a bit more modern a welder, the replacement for the kempomat 250 (the ideal machine in my mind), I wonder if it's old enough tech to be user servicable if anything happens. But it looks a good fit for my purposes.

Gotta say prices have not dropped at all from the Corona crisis, no big selloffs or anything.

 

[Munkul]

We have two kempomat 4200s (same generation and shape as that, only 3phase and bigger)

They're lovely welders and they've done a LOT of work.

The kemppi wire feed setup is second to none. I think you'll be pleased with that machine.