AC Mig?

[Chippie]

Is it usual to Mig weld with AC ?

My last Mig set ( A Clarke 90 model ) was a dc set.. I sold it because of issues with the wire feed (that I now really should have sorted).

I since bought another Mig set ( that was spares or repair…price was right too.) but I find the absence of a rectifier so it outputs AC…

Any comments?


( still learning….)

 

[premmington]

Every MIG I have ever had has been a CV DC - constant voltage DC. When wire hits weld pool it short circuits and makes AC - until you get to spray transfer at 200amps ish.

Then you have pulse MIG - I got one - but someone needs to explain how this works - as I think there is voltage feedback going on?

Rule of thumb - MIG = constant voltage set. MMA = constant current set.

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Hi @Chippie... (old mate from Car Mechanics Forum - decent chap and no picking on him the rest of you! Chippie is OK!)

 

[Jack Ryan]

Is it usual to Mig weld with AC ?

My last Mig set ( A Clarke 90 model ) was a dc set.. I sold it because of issues with the wire feed (that I now really should have sorted).

I since bought another Mig set ( that was spares or repair…price was right too.) but I find the absence of a rectifier so it outputs AC…

Any comments?


( still learning….)

If you look in the economy section of the market you will find AC MIG welders. I have never used one but I imagine it is not a satisfying experience.

If you look on YouTube, there are lots of "add a rectifier to your AC MIG" videos. You could do a conversion - or get used to it.

Jack

 

[Chippie]

Thanks Jack, looking into the rectifier conversion..

 

[Chippie]

Another query..

Tried welding some 0.8mm mild steel sheet....Started ok but blows holes in the sheet...( gasless wire)

Swapped over to some new wire...much the same.....

Reduce the voltage on the machine to its lowest setting, slowed the wire feed down...Same same...

Did some measurements, Open circuit volts varies between 28 on lowest setting to 38 on highest...

I'm guessing the voltage is too high?

The rating of the machine is 40-50 amps on the lowest setting to around 130 on highest...So really not suited to thin sheet metal...

Any thoughts?

 

[Dcal]

Gasless wire on a butt joint in body tin is not easy.

Try putting a bit of copper or aluminium behind the joint to act as a heatsink / backing strap to take some of the heat out of the weld and to give you half a chance.
This assumes you can get at the back.

It will not be not easy or pretty but it should sort of work.

 

[Chippie]

Dcal, thnx for the tips, sadly cannot get to the rear of the joints that I want to weld....

 

[stuvy]

Another query..

Tried welding some 0.8mm mild steel sheet....Started ok but blows holes in the sheet...( gasless wire)

Swapped over to some new wire...much the same.....

Reduce the voltage on the machine to its lowest setting, slowed the wire feed down...Same same...

Did some measurements, Open circuit volts varies between 28 on lowest setting to 38 on highest...

I'm guessing the voltage is too high?

The rating of the machine is 40-50 amps on the lowest setting to around 130 on highest...So really not suited to thin sheet metal...

Any thoughts?

Whilst it’s doable

Look for something that welds at lower amps

Have a read through the tutorial at the top of the page

 

[eddie49]

Tried welding some 0.8mm mild steel sheet....Started ok but blows holes in the sheet...( gasless wire)
Open circuit volts varies between 28 on lowest setting to 38 on highest...
I'm guessing the voltage is too high?

The rating of the machine is 40-50 amps on the lowest setting to around 130 on highest...So really not suited to thin sheet metal...

A medium-quality MIG welder with multiple switched power ranges will typically start at 15 volts and 30 Amps, rising to 30 volts at the highest output power setting. Additionally, with a rectifier the output will be DC, and there will be an inductor ( choke ) to control the speed of the current spike when the MIG wire short-circuits to the work. There may also be a capacitor to smooth the output ripple and stabilise the arc.

Look for something that welds at lower amps

^^^ This.

These gasless, no-rectifier, no-inductor, 40 or 50-Amp minimum machines are just too hard to use on thin sheet.

This thread describes adding a rectifier, an inductor, and a capacitor to a similar machine, and using a 4KW "light dimmer" to reduce the output power:
https://www.mig-welding.co.uk/forum/threads/tm-150-mig-mods.97298/

The Lidl Parkside PFDS 120 A2 is a similar type of AC-output machine to these, but it has a fully-variable voltage output, controlled by potentiometer rather than just 2 or 4 switched ranges:

Parkside Gas less Welder | eBay

<p dir="ltr" style="margin-top:0; margin-bottom:0;">Parkside Gas less Welder.</p> <p dir="ltr" style="margin-top:0; margin-bottom:0;">Bought in error, brand new without its box, dark green in colour, comes with its torch works on main electric.</p> <p dir="ltr" style="margin-top:0...

www.ebay.co.uk

 

[Chippie]

So I flogged the mig set on...(got what I paid for it..) I'm looking at the combi set (mig/tig/mma inverter based) from Static Arc on Ebay now after eading the comments on here about the issues others have had...

 

[Jan-DIY]

EWM got a special AC Mig set.
Very expensive machine.

 

[addjunkie]

So I flogged the mig set on...(got what I paid for it..) I'm looking at the combi set (mig/tig/mma inverter based) from Static Arc on Ebay now after eading the comments on here about the issues others have had...

The tig bit will just be dc, and possible lift tig only…..

 

[Keithmac]

I've had some decent results with this on SIP gasless wire, just moved over to Lincoln gasless wire (Innershield NR211) and it's even better.

Welding outside mainly so stuck with gasless.