For all the Mig welders in the forum (If any)

[husoi]

First a bit of background.

 

2019 I bought a Lidl welding machine.

This is a Parkside PFDS 120 A2

For under £100 the machine is well worth the money. I made so far my trailer's frame.

My Floodlight stand

and a few other minor works.

No complains about it except the wire needs to be a flux core, for those who don't know about mig welding there are 2 types of wire for welding.

 

Now, I know that some, more expensive mig welders can use both FC wire and gas shielded wire and this becomes possible by inverting the polarity (IP).

 

My question is, how can I invert the polarity on this welder?

I've open it but opposite to the mig welders doesn't have the connectors for IP.

The cables connect directly from the secondary coil into the cables. with some small cables feeding into the circuit board, I believe these will be some load protection.

 

I would imagine that inserting 2 connectors just before the cables leave the box will allow the IP and the machine becoming normal and flux core wire.

 

By the way, yes I know the normal wire used without the gas will make a hell of a spatter, even more than flux core.

The reason why I want to invert the polarity is because by mistake I bought a 5kg reel that instead being flux core is normal wire.

Although the normal wire is corrosion resistant because of the copper coating.

 

Thanks in advance

[dynax]

It would be easier to send it back and get some FC wire.

[husoi]

True @dynax but if I can use normal wire instead then it will be cheaper and the wire won't get rust as flux cored one.

Then the postage will be almost the same as the cost of the wire.

A 5kg normal reel is around £20 while flux core is £35 and rust free  

[dynax]

You could always get a secondhand welder.

[Bender]

Some cheap gasless ones are ac output so if that's what you have your reversing nothing.

 

The weld without gas is not worth it, especially, not for a full roll, keep it and I will have it off you next time I'm up Scotland  

[husoi]

3 minutes ago, Bender said:

Some cheap gasless ones are ac output so if that's what you have your reversing nothing.

 

The weld without gas is not worth it, especially, not for a full roll, keep it and I will have it off you next time I'm up Scotland  

AH...

I thought welding would only work on DC 

It's yours if the missus won't sell it on crapface  

[Bender]

Just now, husoi said:

AH...

I thought welding would only work on DC 

It's yours if the missus won't sell it on crapface  

The cheap ac ones give a crap weld with alot more spatter than dc, nothing wrong with converting to gasless if you can, little co2 reg and bottle costs little and if you can pick up an old mig gun with valve in its just a few connections, you need to workout if it's dc or ac out though.

[husoi]

8 minutes ago, Bender said:

The cheap ac ones give a crap weld with alot more spatter than dc, nothing wrong with converting to gasless if you can, little co2 reg and bottle costs little and if you can pick up an old mig gun with valve in its just a few connections, you need to workout if it's dc or ac out though.

Glad I didn't put the covers back  

Just need to plug the multimeter and check what I have.

Glad I asked before starting cutting cables and messing with it  

Just ordered a flux core reel from amazon by £33 free delivery. It will be enough for my few diy projects. I don't need anything fancy to be used a couple times a year.

 

Thank you @Bender and @dynax for your help. Much appreciated.

[Bender]

42 minutes ago, husoi said:

Glad I didn't put the covers back  

Just need to plug the multimeter and check what I have.

Glad I asked before starting cutting cables and messing with it  

Just ordered a flux core reel from amazon by £33 free delivery. It will be enough for my few diy projects. I don't need anything fancy to be used a couple times a year.

 

Thank you @Bender and @dynax for your help. Much appreciated.

If it is ac you could get a spool gun and weld aluminium be thin stuff though.

[Mr Fro]

3 hours ago, Bender said:

If it is ac you could get a spool gun and weld aluminium be thin stuff though.

If it's AC he can bung a TIG lead on it and do it proper like!

 

I've DC MIG welded aluminium before - it sure wasn't pretty but it held together alright.

[husoi]

So this is what I've done with the welder.

 

Change from AC to DC with a 200A rectifier bridge

Added 3nr 20k uF capacitors to stabilise the voltage

All connections crimped and protected with shrink wrap

Replaced the wire feeder power supply with a 12V transformer instead of the power being provided by the welding circuit. The advantage is that there will be little V variation while welding.

 

I had to extend the box as there was no space.

 

The 12V power supply was not strong enough for the new power so I've replace it with a laptop one for 15V 5A one and while I was at it replaced the feeder motor from an old tyre pump compressor.

 

A major change I've made is the size of the spool. Now I can use a 5kg instead of the 900g small one. The practical side of it is less waste, cheaper per m and runs for a lot longer.

 

Turning a AC to DC welder makes the welding a lot easier, although debatable and some will say it can't be done will allow for normal wire instead of flux core wire (so I can use the one I bought by mistake).

 

I could have done it a bit cheaper by using parts with a lower limit, as example I would get away with a 150A bridge instead of the 200A or a 12V cooling fan instead a 230V one.

But this will give me a better performance and savings wasn't my aim.

 

Total added cost (not counting labour) is around £120 in total bringing the welder to £220. Still far cheaper than a DC MIG welder.  

 

It is still to be complete but yesterday I run out of time so this will be done this week. Remaining tasks are connecting the secondary power supply and find a way to fit the side and top covers.