Adding capacitance

[tinker jim]

Hi all just wondering if anyone has added capacitors to a mig welder that didn't have them designed into them before hand.i know it will add a bit of heat to the weld.and some will say sell it and buy a better welder but I bought this mig spares or repairs so not much to lose fixed it's problems and now running OK but starts welding cold then the weld flattens out as you go using mixed gas.

 

[zx9]

I have no idea Jim, it is something I have thought about for my old Sip but I have not gone any further than that. I am sure it must have been done or discussed and someone will comment / add their experiences, in the mean time have a look at the Sip forum threads.

 

[tinker jim]

Hi zx9 yes read most of this site some great knoledge on here.started with a sip over thirty years a go welding up my mk1 escorts (had a few) and was plagued with wire feed issues but that's history now.
these big caps I got cheap so no real loss if they go pop and I know they may put a strain on the rectifier.

 

[tinker jim]

So went for it and connected one capacitor up with some jump leads and had a quick play and the transformation is surprising to say the least welds consistent no cold start and a pleasing sizzle sound that everyone go's on about.also wire speed now has more impact on heat of weld if that makes sense.oh and was on setting three now on two.

 

[tinker jim]

All fitted ready for a comparison test with with out test of mig welding with the same settings same material watch this space.

 

[tinker jim]

Plenty of space up there.copper connecter 's made out of 15mm plumbing pipe and soldered to a length of earth cable off an old mig I had.

 

[wacky7791]

Interesting thread, currently on with a mk1 and started with a SIP which I did all the mods to but eventually replaced it with a 'euromig 200' (cos it was cheap and broken) which I fixed and is loads better than the SIP.
The euromig looks identical to the one you've fitted capacitors to, could you give me more details on the capacitors and how you've wired them in? My euromig seems to weld pretty well however any way to make it even better is well worth a go in my book

 

[tinker jim]

Yes as you have guessed wacky7791 these migs are a rebadged machine I think if I remember made in Italy.mine had a very unstable arc at low power settings I. E. Welding car panel thickness.
The cap bank helps smooth the arc by storing energy and releasing it between dead short and when the wire electrode arcs back think it's called tip transfer.ultimate cap bank value is about 33000uF but as my mig was not designed with caps in the circuit I just used 2x 4700uF and as long as the volts is over 100v and high ripple rated I think your safe.do check though you may well have capicitance bank in the euro mig as it's a bit younger than mine I think so may have uped their game.

 

[tinker jim]

Caps wired in series or positive to post and negative to neg.the the cap bank is wired in parallel with your out put of the mig welder.the negative side must go before the inductor coil usually last coil of thick wire round and iron core before connection terminates at the dinse socket on the front of machine.

 

[tinker jim]

Positive

 

[tinker jim]

Negative before the inductor coil

 

[gaz1]

i found this earlier today so make your own mind up

 

[rtbcomp]

Caps wired in series or positive to post and negative to neg.the the cap bank is wired in parallel with your out put of the mig welder.the negative side must go before the inductor coil usually last coil of thick wire round and iron core before connection terminates at the dinse socket on the front of machine.

Those caps are wired in parallel - total capacitance = sum of individual capacitances.

 

[tinker jim]

Those caps are wired in parallel - total capacitance = sum of individual capacitances.

Yes sorry my mistake they are in parallel

 

[mike 109444]

You might want to add a bleed resistor to that lot.

 

[mike 109444]

i found this earlier today so make your own mind up

note he was using "gasless wire" not sure if that make much difference to his results! Also he was welding on some thick metal and I thing the improvement that was required by op was for use on thinner metal.
I know when I had issues with the connection to the big cap in one of my machines (was intermittently failing on connection and dropping out the cap) that the weld was crap and would not form a decent bead or penetrate well on thin sheet.

 

[normspanners]

I connected 4 similar size caps ( from solar panels I believe) to my old cebora star 180 and it did make a difference it made it work nicer and with more power.

 

[Rig Pig]

My migs capacitors were shot when I bought it, replacing them transformed its performance.

 

[mike 109444]

To add to your tinkering, Jim there was a post somewhere on the forum (looked but I can't find it) of a chap that used an old "buzz box" welder and hacked it to use as (if I recall) a variable inductor (choke).

 

[tinker jim]

To add to your tinkering, Jim there was a post somewhere on the forum (looked but I can't find it) of a chap that used an old "buzz box" welder and hacked it to use as (if I recall) a variable inductor (choke).

Not much room in this mig now for another inductor but have had a play with separate inductor coil in the past but didn't notice much difference to be honest .oh I do like making a silk purse out of a sows ear lol may be I will get a porta mig off santa this Christmas not long to go.