Plug welding with MMA

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Gday all, i need some help plug welding with my arc, its a 170 AC Inverter and im welding 3mm to 3mm mild steel.I did some trials and experimented around a bit with reversing the polarity and changing the amps around. I used 3.2mm GP electrodes. The hole for the plug weld was 10.5mm.I also alternated how i welded the plug by starting in the middle and working out and starting on the outside and finishing in the middle.I had the most success around 110-120amps with electrode+ but my results were very inconsistent, my main issue was more often then not i kept getting slag inclusions. So if someone here is able to shed some light on  the situation for me id be greatly appreciative.
Reply:I'm not sure what's causing your problem, but why such a big hole for the plug weld? - I would try something closer to 1.5-2X the size of your electrode (closer to the thickness of the steel) - that way, you'll make the circuit faster, and won't end up welding over cold slag.  And it will be easier to drill the holes.  I've even had luck drilling holes just over the size of the electrode and 'floating' the stick in the plug-puddle; it looks like a tack-weld when you're done, but if you get full penetration to the underlaying metal, it will hold nicely.
Reply:On that large a plug, you may have to do it in two welds.  That way you can clean the slag from the first and you won't get inclusions.
Reply:Originally Posted by FegenbushOn that large a plug, you may have to do it in two welds.  That way you can clean the slag from the first and you won't get inclusions.
Reply:Don't use gp rods,use low hydrogen as it will scavenge out the slag a lot better.Personally I'd rather use l.h. over g.p. any day as they are stronger and you have a lot less problems with slag incusions.Also 2.5s give you a lot more control in tight spaces.
Reply:Originally Posted by LMSyrusIf you can prevent heat warping from making an 'unbalanced' series of welds...?
Reply:From title I though Randy Couture was going to be punching rod into holes!200amp Air Liquide MIG, Hypertherm Plasma, Harris torches, Optrel helmet, Makita angle grinders, Pre-China Delta chop saw and belt sander, Miller leathers, shop made jigs etc, North- welders backpack.
Reply:G'day mate, I would make the hole for the weld only a few MM wider than your rod and give that a go, that way you just need to go round the edges and it will flow and fuse the parts and tada a perfect plug weld, however if you want to keep the holes the same size then you need to do one side stop chip and wire brush the slag and then continue on the other half of the plug otherwise you are going to be in hell when it comes to slag inclusions and all kinds of other nasties... BTW mods not sure if the word hell is acceptable here seeing as its not a bad word in Australia, let me know if you could thanks.....Tons of hand tools mostly KingchromeArc welderMiG weldersO/A setupMany grindersair compressorsmany air toolsIndustrial drill pressTwo Forkliftsmany more toolsMan has his will, but woman has her way.- Oliver Wendell Holmes