plug welding

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using MIG w/ 75/25 gas and .025 wire currently, and Im practicing on scraps before welding 19g floorpans and 14g frame components on my car. Im having troubles filling the hole on plug welds. Appears that Im getting penetration, I start by going around the circumference of the hole, then attempt to roll the puddle into the center, but usually it doesnt fill. Do I extend the stickout to fill the hole? Also, the two parts are flat to each other when I start, seem to raise during welding causing and void. Any technique advice?? Thanks in advance.
Reply:Make sure the metal is clamped firmly together. Make sure the hole is 5/16" in diameter.
Reply:yeah, tight is key there and clamping each one as it's welded is the best way to do it. the most important thing is that the whole circumference of the hole is completely welded with no voids, any void at the edge of the hole will allow it to separate much much easier when stressed or hit as that's already a start to a rip... if you didn't fill the center but got everything else right then it really should be ok too, but as said above the right size hole should make it so once you've gone around the whole circumference the remaining center fill should be very small if any, but don't make the holes too small because then you have a much harder time really getting penetration to the bottom and you could fill it and wind up having it look good but not really have any strengthmiller 330a bp TIGmiller dynasty 200DX TIGmillermatic 185 MIGthermal dynamics cutmaster 101 plasma cuttersnap-on YA5550 plasma cutterhypertherm powermax 30 plasma cutterbaileigh CS225 cold sawetc....
Reply:I run around the edge, fusing both pieces, with as little stickout as possible. As I make it to the middle, I will gradually increase my stickout, to fill it up.And definitely clamp the 2 pieces together
Reply:thanks for everyones replies, I believe I need to increase the hole size alittle too like suggested. My plugs arent in a place that I can clamp them together, I guess I can place sheetmetal screws close to the plug holes and fill the screw holes later. Im gonna be plugging 19g to 14g, do I set the welder to 19 or 14g heat setting when plugging? Thanks again everyone for your advice.....
Reply:Yup, people may not agree but you don't have to fill the whole plug. Just a nice fillet around the edges is just as strong as filling it all the way up. Unless you need to be able to grind it flush the, extra is a waste. The strength of a plug weld comes from the outer fillet. "weld reinforcement" has absolutely nothing to do with the strength of the weld. If the base is the 14g and the plug is 19g then I'd set a little more towards the hotter settings. But if it's the other way around I would find a happy medium. --Gol'
Reply:Originally Posted by Go1lumYup, people may not agree but you don't have to fill the whole plug. Just a nice fillet around the edges is just as strong as filling it all the way up.
Reply:All Mig mfg's sell tip adapters for plug welding,  it let's you see what you are welding and get the sheets tight by pushing on the gun and you are centered alot of people don't know this,  and with a lot of migs .030 is better, a little hotter but if you need to weld a tear . 024 is best for sheet metal work. After welding your plug weld, on dolly the crown flat to stress relieve and take out the pulling of sheet metal towards plug weld. Sent from my SGH-I747M using Tapatalk 2
Reply:I have always done plug welds the way 4SFED described.  Start with a hot tack right in the middle of the hole on the solid piece, and sort of swirl in a counterclockwise motion as I move outward and around the perimeter.  Do it fast and hot.  Probably 10 different ways to do it right, and just as many to do it poorly.Miller Syncrowave 350Millermatic 252/ 30A spoolgunMiller Bobcat 225g w/ 3545 spoolgunLincoln PowerArc4000Lincoln 175 Mig  Lincoln 135 Mig Everlast 250EX TigCentury ac/dc 230 amp stickVictor O/AHypertherm 1000 plasma