Plug Welding

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I have a miller 175; i'm plug welding 16 gauge sheet metal using .035, 75/25 gas and settings on 3 and 30.  about every 5th plug weld it doesn't stick to the panel. I have new sheetmetal so it's not a problelm with cleaning wondering if I should slow the wire speed or what this is frustrating b/c when I butt weld everything penetrates and is strong weld.  The plugs from the back side look like it's getting penetration but doesn't always stick; since this is a vehicle I certainly don't want all the weld to work themselves loose; any tips, tricks, or advice would be great.thanks in advance
Reply:been thinking since I have two panels on top of each other (16 gauge) should I set welder for the total depth (approx 1/8") and use those settings
Reply:Pictures will help to get an answer for you.
Reply:Cold starts. Except with plug welds, that's all there is is a start, then you're done. Right now you're just pouring hot metal on there. Put that .035 on the shelf and get some .023.. Better current density and it'll give you more time to get some dig and fill in the plug.
Reply:Looks likes sandy and daddy have ya covered but with some pictures of your problem its hard to say. Are you using fluxcore or solid shielded?That .035 wire is most likey not getting hot enuf especally on cold start and that wire is better on the thicker panels over 1/8'. As said go to the .023 try a couple of sample pieces to set your heat and speed.Last edited by specter; 02-01-2009 at 12:30 PM.Co-Own CNC shop:Miller :1251 plasma cutter, MaxStar 700 TIG/Stick, & XMT 456 Multiprocess Welder.&  2 Hypertherm HPR260's Plasma CutterSorry I had a bad stroke but now I am back.
Reply:I didn't see any mention of the hole size for your plug welds. I'm taking a guess and thinking you are not plug welding, (the top sheet has a hole in it, and you weld up the hole against the bottom sheet).  If you are trying you will have better results if you follow the above suggestions, and have a hole. If I am wrong, and you do have a hole, try enlarging the hole so you have more time welding before it closes up.Just my  opinion, not from a book, just from the road.Howes Welding Inc.www.howesweldinginc.com
Reply:I like to pull the trigger then back up prior to going in the desired direction of travel this seem to overcome the cold start. I also visualize the swirl on a Diary Queen soft serve ice cream which helps me bring it back to the center for a good profile to plug weld. Hope this helps along with all the other good advice just keep plugging away :-)
Reply:Turn it up!      MO HEAT........Burn it into the first plate.....If you have some of the same stuff to practice on, keep going up to the next setting on the chart until you burn through and then back off.  In other words get some practice plate to get the heat right.David Real world weldin.  When I grow up I want to be a tig weldor.
Reply:Originally Posted by tessdadI didn't see any mention of the hole size for your plug welds. I'm taking a guess and thinking you are not plug welding, (the top sheet has a hole in it, and you weld up the hole against the bottom sheet).  If you are trying you will have better results if you follow the above suggestions, and have a hole. If I am wrong, and you do have a hole, try enlarging the hole so you have more time welding before it closes up.
Reply:I went back to your first post and you stated the work piece was gauge thickness material and it was on a vehicle. One of the certifications for automotive repair is I-Car and you will find the recommended hole size, profile and the destructive test requirements as well as visual inspection. This certification also covers several other weldments which are required, if your are interested in a good source many community colleges have full programs.The technique I suggested works for me on guage thickness material I like to set my equipment and adjust/adapt my technique to the situation. Good luck.