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I have been having problems welding holes in sheet metal ever since the first day I bought my Millermatic 130xp mig welder. The 130xp is a small machine that runs on 110 volts. There are 4 possible voltage settings and lots of wire feed settings ranging from 10 to 100 with a table on the welder cover with suggested voltage settings and wire feed settings for a range of material thickness. The table is as follows: Voltage Wire Speed Material Gage (0.0xx") 1 30 22 (0.031") 1 45 20 (0.037") 2 50 18 (0.050") 2 55 16 (0.063") I am using the lowest voltage (level 1) and a wire speed of 45 on a fender. I am using a mixture of carbon dioxide and argon gas. The dial gage for cfh flow rate is set at 20 for argon gas. The wire is 0.023" ER70S6 A5.18 made by Radnor (p/n 64001200). The welding tip is 0.023 (RAD11-23-B Contact Tip) made by Radnor. The liner in the gun is 10 feet of 0.030 to 0.035. The polarity is set correctly. The thickness of the sheet metal (steel) is 30 thousands for trim below a 1967 Pontiac headlight assembly to something around 50 thousands for the front fender. I have recently removed the paint from the front fender and decided to spot weld close three small holes for an emblem. The holes did not fill easily and the area of "welding tries" is now 1" by 2" and expanding with associated panel distortion. I have tried using a magnetic hole plug welding tool with only a little improvement. I have recent purchased some 4 inch and 8 inch magnetic copper backers which I have not yet used. I am cooling the welding area with compressed air. The fender is on the car and the car is in a canopy. I am using a 50 foot long extension cord to get from my garage to the location of the car. The measured outside diameter of the cord is about 0.425 inches. I can get a larger diameter cord if that would be helpful. I have ordered the Ron Covell video on patch panels through Miller. The gun I am using is made by Profax. I have recently watched a miller welding video and I believe that I heard that nozzle of the gun should be flush with the contact tip. This is not the case for my gun in its current condition. The measured distance from the end of the contact tip to the end of the nozzle is about 0.20 inches (almost a quarter of an inch) with the end of the tip being located inside the nozzle. Profax offers 7 different types of nozzles. The nozzle I currently have on the gun is "screw on" rather than "push on". Here are the limited descriptions of the nozzles.(1) 3/8", self-insulated(2) 1/2", self-insulated(3) 5/8", self-insulated(4) 3/8, self-insulated, flush(5) 1/2", self-insulated, flush(6) 5/8, self-insulated, flush(7) 3/8", self-insulated, tapered. The nozzle I have been using on the gun is a Radnor 21-50 tweco style copper, 1/2" bore. Yesterday I went to the welding store and bought a nozzle that is about 0.20 inches shorter. The inside diameter of the tip measures about 3/8". The tweco part number is 21T37F or TWE 1210-1302. I have three questions: (1) Should I be trying to achieve as far as a nozzle/tip relationship? (2) Which of the 7 nozzles should I be using? (3) What are some other factors that I need to consider to get a decent weld? Thanks
Reply:What is your experience level? With this material being so thin I'm thinking you need to trigger weld it. I doubt anyone is going to be able to carry a bead on so thin material...( there, that should bring 'em out of the woodwork)
Reply:(1) Should I be trying to achieve as far as a nozzle/tip relationship?
Reply:It's hard to fill a hole in thin material because, due to the surface tension of the molten metal, it 'wants' to form a rounded bead rather than lie flat like water in a pan. Also, if the molten metal is surrounded by other metal, as when laying it on an existing sheet, the attraction of the surrounding metal helps pull it in all directions, but when working at an edge, there is nothing on the open side to do that so it beads up worse. The smaller the amount of molten metal, the smaller the round bead but the slower the work goes too.I would find a scrap fender and cut a hole in it about the size of what you now have, then clean the edges and make a patch to either just perfectly fit inside, or possibly have it just a bit too large with the extra metal flanged so the patch fits flush and the outer edges back up the joint; kind of like a perpendicular (rather than diagonal) 'Z' where the top part is the edge and the bottom continues as the main patch.I would prefer to use a TIG torch with low amperage, (or pulse? if available?) but using MIG with very short welds, more like spot welds, it should be possible. I would try different WFS settings to see what gave me enough true fusion without 'burning through', trying to keep it as low as possible.What about putting some thicker sheet metal behind the patch, welding into the backing, and later grinding it away? Would you be able to get to the patch on the real job? The grinding might be tricky too, to keep from going too deep in places.Practice lots on scrap, before trying on the real project.I have done this kind of job, repairing a bunch of old Jerry cans which had rust pits in addition to being thin; it wasn't easy, but I did finish them! You're probably better at this than I am; If so, maybe the ideas will be useful to someone else here.
Reply:You have a spray setup on your gun now with the recessed tip. A short circuit setup uses a flush tip. Either setup will work for what you're doing though. Filling small holes in sheetmetal, you're not carrying a molten weld pool for long enough for the tip/nozzle setup to make a difference.Use something as a backer to help soak up the heat and keep the metal from dropping out the back. Those copper backers should help fill the hole without making a mess and reduce the distortion too. Main thing though is do like the others said and zap it real quick, wait till it's solidified and the red/yellow color is almost gone, then zap it real quick again. That will help keep the hole from blowing out, as you already experienced. If you sit the torch there with your finger on the trigger for a long time, you'll be doing more cutting than welding, as you already found out.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:How about L-Tec Easy Grind wire which is for auto body work? |
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发表于 2021-9-1 00:45:02