First off, I'm very new to mig welding. I grew up on a farm where we had this honkin' stick welder and I learned to weld in shop cl***. I did take a community college cl*** to learn how to gas, mig and tig weld and I bought a Miller 140 because all my 1 car garage has is 110v. I have done some welding in the 3 yrs that I have had the welder including welding patch panels, welding shut trim holes and fabbing some brackets, etc. I'm now working on repairing some rusted areas with new EMS panels and it is going alright although I occasionally get some burn through. Now you have the background, so here is the problem. I'm trying to weld some pinholes and some of the metal is a little thin so I'm holding a copper on the backside. I'm wanting to just hit the trigger and spot the holes. I noticed yesterday that when I strike the arc, the first thing is a loud "POP" then a nice arc. I have 75/25 gas, o23 wire, I have varied the wire speed, the voltage, the stick out length and done everything I can think of. What do I need to do? What am I doing wrong?
You're welding RUST. Pop comes comes when the arc finally gets through the rust. Oxydised metal also entrains moisture and gases that expand and will blow back like a poorly used cutting torch.
I agree with 48Chubby. MIG is very forgiving when it comes to less than squeaky clean metal but real thin stuff leaves no room for play. If the area with pin holes is accesible you might try cutting out the area and weld in a patch
i agree. also, where there is pin hole rust, the surrounding metal has a tendency to be a little thinner and warping becomes an issue. if you choose to fill the pinholes anyway, go very slow so as not warp the metal or burn through. you can also dial down the voltage a touch too.
if it is real thin, you may need to cut out more old metal, this can be a problem if you run out of patch panel. if you have a thin area cause of a welding issue like you burned a big hole in the panel etc. eliminate the copper and put a strip of steel behind the hole and weld it up. not the most professional way, but i solves the problem with a strong patch. and will put less heat back into the main panel and that always helps reducing warpage. if the pin holes are there from rust, then the section of panel need to be replaced as you may have a much larger area of reduced strength due to thinning by rust what kind of car are you working on?? pics?? the ems guy
Those that are telling you to cut out a larger area and form a patch are telling you the right way to do things. However, there is a way to cheat things. I've encountered pinholes that are truly that. A weak pinhole in an otherwise decent panel. You try to tack the hole up and a bigger hole blows through. Frustrating, eh? Try a technique that I call the stutter-start. Angle the tip toward the side of the pinhole and hit the trigger for a split second. That will leave a small blob of weld. Now hit the blob with a sightly longer trigger hit. The new tack will hook into the stutter blob and allow you to fill the weak area without blowing through. It might take more than one secondary blob. If you have access, you should try to hammer on-dolly these tacks so they don't pull the area low. Not the "correct" repair.... but it works.
Thanks guys...I thought I had it ground very clean but maybe these old eyes are playing tricks on me. I'll keep trying. And yes tinmann I have a couple areas that started off just a little pin hole right next to where the patch panel was in and hit the trigger and now I have a larger hole...I sometimes feel like I'm using the drill instead of the welder. I'll keep going.
If it is too thin, rusty, or work hardened forget it, cut out more metal. Even if you MAKE it work, it is going to **** doing it, and it ain't going to look good.
Old thin tin will kick your *** if you as little experience as me. Cutting for a larger patch is good advice if you consistantly burn through. Sometimes you have to go with what you already have. When I welded the formed metal that replaced the drip rail on my A Tudor body, I had many burn through and pop sitiations. I had to focus the start of each tack weld toward the new metal being attached and then move the direction of the tack toward the thinner rusty metal. Sometimes you would have to chase the new hole created while aiming each fill tack toward your new weld until you hit metal strong enough to not burn through. IT IS A *****. I'm not saying what all I did is right. We, meaning also the man that did most of my patch panel work, filled some holes using a TIG an silicone bronze filler rod. This was done in some of the holes that looked ragged enough to indicate using regular MIG would cause chasing a hole a long ways. The way I have it figured, if you can't learn to weld on old tin and how to patch and repair it, you might as well switch to playing with Tupperware and resin. Not saying all I did and what we did is completely right. I know my car body won't last as well as a body that was saved when in a better condition that what I started with. http://www.jalopyjournal.com/forum/showthread.php?t=394342&highlight=marmonherrington
When you say you're using copper on the backside, I hope you aren't using a penny. They have been 97.5 % zinc since 1982.
No I have a piece of flat copper stock that one person hold on the back while the other welds. EMS guy...are we having fun yet? I had to go to the shop where the car is located today and when I got back home my wife asked if everything was OK with the car. I told her it was fine but Chip Foose had not been in with the Overhaulin' crew to finish up the car. She asked if I really want someone else to finish it up. I told her maybe only the body work!
what kind off metal you welding on.make sure your ground is on a clean spot.when it pops is your wire sticking in the tip (make sure tip not touching nozzle).you could have heat or wire speed set wrong.try speeding wire up a liitle.one more thing you were probably trained on a higher amp welder these smaller welders takes getting used to
I've been working on floors, rockers and rear quarters on a 51 chevy 2 dr sedan. Tip is not touching nozzle and I keep clean tips and nozzles.
The Jalopy Journal
