Welding has been going really well but there is one area I'm having a little trouble with. Lets say I cut a replacement piece of metal out of a donor car and drill out some spot welds so I end up with a 1/4" or so hole that I need to weld shut when placed over the existing metal. There is metal behind/backing up the piece with hole. I figured welding up the holes would be easy but when doing so it seems like the molten metal is being blown around by the Mig gas or something weird is going on. I get it welded but not to the standard I prefer and end up with a sloppy looking weld. Is it possible I have to turn the gas pressure down when welding in a hole? I'm running 15-20 psi. Or is there some other trick to filling these in. Note in all these cases I'm welding vertical or slightly angled overhead. I have no problem welding various other flange joints, butt joints with gaps, no gaps, thinner steel to thicker steel etc, so I think I'm OK with dialing in the wire speed and amps. Just not sure exactly whats going on when doing these holes. Thanks
Jason the cleaner the repair area the better the weld will be and look... That said I have found the best way to do what you are dealing with is too: 1) turn up the speed of the wire a slight bit. 2) make sure the 2 pieces are tight to one another. 3) start in the middle of the circle with tip and in one shot circle outward around the hole. This needs to be done in one smooth shot. Keep the tip close to your work. Let us know how it goes.
Gas regulator for MIG should regulate flow, not pressure. So yes, it's possible you have too much airflow. 10-15 cfm should do it. If you weld in windy conditions you'll experience lack of shielding gas. Start the weld in the center to ensure you have good penetration on the bottom piece.
Wow that was fast - you guys are awesome I wasn't starting in the middle so thats probably a biggy there. Walt, yes my bad, its flow. ou: I think I might be a little high. A double check of my book says set regulator 25-30 CFH (hour) or 12-15 CFM so I need to verify the graduations on the gauge are in CFH or CFM, or perhaps both. Hopefully I'll be done fitting and ready to weld more this weekend and try out your suggestions.
No magnets in the area of the weld as they will really affect the arc. All paint and rust removed and practice on some scrap?
JZ.... make sure that the two pieces are tight together before you fill in the hole. Use a wooden handle and push the two pieces together prior to striking an arc. You could also use self-tapping sheet metal screws but then you have yet another hole to fill in. How is that ESAB wire working out?
Rick, When I asked for the ESAB easy grind wire at two main welding supply places in my area they looked at me like I had one eye in the middle of my forehead. I also called a couple auto supply houses that carry autobody supplies. One of the welding supply places said I'd have to buy a case because that was his min order from ESAB and the other said I'd have to wait until he placed an order to ESAB for other items. I was surprised they didn't stock it or at least be more familiar with it. The one guy said I was the first one to request it. I looked around a bit online but couldn't find anyone selling the smaller 2lb spools so gave up for now. Thanks
Special wire is not needed if you have the wire feed and heat set....just like making a twistee-treat ice cream cone....to weld the holes shut....if the metal is not pinched together....go get a pair of Cleco pliers and pin set...best money you will spend when welding sheet metal together.
Jason - The type of weld you are doing is called a "plug weld". This does nothing for your question but it'll be easier to say or type out should you ever need to again.:grin:
Did some "plug" welding over over the weekend and results are waaaay better thanks to the excellent advice. Just when I thought I wouldn't have any more questions I'm having another problem. o No: When doing butt welds, I noticed the steel has a tendency to sink in at the weld joint and I end up with a dip. I go through all sorts of pains to get the panels aligned perfectly then after I'm done welding I have a dip. I guess its better that it always goes in and not out but I'd prefer if I could keep it flat. I am stitch welding single spots spaced out so it doesn't get too hot. I won't come back to an area until its cool enough to hold my hand on it. Thanks
What you are experiencing is the weld metal shrinking and pulling on the sheet metal. If you can get to the backside of the weld area try putting a dolly behind the weld and lightly tapping the weld with a hammer as it cools. This will expand the weld as it is contracting. The trick here is to lightly tap the weld. If you hit the weld too hard you will have a bigger problem than a slight depression, you will have a high point. Try this on scrap before you practice on your car.
Looks like you fixed you plug problem. As for the butt welds try only tacks and immediatly cooling them with a blow gun. A slight gap of like a 1/32 or so will also help as it doesn't take as long to melt the metal and let the tack penetrate. Be careful with how much you hammer ON dolly on the metal. If you really go to town it can crack.
stubbe the reason that you get a crack at the weld joint is because of the gap you left mig welding wire is harder than the parent metal and filling that gap with just the feeder wire leave a brittle spot....... What ICAR [this is the organization that sets criteria for auto body repairs that body shops are supposed to follow] requires when you leave a gap is to put a backer strip to aleviate the cracking problem but you create a problem with moisture entrapment on the back side between the unwelded part of the backer strip....i you have access to sept 2011 STREET RODDER magazine in Ron Covelle's Professor Hammer column this subject is covered [which was written by me], it covers some of the misconceptions on panel attachment and and distortion
