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Discussion Starter #1
Hey guys, I’m welding patches in the wheel wells and every time I go to weld thin metal like the wheel wells or the quarter panel it blows right through the metal. I have my welder set on low and I lower the wire speed to try and not blow through but nothing works. I’m using a mig machine with argon gas. Should I be using a different welder? How come this keeps happening? Any tips would be appreciated.
 

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what size wire are you using? you may need to cut back a bit further to get to good solid metal. you can also try using a copper spoon as a backer.
 

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100% Argon gas is used for TIG welding. MIG needs an Argon/CO2 mix commonly known as C25 It produces the least amount of spatter, a nice bead appearance and won't promote burn-through on thinner metals....which you seem to be encountering.
 

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I am a totally novice welder so take this for what it’s worth, but here is my limited experience...
  • Make sure you have cut out to solid metal and cleaned very well
  • Make sure the gaps are very tight
  • Tack weld instead of laying a bead
  • Make sure your wire stick out isn’t too long
  • Try using a copper backing plate
 

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100% Argon gas is used for TIG welding. MIG needs an Argon/CO2 mix commonly known as C25 It produces the least amount of spatter, a nice bead appearance and won't promote burn-through on thinner metals....which you seem to be encountering.
Solo,
With the Ar/CO2 can you weld in a continuous bead, or do you still have to do a series of multiple spot welds? (NOTE: I have never tried welding thin panels -- I have just seen the piss-poor welding jobs by amateurs like myself.)
 

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Whether it's tig or mig, on thin metal you must do short beads to prevent warping of the panels. Since you have never welded thin panels, you need to burn a lot of practice beads.....or hire an experienced welder.
 

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Bernnstang can you post some pictures of the area you're attempting to weld?
 
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I found that doing a series of overlapping tack welds (doing each tack a different spot on the panel and then going back around overlapping as you go) was required on the thin metal. I also use a thinner wire...takes less heat for it to melt into the panel. Get some scrap pieces first and practice with different wire settings before you go at the car with it.

My welder is set on about medium for the heat with a pretty fast wire speed for thin metal because you're just laying small tacks. You want the welder hot enough so the tacks sit flat and aren't just tiny balls sitting on top of the metal.

The copper backing is also a lifesaver. This is what I use:

If you do happen to blow through, this supports the puddle and prevents it from getting too bad. Then you can close it up with some small tacks.
 

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If you're blowing right through, you've either got it set up too hot, the metal is too thin (perforated), or you're moving too slow (I say perforated because a skilled welder can still weld thin metal). You should be able to make a solid tack with good penetration if the machine is set up correctly. I'm curious like latoracing- show us what you're doing so we can actually help you...
 
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My Hobart has a sheet on the rear of the door that encloses the wire and feed system.
On that sheet, it lists metal gauges, recommended wire speed, wire thickness, and heat range.
Do you have something like this to get you started?
If not, you are more than likely using too high of a heat setting, wire feed, and moving too slowly.

Decrease the heat and wire speed, and practice on some scraps, while doing tack welds.
When you get the hang of it, write down your settings and the gauge of metal you are working on.
I put pieces of tape on my wire speed display, with the heat setting number on it, to relate the two. This helps when you are tired.
Just remember to go SLOWLY. It's not impossible, it just takes practice and patience.
 

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Is it a 120v or 230v welder? 230v makes it harder on thin sheet metal. Welders usually have recommended settings for arc bolts and wire speed based on metal thickness, wire size and gas type on the inside of the access door. That’s usually a good place to start the. Just for reference, on my 230v welder I’m usually around B2 for sheet metal.
752670

752671
 

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Discussion Starter #12
752673

so this is what I am trying to patch.Don’t really wanna replace the whole panel any ideas? I was using the 230 but it seemed to strong so I went to the 120 and no luck any ideas on how the hellI can patch this.
 

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I can’t really tell for sure, but it looks like you really need to cut out a section all the way back to solid metal and make a patch to fit in the spot you cut out. Strip both sides of the welding surface really clean so you can get good penetration without too much heat. I think you’ve got rusty metal an contaminants that are causing your blow through.
 

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You have overlapping metal in that area. The inner wheelhousing overlaps the outer at the bottom. What I would do is make a patch for your outer wheelhousing first then weld that in. Then make a patch for your inner and weld that in.

I recommend 18 gauge metal for work like this. It is generally slightly thicker then your existing metal so you can point your gun to start on the new metal when you're trying to join the two. I rarely weld beads when doing auto work more a series of dots spaced out about an inch apart. After welding it is best to hammer the welds while they are still hot to counteract the shrinking that happens. In your case, I don't think you'll be able to access the back side in order to hammer and dolly but since it is a wheelhousing it's not that big of a deal. But if you were welding a fender, apron, etc then this is the method you should use.

david
 

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Discussion Starter #15
I’m just trying to make it look decent it’s not gonna be in view but if anyone ever looks in the wheel well I don’t want them to think what the hell is that!
 

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Make sure and watch the angle on your gun. I have found that keeping it so that it is held about at pretty good angle and at a right angle to the weld seems to work best. In other words, don't point the wire feed directly at the joint, have is so that it points at one side and as the arc and bead form, they bridge the gap between the two. Otherwise as soon as you pull the trigger it will poke straight through the gap.
 

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Curious if that is the current state of the metal you are trying to weld, or if you have cut the patch out and cleaned all of the surfaces?
 

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Is it a 120v or 230v welder? 230v makes it harder on thin sheet metal. Welders usually have recommended settings for arc bolts and wire speed based on metal thickness, wire size and gas type on the inside of the access door. That’s usually a good place to start the. Just for reference, on my 230v welder I’m usually around B2 for sheet metal.
View attachment 752670
View attachment 752671
Do you know where that welder is actually made? I ask, and I've said this before too, I think this Lincoln welder and the Eastwood migs are exactly the same. My Eastwood MIG is identical to this. Same knob panel (same knobs, printing, etc). Inside the door is the same sticker.
 

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I am a totally novice welder so take this for what it’s worth, but here is my limited experience...
  • Make sure you have cut out to solid metal and cleaned very well
  • Make sure the gaps are very tight
  • Tack weld instead of laying a bead
  • Make sure your wire stick out isn’t too long
  • Try using a copper backing plate
If you're buttwelding, you actually want a bit of a gap between the panel ends, about 1/32-1/16". But as they say, if you can throw a cat through it you can weld it shut.
 
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