[bing98]

I have read that when stitch welding thin metal it's best to set the welder to the next thicker gauge to help reduce heat and warping. So far that has really worked. I have stitch welded a few 18 gauges pieces into my car with great success, but now that I'm on to the thin 22 gauge stuff I'm having blow through problems. I practiced quite a bit and know I need more, but I have to start assembling as the winter is coming.

I'm using an Eastwood MIG 175 220 volt machine with shielding gas. I was using the .030 wire that came with it, but practiced a little last night using the .025 wire on the 22 gauge metal with much better success.

What impact does tip or work angle have? My work angle is 90 degrees, but even though the gun angle should be around 0-15 I have had my best luck at a 45 with the edge of the tip resting on the metal. Basically very close to the spot I'm tack welding. The minute I start to decrease the gun angle to the 0-15 degree range on the 22 gauge I blow through. I found that if I back the tip away from the metal a tad when I decrease the gun angle the blow through stops happening. Does this indicate my voltage and/or wire feed speed are incorrect or that I just need to back off a bit? This is very important to me because right now I am welding a 22 gauge piece in a very tight spot where a 0-15 degree gun angle would work much better.

Maybe if I under stood what it is exactly that causes a blow out in the first place I could better cope with it. Is it to much heat? Not enough wire being fed into the puddle. To much wire?

Thanks

[weldin mike 27]

Hey there, I've only done one car sheet job, it was only a little one. But talking to a friend who has done lots of them, his way is to do single spots. Just on the trigger and off again, no movement. It's just a quick spot, less than a second. He stressed that you really need to take your time letting each section complete cool, before adding more weld.

Mick.

[cj737]

To add to what Mick wrote, skipping around a lot also helps. Single spot welds is the best method for welding thin panels. You could also switch from using ER70 wire to Silicon Bronze MIG wire. This allows you to use much less heat, softer metal for grinding afterward, and produce less warpage.

Have a wet rag nearby and pad the metal after a few spots to help soak some heat out as you spot weld along.

[bing98]

Thanks for the input. I have actually been doing all of that and have had get success welding in the 18 gauge patch panels. It's when I started to weld in the 22 gauge patches I ran into the blow through issues.

Did some more practicing last night and had what I consider a big breakthrough in my understanding of the mig process. The importance of shielding gas and stick out!!

Correct me if I'm wrong, but this is what occurred. After finally feeling like I had it dialed in on some scrap where I did some nice tacks and also practiced filling some blow through holes I decided to do some more practice welds on some fresh scraps before turning back to the car. I prepped 2 small brand new pieces of 22 gauge. Clamped them down with no gap and began.

Held the gun at about a 10-15 degree angle an pulled the trigger. Blew a hole instantly. Tried again. Another instant hole. I stood back and thought about it and decided to use an approx 3/16-1/4 stick out vs the 3/8 I was using. In addition, with the shorter stick out I was able to move the gun closer to the material. Perfect welds. One after another. Very low crown and excellent penetration.

When I stepped back it occurred to me that I wasn't considering the importance of stick out and shielding gas. At that moment I thought that maybe because of the fact that I was using a longer stick out and was holding the gun a bit to far from the material that the wire was reaching the material before the gas had a chance to shield it. As a result I didn't have a controlled burn and the arc blew a hole in the metal.

Sound thinking or dumb luck?

[cj737]

Stick out is analogous to arc length. The longer the arc the hotter the arc. Too long, and shielding gas becomes less effective. So you stumbled onto the correct assessment of your technique to get the proper results. A 90* angle with the proper stick out (or Contact to Work Distance in MIG parlance) is the best the position, though not usually viable. Keep your panel gaps as tight as you can and you will be fine.

[starvncoyote]

if you have something to use as a backer bar, even just a small one for small stitch welds, it will get you a long ways. I helped a buddy chop his truck bed before and all we had at the time was a stick welder. I was able to get in a large tack before having to stop and peen the weld a little. Good times, I hope you find a method that works for you.

[Mike Westbrook]

Once you find a good stick out distance you can make a spot nozzle if you have lots to do cut the end to length drill four holes around the sides close to the end then cut into the drilled holes making a nozzle with four little legs or you can just buy one

[Thomas O'C]

Interesting tip for the spot nozele. Thanks

[drizler1]

Why not just drop the wire size down to .023. It works better when you are working with that garbage tinfoil they call auto panels. It’s by far the worst junk I ever welded so don’t feel bad. Also holding a crushed piece of copper tubing behind the panel if you can also helps with burn through.
Try to get yourself dialed in on some scrap if you can again because that hardened garbage steel is such [emoji2959][emoji90].


Sent from my iPad using Tapatalk