Any advice for a first time mig welder

[Argeo]

Besides buy a book. Just replacing some rot holes with 18 guage sheet metal. Do I do several spots or one long stream?

Thanks David

[jpnovak]

First get some scrap material that is the same size as what you want to weld. Practice, and change settings to see what the weld does. you can change the distance of the tip from the surface, how fast you move the tip/bead, the wire speed and the voltage. If you burn through you are too hot. If the weld just pops on the top you are too cold. Once you can lay a steady bead for about an inch, you are doing much better. Stitch small sections together (1/2-1") to minimize warpaing. Tehn cut a slot in the material with a cutoff wheel. practice your butt welds by closing up the gap.

A book can be helpful to get initial settings for your welder. Owner's manual works too.

[Argeo]

Thanks. Good stuff. Just wondering. What do you mean by popping?

David

[jpnovak]

YOu will know when you start welding. You want a consistant humming/sizzling sound. Practice a few times and then get back to us. I can guarantee you will have different questions.

[RickM]

Reading and practice is what I'd advise as well.
When butt welding I like to spot weld in alternating locations. This prevents too much heat from warping the panel if done in a sequential pattern. Then I connect the dots in an alternting fashion as well.
There are videos available as well.

[john walker's workshop]

when doing repair panels, spot weld every inch or so around the panel first, alternating sides and checking for alignment as you go. when the weld cools, the gap will be pulled together a bit, so the idea is to stabilize the gap with several strategically placed spots, so it stays put better as you finish the seams. do a 1/2" here, a 1/2" on the opposite side, so the heat isn't all in the same area, to minimize warping. if you go slow, you can do a whole panel without even having to cool it. in fact, more warping is done with a wet rag than if you just went slow. eventually all the 1/2" sections will become a solid bead. i would recommend doing this as a series of overlapping spot welds, rather than a continuous bead. way less chance of warping and burning thru. continuous beads are for thicker stuff. tig is more suited for a continuous bead on sheetmetal. even then, you still need to do short runs, let it cool, and then do an area farther away.

[Argeo]

Thanks again.

David

[fuelie600]

If your welder will allow, get a .023" tip and .023" wire for sheet metal, it's easier to use. Most come with .030".

Make sure you are using 75% argon/ 25% CO2 shielding gas. Try shutting off the gas on a practice piece so you know what happens when you run out.

Practice is the key. I took a weekend class at a local vocational school a couple of years ago, it helped alot.

Good luck!

[awis321]

Assuming I want to patch the following area:



I was thinking of butt welding the replacement piece rather than dropping it in and spot welding it to the good metal. I'm concerned about moisture eventually getting in where the pieces overlap.

I've read it's best to have the work clamp as close to the piece you're working on. If I'm butt welding it in, should I weld a temporary piece of metal to clamp to?

[john walker's workshop]

welding a tab for the clamp would be a good idea. not much to clamp to in that area. one of the seatbelt bolts might work too. butt is better. as you say, the overlapped sections are rust prone because they are bare metal.

[SteveStromberg]

Build a Muffler man first. Then start in on your car.

[lendaddy]

I have never done automotive panel welding, but I do own a welding shop and have welded for over a decade in a production setting. When we have to weld thin steel, we have a few tricks that I wonder if you guys have tried.

1st - Try using straight Argon rather than C25, it creates a wider "flatter" bead that has much less tendancy to burn through.

2nd - Try using silcon/bronze wire, it melts at a much lower temp and has the same flat bead tendancy. It is also VERY stable. By that I mean we MIG with this all the time with NO gas shield at all, and no porosity. I know that sounds crazy, but trust me.

Both of the above methods work great on thin metals and GREATLY decrease the tendency for burnthrough.

[jpnovak]

Great tips LenDaddy, thanks for helping out. Now to find a roll of Si/Bronze.

I tried straight Ar once and I had a hard time keeping a bead going. Maybe I will try it again.

[RickM]

Straight Argon is usually recommended for aluminum.
I've used straight Co2 for steel but it gets messy.

Why haven't I seen Argon alone recommended? Cost perhaps?

Thanks for the tips Lendaddy.

[lendaddy]

The trick with straight Argon is that you can feed ALOT more wire, in fact you have to. It melts so fast that it's almost like "spray welding".

[lendaddy]

My personal opinion is that you panel welders would absolutely love Si/Bronze wire. Try it! It is also softer (plenty of integrity yet) so finishing is easier. We use it on everything from mild steel to brass. Yep, we MIG weld Brass(.025" thick) Can't really give that info away though.

We have tried thousands of different combinations over the years and the SI/Bronze is my fav. BTW, I was not kidding about NO shield gas(though it makes some apps easier to control). I can take a video if you'de like, it's amazing.

[RickM]

Sounds like MIG Brazing.

Would the difference in material properties haunt us in the future?
Stress properties adequate for higher load areas?

[lendaddy]

Good question on stress, but it is used by use in a very high vibration application with no signs on cracking over the last 2 years. Also, you are correct that it would technically be considered electrobrazing but we are miles outside the "recommended" settings and procedures, and it involves dissimilar materials with a butt joint. It was something that both Miller and Licoln told us was impossible. It took us 16 months to get it right.

[awis321]

Great information as always. Thanks again guys!

-Dennis

[fuelie600]

One other trick I learned after doing it the hard way far far too long, if you are but welding a patch piece and have a large gap to fill (like you cut the piece a little bit wrong...) put a piece of copper behind the gap and the mig weld will span the gap instead of burning a hole. You can do the same thing to plug weld a hole.

I bought a few 1 inch copper pipe fittings at Home Depot and bent them into various shapes. I hold them behind the panels with vise-grips.

Works great....