MIG Welding Exhuast with flux core 101

[jredgo1234]

Hey i am doing my exhaust and i bought one already custom made by someone, but it hits the oil pan and rear dif. So i am going to cut , turn and reweld the dp, and put in some different bends in the rear section. My friend has a welder.

Has anyone mig welded with flux core their exhaust. Any tips or sellings you suggest?

How long will this take me to learn? Thanks

 

[brute]

Practice a lot before working on your exhaust. Use the same material as your exhaust to practice on. Figure out the best temperature and everything for the material. Then when you feel comfortable, go ahead and start on the exhaust.

 

[SlowSpyder]

get some scrap roughly the same size as the material you are welding. This way you can play around with the settings, fine tune the welder by doing a couple of beads on the scrap material. Since its flux core youll need to chip off any slag after you weld. Welding over slag can make the welds look really nasty and fuse like crap. Just remember to get the settings right for amperage and wire feed. keep the cup maximum of 1/2 inch away from the material from welding and make sure your gun movement is at a nice steady pace, ie not too fast not too slow.

Remember to mock it up on the car and tach weld at least 4 spots. Take it of the car and finsh the piece. depending on the wire size you use you may need to limit the length of the beads to 1-2 inches to keep the material from warping

 

[7"exhaust_tip]

get some scrap roughly the same size as the material you are welding. This way you can play around with the settings, fine tune the welder by doing a couple of beads on the scrap material. Since its flux core youll need to chip off any slag after you weld. Welding over slag can make the welds look really nasty and fuse like crap. Just remember to get the settings right for amperage and wire feed. keep the cup maximum of 1/2 inch away from the material from welding and make sure your gun movement is at a nice steady pace, ie not too fast not too slow.

Remember to mock it up on the car and tach weld at least 4 spots. Take it of the car and finsh the piece. depending on the wire size you use you may need to limit the length of the beads to 1-2 inches to keep the material from warping

great info.

you sound just like my welding teacher.

 

[eldiabloz13]

Im sorry you have to learn welding on such a advanced way. Not advanced but flux core is a PITA. Welding isnt that hard to learn but when it come to flux it gets a little more tricky. Now I'd say do you have your stock exhaust, if so, why not cut that up and try your hand on that. Metal now a days it getting expensive expecially if your just going to ruin it.

 

[forcefedtuner]

If you are looking to have "pretty" looking weld beads, then forget the flux core..It slags and spatters all over the place, but it is a strong weld, if done properly. There is a night and day difference when you MIG weld though, I can get the strength of a MIG weld, and the look of a TIG weld, just from using a basic MIG machine. I learned to weld on a flux core machine, but the first time I used MIG, it was so much easier, and cleaner looking. Flux core will get the job done, but dont expect it to look that good.

 

[UofACATS]

get some scrap roughly the same size as the material you are welding. This way you can play around with the settings, fine tune the welder by doing a couple of beads on the scrap material. Since its flux core youll need to chip off any slag after you weld. Welding over slag can make the welds look really nasty and fuse like crap. Just remember to get the settings right for amperage and wire feed. keep the cup maximum of 1/2 inch away from the material from welding and make sure your gun movement is at a nice steady pace, ie not too fast not too slow.

Remember to mock it up on the car and tach weld at least 4 spots. Take it of the car and finsh the piece. depending on the wire size you use you may need to limit the length of the beads to 1-2 inches to keep the material from warping

OK, not contradicting this good information, just adding from my experience.

MIG is one of the easiest welding techniques to learn. Having said that, I wouldn't call it "easy" Of course those who know how to MIG weld will say "it's EASY!!" and they'll be correct, once you're experienced.

Using dual shield FCAW, you don't have to chip off the slag after weld completion. In fact, the slag can help protect the weld in harsh conditions, such as underneath a car.. To clarify, (this is probably what "SlowSpyder" was saying) if one chooses to make multiple passes using flux core, then the slag absolutley must be chipped off and cleaned. If not done, your weld will be porous (unacceptable porosity) and weak.


To further, I'll add that it's easy to weld incorrectly. Beginning students usually do. One mistake I made is that I relied on how the weld looked to judge its soundness. I have one welded piece from every day of my welding class, and after completion, I noticed my earlier welds, although they looked good, lacked sufficient penetration. This is obviously important, especially to welds subject to stress such as your exhaust system.

Your weld will warp. There is no way around it. What you can do is limit the distortion by (the earier suggested) tack welds, weld shorter distances then allow to cool somewhat, weld one side, then the other, etc. Allow your welds to cool naturally. More advanced technique to prevent distortion is a jig, which limits the piece from warping while cooling, or heat sink, which slows the cooling process, reducing the distortion of the piece.


I'm not a teacher, but my advice is to experiment with your technique before starting your project. When I say experiment, I mean, weld too fast, too slow, heat too high/low. Just see what happens, experience is key.
A good book I've read suggested to go ahead and burn through the piece you're testing on. This is to show you how much heat is required for sufficient penetration, as most beginning students weld too "cold."

Above all, when you hit that "welding sweet spot," you'll hear it.

Good luck, post back questions and results..

 

[talon212]

I agree with these guys, but what is not mentioned is safety..Don't forget welding gloves,helmet. And for when your going to clean up your welds or see if your leaking you'll need a grinder with a wire wheel attachment, face shield and time.

Tip: When welding get a good puddle and push or pull it in little (C) s

 

[UofACATS]

I agree with these guys, but what is not mentioned is safety..Don't forget welding gloves,helmet. And for when your going to clean up your welds or see if your leaking you'll need a grinder with a wire wheel attachment, face shield and time.

Tip: When welding get a good puddle and push or pull it in little (C) s

Oh, so true. Safety = Good. A little knowledge is dangerous, eh?

The smoke/fumes that result from welding (some metals are worse than others - do your research please) are in short, bad. A glowing hot piece of melted metal will burn through your protective clothing with surprising haste.

Be careful.

 

[xveganxcowboyx]

On top of what everyone else said, be sure to cut the metal and match it up as seamlessly as possible. Filling gaps with flux is a pita.

 

[VanIsleDSM]

while metals can give off nasty fumes, the flux definitely will.. ventilation a must, and ya everyone pretty much covered the rest, though with exhaust pipe I'd be tempted not to focus on making the C's, but that's me, everyone has their own style, you'll get your own too... I'd gently pull the puddle in little whisking motions making sure you watch how it's solidifying, if your puddle goes dark red you're about to burn through, stuff the wire (move your stinger closer to the work) or stop... on your real project that is, burn through all you want practising like mentioned above.. a longer arc welds hotter than a short arc.. this is a good way to control a limited amount of heat while you're on the fly.

 

[gijoe985]

So if I were to borrow my friend's MIG to do an exhaust, what would I need to get the job done? I don't know what material I am going to use yet, but from what I've read exhausts are usually aluminized steel or stainless. Can I MIG these? I've done a bunch of MIG wleding back int he day, but I never really learned about what to select as a wire for different types of materials. So I got pretty handy, just never learned about what I was using. (It's on my "to learn" list.)

So, can I MIG the AL-Steel or stainless, or should I go with something else? I have to admit I'm trying to cheaper... But I want to do it myself either way I go. THANKS!

 

[eagletalonjohn]

just a little pointer.when welding a exhaust on a car remove the negative off the battery.

 

[tkelly27]

aluminized just has a small layer of aluminum on top of it to keep it from rusting. Blasts right off. I wouldn't do SS with mild steel wire, but I think you can... I'm a TIG man myself

CLEAN! PREP! The best welder in the world will have a hard time making a decent weld on dirty metal that's poorly aligned.

 

[ricktb]

Does anyone know the average gauge of steel found in a stock 2g downpipe? I have to weld a bung on with my argon mig welder

 

[gijoe985]

Ok, welders, correct me if I am wrong. To weld SS, use SS wire and pure argon gas. I am guessing if the AL coated stuff is just coated, then I can just use mild steel wire. Should I then use a rust preventative coating on top of that? What gas should be used with the mild steel? I thought that I just used argon when I used to do steel, but I have hear that C02 or a mixed ga is the way to go with steel. Thanks.


Remove battery... I'd better write that down...

 

[GVR4592]

Ok, welders, correct me if I am wrong. To weld SS, use SS wire and pure argon gas. I am guessing if the AL coated stuff is just coated, then I can just use mild steel wire. Should I then use a rust preventative coating on top of that? What gas should be used with the mild steel? I thought that I just used argon when I used to do steel, but I have hear that C02 or a mixed ga is the way to go with steel. Thanks.


Remove battery... I'd better write that down...

That's correct on the SS.

For the coated steel, grind, sand, or blast coating off. For the wire just use an all purpose wire for mild steel, something .030 or smaller and a 75/25 mix of Argon/CO2. Most people with mig setup's have the 75/25 already.

Spraying the weld with a coating after it cools is a good idea, it should help prevent rust from forming.

 

[gijoe985]

something .030 or smaller

Would that apply for the SS as well? I will need to find a place to get the wire. I'm certain my friend won't have it. I'm hoping to save up for a TIG, but until then MIG it is... I guess I'll need to find a place for bent tubes as well. I think I'd have to go to Yakima to get them if I wanted to shop locally (I noticed you're from WA)

 

[GVR4592]

Yes it would apply to SS as well.

Columbia River Mandrel Bending

This is where I get most of my mandrel bends, they're prices are decent and they're down in Oregon, so it's about the closest I could get to dealing with a local business for mandrel bends.

 

[GreenGSX]

Most welders will have a wire speed and voltage chart on them somewhere. Those settings will get you close enough to get started.

Practice on scrap peices until you get your technique and settings correct. You'll know you've got things set right when it sounds like "eggs frying in a pan" and it doesn't burn through the pipe.

When fitting the pipes together take your time so there are no gaps. That can be hard to do so when you have to weld up a gap one trick is to drop the voltage (power) setting and lay down a small bead on each side of the gap and then go back and close the gap with your higher power setting.

Clean, clean, clean! Don't think you can weld the whole seam in one shot. I weld 1" at a time and then move on to another section to weld. I also keep a wire brush handy so I can clean off any slag or soot. Keeping everything clean will also let you inspect your welds so you can catch those pesky pin-hole leaks.

When your all done paint the welds so they don't rust.

and above all remember that nobody makes pretty welds with flux-core but that doesn't mean it doesn't work. Plus once its under the car nobody will ever see it.