Beginner Welding

[A4drei]

Alright so tomorrow or in the next couple days im gonna start learning how to weld. First project, My cats. Is it okay to be using MIG on exhaust? (i was reading an older thread about exhaust and it said that it was falling apart because it was welded with MIG or something like that.)
And if you guys could give some tips on welding, thatd be great. i know itll take lotsa time and patience, i got both :)

[Poopie]

go to a scrap yard and pick up some steel and practice welding. Its very easy to blow a hole in exhaust piping. what welder are you using? sign up to weldingweb.com

[xstwin]

Just as stated above. Get some scrap and start laying some beads. Then learn how to grind out errors :)

Just be patient. Clean beads are a combination of experience and mating surfaces. Oh, for scrap, get some 16 gauge, don't go thinner until you learn to control the arc and feed.

[darkstar]

Using a MIG on exhaust is just fine, that is what most exhaust shops use. Like stated above i would start out with some practice pieces first. If you have the option to use gas 75/25 CO2/Argon mix I would, flux core welding is horrible! Take your time when it comes to the prep make sure both your joints are stripped down to clean bare metal good ground point.

[aluthman]

MIG welds in general are just ugly.

[lorge1989]

Using a MIG on exhaust is just fine, that is what most exhaust shops use. Like stated above i would start out with some practice pieces first. If you have the option to use gas 75/25 CO2/Argon mix I would, flux core welding is horrible! Take your time when it comes to the prep make sure both your joints are stripped down to clean bare metal good ground point.

This.

I have done a ton of welding with my flux core unit from HF. Never had any issues, I will stand on my welds without thinking twice. Its the person that matters not the machine.

The machine and the type of wire definitely does matter. A good welder can weld well with a crappy welder, but the welds will be more consistent and much easier to lay down with a quality machine. Being able to stand on your welds is not really a testament to the quality.

MIG welds in general are just ugly.

Nope. MIG welding and TIG welding both have their uses and as long as you arn't using flux core your welds should be pretty.

[Instructor31]

If you go to a local exhaust shop, just ask them for the tubing. Most will have carbon steel, if they have galvanized don't buy it. it's like the metal tube that is used to make fences.
If you're going to be using SMAW/MIG then do what was stated above. Because the exhaust won't have weight on it preferred method is vertical down "Z" motions; very simple to do and control also less chance to blow a hole in your metal.
If you're taking the whole exhaust system off, set your exhaust on a stand where it's stable and you can do the sideways " J" motion.
75 aragon 25 oxygen mix would be ideal unless you're going to use pulse MIG then go with 90/10.

Simple steps to get through this project would be. Tac weld your tubing/CATS in place, around four tacs to make it a little easier. Tac in opposite sides to avoid the tubing/CAT from warping to a set direction. Once you have all your tacs in place, run a straight pass from tac to tac. Once you've played that first pass and it cools down, then go over it from tac to tac with the vertical down " Z" motion to give it a cap layer.

150-180 AMPS is your working range.
Making adjustments, always adjust one at a time wire speed or amps.

Anyone feel free to correct me or add on to this.

Hope it helps!

[cspcrx]

Great tips above. I ditched my HF a few years ago and picked up a Hobart MVP210 running 75/25 gas. I was amazed how much better my welds were just because of the better machine. But then...

I took a 2 hour, one on one, welding class at a local welding supply shop. Now that made a huge improvement in my welds, mostly because he helped me improve my technique. Then it just comes down to practice!

Sure is fun getting metal to stick and build something. This winter I plan on building a new shop bench!

Good luck and have fun!

[mufflerman]

All advice above has been spot on. Except for Mig welds being ugly, tig welds can be the best looking if done by someone with the appropriate experience, but can be very messy if done by an amateur. Mig welding is the most common type of welding associated with anything automotive and is very attractive and strong if done properly. As mentioned, don't do anything with flux core if your concerned about appearance, its a dirty weld and also doesn't have the penetration of a gas fed shield. You don't have to use the more expensive Argon or Argon mixes, C02 does the trick and is cheaper. As far as the machine, stay away from Harbor Freight and the cheap overseas built welders, HF tools have their place, complex electrical tools aren't one of them. I am a big fan of Miller, lots of choices for different applications and they last forever, we have 7 different machines in the shop 3 of which are almost 20 years old and still used everyday. As far as your first project being cats, I would strongly advise against this. You very well may be looking at one of the more difficult welding projects on a car when your talking about cats on a European car. Pipe is already a difficult thing to weld if you don't have experience because it is round and more difficult to follow with the lead, ever spray painted a bicycle? It's similar in it is difficult to keep you paint spray even on a tube VS. a flat surface. Also you don't want any leaks in the cats. Besides the obvious exhaust leaks being annoying and potentially dangerous, even small leaks in the welds can change the effectiveness of the correction values of the catalyst specifically to the NOX. A good suggestion already made above is to go to a local muffler shop and ask for some scrap, we throw away lots of remnant tubing that is great practice material. Good luck!

[Aiserock]

If you go to a local exhaust shop, just ask them for the tubing. Most will have carbon steel, if they have galvanized don't buy it. it's like the metal tube that is used to make fences.
If you're going to be using SMAW/MIG then do what was stated above. Because the exhaust won't have weight on it preferred method is vertical down "Z" motions; very simple to do and control also less chance to blow a hole in your metal.
If you're taking the whole exhaust system off, set your exhaust on a stand where it's stable and you can do the sideways " J" motion.
75 aragon 25 oxygen mix would be ideal unless you're going to use pulse MIG then go with 90/10.


Simple steps to get through this project would be. Tac weld your tubing/CATS in place, around four tacs to make it a little easier. Tac in opposite sides to avoid the tubing/CAT from warping to a set direction. Once you have all your tacs in place, run a straight pass from tac to tac. Once you've played that first pass and it cools down, then go over it from tac to tac with the vertical down " Z" motion to give it a cap layer.

150-180 AMPS is your working range.
Making adjustments, always adjust one at a time wire speed or amps.

Anyone feel free to correct me or add on to this.

Hope it helps!

You're not gonna want to use oxygen, CO2 would be a better bet for you.

[32drewsalazar]

All advice above has been spot on. Except for Mig welds being ugly, tig welds can be the best looking if done by someone with the appropriate experience, but can be very messy if done by an amateur. Mig welding is the most common type of welding associated with anything automotive and is very attractive and strong if done properly. As mentioned, don't do anything with flux core if your concerned about appearance, its a dirty weld and also doesn't have the penetration of a gas fed shield. You don't have to use the more expensive Argon or Argon mixes, C02 does the trick and is cheaper. As far as the machine, stay away from Harbor Freight and the cheap overseas built welders, HF tools have their place, complex electrical tools aren't one of them. I am a big fan of Miller, lots of choices for different applications and they last forever, we have 7 different machines in the shop 3 of which are almost 20 years old and still used everyday. As far as your first project being cats, I would strongly advise against this. You very well may be looking at one of the more difficult welding projects on a car when your talking about cats on a European car. Pipe is already a difficult thing to weld if you don't have experience because it is round and more difficult to follow with the lead, ever spray painted a bicycle? It's similar in it is difficult to keep you paint spray even on a tube VS. a flat surface. Also you don't want any leaks in the cats. Besides the obvious exhaust leaks being annoying and potentially dangerous, even small leaks in the welds can change the effectiveness of the correction values of the catalyst specifically to the NOX. A good suggestion already made above is to go to a local muffler shop and ask for some scrap, we throw away lots of remnant tubing that is great practice material. Good luck!

Getting some practice is a good idea, not to beat a dead horse or anything but a little practice goes a long way. Another suggestion try stick welding first it is an old school method but it is by far simpler and is a great way to learn the basics and fundamentals. My grand father was a certified welder in the Air Force and taught me everything I know on a stick welder...

Just a thought

[DaleCarter]

My teacher, a machinist by day and vintage airplane restorer by night, is teaching me to gas (Ox/Acetylene) weld first. He explained that gas welding is the same as TIG, but using a gas flame instead of a plasma arc. He explained how learning this way would lay a solid foundation in basic techniques and I trust him. I watched him weld a patch on a race car header using my dinky little "plumber rig" and a coat-hanger for a rod. As he progressed he told me we would see a "fusion weld" very soon and, of course, he was right.

Turns out that welding, like driving a road racing car or playing a bass (which he is top flight), is more about the "arrow" than the "indian". That said, a quality Miller or Lincoln rig, with proper gas, DOES make things easier :-)

I will echo the advice to practice, practice, practice... then practice some more.

[WeldLife88]

+1 on using TIG, yes you can get quality welds on exhuast using GMAW.. especially a pulse capable machine(great on thinner materials) however TIG welding allows you to control heat input, filler wire etc..when done right..it's beautiful especially stainless. As others have correctly stated pls practice on scrap 1st! Then when u think you've got the hang of it ...practice some more

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