Buying a Mig welder

[Brian5475E]

Well I decided to buy a mig welder. I guess I"m gonna build my own exhaust header, and full exhaust. and a strut bar. I think the Aveo can benifit from a exhaust header. Hard part will be making the flange. Guess I can use my cutting torch, and smooth the cuts with a dremel tool? where can you get flat steel. I don't thik they have that at home depot

[AcingTeam]

Well I decided to buy a mig welder. I guess I"m gonna build my own exhaust header, and full exhaust. and a strut bar. I think the Aveo can benifit from a exhaust header. Hard part will be making the flange. Guess I can use my cutting torch, and smooth the cuts with a dremel tool? where can you get flat steel. I don't thik they have that at home depot

Can't you use stock flange and just weld it together?

[daewooluvr]

Use a plasma cutter to make the flange. As for the flat steel, I'm not sure.

[TheGreatAndPowerfulOz]

Do you have a metal yard near you?
There is one not far from me and I can get just about any type of metal, in just about any shape, thickness or size.
Even better, my dad is friends with the owner.

[PrecisionBoost]

If you think that it's going to be as easy as "I'll just buy a Mig welder and make it myself" you are in for a big surprize.

First off.... welding a flange will warp your flat plate unless you follow a very specific technique of welding..... ideally to do it right you would have to bolt it down to a nice thick flat surface with the same bolt pattern.

Then you would weld about 1/4" of material on one side.... then move to 180 degrees to the exact oposite side and weld 1/4" and then move 90 degrees and weld another 1/4" and then move 180 to the other side and weld 1/4"

This makes sure that you don't concentrate the heat on one side.... this technique is also used in autobody so as to keep the sheet metal from warping.

If you are a beginner you will end up with a big mess.... especially if you buy one of those cheap "handyman" mig welders at the local Home Depot.

If you want it done right your going to need to spend several thousand on a welding machine.

Even after following all these steps you still might need to get the surface milled at a machine shop to make it flat.

Cutting the flange with a torch is absolutely out of the question.... it will warp the hell out of the flange (making it completely useless )

Even a plasma cutter might be questionable..... you would be better off purchasing a bimetal hole saw and cutting it out on a drill press (use lots of cutting fluid and take breaks to ensure that you don't overheat the plate or hole saw )

Flat steel can be purchased over EBAY very easily.... just look for someone in your area.

If you really want a decent job you should find yourself a metal fabrication place and ask them to do it for you.

It might cost you a few bucks but then again you were planning on buying a Mig Welder so it's probably going to be comparable money wise.

Another thing to consider is how your going to bend your header tubing.... simply throwing it into a pipe bender won't work very well.... you will get crushed spots in the radius and your tubing will not be circular ( more like an oval shape )

The worst part is the collector where all the pipes meet..... it's very time consuming to make a decent one.

My opinion is that you would be far better off by simply modifying your cast factory manifold ( light porting and polishing... perhaps extrude honing might be a good idea )

You will gain way more power by changing out the rest of your exhaust to a mandrel bent system than you would by adding a header.

Oh..... if you do manage to make your own header make absolutely sure that you make the holes for the bolts slightly larger..... the manifold will expand quite a bit and tight holes will result in shearing off bolts within a few days weeks or months.

I can't remember what the rule of thumb is for sizing.... if your using mild steel I think that you only have to oversize it by 1/64 but if you making it out of stainless you might need more than that ( say 1/32 )

[Brian5475E]

I know how to weld. No problem there. I can buy a collector online for it. I'm buying SS U bends. So no crushed bends, Oh yeah the Aveo already has mandrel bend on the stock exhaust. Assembly of the runners won't be a problem for me, I've done a lot of exhaust over the years. The only problem I would have is making the flange.I guess I would have to start with a round hole saw, then bore out the oval shape. I'm not planning on a quicky job. I will do it right. It's a 100 amp mig welder. you don't need a mega expensive welder to do this. I've welded up many exhausts with a standard 100 amp wire feed mig. Just have to know what you are doing.

[DomWoo]

i found it easyer to use bi-metal holesaws to cut the flag.. unless your using a computer plasma cutter, almost all headers are not welded with a mig welder.. they are welded with a TIG welder because ... well its just night and day between the two. the biggest problem is when a mig welders welds it usually messy and has little holes

i think it woudl be easiest for you to buy a header with the same pipe spacing as the aveo then cut them off the flang and weld on the new one

[Brian5475E]

yeah maybe. closest I found to the Aveo setup is a Honda b16.