figured i'd ask before i buy some scrap tube to experiment. i have a downpipe that needs to be sized on the car to finish, just no way to fit it and run down the street to tig UNLESS i use my trusty lincoln ac225. so, the question is

1. should i attempt to do complete welds with 308 or 309 rods

or

2. tack it with the stick and run down the street to my fab master neighbor with the syncrowave

this seem like a silly question? it probably is, i just haven't ever tried to stick stainless before. weld strength is the other concern

 

Line it up, use sharpy to mark the position of the tubes and then bring it to him to tack?

 

you can do it! i have that exact welder, and did the same thing. i use 309 rod, although 308 should be fine too, amperage set at 75amps, its not as bad as you would think. i really dont even feel like had to move that fast either.

 

Probably would work, however the person welding won't thank you for it.

Prep is 90% of the job, when people bring there own jobs in i'm never happy with the prep so the welding ends up costing more and the job isn't as good.

 

I cut a stainless bmw muffler in half, changed some of the baffles and welded it back together. Worked perfect and didn't look half bad either.

If you tack it just make sure the flux is cleaned off before tig welding it.

 

i would say cut/shape the DP as needed on the car. use tape to hold the pieces together to make sure everything is where you want it. use a scribe to mark the pieces going together in 3 places around the seam, and add a number or letter to each piece to signify which piece goes where, that way the guy welding it will know what goes where so it doesn't get screwed up. as others said, prep is 90% of the job. if you throw some tacks on it, he is going to have to take it back apart and clean it to ensure that where the tack was isn't a weak point. so just mark it up as needed, and give it to him to do all of the welding

 

x2

its always a pain in the *** to prep.

 

it's all brand new metal. i'll see how it goes with the tape and sharpie, only tack if necessary. if i do i'll give that a go with 75 amps and 309 rod