Novice here to get some general help and tips

[livelyjay]

I'm an automotive enthusiast and I have a small project car that I've been working on to learn everything I can from maintenance to rebuilding an engine. I just swapped in a new engine and transmission and now I need to build an exhaust system. I took an 8 hour MIG welding class that went over the basics of welding and we practiced some basic joints on mild steel. My exhaust system will be a combination of metals and I'm going to need some help putting everything together.

So far welding has been pretty fun and I can see the usefulness and how I'll probably never be able to master this art form, but with your help I might be able to finish up some projects down the road.

[wb4rt]

Hi, Livelyjay.
Welcome to the forum. You can add your location to your profile so if someone is close to you, they may be able to help you.
Post some pictures and ask questions.

[livelyjay]

Done.

My co-worker will be letting me borrow his Lincoln MIG welder. I picked up stainless T309 .030 welding wire from the supply store and the retailer made some comments that concerned me. The project is indeed not ideal for a beginner. I'm not looking for pretty welds, since this is not a show car. I just want to make sure I'm doing things right so my exhaust system doesn't fall apart on the track.

Downpipe = mild steel
Flex pipe, 180 bends, straight pipe, muffler = T409 stainless
Resonator, V-band clamp flanges = T304 stainless

All the material is 16 gauge from what I can tell, but I can measure everything with a caliper to get a more precise measurement if it will help you to help me. The retailer sold me T309 wire because he said it should work best for all three materials, but he said welding T409 is a pain. Is that true? He also said I need tri-gas for this project as well. Could I empty an Argon/CO2 cylinder and fill it with tri-gas, or do I need to buy a separate cylinder?

Picture of the supplies, disregard the OEM exhaust system at the top.

[DSW]

If all you are doing is looking to "glue" the pieces together, you can probably make do with what you have. The joints won't be as corrosion resistant however as they could be and will be more prone to cracking and premature weld failure. My bet is your welds will fail due to lack of experience and skill before the weld material itself causes issues.

My supplier can supply me with small cylinders of trimix with advanced notice. He doesn't keep all sizes in stock and might need a weeks notice to get the size cylinder I need filled and shipped in. However many times the cost of getting a small cylinder filled is almost as much as just getting a full sized cylinder, so many times it's not cost effective to get special gasses.

Note that welding round pipe or tube is much more difficult than welding flat plate. You need to constantly keep changing the gun angle in relation to the surface where you are welding. Also round pipe usually means you have to weld out of position. Often transitioning from overhead to vertical and then finally flat at the same time you are changing the gun angle. Add to this that you will probably have to weld some of this under the car while laying on your back in an awkward position.

I would strongly suggest you do a lot of practice with "scrap" before doing the actual job. Practice some on the bench, then tack the pieces up under the bench and try to weld them while you lay on your back. Keep in mind with stuff like this fit up is key. if you have big gaps, you will have a nightmare to deal with and make it even harder to do.

I'd be real surprised if most of this is 16 ga. I'd expect it to be thinner myself. The thinner it is, the harder it will be to weld. Your best bet will be to do socket welds where you flare one piece and insert the other and weld the lap joint where the two meet. trying to do but joints on thin material out of position under the car will be tough. Investing in a tail pipe expander will probably be money well spent.

[livelyjay]

The 5' tube you see in my picture is pretty much all spare material. The total exhaust length isn't long because the total length of the car is 166.5". The downpipe is already built out of mild steel and the entire exhaust system will be three pieces, so I shouldn't have to do too much under the car outside of tacking pieces in place.

I plan on cutting off pieces of the long straight tube, tacking, then attempting to weld them together. Rinse and repeat until I get a decent feel for it, which might not be ever. I don't have a tube expander, but I'm pretty sure I can find someone who can do it for me for minimal cost.

I'll measure the wall thickness of my materials and post them up. I looked up some videos of welding thin exhaust tube and a few of them just showed tacking little by little all the way around the tube instead of doing a continuous weld. Is this method recommended?

[livelyjay]

So I have some general measurements of my materials:
Flex Pipe = 18 gauge T409
Muffler = 18 gauge T409
Resonator = 19 gauge T304
180s = 16 gauge T409
Straight Pipe = 14 gauge T409

[livelyjay]

My coworker brought in his MIG for me and I set it up last night. I played around with the settings on some scrap from my MIG class. It's about .15" thick, so it's between 1/8 and 3/16 mild steel, and not the cleanest steel either. First bead wasn't hot enough so I got the heat up higher and started playing with wire speed. Below are some photos of my work. Please make some comments and let me know how to improve.

One thing right off, when I can feel the wire catching, what does that mean? Too cold, too fat wire, too fast technique?

First weld with this setup, butt joint (mostly, there was some metal overlap), not hot enough


Some end joint practice, second attempt was a little better



Playing with some of the welder settings

[DSW]

[QUOTE=livelyjay;1603591]My coworker brought in his MIG for me and I set it up last night. I played around with the settings on some scrap from my MIG class. It's about .15" thick, so it's between 1/8 and 3/16 mild steel, and not the cleanest steel either. First bead wasn't hot enough so I got the heat up higher and started playing with wire speed. Below are some photos of my work. Please make some comments and let me know how to improve.

One thing right off, when I can feel the wire catching, what does that mean? Too cold, too fat wire, too fast technique?


1st please resize your picts 1st. This forum cuts off text if the picts exceed the max size. It makes it tough to read your post that way.

Knowing what machine you were using and what the settings were would help. Most machines have a suggested setting for different material thicknesses under the wire feed door. Start there. Remember, the more info we have, the better we can answer your questions and help.


Not sure what exactly you mean when you say the wire was "catching". If your wire speed is too fast, you will feel the wire stubbing into the plate thru the puddle before it can arc and melt back. Usually the gun feels like it is "bouncing a bit, or it feels like the gun wants to push away. If the wire isn't feeding smoothly, your feed will be erratic. One of the causes is if the wire is binding in the liner. Any number of reasons this might happen, wrong size wire/liner combo, dirty liner, kinked liner, gun lead making to many tight turns, just to name a few.


To me all these beads look cold and could use more heat. Knowing your machine and settings, I might be able to make a suggestion other than crank up the voltage more. If this is a small 110v mig like I think, on 1/8" material, you will want to be on max for your heat most likely, and adjust wire from there. Your push beads look the best, and the three beads of the long "push" one shows decent consistency for a newer welder.

[livelyjay]

This forum will not allow me to edit my old posts to update with resized pictures. So from now on I'll post smaller sized photos. I deleted the old photos so they'll show up as [X] and fix the text. Otherwise a moderator might have to get involved and fix it.

You pretty much answered my initial concerns though, as shown below. This weekend I'm going to do some additional practice on some thinner flat plate. The plate in the pictures is 5/32 as the caliper showed .155 inches, where my other scrap is closer to 1/8". Also this weekend I'll pull the downpipe off of the car. It has about 6-8" of material that I'm going to cut off, so I'm going to practice on it before I cut it off. I'll use a die grinder and cut slits into the pipe and weld it back together. Then I'll cut off smaller full sections and try to weld it back on. Then if/when I'm ready I'll cut off the full section and get to the real work.

Originally Posted by DSW

Knowing what machine you were using and what the settings were would help. Most machines have a suggested setting for different material thicknesses under the wire feed door. Start there. Remember, the more info we have, the better we can answer your questions and help.

The machine is cheap, not a name brand like Miller or Lincoln. I'll get the make, model, etc when I get home but I'm pretty sure it's a 110v. It plugs into a regular household outlet. It does have suggested settings in the manual, and I found that on this metal the hottest setting felt like it was working better. There are four heat settings and the wire speed is a "clock" setting, so it doesn't have the normal settings I have seen on this forum.

Originally Posted by DSW

If your wire speed is too fast, you will feel the wire stubbing into the plate thru the puddle before it can arc and melt back. Usually the gun feels like it is "bouncing a bit, or it feels like the gun wants to push away.

This is exactly what was happening. Thanks for clarifying what was causing that feeling.

Originally Posted by DSW

Your push beads look the best, and the three beads of the long "push" one shows decent consistency for a newer welder.

I think just how I had the rig set up I was more comfortable pushing, at least on flat plate. During class I felt more comfortable pulling, but that might have also just been how the welding station was set up.

[livelyjay]

Welder is set up a lot like the Lincoln Electric K2185, only it is 110 and not 115. Four heat settings 1/2 on first switch, min/max on second switch. Wire feed has no numbers and the instructions just say clock position.

So here's my first attempt at the real work. I cut some slits in the pipe with a die grinder and attempted to weld them back into place. I then used a pipe cutter and sliced off 1" off the end and attempted to weld it back on. Picture captions explain what I was doing. Pipe is about 15 gauge, .065" thick mild steel.

Gap fill #1, heat setting #1, wire feed at 12



Gap fill #2, heat setting #2, wire feed at 12, tried pull at top, push at bottom



Wider gaps, same MIG settings, big time fail

[livelyjay]

Butt joint: A = heat #1 B = heat #2
Inside tube picture, A would be on the right, B is on the left



Butt joint: C = heat #1 faster weld D = heat #2 faster weld
Inside tube picture, no burn through visible



Butt joint: E = longer continuous weld F = bad position continue of E
Inside tube picture, no burn through visible



Butt joint: G = better position continuous weld, tried to move at a decent speed
Inside tube picture, very slight burn through

[livelyjay]

Here's my first attempt at just welding all the way around the tube. I'm definitely more consistent with technique from about 11 o'clock to 2 o'clock positions. I made it around with 6 welds. I hit the thing with a BFH afterwards and the pipe didn't break off, so that's a positive right?

Please provide feedback on technique and settings. MIG was set to heat #2, wire speed at 12o'clock.

Only burn through was when I first started

[livelyjay]

Here's my latest effort. I tried the "T" technique on some flat scrap and it worked out pretty well. I did a final practice run on the pipe (at the top of the pipe in the pictures) and took a shot at the first real weld.

All advice would be greatly appreciated.

Trying "T" technique on some 1/8" flat scrap


Final practice on pipe. "E" technique on both, first looks like blob, second has a better layered look



Flex pipe welded, was a lap joint since it fit over the other pipe

[weldbay]

309 is not a bad choice for dissimilar metals, 312 is better, 75/25 will work but the whetting will not be as good and neither will the color. You look like you are getting the hang of it. Since welding pipe is in deed an all position affair. Mount the system on stands and have a friend turn the pipe so you can always stay in a comfortable position, or turn it your self.

Tack first!

[livelyjay]

The guys at the welding supply shop recommended 309 for what I was doing, and was also kind of a jerk about my project since I'm a noob. They didn't have a huge variety of stainless wire either and I'm almost positive I didn't see 312. Coloring is of no concern, this is not a show car. I just want to make sure my exhaust isn't going to fall off of the car right away.

I also noticed the carbon steel wire is .020", which isn't recommended for these thicker gauges. It seemed to work ok, but the stainless wire I got is .030 and it looks huge in comparison.

Thanks for the tips. When I was welding the pipe pieces I tacked at positions 12, 6, 3, and then 9. Then I attempted to connect the dots. I went around in a straight line connecting the dots. Would it be better if I did opposite sides to prevent distortion?

I'm going to look at a welding table someone it selling which is taller than what I'm working with now and is all metal, so the ground cable won't be in the way. I like your idea of building some sort of jig for the pipe. I think I have a good idea of what I could do to make this project a lot easier. Thanks for the advice.

[livelyjay]

I could use some help with stainless steel welding. Here's the situation:

Before: 16 gauge mild steel tube, .20 carbon steel wire, Argon 75/25. I set the machine to power level 3, wire feeding setting at 11-12 o'clock and it seemed to work fine.
After: 14 gauge T409 stainless tube, .30 T304 stainless wire, Argo 75/25. Same settings and I was burning right through the tube. I settled on power level 2 and wire feed at 9 o'clock.

The "T" technique to get the stack of dimes that I was having some success with before did not work well and I burned right through the butt joint. I ended up just weaving a "U" shape back and forth and that seemed to get me a balanced bead and there's a just a slight burn through visible on the inside of the tube. I didn't have a chance to try the lower case "e" because my tube cutter broke (a better one is en route).

Should I try the cursive lower case "e"? Should I not even worry about it and just use the "U"? Pictures below.

Top 1" is T409, rest is mild steel