Need advice for welding exhaust

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I need some advice on doing some exhaust system welding for a friend on his project car.  He has the pipes all cut and laid out, marked for the correct positioning etc.  Everything is new/clean and all of the welding will be done off the car on the garage floor. At first I thought he was just going to have me weld on some hanger brackets for the exhaust but he showed me some pictures and now it looks like it will be much more involved.  It looks like about 2 1/2 inch pipe (mild steel) and he says it is all 16 gauge.  He is not concerned about having pretty welds but just that it holds together and of course it would have to be sealed up.  As it turns out there will be about 10 pipe-to-pipe welds (all the way around the circumference of thep pipe) and about half a dozen brackets.  Some of the welds will be butt-welds and others are lap welds where he currently has clamps but would like to remove them in favor of a welded joint.At this time, all I have available to me is an AC/DC buzz-box so it will have to be stick welded.  I asked for some scrap pieces of pipe so I can get my technique down and see if it meets his standards.  My main concern is trying to avoid burn-through.Any advice on technique, electrodes and settings would be appreciated.  I have a lot of 3/32" 6013 on hand and a little 1/16" 6013 but haven't used the smaller stuff much.  If something else would work better, let me know and I can go out and get some.I was thinking of first tacking the butt welded sections together with a small gap (what size is optimal?) and then welding starting off horizontal and moving downhill at a pretty good rate of speed and a 60-degree drag angle welding one quadrant of the pipe at a time.  The next weld would be again starting at the top near the start of the first weld and welding down to complete the next quadrant.  Then flip the assembly over to repeat on the other side.So, with that, any alternate methods, electrodes, settings (amps, polarity, etc) and anything other helpful tips would be appreciated.  Also, does this sound like a one- or two-case of beer job?
Reply:Originally Posted by IrishBrewerI was thinking of first tacking the butt welded sections together with a small gap (what size is optimal?) and then welding starting off horizontal and moving downhill at a pretty good rate of speed and a 60-degree drag angle welding one quadrant of the pipe at a time.
Reply:If I can't get decent results with stick, I may be able to borrow a 115 Lincoln MIG which would be ideal for the job.  But at this point, I'd like to give it a shot with my stick if at all possible.  Some of the subassemblies may lend themselves to a positoner (i.e, the car's owner) but once you start putting them together, the thing may be a bit unwieldy to rotate in a steady, uniform fashion to be workable.  As such, most of the welds will be made in segments.
Reply:Borrow the MIG! I have stick welded exhaust, it sucks.  If you can get a MIG, it will be beautiful and strong.NO gap, This aint schedule 80 pipe.  If you could make them all lap welds it would be much nicer.I weld a lot of them with my SP100 and C/25.  There is no better way.Here is a pic of 110v MIG and some 1/16" 6013, DCEN 40 something ampsand here is the stick.  I have been welding for 30 years, this is the best I could do.  I have not stick welded an exhaust since I bought the SP100 20 years ago.Last edited by David R; 11-12-2007 at 05:29 PM.Real world weldin.  When I grow up I want to be a tig weldor.
Reply:Originally Posted by David R  Borrow the MIG! I have stick welded exhaust, it sucks.  If you can get a MIG, it will be beautiful and strong.NO gap, This aint schedule 80 pipe.  If you could make them all lap welds it would be much nicer.I weld a lot of them with my SP100 and C/25.  There is no better way.
Reply:Yeah you could use an expander.  You only have to expand enough to get a good weld.  So they work pretty good.If you do this and are good at it, there is a pretty good demand for it.  The pics I posted were done on the car on jack stands.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:I have my doubts that an exhaust sytem with that many joints welded on a garage floor is going to fit the car afterward.  With butt joints like that a tiny gap on one side can translate into a huge positional error over a distance of one or two feet.  I have tacked up systems on the car then removed the them and fully welded them only to have the weld pull enough to cause fit issues.  I'm not doubting your abilities, but I just cannot imagine the system will fit well when you're done unless you do it on the car.If you can get a mig welder by all means go that route!  If you have an O/A torch set I would consider that over stick...Jason
Reply:For the joints that are butt welded, I do not have the opportunity to make them lapped because they are already cut to length to be butt welded.  The guy was pretty precice in cutting and positioning the parts to fit properly and there will still be some clamped joints to give some wiggle room in final fitup.I've never welded with a torch so that would be a whole new learning experience for me and I don't have any equipment for that.  My MIG welding experience is pretty minimal and I've only been doing stick (self taught) for about a year.  I do hear that MIG is pretty easy to pick up in comparison.  I think I'll give the stick a try on some test pieces and see what kind of results I can get.  I'll take some pics to share with the group.Thanks for the advice thus far - anyone else with some ideas, go ahead and chime in.
Reply:Originally Posted by IrishBrewerMy MIG welding experience is pretty minimal...  I do hear that MIG is pretty easy to pick up in comparison.
Reply:I did some test welds on some scrap pieces last night and in the end I had decent results.  I started off by using a flap disc to remove the aluminizing in the areas to be welded and followed up with some acetone.Welding the slip jointed pieces was pretty easy.  I used 3/32" 6013.  The only difficulty I had on these is that the pieces that I had had been clamped and at the end the belled end flared out due to the clamping leaving a gap in some areas.  When the gap was wider than the thickness of the electrode, I would have to burn the edge of the outer pipe back to where it was closer to being in contact with the inner pipe.  In other areas, I could get some nice looking welds.  In the burned back areas, it took quite a bit more weld and although it looks sound, it doesn't look as nice.The butt welded joints were a lot trickier.  I tried the 3/32" 6013 electrodes on these joints as well.  This worked fine to tack things up.  When I went to weld the joint, I had to move at a pretty good rate but even so, in some areas I was burning through.  This was with a pretty tight joint - opening less than the thickness of a piece of paper.  You can open up a pretty good hole in a split second.  Some of the holes I was able to fill in without too much effort but I did burn one hole that would have been difficult to fill.So, I tried some 1/16" 6013 that I don't typically like to use because you burn through them so quickly.  With these, I didn't burn through at all and it looked like I was still getting good fusion.  It takes about 6 or 7 sticks just to run around a single joint with one pass.  In some areas the weld looks a little thin so I may end up going two passes.  I may try going back to the 3/32 on the second pass.I took some pics and I'll post them later.
Reply:Originally Posted by IrishBrewerThe only difficulty I had on these is that the pieces that I had had been clamped and at the end the belled end flared out due to the clamping leaving a gap in some areas.  When the gap was wider than the thickness of the electrode, I would have to burn the edge of the outer pipe back to where it was closer to being in contact with the inner pipe.
Reply:This thread is exactly what I needed to read!  I'm looking to do a similar project but for a motorcycle, and I'm in the same boat with arc being my weapon of choise.Could you (or somebody) give a reccomendation on what amperage to use for say the 1/16 6013 rod?  What setting did you use on the 3/32 that it burnt through?This thread is PERFECT.
Reply:Micah,I recorded the settings but these will be be welder dependent.  At any rate, when I get a chance, I'll let you know where I have mine set.  My recommendation would be to do some test welds and crank it down to where you don't have too much trouble with sticking on the starts and you still get a good bead profile.  Andy,I had the same thoughts on closing up the gap for better fitup prior to welding but I was thinking of maybe reclamping them really close to the end to draw the pipes back together (I considered the BFH as well).As far as heat goes on the 3/32, I may be able to go down a little more but not much without having problems sticking.  I'll try doing more weaving across the joint with the 3/32 to see if I can avoid burnthru.  Problem is that it is hard for a novice to get a good consistent weave going around a relatively small diameter pipe because you have to constantly change your position and the angle of the electrode while weaving at the same time.  Even with stringers, I had lots of stops and starts.
Reply:Originally Posted by IrishBrewerAndy,I had the same thoughts on closing up the gap for better fitup prior to welding but I was thinking of maybe reclamping them really close to the end to draw the pipes back together (I considered the BFH as well).
Reply:The belled joints are a piece of cake in comparison to the butt joints, especially if the mating is good so if I can get them closed up it'll be no problem.The other issue with the belled joints is that since my friend already has them clamped up tight, they are a bear to get apart.  He said for the couple that he had to disassemble he had to cut a slit in the outer pipe to get it apart.  I'll have to weld those slits when I do those joints.
Reply:Originally Posted by IrishBrewerMicah,I recorded the settings but these will be be welder dependent.  At any rate, when I get a chance, I'll let you know where I have mine set.  As far as heat goes on the 3/32, I may be able to go down a little more but not much without having problems sticking.  I'll try doing more weaving across the joint with the 3/32 to see if I can avoid burnthru.  Problem is that it is hard for a novice to get a good consistent weave going around a relatively small diameter pipe because you have to constantly change your position and the angle of the electrode while weaving at the same time.  Even with stringers, I had lots of stops and starts.
Reply:Not to hijack the thread, but how would butt welds finish?  Unlike IrishBrewer I need my joints to disappear and be finished to look like one uniform piece of metal.  Would butt welds do this well or should I consider beveling the edges?I was planning on using flapper wheels, any suggestions?Again, I don't mean to hi-jack the thread, all in the name of sharing knowledge!
Reply:Originally Posted by Micah22Not to hijack the thread, but how would butt welds finish?  Unlike IrishBrewer I need my joints to disappear and be finished to look like one uniform piece of metal.  Would butt welds do this well or should I consider beveling the edges?I was planning on using flapper wheels, any suggestions?Again, I don't mean to hi-jack the thread, all in the name of sharing knowledge!
Reply:Excellent.  I doubted beveling would be needed, but I suspected the small imperfections you reffered to, I'm a perfectionist myself, especially because on a bike its all much more visible.What did you use (or would you recommend) for smoothing out the welds?  Flapper wheels?  What grits?  <- thats my last off topic question I promise. Back to amps for 1/16 6013 rod; IrishBrewer??
Reply:I think I was set at around 40A for the 1/16" with straight polarity (DCEN).  I'll check on that.A flap disc should work fine for grinding the welds smooth.  I would start with something like a 24 grit to take the tops off and work down as you get close to being flush.
Reply:Originally Posted by Micah22What did you use (or would you recommend) for smoothing out the welds?  Flapper wheels?  What grits?
Reply:Glad I stumbled on to such a helpful site.  Thanks guys.The whole system headers to can will be getting high temp flat black paint, chrome is not my flavor I hadn't thought of useing my palm sander rather than a flapper, that might be more cost effective for me... of course in the long run I'm sure I'll need some flapper wheels someday.  I'll see how it goes.Thanks again guys, I'll try to post up pics of what I come up with when I get this project done this winter.Cheers,Micah
Reply:Originally Posted by Micah22Glad I stumbled on to such a helpful site.  Thanks guys.The whole system headers to can will be getting high temp flat black paint, chrome is not my flavor I hadn't thought of useing my palm sander rather than a flapper, that might be more cost effective for me... of course in the long run I'm sure I'll need some flapper wheels someday.  I'll see how it goes.Thanks again guys, I'll try to post up pics of what I come up with when I get this project done this winter.Cheers,Micah
Reply:Today I have to replace a CAT, so I will take the camera along and take some pics.  One end stick,the other MIG.I use 40 amps on 1/16" 6013 DCEN.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:cool... thanks david! i'm really interested to see a GOOD stick weld on exhuast.later,AndyOriginally Posted by Micah22Glad I stumbled on to such a helpful site.  Thanks guys.The whole system headers to can will be getting high temp flat black paint, chrome is not my flavor I hadn't thought of useing my palm sander rather than a flapper, that might be more cost effective for me... of course in the long run I'm sure I'll need some flapper wheels someday.  I'll see how it goes.Thanks again guys, I'll try to post up pics of what I come up with when I get this project done this winter.Cheers,Micah
Reply:Originally Posted by David RToday I have to replace a CAT, so I will take the camera along and take some pics.  One end stick,the other MIG.I use 40 amps on 1/16" 6013 DCEN.David
Reply:Originally Posted by x1riderSorry for the thread jack but you might want to consider TechLine Coatings Black Satin as far as thermal coating goes.  Here is a link to a DIY I posted on another forum regarding an exhaust manifold I coated with that stuff.http://www.audigeeks.com/forums/index.php?topic=2577.0...again, sorry for butting in!
Reply:Originally Posted by aczellerthat manifold turned out pretty nice. i like the silicone trick. you can acutally use DOT 5 brake fluid in a similar fashion... DOT 5 is silicone based so it makes everything shiney. DOT 3, DOT 4, and DOT 5.1 are not silicoe based and will eat through your paint rather quickly. if the 3, 4, or 5.1 fluid is left on long enough, it will actually soak into the base metal and won't let you ever re-paint that spot again. long story from auto tech school taught me that... i won't get into it. anyway, how has the silicone held up so far? i woudl tend to think that it would have burned off with a rather putrid smell by now, but i don't have any proof to back that up. i showed my little brother to use it on his bike, and he uses it like wax... it stops him from using my good, expensive stuff on it.later,Andy
Reply:Originally Posted by David RToday I have to replace a CAT, so I will take the camera along and take some pics.  One end stick,the other MIG.I use 40 amps on 1/16" 6013 DCEN.David
Reply:Originally Posted by David RToday I have to replace a CAT, so I will take the camera along and take some pics.  One end stick,the other MIG.I use 40 amps on 1/16" 6013 DCEN.David
Reply:I welded my exhuast at around 60 amps with 1/8" 6011 on ac. It was all I had and I was trying to route my exhuast to the back on my truck. I basically welded in a straight section where the muffler was (diesel 4") It works fine bit hard to weld.   SOrry its a bit dirty I just hacked of the clamps on the muffler slipped them over a piece of 4" pipe and welded it up. NO leaks in the weld but a small leak past one of the clamps haha.HTP Invertig 201Lincoln Idealarc SP250Miller 180 AC StickBy farmall:They should have held the seagull closer to the work, squeezing evenly for best deposition.
Reply:Originally Posted by IrishBrewerDavid,Do you have a good source for 1/16" 6013?   They stock Lincoln Electric at Lowes/HD in tiny boxes.
Reply:Originally Posted by aczellerwhen i welded mine (i used a self-shielded flux-core welder), i used 15 ga pipe and used no gap, except what was there due to un-even cutting. when you are welding that stuff together use a low amperage setting, and move as the puddle allows you to. it doesn't take much to get the piece hot, and start to form a puddle. i tacked mine, and held it in a vice so it didn't roll anywhere, then jsut weaved back and forth over the joint until i got to a point where i needed to turn it. i was able to get about 1/3-1/2 of the pipe's circumfrance done in one swipe, but i had to turn it due to the vice. if your buddy can roll it at a constant speed for you on the floor, i would get him to do it. that would let you run a continuous bead. i then coated all the pipes and new muffler with 1200 degree paint from DuPont for rust protection. it looks great and i don't have any leaks.as far as payment, i personally don't take food as payment. i prefer cash, but if i did take food, i'd charge about 12 cans of your favorite adult beverage for consumables, and possibly 6-12 more for labor, dependant upon time constraints.later,Andy
Reply:Originally Posted by TubularFabI have my doubts that an exhaust sytem with that many joints welded on a garage floor is going to fit the car afterward.  With butt joints like that a tiny gap on one side can translate into a huge positional error over a distance of one or two feet.  I have tacked up systems on the car then removed the them and fully welded them only to have the weld pull enough to cause fit issues.  I'm not doubting your abilities, but I just cannot imagine the system will fit well when you're done unless you do it on the car.If you can get a mig welder by all means go that route!  If you have an O/A torch set I would consider that over stick...Jason
Reply:OK folks, I did it today.  I had to replace 2 cats in a cheby.  I welded two connections with stick.  THIS IS THE LAST TIME!  I bought the SP100 for stuff like this and I know why.  What a pain in the butt.Here are the pics of stick welds.First is 3/32 6013 DCEN 50 amps.Then I got out the 1/16 rod and turned it down to 40 amps and fixed the stinkin hole.  What a mess, but here ya go.Then I had another connection that was tight and gave it one more shot.Slag onSlag offNever again as long as I have a 110 mig.  I make part of my living doing this stuff, so screwing around with stick is a waste of my time and money. MIG IT!I made another post with the whole job in projects and pictures.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:thanks David... i was kinda curious how bad the burn thru was with the stick. now we know... i agree... if you have the opprtunity to use MIG, do it. later,Andy
Reply:Yeah, I tried to use arc to weld my last muffler job just cause it is easier to setup for me.  I ended up burning holes and making a mess and then ended up breaking out the o/a and cleaning it up.  I love the oxy/acet, I can build up meterial as much as I want and make nice clean welds.That's a VERY nice job on an exhaust pipe posted above!
Reply:Here is a link to 1/16" 6013 for those that dare to use it.  http://store.weldingdepot.com/cgi/we...ot/160062.htmlDavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:Micah,I posted some pics of my technique and results HERE.
Reply:I would avoid a 24 grit on thin pipe. Those things could eat right through. Use a 60 or 80 to start and go down to 120 this is the smoothest I know of www.lawson.com. 3M makes a product called rollok it is basicly a piece of scotch bright on a grinder. If you have air and a cheap die grinder you can get the scotch bright stuff at wallmart and home depot. The brown are rough the maroon are medium and the green are fine and get finer as you use them. The best finish in no time. Steel Thunder Welding LLC. St. Thomas VI USAMM350PBOBCAT 3MAXSTAR 150 STH375 EXTREME PLASMA6.5 HP COMPRESORDEWALT 18, 24, AND 36 VOLTO/A TORCH SETAND SO MUCH MORE I DONT REMEMBERALL IN MY 2005 2500HD EXTENDED CAB L/B