SS welding question for Zap et al

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I have to weld a bunch of (80') track for a rolling cabana out of 316l The track is 3/16" x 3 and in the center I am welding a 3/4" solid round bar. I only need welds every 12 -18" along the length. I experimented with a few different ways to weld it, as well as a few different processes to see what was the best I could produce with my equipment. I Tried MIG using .035 316 wire, in the groove (fillet), as well as TIG using 3/32 filler, and stick using 3/32 rod. I also tried punching the flat bar and plug welding. The TIG fillet was the best followed by the stick fillet. The thing I didn't like about the stick fillet was the clean up. So I settled on TIG using my Sync 180SD, 3/32 ceriated tungsten and 3/32 316L filler doing the fillet weld. For the test piece I just put it in the vise, but the track pieces are 12' long. I was considering clamping them to a 6" WF that I have  and just setting it up on the bench. It is very convenient to turn the groove up, so that I am welding in the flat position, but I am unsure if welding all one side, then flipping the WF over and welding the other side is going to work well without creating a curve in thte piece. Is that possible, or should I leave the WF flat on the table and do one side then the other, orweld on one side, skip 12" weld on the other while the first weld cools then come back and weld the opposite side? I don't normally weld a lot of SS, but can (and do a respectable job), I am doing this for one of my best customers as part of a much bigger steel project. Thanks for the help.
Reply:A picture or quick sketch of what the profile is to look like, helps a bunch.IOW-does the .75 round rest on the top of the 3/16" edge or is the roundto run along the center of the 3" flat.....or is it none of the above???What is the finished straightness requirement for form, fit  and function?.....and how is this checked?Welding on one side--then hoping to flip and weld the other side--especially in SS--don't work.Heat straightening is a poor last resort, when distortion control via pre-stressing addresses the problem before the fact.Blackbird
Reply:The flat bar lays flat on the ground (horizontal), the 3/4" round bar sits in the middle of the flat bar. It forms a sort of railroad track. The flat bar also gets holes in each side to screw down to the ground. So, at each set of welds (1"ish long, one on either side of the round bar) should I place a small shim under the flat bar in the middle and clamp both sides down?
Reply:Originally Posted by walkerThe flat bar lays flat on the ground (horizontal), the 3/4" round bar sits in the middle of the flat bar. It forms a sort of railroad track. The flat bar also gets holes in each side to screw down to the ground. So, at each set of welds (1"ish long, one on either side of the round bar) should I place a small shim under the flat bar in the middle and clamp both sides down?
Reply:So, weld one side, skip ahead 6" and weld the other side,zig zagging back and forth for the length?
Reply:As always, many different ways to skin a cat....So, if I'm understanding this right you've got roughly 160x 3" welds to complete?IMHO TIG isn't the right process for this job, apart from it being painfully slow, you'll also put alot of heat into the material and have more distorsion to worry about.We can all spend all day making pretty beads with TIG, but if you want to make any money from the job (I'm guessing that's why you're in business?) then I'd 100% use MAG. As for distorsion, either clamp the flat bar to the bench with a filler rod across the middle to pre set it, or drill out some channel and bolt the flat bar to that, again with a TIG filler rod in the middle, whatever's easier.Personally, I'd lay it flat on the bench and weld opposing sides, probably weld the end ones first, then the middle one, then work my way out from the centre.Last edited by Baila La Pinza; 09-28-2011 at 05:35 AM.Reason: more info
Reply:Originally Posted by walkerThe flat bar lays flat on the ground (horizontal), the 3/4" round bar sits in the middle of the flat bar. It forms a sort of railroad track. The flat bar also gets holes in each side to screw down to the ground. So, at each set of welds (1"ish long, one on either side of the round bar) should I place a small shim under the flat bar in the middle and clamp both sides down?
Reply:Dave, ya pretty much nailed it on the head! It is set up like a v groove roller. On one side I will leave the wheels able to slide on the axle so that it won't bind. As far as total tolerance I could probably do +- 1/8" widthwise and not be too bad off. As far as up and down, I don't know. I will be able to shim things straight, but would just like it as flat as possible to ease the burden of trying to true it up when installing. "If this is some architect's pipe dream, now's the time to raise the flag", It is, and that's funny! I did raise the flag, but they still want to go ahead.
Reply:Is the track going to be anchored to the ground in some fashion?  If so, I wouldn't be very concerned with distortion if you can just bolt it flat.Also, MIG is 100% the way to go here.  Much faster, with lower heat input (less warping) means more money in your pocket and a happy customer.Have we all gone mad?
Reply:Originally Posted by walkerDave, ya pretty much nailed it on the head! It is set up like a v groove roller. On one side I will leave the wheels able to slide on the axle so that it won't bind. As far as total tolerance I could probably do +- 1/8" widthwise and not be too bad off. As far as up and down, I don't know. I will be able to shim things straight, but would just like it as flat as possible to ease the burden of trying to true it up when installing. "If this is some architect's pipe dream, now's the time to raise the flag", It is, and that's funny! I did raise the flag, but they still want to go ahead.
Reply:Thanks DSW. Yes I am doing the install as well. Fortunately I was there when they were putting up the gunnite walls and was able to steer it a little and correct some bad errors before they actually shot it. The cabana weighs in at 12,000 pounds, split in two sections, so 6 grand apiece. It is supposed to hav a gear motor drive on it, but I have not seen the mechanical drawing yet. I have experienced the bus, and have found a nice indent in the asphalt to lie in while it drives past.
Reply:The kind of loads you are looking at and the word "gunnite" wants to make me run away as fast as I can. I doubt that indent in the asphalt is deep enough to cover your azz from the bus.I've yet to see a gunnite guy who even knew what a level was. "Flat" wasn't even in their vocabulary.In this case I might even want to think about doing the whole job on site. Set your flat bar straight and level, shim grout and secure as needed. Then mig the round stock in place using the anchored flat stock to help reduce warpage going from side to side alternating as you go down the length making corrections as you go to keep the whole thing as straight and level as possible. The up side is that chances are you will get the least amount of distortion since the base is firmly " clamped" when you anchor it. ( be sure to let the grout dry before welding) The downside besides the need to work onsite and it's weather related issues, is that if something shifts radically for some reason. it will be harder to correct. If you are careful I don't see that as being a big issue however..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:The gunnite walls were engineered for the load, and I was able to check the level of the form before they shot it, so I am not so I don't have a huge amount of worry, just a lot.
Reply:Originally Posted by walkerThe gunnite walls were engineered for the load, and I was able to check the level of the form before they shot it, so I am not so I don't have a huge amount of worry, just a lot.