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I am attempting to weld up my first bridge. It is going to be made out of 1/2x1/2x16 gauge steel. I don't have a wire feed. So I am wondering if anyone has tried welding with acetylene on this gauge before?. I am concermed with it warping too bad. Other wise I am going to stick weld it.  I am better with the torch so I thought I would ask if anyone had any insight?
 

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I have never welded anything in my live but for a while was into custom pickup trucks. It is my understanding that if you get the sheet metal to hot it will warp. So the way I was told they do it is to tack weld the pieces in place with just a couple of welds and let it cool. After it is cold go back and tack weld it again in other places. Let it cool and go back and do it again until it is tack welded about every half inch. Then go ahead an weld it all up. I've had tailgate covers add to puckup tailgates as thin as 18 gauge without any visable problems.
 

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Gas welding..wow!! I haven't done that for over 20 years..last time was on a airplane frame we were rebuilding.


If you don't have a mig welder with that small of stuff then I'd use the stick welder with 1/16 rods...they're really small but they will weld that stuff just fine...it will all depend on your welding talent. The only problem will be seeing where to weld because by the time you close the welding hood and strike an arc and your eyes adjust to see where the elecrode is in relation to the work the welding will be over or burned thru. Practice a bit and you will master it though..:D 
 

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Personally,I think you will have alot more warpage with the arc welder then the gas. RPC, has the right idea, you need to alternate your welds to spread out the heat throughout the structure. So if you weld on the front right corner, you want to move to the back left corner, etc. Metal can and will do strange things when heated and no amount of clamping will prevent warpage if it wants to. I used to build wrought iron gates for a living and built thousands of gates while I worked there. I've built very large gates that required alot of welding and they came out perfect and then built a twin of the first and it twisted and warped like crazy. I really believe it is something in the metal that predetermines whether it will warp or not!

The other option is to check with your local rental center and see about renting a MIG welder. All you need is a Lincoln Weldpac 100 or similiar. These are little 120 volt flux cored wire feed welders.

Steve
 

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I agree with Steve on the Weldpac 100. Another option might be contacting an industrial arts teacher at a local high school or vo-tech if one is nearby. Most of the time they will jump on a new project, and telling them your building a railroad bridge just might do the trick. Just a thought.

Chuck
 

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I don't see why you couldn't braize it...just make sure that you localize the heat to prevent distortion, as well as use good flux & braizing rods.


I've got a 110V wire-feed welder and I've welded sheet metal as thin as 20gauge...but I've had to make many many small tack-welds, as described above.


AND, whatever welding you do, go get a self-darkening hood.  I've got a Craftsman model, and what a difference!!!  I can see just fine when positioning the wire or welding rod, and it darkens instantly, so no "spots" in my vision!  It goes back to normal in a fraction of a second, so I can see what I've done (or missed).  Self-darkening hoods are worth their weight in gold, I guarantee it!!
 

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Chuck and Warren,
Thanks for bringing up those excellent points. I had actually planned to mention those in my original post but got caught up with the warpage control and forgot!

ANY TIME you are welding on something that is thin or lightweight material you want to use the alternating welds method I described above and then when you are doing the final welds you want to do stitch welds. Stitch welds are just what they sound like, short welds alternating with open spaces that end up looking like stitching on clothing.

Steve
 

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If using gas welding on angle and other type structual shape steel, you can take cloth towels soaked in water and place around the steel close to your welds, and as the heat flows away from the welded area, the wet towels will reduce the heat flow, Be sure and use care when handling the wet towels after the weld is completed because they will be hot, This technique works well anytime heat transfer can cause problems with most any types of welding, such as welding close to wiring or other fragile material. Brazing can produce very rewarding results, try to always hold torch so the flame flows up the rod, flux coated rods work well, I also keep a can of powder flux to dip the rod in if needed. With that thin of material use small diameter rods 1/16 or 3/32. Good luck, and practice on a few pieces before going to the real parts.


Dennis
 

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When it comes to doing a large amount of welding on the thin stuff , I usually use my TIG but for small tack ares a MIG will do fine. As far as heat distorsion goes what I use is aluminum flat bar clamped on opposite sides just a couple of inches on both sides of the metal of the joint . now it wont take alot of aluminum  just some small pcs. of scrap about 1/4 thick and anything from 2 inches in length or better to act as a heat sinc and draw the heat to the aluminum because it disapates the heat alot faster than letting the steel cool naturally. using water is sometimes not always a good idea either it be on rags or out of the tap as it tends to fracture the welded areas especially in oxy acet welding.
A good budget MIG welder can be found at Northern Tool or on Ebay I personally recomend the Clarke 130 EN wire feeder it come dang neared ready to weld rigth out of the box and is a great little 110v welder , you can use it with or without mix gas, it weld aluminum GREAT. anyways hope this helps
Take care
Ben
 

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Lots of good advice here from some knowledgeable people.  But, I am guessing people did not notice really that you are intending to weld very narrow strips.  You haven't said if your intention is to weld the narrow ends together or if you are trying to weld them along the long edges.  I think that can make a difference in our advice.  First thing tho is I am wondering why you want to work with such thin metal.  An idea of what kind of a bridge your building would help.  Seems to me like .0625 cold rolled steel might suit you better and be easier to weld and it comes in 1/2" wide strips.
If you have the right kind of torch it is easy to weld this small stuff.  The popular Lil' Torch is a good one to do small stuff and Victor makes a miniature torch too.  These are usually used to solder jewelery and silver soldering but will heat metal enough to weld them.  I know, I do it all the time in my sculpture work.
 

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Discussion Starter #12
I just stick welded it and filled in with solder. I then used a bed liner paint to finish it off. Here it is:
 
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