learning more with the TIG

[thingsthatfly2]

started with stainless last night.


easy to weld but not to make look pretty! I anm being told that I should not use filler with stainless this thin.... how does that work without undercut?

the top part was the last of the evening and the bottom was the first. fun stuff! I cant seem to move fast enough down the panel it also does not flow like aluminum or steel. if you get a big lump of filler and you try to walk it down the seam it does not want to do that!

[patman]

looks like you are making good progress Brent! Tig welding can be frustrating making strong welds is one thing but making strong welds that are pretty is a completely different thing. One thing to remember with stainless you can weld it too hot and this changes the structure of the metal and can lead to some problems but for most of what a shaper will do this is not much of a problem. What does the back of your stainless weld look like? is it like the front or is it discolored and have some crusty stuff on the back? You can really take your time on stainless one thing you can try is to mark your your parts every 3/16 with a soap stone (not on the joint) and take a file and put a scratch on your filler rod every 1/8 or so to help establish a your movements and adjust the distance on the part and the rod to get the beads the way you want them to look that's a neat little trick that I learned from a sprintcar chassis builder. Another trick for problem joints is to find a hose clamp that will slip over your cup and weld a little foot to it so you don't have to concentrate so hard on your torch angle, some time look at how nice bungs are in semi tanks look like they are welded in one pass some times a guide is a good thing when you can't win cheat

Pat

[nightperson]

pat are you saying to rest the torch on the foot and just drag it along?

[JPoland]

I am not a welding expert and definitely not on the thin stuff with stainless so take this with a grain of salt. It is pretty much just theory that I have learned.
Some of the vertical weld looks good. Its fine when you get a straw/copper color along the bead but when it turns blue that means that carbide precipitation is starting to occur. Gray or black means that the chromium precipitated out of the base metal and bonded with carbon. This means the corrosion resistance is reduced a lot.
The way to prevent precipitation is to get the puddle to cool as quickly as you can. So moving quickly and filler rod helps (perhaps you got the recommendation of no filler for thin stuff so you can just haul arse?) Also using tacks ahead of time and don't pre-heat. Assuming you are using 300 series stainless then turn your amperage down a bit compared to mild steel.
Bottom line is move quickly and don't hesitate.

Like I said that is my limited knowledge so take it with a grain of salt.

[patman]

Sam that is right but you foot has to be offset so that it doesn't touch the joint, one more way to think of using a guide roll cage & chassis work) you have a piece of tubing right up to your chest and you can reach the next joint but it is not comfortable to hold the torch like a pencil and try to keep your angle right. weld two hose clamps together one for the tig cup and one for the roll bar or chassis part and just slip the one hose clamp around the tube and tighten it so it still moves freely but will not fall off and slip your torch in the other then your angle is fixed by the hose clamp on the tube and the tig cup on either side of the joint (Big gas lens cup)
user235_pic14523_1379441749.jpg


Some times a little gap on stainless doesn't hurt (1/32) just so it is a little easier to get full penetration with less heat.

Pat

[Jere]

Brent:

What was the thickness of the material you were welding?

When you weld corners together like in the lower piece if you have the two inner most edges touching you should be able to run that weld for it's full length without stopping or using any filler rod. I keep a short length of .035 in hand just in case it needs a little help maintaining flow. If done properly the radios of the corner will be the same as the thickness of the material welded.

Jere

[weldtoride]

Originally Posted by patman

Another trick for problem joints is to find a hose clamp that will slip over your cup and weld a little foot to it so you don't have to concentrate so hard on your torch angle, some time look at how nice bungs are in semi tanks look like they are welded in one pass some times a guide is a good thing when you can't win cheat

Pat

Pat, so slick, thanks a lot for that and the subsequent pic.

[RockHillWill]

Neat trick Pat. Also, when I was 'tack' welding sheet metal interiors in the race cars, I would not always have room to wear a helmet in some of the rear interior sections, so I would clamp a bent piece of welding wire to the cup. It would not only hold the torch at the correct distance from the weld, but once you put down a solid 'tack'' you could drag the wire pointer along the joint until you were stopped by the tack you just completed, then pull the trigger again, still with your eyes closed. You could run off a good foot or more of tack welding before having to open your eyes. You most often got a sunburn, but our shop was 2-blocks from the Daytona track and nobody paid any attention to red faces. Some nights, I would have to soak my eyelids with raw potatoes, but no big issues ever occured.

[rkolenda]

Brent ,I weld a fair amount of thin stainless when building headers and exhaust systems at the shop.It was recomended to me that I should allways back gas the weld seam to get a good clean joint. If you look at the back side of a stainless weld that has not had argon coverage it is usually not pretty like the front side. I have switched from back gassing most pieces to using stainless flux on the back side .Solar brand stainless flux is in powdered form and you mix it with alcohol to form a paste. Brush the paste on the back side on the joint before you weld. I often use this method and the back of the weld looks clean like the front. Bob

[metalfab]

brent,

i totally agree with bob. at our shop the cost to purge all ss that we weld would be to costly! we use solar flux, mixed per directions on can. apply with a small brush like you would use for solder paste. your results will improve 100%. good luck

jim p @ metalfab