TIG noob here... been practicing about a month so far. Slowly getting the hang of it. TIG is much trickier than I thought it would be, haha. My focus is on stainless steel exhaust pipes.
Sometimes my practice goes smoothly, but often times I am getting spattering and popping and I end up with disastrous spots in the welds, as shown in pic below, bad areas circled in red. When I actually start doing this for real (on my car), I plan on purging, I have a dual flowmeter ready to use. But I am NOT purging on these practice parts. Am I getting the spattering and popping because of no purging????
That is symptomatic of contamination on the inside of the tubing being pulled out due to the heat. You should always clean the inside 1/2" or so to bare shiny metal whenever you're welding up tubing. Purging will help with preventing any contamination (sugaring) on the inside. I hope you practicing on new, clean tubing? If not, expect lots of ugly welds going forward.
cj737 wrote:That is symptomatic of contamination on the inside of the tubing being pulled out due to the heat. You should always clean the inside 1/2" or so to bare shiny metal whenever you're welding up tubing. Purging will help with preventing any contamination (sugaring) on the inside. I hope you practicing on new, clean tubing? If not, expect lots of ugly welds going forward.
Ahh, OK, thanks! That makes sense. I bought a bunch of 'practice' pipe pieces from local custom exhaust shop, and they do have lots of dust and dirt on them.
When I do this for real, I will clean as you suggest. For the inside, is acetone wipe sufficient, or does pipe need light scuff with Scotchbrite or sandpaper or wire brush????
Mojo88 wrote:
When I do this for real, I will clean as you suggest. For the inside, is acetone wipe sufficient, or does pipe need light scuff with Scotchbrite or sandpaper or wire brush????
Thanks again!!!!!!!!!!!!!!!!!!
Your practice welds should be as close to the real conditions as possible, cleaning the material is #1 on the list, even for practicing
At the very least clean with acetone, if not very dirty you can just use isopropyl alcohol, a light scuff with scotchbrite, sandpaper or wire brush is good too
LtBadd wrote:..... Your practice welds should be as close to the real conditions as possible, cleaning the material is #1 on the list, even for practicing .......
@ Mojo88 - what stainless grade was used in the photo shown? T409 is an inexpensive variant commonly used for SS exhausts. And many times 409SS is coated with Aluminum to aid in preventing corrosion. If your practice SS sections were Aluminzed 409, then the popping you experienced could have resulted from Aluminum remnants outside/inside the pipe. T409 is substandard for exhausts, IMPO, and barely contains enough Cr (10.5%) and Ni (0.5%) to combat road salts and fight corrosion.
Most true SS exhaust are fabricated with 304 grade.
As others stated, clean:clean:clean all tubing Inside (1-2” from end) and Out BEFORE you weld. Plus, Ar or He backing gas during weldout.
Purpose, then passion. Practitionership. Obsession and hard work. That's the discipline.
Just throwing this out there but it also looks like normal Tig learning curve issues - probably too much heat build up from too slow a travel speed - maybe bit long an arc - possibly not perfect fit up - all these will make backside contamination worse as the hotter & longer the weld takes the more stuff gets sucked up into the pool - also too small a cup size can do it as lack of shielding over the area still hot will cause problems - if you are traveling slowly the area needed to be covered is larger as it takes time to cool off - advise would therefore be plenty of amps - sharp tungsten - shortest possible arc length - fastest travel speed you can keep control - largest cup you own - allow cool off time when re-positioning - best fit you can achieve - hope it comes together for you.
Arclight Ironworks wrote:@ Mojo88 - what stainless grade was used in the photo shown? T409 is an inexpensive variant commonly used for SS exhausts. And many times 409SS is coated with Aluminum to aid in preventing corrosion. If your practice SS sections were Aluminzed 409, then the popping you experienced could have resulted from Aluminum remnants outside/inside the pipe. T409 is substandard for exhausts, IMPO, and barely contains enough Cr (10.5%) and Ni (0.5%) to combat road salts and fight corrosion.
Most true SS exhaust are fabricated with 304 grade.
As others stated, clean:clean:clean all tubing Inside (1-2” from end) and Out BEFORE you weld. Plus, Ar or He backing gas during weldout.
Thanks for comments. I didn't do the magnet test on the pipes too see which grade the pipes are. They could even be a mix. I know that my 'real' system (to be welded/installed this Winter) is indeed a mix of 304 and 409 grades.
noddybrian wrote:Just throwing this out there but it also looks like normal Tig learning curve issues - probably too much heat build up from too slow a travel speed - maybe bit long an arc - possibly not perfect fit up - all these will make backside contamination worse as the hotter & longer the weld takes the more stuff gets sucked up into the pool - also too small a cup size can do it as lack of shielding over the area still hot will cause problems - if you are traveling slowly the area needed to be covered is larger as it takes time to cool off - advise would therefore be plenty of amps - sharp tungsten - shortest possible arc length - fastest travel speed you can keep control - largest cup you own - allow cool off time when re-positioning - best fit you can achieve - hope it comes together for you.
Thanks for the advice. The fitup on the pipes was horrendous, there was huge gap, but I didn't really care as it was scrap pipe.
Again, thanks for the tips. I do think I am moving too slowly most of the time. It seems almost impossible to maintain precise arc length while maneuvering around a tube!!!
TIG is quite challenging. I wish there was somewhere I could go for a private lesson or two. I am improving, but I hate to think I am learning bad habits as I go along................
I realize this is only practice but a bad fit up & gap combines to make getting a good weld difficult even if you had hundreds of hours of experience - obviously you don't want to spend hours prepping a practice piece but it does need to be like 90% right before you start or the results will always be bad - Tig just requires a lot more attention to detail than other processes - I think your weld actually looks OK for a novice under the circumstances - many with more hours than you are leaving piles of poo not weld ! smallish diameter thin walled tube is the worst to learn on - it may even be an idea to try on flat plate till the torch movements become natural & you can hold a tight steady arc then go back to pipe - I imagine if it's for exhausts rotating the part would be impractical but it maybe possible on shorter sections & an improvised positioner would be worth it's weight in gold ! if not get a Tig finger or improvise with fiberglass exhaust wrap tape so you can rest your torch hand close to the weld without burning - also try for a fit up where an autogenous weld is possible but have some very thin filler in the hand ready to make up any imperfections if needed - I find this works for me.
Couple customers begged me to build them a couple turbo cars. So, being in the auto industry as a full out repair and a passion for performance, I've spent 20 years with a mig here and there. Unfortunately mig won't fly when doing these types of builds. So, needed to buy a tig for home/performance builds. These were really the first time I had picked up a tig, within the first few days. So, not my greatest work as it was a bit ago. But, I can share my experience. These welds were stainless V band flanges to aluminiumized 3.5" and stainless to stainless. I found when learning it was easier to pulse with the pedal to keep the heat down. It will also allow you to work a bit slower as learning. Make the puddle, start backing off the pedal as your dabbing rod. Kinda like running the pulse feature, but manually. These welds weren't back purged, as they were budget builds and time/funds weren't (no expense spared). Still needed to be presentable.
Lots of people disagree with the pulsing manually, but it works for me.
noddybrian wrote:.... get a Tig finger or improvise with fiberglass exhaust wrap tape so you can rest your torch hand close to the weld without burning - also try for a fit up where an autogenous weld is possible but have some very thin filler in the hand ready to make up any imperfections if needed - I find this works for me.
Thanks again for great tips! I do have a 'TIG finger', but have not yet tried it.
I have been practicing my autogenous welding. It seems to be getting better, as long as fit-up is real good. I keep getting little dimples when I pause... is there a way to taper off without getting the dimples? Below is a pic of AutoG weld I did last night:
Thanks, Dave F.
Last edited by Mojo88 on Tue Oct 24, 2017 11:27 am, edited 1 time in total.
HoodLyfe wrote:......These were really the first time I had picked up a tig, within the first few days. So, not my greatest work as it was a bit ago. But, I can share my experience. These welds were stainless V band flanges to aluminiumized 3.5" and stainless to stainless.......
My friend, if you were doing these welds after only a few days of TIG'ing, then I am am way behind the curve, LOL. Nice work. Thanks for posting the pics, and for the advice.....
HoodLyfe wrote:......These were really the first time I had picked up a tig, within the first few days. So, not my greatest work as it was a bit ago. But, I can share my experience. These welds were stainless V band flanges to aluminiumized 3.5" and stainless to stainless.......
My friend, if you were doing these welds after only a few days of TIG'ing, then I am am way behind the curve, LOL. Nice work. Thanks for posting the pics, and for the advice.....
I had a 2.5 hr quick crash course with a welder/fabricator friend at his shop.
Someone who has been spending his whole life tig welding and also builds custom stainless commercial kitchens and tops for the medical field.
This brought me light years ahead of the game, rather then "figuring it out".
My suggestion is to pickup a phone book, look up "custom sheet metal, and welding". Drop by their shop, ask politely for a quick lesson. Hell even offer beer money. Tell them you want to learn from the best type deal. Show up with your helmet in your hand. I've had many people want to learn how to do small things on their cars, and I even encourage them to try and learn. So, I have in some down time babysat and watched closely while they have made attempts. Now, you won't be able to walk into a bigger place, and ask this. Try a small welding shop. As the bigger commercial workplaces have rules/codes/etc. But, small places will more likely spend the time with you. It makes their head bigger.
2 hours with a professional will = 30+ hours of you tube watching and 100 hours of trying to figure it out on your own.
HoodLyfe wrote:......These were really the first time I had picked up a tig, within the first few days. So, not my greatest work as it was a bit ago. But, I can share my experience. These welds were stainless V band flanges to aluminiumized 3.5" and stainless to stainless.......
My friend, if you were doing these welds after only a few days of TIG'ing, then I am am way behind the curve, LOL. Nice work. Thanks for posting the pics, and for the advice.....
I had a 2.5 hr quick crash course with a welder/fabricator friend at his shop.
Someone who has been spending his whole life tig welding and also builds custom stainless commercial kitchens and tops for the medical field.
This brought me light years ahead of the game, rather then "figuring it out".
My suggestion is to pickup a phone book, look up "custom sheet metal, and welding". Drop by their shop, ask politely for a quick lesson. Hell even offer beer money. Tell them you want to learn from the best type deal. Show up with your helmet in your hand. I've had many people want to learn how to do small things on their cars, and I even encourage them to try and learn. So, I have in some down time babysat and watched closely while they have made attempts. Now, you won't be able to walk into a bigger place, and ask this. Try a small welding shop. As the bigger commercial workplaces have rules/codes/etc. But, small places will more likely spend the time with you. It makes their head bigger.
2 hours with a professional will = 30+ hours of you tube watching and 100 hours of trying to figure it out on your own.
Mojo88 wrote:
I keep getting little dimples when I pause... is there a way to taper off without getting the dimples? Below is a pic of AutoG weld I did last night:
Two things: increasing the flow of your purge slightly can help. The other, when doing fusion welds, taper off the heat just prior to finishing that "segment" so as not to keyhole. Those dimples are an indication of a lack of filler/too much heat for the travel speed. Pretty common challenge for fusion welds. But you're welds look pretty darn good for a new TIG welder!
HoodLyfe wrote:Couple customers begged me to build them a couple turbo cars. So, being in the auto industry as a full out repair and a passion for performance, I've spent 20 years with a mig here and there. Unfortunately mig won't fly when doing these types of builds. So, needed to buy a tig for home/performance builds. These were really the first time I had picked up a tig, within the first few days. So, not my greatest work as it was a bit ago. But, I can share my experience. These welds were stainless V band flanges to aluminiumized 3.5" and stainless to stainless. I found when learning it was easier to pulse with the pedal to keep the heat down. It will also allow you to work a bit slower as learning. Make the puddle, start backing off the pedal as your dabbing rod. Kinda like running the pulse feature, but manually. These welds weren't back purged, as they were budget builds and time/funds weren't (no expense spared). Still needed to be presentable.
Lots of people disagree with the pulsing manually, but it works for me.
You're right, lots of folks avoid manual pulse, but if thats all you have for a machine, it works rather well. And in all reality, to a degree every foot pedal is "pulsed" when fluctuating the heat as you go. True "pulse" is obviously more distinct.
I would offer a bit of feedback on the weld in this picture (and an inherent danger in foot pulse): the toes of that weld are on the cold side. Not the end of the world by any stretch, and given when they were done per your experience, they are very consistent. But the heat was insufficient overall in the background to keep the metal hot enough to help the fusion. Thats where a machine with pulse really does help as you can often set the parameters to On, Background, Slope, etc.
HoodLyfe wrote:......
My suggestion is to pickup a phone book, look up "custom sheet metal, and welding". Drop by their shop,... Try a small welding shop. As the bigger commercial workplaces have rules/codes/etc. But, small places will more likely spend the time with you. It makes their head bigger.
2 hours with a professional will = 30+ hours of you tube watching and 100 hours of trying to figure it out on your own.....
Gawd damn, that's a great idea. I will do that. I don't mind paying real money for a good lesson........
cj737 wrote: Two things: increasing the flow of your purge slightly can help. The other, when doing fusion welds, taper off the heat just prior to finishing that "segment" so as not to keyhole. Those dimples are an indication of a lack of filler/too much heat for the travel speed. Pretty common challenge for fusion welds. But you're welds look pretty darn good for a new TIG welder!
Thanks very much!
I wasn't using a 'purge' there, but did you mean increase my gas flow at the torch?? I am at about 15CFH using 1/16" Lanthanated blue tungsten and #8 cup with gas lens. Machine is set at 80 amps DCEN with no automatic pulse, but I'm using foot pedal to keep it lower..... or should I just set machine at 50 or 60 amps and then floor the pedal?? Thanks
Mojo88 wrote:
I wasn't using a 'purge' there, but did you mean increase my gas flow at the torch??
No, I thought you were also purging here. Doing so would also help, but your torch CFM is fine. One benefit of purging is it helps keep the weld "up" if you will, by having back pressure and preventing the contamination from drooping internally. This is even more true with filler added.
Its been my personal experience, when welding stainless tubing, that if I get these dimples or recessed welds, I can increase my purge flow pressure and things get a whole LOT better-er. But then again, I am far from a professional welder...
Orange-brownish dust of death = you dipped the tungsten or ran into some heavy contamination. In either case, you need to grind out the contaminated portion because it is likely full of wormholes.
I do have a 'TIG finger', but have not yet tried it.
