First experience at Aluminum Tig. Some questions

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I spent about 2 hours practicing welding aluminum with my new TIG welder today.  I wanted to try to learn a few things before asking questions, and after a couple hours I was able to occasionally put down a reasonable bead.  Here are my questions after my first experience:Black soot.  When I weld, I get black soot.  Is that normal?  It doesn't seem to affect the welding much until I stop, and then I have to clean it or I can't start the bead again.How do you feed the filler rod when wearing welding gloves?  I weld until my fingers get too close, then I have to stop and use both hands to move the filler in my fingers  .  Then I have to clean off the soot before I can start again. Any good tricks?Angle of the torch?  Should the torch be orthogonal to the work surface, or at some other angle?  It's sure easier to see what's going on when it's at an angle, but it welds better when it's straight up.Any help will be greatly appreciated.  Thanks.  John.
Reply:Conditions:  My welder has DC and pulse DC mode.  In pulse, it puts out a 50% dutycycle pulse of .5 Hz to 250Hz.  I am running it in DC mode.  I am using pure argon at about 15 CFH rate.  I am using about a 1.8mm tungsten rod and 2mm 4043 filler on 6061 square tubing that is 2.2mm thick.  I have cleaned the aluminum thoroughly using a stainless steel wire brush.
Reply:ok well you'll need heilum to tig alum with a dc machine  you need a stainless brush to clean off that alum and thats all the brush should ever cleanChuckASME Pressure Vessel welder
Reply:soot= contaminated tung. or contaminated surface clean an restart..glove or no glove i weld without a glove on filler hand..angle  the tourch works for me just so i can see the weld ..  and yes use only one brush for  that job never use it for rusty metal/oily  i use a (lincoln250 tig ac-dc) ac works better for alum--dc for S/S
Reply:Yes, I know about only using the stainless brush on aluminum from my experience mig welding aluminum.Helium huh?  I can get that here, but I'm not sure how expensive it is.What is the downside of tig welding aluminum with DC?  Strength of weld, aesthetics, other?Maybe I should build my project from stainless steel instead of aluminum.
Reply:unless i'm doing real thick aluminum...i use A.C.... ...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Originally Posted by yellow73bbConditions:  My welder has DC and pulse DC mode.  In pulse, it puts out a 50% dutycycle pulse of .5 Hz to 250Hz.  I am running it in DC mode.  I am using pure argon at about 15 CFH rate.  I am using about a 1.8mm tungsten rod and 2mm 4043 filler on 6061 square tubing that is 2.2mm thick.  I have cleaned the aluminum thoroughly using a stainless steel wire brush.
Reply:back to the start--what is the project?????
Reply:Originally Posted by yellow73bbYes, I know about only using the stainless brush on aluminum from my experience mig welding aluminum.Helium huh?  I can get that here, but I'm not sure how expensive it is.What is the downside of tig welding aluminum with DC?  Strength of weld, aesthetics, other?Maybe I should build my project from stainless steel instead of aluminum.
Reply:AC won't clean out all of the impurities, but it is the way to go if your parts are not real thick and cleaning action is a necessity. I have alwats welded on AC, but am tempted to try the DC way. I have not had a thick part to weld although. Also try heating up the parts to be welded with a propan torch. This preheating really helps out.
Reply:if you're gonna weld aluminum w/dc ,it will only work on THIN aluminum(very thin) with dc positive.hafta use a 1/8th inch (3 m m ) tungsten with not much amps , maybe 50 amps or so , any more will explode the tungsten. Don't even think about using dc neg  on aluminum -won't work worth a darn. on thick aluminum , (1/8th inch or more , you'll almost have to use helium gas , argon too dense  for thick alum, although sometimes you need a mix (a small amount of argon , just for cleaning action ) these are only some loose suggestions , you have to try things and see what works for YOU in YOUR particular projects .
Reply:sorry roy buy dc tig is used for welding thick alum and you run it like you do for steelChuckASME Pressure Vessel welder
Reply:What ever . If it works for you  , great. I find it funny that the U S  navy didn't know that . ( During the time i worked for them at the navy yard . 1965-1969  & 1983-1995 )
Reply:dcne tig with helium on aluminum works great and makes a sound weld.  You get an instant puddle on very thick aluminum.  I have welded 1/8th aluminum using this method but that was an experiment.  On most aluminum I use ac high frequency with argon.
Reply:Roy i did not mean to contradict you but i know from doing it and from a book printed by REYNOLDS METALS the COMPANY that made aluminumChuckASME Pressure Vessel welder
Reply:O K .  To  me & my machine (miller dialarc 250  hf ) " THICK aluminum seems to start at about .100"to .125 ". that's when I seem to have to change from argon to helium. but, that probably depends on which alloy  it is , also. seems there are so many variables. what i LIKE welding is about 1/8th  to 3/16 alum. ( so far as aluminum goes) my favorite things to weld is probably mig on steel thickness  1/8th up to 1/4" steel and stick welding 1/4" thick & 3/8th" steel with  good ole  7018  ( or 8018 or 110-18 )  even enjoyed ,sometimes stick with  A C 7024 (flat welds ) & flat fillets . as good as mig or tig is , sometimes stick is very satisfying . Almost wish i had a big shop & do  subarc.  very old process , but boy can you get some weld done -on long flat( position )  stuff . and , you don't need a welding hood . when I left Kaiser steel , in 1981 - they welded pipe (long seams ) with 2 heads ,each with 5/32 hard wire - 1 was  d c fed about 1200 amps , the second head  A C (for filler) at (i think) about 1000 amps , each wire was maybe only 1" apart  from other . And, they were  experimenting , trying to use  4  heads !  i thought that would be "cooking " the pipe too much . I don't know how that trial  ended up . sucessful or  not ?
Reply:Miller has a  little tig guide that has a good summary of the benefits of argon, helium and mixes when tigging.  I use a dialarc also, the regular one with a simple hf box added.  I have done approximately 1/4 inch (old aluminum car rim) with it, but it aint easy and definately not a fun.  It requires a bunch of pre-heat just to make it happen...I recently got a tank of helium to give the DC method a try, but nothing has come up yet.  I guess I need to break something.http://www.millerwelds.com/pdf/gtawbook.pdfSmithboy...if it ain't broke, you ain't tryin'.
Reply:Smithboy. I am curious;  what torch are you using on the alum car rim ? & what size tungsten & how many amps ? the charts say how many amps each  size tungsten can carry.   I use a wp-20 watercooled torch , i have a bernard (?) watercooler , & foot control (is there ANY other way ? ) I gotta hunch a car rim is one tough way to go . heck, the sucker is a very efficient "heat sink" . you said it needs a lot preheat . i believe that . I think if it's got a lot of weld needed , it's just about a candidate for mig . it maybe just about needs constant heat (some to maintain the heat )  WHILE welding on it, but, boy, i don't wanna be doing it , you get cooked . ( all the radiant heat ) ....................reminds me when I was at Kaiser steel , they had some weld repairs on some new hydraulic cylinders ( beeg juans  ! ) and they required preheat of 550 degrees ! welders had to work on the top side of them . air arcing out bad sand pockets , then grind them clean, finally weld repair them . wow . talk about a hot job! lucky i didn't hafta do that .
Reply:oh, btw: i have about 6 or 7 other torches , i NEVER use them , the wp-20 , in my opinion is the cats  meow.
Reply:I borrowed the torch and don't currently have it, but it was a 250 or 300 amp weldcraft air-cooled torch.  It was fresh on the market when I used it.  I can't remember the model.  It was very nice, I think the link below is the one, but I don't think it was this color, so I am not sure.  It got HOT...Red hot, but it worked.  It felt like I was standing next to a nuclear meltdown.  I don't see how folks could do this kind of welding all day long without spontaneously combusting.  I think the tungsten was 5/32 diameter (the type was either black 1% lan. or pure, my friend bought both the torch and tungstens from arczone, but I don't recall which type I ended up using, most likely pure), but again, it was a long time ago (3-4 years).  I had to wire my welder directly into the breaker panel because it kept tripping a 60 amp breaker running at full throttle (250+ amps, what ever the max is for the dialarc).  But, I don't think it would have worked at all without the preheat.  Generally, I don't weld anything above 1/8th in aluminum ("generally" is the word).  My dad has some grain hoppers for cows that are made of aluminum sheet and aluminum angle about that thick (maybe a bit thicker, but not much).  They are light so he likes to move them around where he needs them...usually, they move pretty easily, but sometimes he will punch a hole in them or break a support or split one at a seam...my dad is rough on stuff that I can fix.Followup: The weld on the wheel was NOT great, but it wasn't too bad.  I ended up using it as a spare, because I wasn't sure how good the quality of the weld was.  It was on an old TRX (metric) wheel off my '87 bmw 535i.  I ended up recycling the rims and getting some standard 15" ones when I found out the price for replacing the tires ($350 per tire...I paid $1200 for the car).http://www.arc-zone.com/catalog/web_...id=4628888_800Last edited by smithboy; 05-24-2006 at 10:17 PM.Smithboy...if it ain't broke, you ain't tryin'.
Reply:yeh, my dial arc is wired direct to a 100 amp breaker , miller said it needs a 90 amps, i think i remember them recommending 100 ,anyways, no problem , after that .it seems the hy freq needs a lot of juice?  somethin sure does . maybe......some the newer ones are more efficient, i don't know. i am too old to buy anymore new stuff . Did you ever try ,on that machine, to stick weld with hy freq  START ?  its cool , really lights off a rod that might balk at starting the arc when you strike it . Many times in a submarine , standing on my head , trying to weld overhead , under some foundation(steel table) with some lousy 3/32 7018 i sure could have used a hy freq  start . i might have ruined 30 rods before i got it lit and welding good . (3/32 known for sticking on the first attempt to start the arc. )especially certain BRANDS. BUT, when the Navy had 90,000 pounds of this batch , you had to make the best of it . yeh, boring , i probably got a thousand of these stories .
Reply:Wow, hadn't checked for a couple days and what a lot of posts.  Thanks for the input.  My project is a CNC plasma cutter I want to build.  I'm using Aluminum because its lighter and mostly just to learn about aluminum.  The aluminum I'm looking at is 2mm thick (about 0.080") 40mm square tubing.  I'm currently also using a 2mm (I think, it may be 2.4mm) tungsten and a 2mm filler rod.  I cleaned and cleaned and then cleaned each time I started to weld again.  I was getting reasonable beads at the end.  I think I'll try the preheat next.  At leat I'm finally getting to where I don't touch the tungsten with the filler rod  .
Reply:I had been welding for several years and when I read in a welding book that you can weld thick aluminum with helium and negative electrode (tig), I thought it was a misprint.  After trying dcne with argon and making a mess I thought it was crazy.  Then came some one inch thick aluminum fixtures to be welded.  Bought some helium, did the dcne and it worked in a beautiful way.  The book was correct.  It does leave a soot but that comes off easily and leaves a beautiful sound weld. Chopper5 has it right.
Reply:Yellow,You'll get the hang of tig.  It's not that hard.  I have taught several friends to do descent tig welds in just a few tries.  If you can pat your head and rub you stomach at the same time, you can tig.  Be careful with the preheat on thinner stuff.  You can build up too much heat and cause melt-through.Smithboy...if it ain't broke, you ain't tryin'.
Reply:Well, I was finally able to get some more practice today, and I did a lot better.  One thing I did was remove the left glove, and the other thing I did was get a stool to sit on.  I still gotta learn how to coordinate my fingers to feed the filler rod though.