A few basic TIG questions

TIG welding class today resulted in a few questions that I thought would be
better answered here, and so I shall ask.
1) I was using my zircon (white) tungstens with AC on aluminum (supposedly
6061) today, and after a short amount of use they kept turning blue.
These are 3/32" tungstens on 1/8" aluminum, pure argon for a shielding
gas. My guess is this is resulting from the instructor's edict that
no student shall use more than 10 CFH of argon or have more than 5
seconds of postflow due to a slim budget for supplies (cutbacks in
California, dont'cha know). Is this the likely cause? I had less
of this when I used pure tungstens, which makes me wonder if they run
cooler or something of that sort.
2) For the aforementioned welding setup, what kind of amp range should I
be using? The instructor says "about 80 to 90" but my books and
reference card (one of those Miller sliding weld calculator things) put
it up closer to 125. Using the class machine, a Lincoln Precision TIG
275, leaving the dial set at 85 amps seemed to work fine. But on my
machine at home, a Miller Syncrowave 180SD, I couldn't even melt the
stuff with it set at 90.
3) My weld beads were looking awful today, and for some reason they kept
filling up with this skin of crusty black crud that looked like when
you weld stainless with improper gas shielding. Is this also something
that could be caused by a lack of shielding gas? When I did the same
welds at home with the same materials, the beads looked better but
had this sort of crystalline and sandy texture to them, even though they
were shiny and reflective. I was fairly careful about the cleanliness
of my setup... stainless steel brushed everything and then wiped
everything down with acetone, so it seems like it should have been
suitably free of contaminants. What sort of thing might cause these
conditions?
4) The instructor gave us an equation to use for determining the amp
setting for a given tungsten. He said, "You multiply the diameter
of the tungsten by .125 to get the amps. So if we're using a 3/32
diameter tungsten, that would be 90 amps." Does anyone have any
idea what the hell he was talking about? What kind of new math gives
you a result of 90 when you multiply .09375 by .125? Ok, maybe that
one is a rhetorical question, but still.
Thanks in advance for any help... learning curves get mighty sharp when
books don't have all the answers and there's nobody in class to ask!
Bryan
Reply to
The Hurdy Gurdy Man
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Gas shield post flow needs to be increased. Your gas is shutting off while the tungsten is still hot. 15-20 seconds is common. Also don't move the torch around a lot when you stop a weld. Just let the torch sit on the end of the weld while both the tungsten and weld cool. Moving the torch quickly can interupt the post-flow gas.
That is ludicrous for post-flow. With a gas lens collet body 10 CFH is workable, but you need at least 10 seconds of postflow gas to protect the tungsten.
On aluminum and steel, on a flat butt weld: 1 amp per 0.001" of thickness, so 1/8" metal = 0.125" = 125 amps. Simple
Now for an Inside fillet weld increase anperage by 30%. 1/8" metal = 0.125" = 125 amps + 40 amps = 165amps.
For an Outside fillet subtract 30%. 1/8" metal = 0.125" = 125 amps - 40 amps = 85amps.
Very simple math.
Your torch is too far away from the materiel so your arc is erratic and your gas shield is insufficient.
Wow. I have no idea wht drugs he is on, but they must be really expensive.
Amperage has nothing to do with how thick your tungsten is. It is all about how thick your BASE METAL is. Your base metal thickness and welding position determine the amperage needed. That amperage will determine the size of tungsten needed.
Base amperages for metals for flat buttt welds Aluminum and steel are both 1 amp per 0.001" Stainless steel and nickle based alloys are 30% lower than that. Copper is twice the amperage of steel and aluminum. Bronze is 50% of steel or aluminum.
Especially an instructor who is not a TIG guy. At school I am the TIG guy. The rest fo the teachers can TIG weld to some degree, but they are all much more into structural stuff that me. I live for TIG. It makes a big difference.
eMail me a mailing address I can send you a handbook.
Reply to
Ernie Leimkuhler
Ernie, you're offering a hand book now? A handbook from "The TIG Master"? I'll take one.
lane at copperaccents dot com
"Ernie Leimkuhler" wrote in message
Reply to
Lane
Hell, I would take one too.
jess
Reply to
jessp
That's what I figured... when I ran the same setup at home using what I figured would be a more reasonable flow rate and postflow, my tungstens stopped turning blue. I'm still wondering why the pure tungstens had less of a tendancy to turn blue, though... I may just stick with them in class until argon becomes more plentiful, if ever.
Hmmm... maybe I should invest in a gas lens then, since it sounds like it'd save me a lot of hair pulling. And probably be a decent way to save on gas with my home setup.
I wonder why the machine in class was able to do the job when set to 90 amps then... could it really have been that inaccurate? My home machine behaves exactly the way your equations would predict, but in class it seems to be quite different. Maybe the instructor is pumping hallucenagens into the gas mix.
Would this cause both the black crud and the gritty texture, or just the black crud? During my tests at home with a sufficient gas flow the crud went away but the grittiness remained... is there some chance that I'm just attempting to weld some crap aluminum?
That would definitely explain where all the money in the budget that was supposed to go to purchasing argon went!
Well, he's SUPPOSED to be the TIG guy. He even went on a tirade about how all the info he gives us is absolutely correct, even thought much of it contradicts the classroom text. He made some speech about knowing all kinds of award-winning TIG guys who can support his claims and how he can go out into the lab and prove to us that his facts are correct. Which is all well and good, I suppose, but it's also a fact that my welds come out better when I follow your advice instead of his!
Gladly, and thanks! I will mail you separately from this post. I really do appreciate the information you've given, it helps a lot. Now if I could just get you to take on the instructor in a TIG welding deathmatch, it might turn that class around.
Bryan
Reply to
The Hurdy Gurdy Man
It gets a bit tricky. I made these 2 handbooks for my students at school. A General welding handbook and a TIG handbook. They are both just masses of plagiarized reference materiel, some digested posts from RCM and SEJW newsgroups showing questions and answers and some ramblings of my own. They are completely illegal to sell, because they are about 95% copyrighted materiel.
AT school we can legally xerox them for our own use, but they can't be sold off campus.
I have been trying to get them to a point where they could be uploaded to the web as PDFs, but right now they are massive Canvas 7 documents, 240 MB and 320 MB.
I offered one by reflex, now I have to figure out if we have enough at school that I can mail a few out.
Reply to
Ernie Leimkuhler
Downside of pure tungstens is that they can take about half the amperage of Zirconiums. You could try Lanthanated tungstens. They have a smoother arc than Zirconium and are almost as good for AC, plus they are great on DC.
Gas lenses are all I use.
Machines can vary quite a bit on output, so use my numbers as a base, but you will have to adapt to whatever machine you are cursed or blessed with.
If the torch is too far from the materiel you can pull air into the weld zone, which makes for cruddy welds.
Scrub your aluminum really well with a NEW stainless steel brush before welding. That should knock off most of the oxide layer.
Just try to be diplomatic. There are a lot of guys who have learned one way to do things all their lives and they get really annoyed if you try to explain that it isn't really the "right" way. Their way may work, but that doesn't make it the correct technique.
What I preach is good technique that should save time and trouble down the road. A lot of weldors would rather argue than just try a new way that might just work better.
Oh, I see a new spin on Junkyard wars.
Welding Deathmatch.
Reply to
Ernie Leimkuhler
What about putting them on CD's? Lane
Reply to
Lane
or putting them out for DL on a server somewhere? can they be compressed? 250 and 320 MB seems a little large for a PDF. I sure would like something like that too.
Reply to
Don't Bother
That would actually make for sense right now. Both would fit on one CD.
I could burn them as Hybrid Discs.
I will try this out.
Reply to
Ernie Leimkuhler
Actually the file size is for the Canvas 7 files. I haven't tried proccessing the entire file into a PDF since it will take a few hours for my computer to chew on it to do that.
I will see what happens if I try to convert them to PDFs as is. If they both fit on a CD then I suppose I could just burn discs, and mail them out.
I would ask for postage and the cost of the CDR blank.
I take Paypal :-)
I will see how practical this is, and post the conclusion.
Reply to
Ernie Leimkuhler
What's a hybrid disk?
Ted
Reply to
Ted Edwards
Hybrid CDs can be read on Macs or PCs.
I use a Mac.
If I use a PDF format and burn Hybrid CDs they will be platform independant.
Reply to
Ernie Leimkuhler
Ahh. The Joliet format can be read and written by PCs running Windoze or OS/2 (don't know about Linux but would be surprised if there was a problem) and Macs. I have exchanged CDs with the above.
Ted
Reply to
Ted Edwards
With aluminum you can suck up contaminates from the other side of the part such as from a dirty table . You should always be aware of drafts or breezes when you weld . Some one could move a weld curtain and cause the fan of a welding machine to blow your way and cause enough turbulence to mess with your shielding . The tungsten that could handle the most heat would enable you to have a smaller ball at the tip and could increase your control with aluminum .
Over the years I spent a lot of time trying to find the best weave, only now that I have a constant shake do I feel content !
Reply to
Lewis Edwards
My boss at school calls that the "Palsy Pulse"
Reply to
Ernie Leimkuhler
I though this might be part of the problem, so I elevated the work up off the table so it wasn't in contact with anything plus I cleaned both sides. I still get schmutz on the work though... part of that is because it's tough to thoroughly clean the welding coupons in the class environment. But even so, I'm beginning to think much of my problem stems from how I handle the filler rod. If it's hot enough to be soft and sort of liquid even when not in contact with the puddle, it'll contaminate as soon as it's outside the gas shield... the thing is, it looks like you can't keep the rod too close to the arc between dabs into the puddle or else it gets hot enough to droop and spill before too long. So now what I'm trying to figure out is just how far away from the arc I can hold the rod... in watching the instructor, it seems like he keeps the rod really far away from the arc only darting it in long enough to add to the puddle then pulling away. Somehow the rod manages to cool before it leaves the shield and doesn't get contaminated... I don't seem to have any such luck. I'd love to hear some tips on it. I do beautiful welds (for a beginner, at least) on steel, but aluminum and I aren't friends at all... I'm not sure what the technique differences are between the two such that I'd have that problem, other than having to add filler faster and more often for aluminum. I guess I just need practice, but I seem to be at something of a wall in the path of figuring out aluminum.
I'm thinking I'll stick with the zirconated tungstens from here on out, although at points the pure ones seemed to work better... the zirconated ones seem to handle tons of heat and last forever as long as you don't dunk them in the puddle and have a long enough postflow.
I seem to be ok with my torch handling, now it's all just filler rod technique problems... the books I have seem to give descriptions that are too sketchy for me. Oh sure, you dab it in and pull it out, but how quickly do you pull it away? And how far? Does the distance from the arc matter for different fillers? It seems like it does, at least with aluminum. I have figured out I get prettier welds by moving the torch in this sort of "two steps forward, one step back" kind of motion instead of just moving at a slow and constant rate. But again, it's hard to know... different people seem to prefer different things, and I need to find what works for me. But most of all I need to figure out a filler rod technique, because right now it's a major hurdle for me.
Bryan
Reply to
The Hurdy Gurdy Man
The rod contamination does matter , especial for x-ray quality . Oil from your skin will give the arc an orange glow and effect the puddle . general oxidation on the rod doesn't make a big difference to non x-ray work . You might be trying to heat up the metal too fast . Aluminum transfers heat quickly you have to " adjust " for this . Start off with a heat setting where it takes 5 seconds for the puddle to form , this will set a easy pace at witch to weld . First you heat up the proper amount of metal (remember 5 sec.) , penetration is what you want on but joints , leg size and root penetration is want on fillets and lap joints " open root " starts quickly but keep in mind the size pass that you want . Your filler rod should be on the edge of where you can focus on it . Now slowly touch the rod to the leading edge of the puddle being hot it will suck off some metal . at this point the puddle cools and the filler gets hotter so pull it out of the arc , keeping it within the shielded zone . To great of a torch angle ( more than 5 deg. ) causes heat to be spread towards the filler metal causing it to prematurely heat up . Keeping your foot at the same spot should give you about one second before the puddle heats up to the right point then you dip it again . A meaningful thing to do is to back of on your heat very slightly until the puddle starts to solidify ,this is the heat setting you need to start at .... You can pull a cool rod out of the gas coverage when you are just getting used to a certain thickness of metal That is how you come by the ripples in a weld , they are caused by the cooling down of the puddle while you are adding the proper amount of filler wire . You will build up a rhythm of heat dab heat dab until finally you increase your heat input to where you have to dab at a quicker pace wich keeps the puddle to a certin size and witch will seem like a smooth flow . You can also keep the rod in the puddle and melt it as you move ,something that comes with time and familiarity to the amount of metal that is in the cross section of the filer and how to keep just that size of a puddle . I worked with a guy that got trained in the Navy , he had a very quick jab to his filler metal and ended up with a very tightly rippled weld . Now we are coming to end of the plate ,it is saturated with heat , and your puddle is getting bigger fast . This is where you find out that yes aluminum has a low melting point ,so back off on your heat big time and keep the filler flowing , are those your cloves I smell burning ? This is neat , try pushing the filler metal through the plate hit the middle of the puddle and push then back off . .you will see the rod protruding out the back side of the weld , that is why you should touch the edge of the puddle . This is another aspect of tig welding which becomes easier when the rod stays close to the puddle . It's easier on you to stick to the same thickness of metal until you get a fell for all of this .
Over the years I spent a lot of time trying to find the best weave, only now that I have a constant shake do I feel content !
Reply to
Lewis Edwards
I just bought a little syncrowave yesterday... and realized today that I don't know how to tig weld at all. Reading this, I was smiling the whole time... recognizing what I was doing wrong every step of the way. >;-} Tomorrow hopefully I'll have a little time to try again... thanks for the lesson! David
P.S. Yes... those were my gloves that you smelled burning.
Reply to
David Courtney
The suncrowave tha I used to weld with had a door that opened up on the botom sectio of the front you could see an second adjustment for the hig frequecy . I think it said intencity but I forget you might have one too I only turned it down on .012" aluminum . It could come in handy to turn it up for dirty , or cast aluminum ? Have fun with your settings after you get a handle on things .
Over the years I spent a lot of time trying to find the best weave, only now that I have a constant shake do I feel content !
Reply to
Lewis Edwards

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