Why do my TIG welds suck?

Hello, Please see the following link for the pictures of the welds and project: http://users.rcn.com/tomeberhard/SuckyWelds/SuckyWelds.shtml
I am building a type of chair: Le Corbusier's famous "Relaxation Machine". Costs $700 to $1350 to buy, so I decided to make my own. Given how much time I've spent bending tubing, griding and filing joints, it might be cheaper to buy it,but oh well. I'm having a good time.
The problem is the welds. I've got cracks, blown holes, ugly surface. The welds didn't break when I beat them with a hammer, so that's encouraging. I wait about 2 to 5 minutes after welding before banging on the tubes.
The details: TIG welding, 110Amps, 1/16" 303 stainless steel filler rod, 1/16" thoriated tungsten, 15cfm gas, 75%Argon / 25%C02 mix. The tubing is 1 1/4" diameter pipe, wall thickness is about 3/16" to 1/4".
Questions: 1. When I turn the machine off, I hear some hissing where the gas line connects to the machine. Is this a leak? (If I wiggle the cable the noise changes, so that's probably a leak. Can I put teflon tape to seal this?) 2. Why do the weld surfaces look like solidified lava / slag? (See S1 in weld2)(C02 in the shielding gas?) 3. Right after I'm done welding, the weld surfaces spit out little pieces of metal. Why? 4. Why are there so many cracks? (Cracks C1,C2,C3 in weld1, etc) 5. Why did I blow a hole? (See weld1) 6. Does E1 or E2 look good in weld1? (filler to base joint) 7. Why did hole H1 occur in weld 3? 8. Why am I not getting the neat "stack of coins" look? (Inexperience, right?)
Thanks! Tom.
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Sounds like you might have some problems with your sheilding gas actually sheilding, with leaky hose, etc. I'll let others who are better at long-distance diagnosis pick apart your details.
I will harp on something I know well - you will get much better results if you practice on something other than your final workpiece. Make up some practice pieces which are exactly that - weld, cut, weld again - and practice until you can get a decent weld, then go back to your actual project.
Tig welding, like gas welding, is a prcess which calls for considerable skilled handwork. This does not mean "you're born with it" or "you are not born with it". Though some people seem to fit thsoe two camps, the vast majority of us can do it, if we put in the work to be able to do it, and that is a matter of practice.
Due to what I need and can justify spending my limited funds on, I have not done TIG welding since college, and have not done Gas for several years, either. I have been reasonably good at both, but at the moment I'm a stick-arc brute. I know for a fact that when I am equipped to do those again, I will need at least a few hours, and perhaps up to a couple of weeks, of actually doing hands on practice before my hand skills are back to where they once were.
--
Cats, Coffee, Chocolate...vices to live by

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From a fairly amateur perspective, you are using the wrong gas, the wrong tungsten, the wrong amperage. You should be, for Tig welding steel, using pure Argon. Any CO2 will ruin things. You should be using about 1 amp per .001" of wall thickness, so about 190 to 250 amps. You should be using a thicker tungsten to take that much current. I presume you are using DC Neg polarity. I would think that SS filler rod is ok, but I might use a thicker filler rod for .250" wall. In fact, I wouldn't Tig this, I would Mig it, personally. I tend not to Tig over .125" thickness as a rule of thumb.
Brian

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Sounds like you need to do some reading before you start playing. You are using a MIG gas mix rather than the 100% argon that you should be using.
But keep us updated on the progress on your project. Looks like a fun project.
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well, he's using a MIG/MAG mix.
wrote:

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eh, uhmmm, (and among other things), what is the tube stock material?

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It does sound like you may have a leak at the connection of the gas line, although you may be hearing the after flow. You don't mention what machine you are using, but TIG welders usually continue flowing the shielding gas after the arc is shut off to facilitate cooling and protecting the weld from the atmosphere. The duration of the after flow is also adjustable on some machines. You are using the wrong shielding gas...100% Argon for TIG. The mix you are using would be fine for MIG. Bump up the amperage to approx. 1 amp per .001" of material thickness. Also, check the wall thickness of your material so you can set the amperage of your welder accurately. Get a larger diameter tungsten as 1/16" is too small for the load you are going to need. Practice, practice, practice.
Rex the Wrench
Tom Boston wrote:

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Tom Boston wrote:

Fix the leak!

Try 309 SS but Fix the leak.

That's MIG gas. Try straight Argon or 75/25 Argon/Helium after you fix the leak.

What material? That should be fairly easy to weld - it's the really thin stuff that's hard.
Did I mention, "Get the right gas but fix the leak!"

Yes but that's fairly easy to fix. After dealing with the above, get some scrap flat stock of about the same thicknes and try running beads without filler. Then try with filler. A couple days practice with the right set up will make a huge difference.
Ted
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Thanks for all the input folks. I went back and measured some things and have more details:
The filler rod diameter is 0.095 or 3/32. The tungsten was 1/16, I'll change that to 1/8.
The pipe material is your basic dumpster-dived black pipe of unknown composition. Wall thickness is 0.157 or 5/32, so I'll try 160 amps. Sorry about calling it 1/4" earlier, I was raised on metric. Since (most) welders use a foot control, isn't the actual amperage going into the metal much lower in practice?
I'll fix the leak. Can I use teflon tape?
I had asked for 100% argon, but they shiped the wrong thing. Can't return a bottle via UPS, so I'm stuck with it for a while. I'll get the gas replaced once my car situation improves. See my other post on "Why does my car suck?" (kidding, no such post)
Thanks again! Tom.
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Tom,
Here is something to think about.... I'm willing to bet you are going to have at least 50 hours into your chair by the time you bend, weld, and upholster it. When you finish it, you are going to be _really_ pissed that you didn't spring for some nice stainless steel tubing. Using the cheapest "dumpster-dived" pipe is fine for maybe a welding bench in your shop, but not something where you are aspiring to reproduce a museum piece.
At least, that would be the case for me. Every time I've used scrounged pine for something like book cases or tool chests in my shop, I've regretted it.
Take a look at www.onlinemetals.com to get an idea of what stainless will cost you. You will probably be able to find it cheaper locally, though.
-Aaron
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Tom, you can't tig weld with a co2 mix. You just can't. Might as well use no gas at all.
Brian

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use
No that's not true, I've tried it, co2 is definately better than no gas at all. It must be at least 10 percent better, but I'll agree it sucks.
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Tom. Don't forget to purge your tubing with Argon and plug the tube to keep it in them (it's called back-gassing) or it will still go bad for you.
Sniffer.
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in
That's assuming you are using stainless steel. Sniffer
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it
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Is the tubing Stainless also? I like to use 316L filler on S.S. Straight Argon is the best for TIG. don't pull the torch away when you are done with a bead...hold the ARGON on the weld until it cools so it is protected from contamination (called postflow). WAY too small of a tungsten...3/32 would be better...1/8 might be better yet. It is sometimes tough to fill a hole in something that is hollow because gasses fill in the chamber and want to get out so they exit right where you are trying to fill and will "spit" back at you. do you have a nice SHARP point on your tungsen...with the grinding marks going the length of the tungsten (quite important)? Tungstens should be sharpened on their OWN wheel so they are not contaminated with junk.
teflon tape will not fix the leak. these are flared fittings...they sell repair parts
is the tubing really that big in diamater and wall thickness.!! man, thats huge!, you will be able to drive a truck on that thing. The one you buy is maybe 14 or 16 gauge. stainless pipe is EXPENSIVE...probably cheaper to go with steel and have it chromed.
Oh well...at least you can get away from the wife for a while!! except now you have her dryer full of tools!! LOL!!
Good Luck...we're happy to help,
Doobie
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1" x .065" stainless 304 is around $20 for 8'. So maybe he will be under $150 for the tubing for a chair that costs $1300? And if he was going to use mild steel, he might as well just use MIG. Or using tig on mild steel with silicon bronze rod might look nice if the tubing and welds were sanded, buffed and lacquered. Would 1" x 16 gauge be strong enough for a chair? I'm sure one of the regulars can answer that.
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yep, measured with a micrometer.

Don't have a MIG machine. But I'm curious about this lacquering business. I was planning on using a dremel on the tubes and making all sorts of marks so that the metal reflects light at many angles. It would kinda look like a diamond. I was planning on epoxying the tubes afterwards, is lacquering a better idea? What product is used and where can I get it?
Thanks! Tom.
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I was using lacquer as a generic term for a clear finish. So if you are sticking to steel, the reason why you would clear coat it would be to prevent oxidation once you polished it. The downside of finishing metals with a clear coat is that scratches show up pretty obviously and it is hard to touch up. I'm sure you have you seen brass door knobs with the finish partially off...
However, if you use stainless, it will take a mirror polish and any scratches can be buffed out. Or as someone else mentioned, you can always get the chair chromed.
You really should consider taking a piece of your pipe and practice your desired finish on it before going any further. The dremel sounds fine if you are being held captive in your house and are trying to fritter away many hours.
So are those chairs comfortable?
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hey; if nothing else, upgrading to stainless tube is bound to be a better match for the selected filler material....
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