Contamination problem

[drewworm]

Help. I've been working this all morning up to 3:00 this afternoon. I'm tig welding square tubing into a frame for a gate. Tubing is steel .120 wall. Tungsten is 3/32 orange band (ceriated?). Straight Argon at 11 to 15 cfm. All joints are square and tight. I've sanded off any scale (actually, all surface around joint) and I'm cleaning with laquer thinner all around and IN the tube as well.
What the F**K? Even my filler (er70s2) is clean. I've reground tungsten too many times. Probably started with 7" and down to 5". I keep getting contaminants where the tungsten appears to be eroding and turning a slight (burned?) color. The weld puddle is bubbling before my eyes leaving some porosity behind. I'm keeping the tung out of the puddle and probably somewhere around 1/8 to 3/16 from the work. I'm even seeing sparks at some points.
I could just Mig the **** thing, but I don't want to give in. I'm determined to get done with TIG.
The "lift arc" has been a source of trouble for me. I have a syncro 250 and it seems everytime I use the lift arc I can feel the tungsten fuse to the work and I'm positive it's pulling off a tiny piece of steel. What other technique do people recommend? By the way, I barely touch the tung to the work and it fuses. Help syncrowave users!!!!
Any help out there?

[tigman250]

i run no less than 20 cfm on my regulator, you may want to bump yours up a bit to see if it helps. you say you are keeping tungsten away from puddle 1/8-3/16 how much is your stickout? if you are running a 1/2 stickout and keeping tungsten 3/16 away i think that would cause your problem. i normally run 1/8 MAX stickout for steel then keep tung away 1/16-1/8 your sheilding gas has to be able to reach your work in order for it to perform properly.

for your lift arc, try touching it off on a piece of copper to establish your arc, this should reduce it's tendancy to stick.

if the suggestions don't fix your contamination problems i would inspect your hoses, making sure you are getting complete flow through them.

Good Luck

[drewworm]

I was running about 1/4" stickout, but after reading somewhere that stickout should roughly equal cup diameter I started sticking it out further. I'll move it back in. I'm getting good sound of gas at cup, but I'll also try more cfm.
Now, on the lift arc - how do I start it off some copper? Do I clamp some copper to the work near the joint?

[tigman250]

i used to use a penny, it has to be a pre 1984 though, before that they were solid copper, after that they are only copper coated. it's small enough you can put it almost anywhere, i used to put it to the right of where i was going to start the bead (right handed) worked great from what i rember.

good luck and let us know how it works out!

[Billet Benny]

From your explanation I say 95% probability of a gas problem.. The combination of porous beads, sparks, and discolored tungsten combined with how you've cleaned the tube doesn't lead me to think it's a contaminated work piece problem.

Are you sure your gas is 100% argon?
Are all hoses sealed and are all connections leak free? Don't want to pull atmosphere into your gas plumbing.
Is the gas freely flowing from your cup?
Is the torch itself cracked or damaged?
What dia. cup are you using?
Keep stickout no more than half the diameter of the cup.
Keep arc length as short as possible and no more than the diameter of the electrode you're using.
Turning up from 15 cfh to 20 cfh probably won't fix your problem cause something seems more serious.

Big one.. How still is the air in the shop? Stay away from fans, blowers, drafts, etc. Don't weld in front of the welder while the fan is running. Any movement of air will get you everytime.

Got pics?

Good luck!

If all else fails it's possible you have bad/contaminated gas. Try a 2nd cylinder.

[Laiky]

sounds like bad argon.

[MMW]

I use a syncro 250 at work a lot. First a question--Why are you using lift arc & not the high frequency to start the arc? Settings--Tungsten stickout should be 1/16 to 1/8 with argon at 15-20 cfm. Machine should be set on dcen (straight polarity). 1) If it's only bubbling at the end of the joint when you are closing it up, it could be pressurizing & blowing out the weld. 5) Try grinding the tubes with a different grinding wheel. 4) Have you used the bottle of argon on other stuff without any problems? 3) Is the tube plated/galvanized? If you don't grind ALL of this off it will bubble & pop. 2) Try welding other material as this will tell if it is the machine or material.---MMW---

[wb5jhy]

Are you welding outside?
Might try a gas lens setup and/or more gas flow.
Don't use laquer thinner unless you really have an oily workpiece. Try acetone if you must degrease.
If you have contaiminated the tungsten with base metal you should grind enough off the tip to remove all the base metal that may have wicked up the side of the tunsten. Likewise grind away any tunsten that may be embedded in the workpiece.

[drewworm]

Thanks everyone for your feedback.
The gas is definately 100% argon.
Sounds like my stickout is too far from what I've been told. I will reduce it to about 1/4" or less beyond the cup which is a #7 I think.
How do I know if the hoses are sealed tight against leaks? I don't hear anything (also I figured that gas would just seep OUT, I didn't expect it to suck IN atmosphere). I may change the gas hose anyway as I don't know it's age.
I'm in my garage, but it was kind of breezy today. I set up some plywood
(4x8) shields.
I'm also probably running too far an arc length. It's kind of hard to see without getting my helmet right down next to the weld and then it's hard for me to maintain 1/8 without dipping.

[drewworm]

Help me mmw

Give me some more info on the HF starts mmw.
I've been trying "lift arc" because I didn't know any other way. If I set the machine to HF, what special things to I need to do? How do I start with HF. I called Miller on the lift arc and they made it sound like the way to go, but I swear that it momentarily sticks to the work and I would think it's pulling off a microscopic piece of steel.
Do I need to do anything special to the syncro to do HF starts?

Again...all great info guys. I have lots of things to try, but I'll wait to hear from you, mmw, on the HF.
Thanks

[Fishy Jim]

Just set the machine to HF, then hold the torch above the work at about the right height for welding and depress the pedal. Too easy.

My tigmate had a bit of wander at first while the arc stabilized, but the sync 250dx just sparks and is rock solid from the start.

[Billet Benny]

Use HF Start and not HF Continuous.

[drewworm]

Why would Miller employ "lift arc" if HF start is so easy? Sometimes there are just too many options and it's best not to try and re-invent the wheel. I can't wait to try it. I've been fooling around with that darn lift arc too long.

[Tailshaft56]

Lift arc is there in case your are in an enviroment where the HF might damage sensative electronic equipment.

[drewworm]

Lift arc is there in case your are in an enviroment where the HF might damage sensative electronic equipment.

I've read this and was wondering if HF start can cause the same damage as running HF program? My welder is at home (around sensative electronics?) Does my computer or TV or the fridge consitute sensative?

I'd really like to get away from the lift arc. I'm not welding again until Thursday so any further input from the field is appreciated.

Just a side note - Anyone out there watch "Driving Force"? I just finished the episode where Ashley gets her funny car license. She laid down a really sweet pass of 4.93 at 315. I can only dream. They're making history. I think it's cool.