Welding Tips and Tricks

Hi,

I am new to TIG and starting with mild steel. I've been at it for three weeks and can't get past a contamination problem. My welds develop a brown or black residue and sparks fly out of it towards my helmet. The tungsten needs re-grinding every few minutes. There are pinholes in the weld.

I have tried cleaning everything with acetone - steel, filler wire, torch cup. The collet, and collet body look clean and undamaged. I think I am keeping my torch angle as close to 15 degrees as possible. My arc is short enough that I dip the tungsten or get it contaminated pretty regularly . My tungsten stick-out is about 1/4" for flat welds and up to 1/2" for reaching into fillets. My welds still look, in Jody's parlance, like Fido's butt.

Everything I have read and seen in videos suggests that I don't have enough gas coverage. So, do I need a different collet? Gas lens? Just more practice? Any advice would be welcome.

Details:
Lincoln Square Wave 200 welder. Currently using just 120V
Lincoln's PTA-17 torch with #7 ceramic cup.
Lincoln's regulator (I have ordered one with a flow meter). Pure argon, approx. 15 CFH
2% La 3/32" tungsten sharpened on bench grinder while turning in a hand drill
Mild steel cleaned with #60 flapper grinder, then wiped with acetone
Filler rod ER70S-2 1/16 or 3/32"

You cannot stick out that far with a normal gas nozzle. Absolute Max is about 3/16. Try stepping up a cup size. 8 or a 9. We use standard collets and collet bodies at work on steel with small stick out, upto 190 amps. Happy days. Play with your gas flow, too much gas for the cup size can suck in air.

And be dead certain you are using 100% Argon when you TIG weld. Check the bottle in case you've got a MIG gas connected.

I would like to see some photos of what's happening, but it is possible you are sucking in grime from the backside. The brown haze makes me think gas issue too, but a picture on the internet is worth 1,000,000 guesses.

A quality gas lens is worth the money too. They truly do help with settling the gas and providing great coverage.

OK. You asked for it! This is a little embarrassing, but maybe I will be able to post improved pictures soon.

Thanks for your comments and suggestions. The gas is definitely pure argon; I am working on my second cylinder. Maybe the flow rate is way off. Lincoln's regulator is not one of the most inspiring parts of this kit, so I am looking forward to receiving the flow meter from Weldmonger. I will definitely try to shorten the tungsten stickout.

How about a snapshot of your regulator gauge face? Perhaps it is listed in LPM versus CFH?

Here is the regulator. The outlet pressure drifts up when no gas is being used which makes me wonder about it. I used to work in research labs and the regulators would hold their pressure setting. They probably were much more expensive than this one though.
Also, the torch with a newly ground electrode. I only have the #7 cup right now. Should I buy a set of these standard cups or drop that system and switch over to gas lenses? If the later, who makes a good gas lens set?

Flow looks correct, but only a hard diagnosis of the flow rate can determine if the regulator is passing correctly.

Weldmonger.com store has very good TIG kits with gas lenses, cups and insulators.

It looks like you’re doing everything right, so it must be the equipment

Two things to check....make sure the collet is in the torch properly. If you put the collet in backwards it will let some gas through, but not enough. The skinny end of the collet is towards the front. I only say this because I had a friend who couldn't get decent welds so he brought his setup over and the first thing I did was take the torch apart to sharpen the tungsten and found the collet in backwards...problem solved.

Second, make sure you're getting all of the mill scale off the metal and it's down to clean, bare, white metal that's shiny. I like to follow a flap disc with either a deburring wheel or a non-woven abrasive wheel (compressed scotchbrite)....that leaves a shiny surface ready for a wipe of acetone.

Thanks! I'm pretty sure I have the torch assembled correctly, but will check it again. Will find the polishing wheels you recommend. After the flap disk the surface seems clean, but it really is too rough to wipe properly with acetone. And, maybe the new flow meter will make a difference.

You guys have offered great suggestions. Thanks again. I will try to follow up with pictures of perfect TIG welds!

All the previous suggestions are spot on. Also make sure you do not have any holes in your gas line. This happened to me once and it took me some time to figure it out. I ended finding the leak by removing the sleeve from my setup completely and spraying soap/water mixture along the gas line while I had gas flowing through the torch. If you get good coverage for the first few seconds of welding and then coverage degrades this is most likely the cause. Another thing I would check is how low the flow goes once you hit the trigger/foot pedal. I like to set that type of meter to my desired flow rate with solenoid open as they tend to drop some. I set it closer to 20 for standard collet setup and around 25 for small gas lens and 28-30 for large gas lens. My go to setup is a #8 cup and small gas lens for steel and stainless. For titanium I use a large lens and #12 cup. For Aluminum I use mostly standard collets with a max 3/16 stick out. Good luck and let us know how it goes.

All good advice, make sure you set the flow rate while you have the pedal pressed and gas flowing, with a regulator like that if you're set to 15 working pressure your gauge will generally read closer to 19-20 when it creeps up. If you're welding outside that will jeopardize shielding even more and your technique and torch height will need to be absolutely perfect, especially without a gas lens.

To check for leaks I like to set my pressure then shut the bottle and and leave it for an hour or two, your gauge shouldn't go down much in that time.