Swiss cheese welds and how to prevent them

So this was probably due to some sort of contamination.  I think it started when I began to run out of gas without realizing it.

I've ground it out twice now and it still comes back.  Last time I ground through damned near half the thickness of the base metal.

WTF?

In reply to Mr_Asa :

You need to clean the area to be welded up much better, prior to welding it.  And once you draw contamination in, you need to grind it *all* back out.... Otherwise it'll just keep drawing it up to the surface. That contamination is in there. If you just skin the surface and try to weld over the top, you'll never stop fighting it. 

What I would do is grind back into the base metal. Increase the area you've ground down around the weld area and make sure you don't have any contamination or blockages in the diffuser in the cup. That can cause lack of shielding gas coverage as well. And that can easily happen when you get welds starting to pop and spatter like that one did. 

I ground down again, actually ground through the plate completely in one spot.
I'm thinking the contaminants flowed along the tab clear through.  I'll put it on a mill and see if I can cut it all out then drop in a slug.
Bleh.

I originally cleaned everything very well, removed all mill scale, got it to clean metal, dropped it in an acetone bath before welding.  Then the argon went out and...
I have been cleaning it almost that well since, but got frustrated here I guess

This is the un-welded design:

That's what my welds look like when I forget to turn the argon on

Maybe you need to up your flow, or verify that all the flow is actually going to the weld and not getting lost in a leak somewhere?

I'm a terrible welder, but I agree.  Just this morning I was welding up some steel tube and forgot to turn on the gas.  Bubbles galore.  One other spot I forgot to prep, so at the last minute I hit it with some sandpaper instead of properly prepping.... more bubbles.

I also am finding with this project (lots of little welds and pushing the heat) I get bubbles when I'm on the edge of blow-through.  I'm guessing impurities in the steel are reaching vapor point?

But you probably shouldn't listen to me.  I'm one of those that can lay a perfect bead when everything is right, but when a bead goes sour I have no idea what is wrong.  I just observe and store it in my brain for the future.

In other frustrating news, I just realized today that my regulator died.  No matter where I adjust it, the needle just pegs on the regulated side and the stinger sounds more like an air nozzle on an air compressor.

In reply to Pete. (l33t FS) :

This is what some of the other welds looked like today.  The edge/butt weld was just fusion weld, but the T-joint was your normal additive.  I'm still relearning TIG, but I think the general settings are good?

I have had some luck with holding heat on the pool in that area for a good long while.  Get it melty and just let it boil the contaminants for a while.  Sometimes that will get them to float to the surface and you restore a "good" weld with just a surface imperfection.  But I hate how picky tig can be with contamination sometimes.  

But..  for the good advice Gumby will be along shortly.  Unless he thinks this is a MIG thread..

In reply to nocones :

I tried that and it would kind of work.  I'd grind the surface and then try again and... blup blup blup.

In reply to Mr_Asa :

That sucks.  Do you own a mig?  At this point I'd grind it back and do that section with a MIG before you destroy the part trying to TIG it.  

One other thing that doesn't help now but make sure you wipe down the filler rods.  I've had contamination from them before.  

Fluxcore Hammer Store MIG, yeah.  So... no, not really.
I might be able to take it to work and use the one there?  Might be able to go visit my friend at the USF art dept and use theirs?

I've ground out enough and tried to weld it again that I'm starting to notice it warping slightly.  Gonna have to bolt it to one of my spare blocks before trying to weld it again.

I'm gonna sleep on it, I think.

After you have cleaned everything, gas coverage is key and often finicky. Affected by small changes in technique as much as regulator setting, cup size, gas lens, etc etc.

I don't have anything to add beyond what GaryC83 covered, except that those laser'd edges will definitely get ya too.