Welding Tips and Tricks

Hey guys.

I'm getting a crater crack when I pop out on these welds. Like aluminum, it seems if I back off and wander away from the end of my weld before I shut down it happens less. Trouble is I'd rather not have that dragging appearance in the puddle caused by this practice. I've done a good deal of mirror polished 304 and never had this, so I'm scratching my head here.

Fusion welds
304 1" TUBE
16 GA wall

Thermal Arc 186
Foot pedal
70A
1/16 2% Lan

The image where I cooked it and turned purple shows this the best, The other image is the best one I could get on a peice that came out nice and gold. The crater is right next to my thumb.

Any and all help, criticism, verbal and physical abuse, etc. is appreciated.

Did you prep the tube? It looks dirty. Need to work on consistency/steadiness for fusion welds. Assuming this wasn't done on a positioner? We're you max pedal, 70a seems kinda hot

Yeah, I hit the tube inside and out with acetone. Only went about halfway up from the joint though.

Flat position in a drill press vice.

Nowhere near max pedal. Just set at 70 'cause I like a little headroom.

Did you wire brush it or scotchbrite it? You need to do that then acetone. Did you back purge?

Wes917 wrote:Did you wire brush it or scotchbrite it? You need to do that then acetone. Did you back purge?

I agree with this line of reasoning because any crud that gets caught up in the puddle will simply get taken for a joyride and float on the surface of the weld bead, and right where you terminate the arc, is where it ends up. So it's not always a crater, just because you see a "dot". To be absolutely sure this isn't crud that was stuck to the tube in the first place, it needs to be clean clean clean. Right angle die grinder with a 2" roloc 40grit flap wheel will quickly get the outside clean. Honestly from the blurriness of those pictures I can't tell. To me, it looks like just a crud/grime dot and not a crater/dimple. Better lighting would help. But if you say it's a crater, it's a crater. Swirl the arc around in a small circle as you let off the foot pedal.

There's no harm in keeping a little piece of .035 308 mig wire handy to button off the puddle, and eliminate the crater.

Steve S

Wes917 wrote:Did you wire brush it or scotchbrite it? You need to do that then acetone. Did you back purge?

File to debur, acetone to remove the diesel they spray on to prevent rust.

Stainless fusion welds that weren't purged don't look like that.

I'll give her a shot tomorrow with the swirl (hehe) technique, failing that, Steve's 035 wire sounds like a good idea (Thanks fellas).

I'm still all ears, got some more test peices to run out tomorrow before things get serious Monday.

Thx again.

The only advice I can offer to add to what everyone has said is try backing off your amps slower, either while swirling or backing up. Not to long though. I have found that slowly backing off with a swirl, when the puddle solidifies with a little heat it typically does not crater.
I would have to also agree that the picture does look like impurities left in the center, at least right off the bat. Could be wrong though.
Good luck.
-Jonathan

newschoppafowah wrote:

Wes917 wrote:Did you wire brush it or scotchbrite it? You need to do that then acetone. Did you back purge?

File to debur, acetone to remove the diesel they spray on to prevent rust.

Stainless fusion welds that weren't purged don't look like that.

I'll give her a shot tomorrow with the swirl (hehe) technique, failing that, Steve's 035 wire sounds like a good idea (Thanks fellas).

I'm still all ears, got some more test peices to run out tomorrow before things get serious Monday.

Thx again.

While filing to deburr is good, you still need to clean back about 1/2" from the joint inside and out with scotchbrite or stainless wire brush. Also on unpurged stainless welds the visible part of the weld wil look like that but the inside wont, which can pull impurities to the outside of the weld.

I do agree with the pull back as ramping down, that's how I terminate on these types of welds, or trail off while moving forward.

Backing off more slowly and snapping out at the toe of the weld was it.

Got the technique and the physical setup of these damned things dialed in, started cranking these buggers out. Pretty enough to send home to grandma.

Thanks again for the tips, and that MIG wire one was a damn good idea I'll keep in reserve in case I wind up in a jam.