I'm trying to arc weld a nut to an exhaust pipe.  I want to get a nice smooth finish to the metal around the nut, so that it takes paint well and doesn't rust.  When I chip off the slag, it comes out in pockets.  So when I grind it smooth, it ends up looking like a a putting green... after John Belushi is through blowing up the gopher.

Is there some way to move the "puddle" around, so that the slag is on one end or the other, or on top, but not in pockets?

yeah, TIG weld it on a bench

Maybe I should just leave the slag.  It's much smoother until I chip it away; even smoother than I can get the surface with a grinder.

Quote from: Rema1000I'm trying to arc weld a nut to an exhaust pipe.  I want to get a nice smooth finish to the metal around the nut, so that it takes paint well and doesn't rust.  When I chip off the slag, it comes out in pockets.  So when I grind it smooth, it ends up looking like a a putting green... after John Belushi is through blowing up the gopher.

Is there some way to move the "puddle" around, so that the slag is on one end or the other, or on top, but not in pockets?

I'm not a good welder, but it was Bill Murray blowing up gophers. :lol:

That so explains Groundhog Day!

Let's see a pic of the weld.

It sounds like you're doing several things incorrectly:

1)  Arc too long.  (It should hiss, not buzz)

2)  Moving the arc too much with shaky hands. (Use both hands on the stinger if you need to)

3)  Not using a fluid motion.  (Relates to shaky hands.  Welding small circles with arc takes lots of practice.  You can't stop and start.

4)  Possibly too low a current.  (Puddle is not forming a keyhole)

Let's see a pic of the weld with the slag removed, and tell me what rod at what current.

just mail it to me and pay the return shipping.

You've probably got something about the low heat: I was afraid to burn through the tailpipe, so had it turned down pretty low.  (I did, actually burn through the side of the bung once).  Maybe an exhaust pipe is just too darn thin for arc welding.

Sorry, I ground it smooth, and am not sure whether I'll bother to try yet again.  Here's how it looks.  The black fissures are where there were slag pockets.



I probably just should have tacked it on, and let the exhaust clog up any gaps where the bung met the exhaust pipe.

If I redid it at this point, I'd probably just saw the bung off flat, and use another bung.  The O2 sensor isn't threading in too smoothly now.

Arc too long, current too low, and not holding the stinger steady.

Remember, for a SMAW square or acute angle weld you need to shorten the arc to the thickness of the rod cover for the root pass or it won't fill.

Remember too, you can't put the arc out if the heat is right.  If you didn't know this, run a few beads on a piece of 1/8th inch plate at 100 amps with a 1/8" 6013.  Push as hard as you can.  You can't put the arc out.  This is especially the case with 6011.

If you want to try again, use a 1/16" 6013 at about 40 amps.  Keep the stinger steady with both hands.  Trail the rod by about 30 degrees.  Watch the slag for the keyhole.

But yeah, it takes muchos practice to weld a 1/8" pipe bung onto 18 ga with a buzz box and have a perfect weld.  You did fine.