Blowing bubbles.

  1. dave_w11 Member


    I'm trying to MIG weld some 1.5mm thick square tubing using argon/co2 mix, 0.8mm wire and a clarke 151TE welder.

    At power setting 4/6 it seems to make a nice weld and penetration seems ok when I weld on a flat bit of metal. When I try to join two pieces of the tube at right angles though there doesnt seem to be enough penetration.

    I've been trying to weld on setting 5/6 to get more penetration, but when I finish welding (on a flat bit or joining two piece at right angles), a big bubble sometimes rises up from the weld at the end where I stop welding. It seems to happen more when I move along slowly. I'm worried that there might be gas of some sort trapped in the weld even when it doesn't blow a bubble.

    What do you think is causing the bubbles?

    Thanks for any help!
  2. malcolm

    malcolm & Clementine the Cat

    Bedford UK
    Probably the bubble is caused by oxidation - if you keep holding the gun over the end of the weld and blow shielding gas at it for a couple of seconds it should protect the weld until it cools enough.

    I often end up with a little pit at the end of a weld even after keeping the gas running. I think the same sort of thing is happening, just to a lesser extent.

    For welding inside a right angle it's normal to need to turn the power up a notch. Might help increasing the wire speed a little to reduce the tendancy for the wire to arc away from the corner.
  3. dave_w11 Member

    Thank you for the advice. I'm getting there :D