Sub-arc questions

Date 04-30-2007 15:29

My shop is finally getting around to setting up a SAW station. We have an old unit we aquired from another shop and finally got it working.

Question pertains to terminating the arc at the end of a bead. The machine runs great and is laying down some good beads, but when it comes to the end and the welder stops the machine, the wire sticks to the weld and has to be cut with wire cutters so the machine can be moved. The resulting discontinuity is a small round unfused wire at the end of the weld bead. I say unfused, but in actuality when the wire is snipped flush with the reinforcement, there is a small visible piece still left. All the welder is doing now is pushing the stop button on the machine and the pipe rollers and it gets stuck.

Any helpfull hint on what the problem could be?

material thk is 3/4" sa-106-b pipe; 5/32" F7A5-EM12K wire at 350 amps and 30 volts.

Thanks in advance.

By new tito (***)

Date 04-30-2007 16:05

Nevermind. Amature question...got it figured out now. The welder was used to a newer machine to where when you pressed stop, it stopped and the end of the bead was fine. With this old dinosaur, you have to come out of the puddle manually. It still looked a little rough, but it get there with a little practice.

By RonG

Date 05-02-2007 14:16

What machine are you using? Lincoln? NA-3 maybe.

By new tito (***)

Date 05-02-2007 14:42

Yes, well, an NA-3N. Our welding rep came out today and got us lined out. Seems the control box can be opened and...what do ya know.....there are 3 more controls in there. Can't remember exactly what the bottom one was called, but it was set on zero, which was causing the sticking. We turned it up a notch or two, and now the stop button actually stops and the wire doesn't stick.

By RonG

Date 05-02-2007 17:05

Burn back"! Well Okay! That's was what I wanted to tell you if you were using a Lincoln. We used that NA-3's for many years then moved up to the NA-5's (roughly 20 years ago). Other than more bells and whistles the biggest difference is in the voltage control.