spoolgun specter

Date 08-23-2005 19:28

I am using an rpg250 spool gun, purchased from HTP, but i think it is a standard. lincoln makes one like it. after 2 years of use, it has begun to have intermintant arc stability on aluminum. i sent it back for repair , and they ran my spool of .030 super glaze 4043 through with no problem, however, upon its return it exhibits the same problem. i use an HTP200 mig machine which never has problems, but the spool gun is killing me. the wire feed is on the gun, and has a very limited useful range. 10 is often too slow and 20 is too fast on a 100 point dial. but there is no consistancy. i get dialed in and run a perfect bead, then the next is fast, slow, dropping out, spattering, leaving a very rippled bead. often, it is dull grey in color. then it will be fine for a bit. i do notice a rhythm to it, every 5-6 dimes, it will go bad. any clue would be helpful. i have considered getting a different gun, but do not how to integrate to my welder.

By supermechanic (**)

Date 08-24-2005 00:18

possible problem with wire speed control potentiometer.
test by removing pot from circut, connect to ohm meter.
run pot both ways, a non linear responce indicates a problem.
in this situation, a cheap 'old fashion' swing needle meter is better to use.
the new digital meters might not put enough of a load across the pot to get an accurate reading.
be shure all connections in gun are good, as the motor runs on low-volt dc current, and is sensitive to very minor fluctuations in voltage.
good luck.

By superK

Date 08-24-2005 00:41

that was what i originally thought, but the curve is good, and it worked fine at the shop. I have not liked this gun too much since i got it, but, i guess it works. The fact that it speeds up and slows down during a single weld makes me think that my machine is not working right with it. i really just don't know.