What is wrong with my Spoolmatic 30A?

[spanky]

So I began working at a job a week ago, still working out all the quirks of some of the equipment. Most of what I do is maintenance, construction, modification, and fabrication. Yesterday I was assigned a purely aluminum project that should take me about 4 days to complete. At the end of yesterday I was not even 1/10 of the way along. I was running the shop's MM251 with Spoolmatic 30A, 0.035, 4043. I went through 4 contact tips before lunch because the arc was soooo freakin long no matter what (reasonable) wire speed I set. For 1/4" and 0.035 wire on aluminum the machine recommends 23V and 520ipm which is where I started; repeatedly melted the wire back up in the tip. So I upped the wire speed to 550, then 570, no consistent difference. Lowered the voltage some, still no real difference. Some times I could go 4" before the wire melted back up in the tip, sometimes I couldn't go more than 1-1/2". I opened the gun and cleaned contacts, removed the wire, air-hosed it out and did a manual check of IPM (6 seconds on a stop watch and measured it) and came up with 410ipm with the gun set to run 550. So I listened to the gun when I had the trigger down and you can hear the drive roll turn slower, A LOT slower, than its supposed to for about 4 or 5 sec. then it picks up and whizzes right along. All this happens in one constant squeeze of the trigger.I have asked around locally and no one seems to have a valid answer as to what is causing this or how to troubleshoot it. This is a $1000 spool gun and I really hate to tell my boss we need to replace it, especially since I haven't even finished out my first month there. Any any advice or insight would be greatly appreciated.

[aametalmaster]

http://www.millerwelds.com/om/o1213al_mil.pdf scroll down to the 7 section...Bob

[ryanjones2150]

What is wrong with my Spoolmatic 30A?

I had a similar issue when I first set up the aluminum mig contraption I'm currently using. It's not a spool gun, but it works pretty well. Anyway, what helped me was I lengthened my stick out by about double. That seemed to work well, most of the time using 3/64 wire at least.

[walker]

Too much brake pressure, wrong polarity ( should be DC+), wrong size contact tip (should ne .045 for .035 wire). Also, what gas are you using, and how many cfh?

[spanky]

Sorry, should have mentioned that I have already referenced the manual and the troubleshooting doesn't really cover my problem; the drive roll is turning slowly for about 4-5 sec. then directly to set speed all in the same squeeze with no wire in it. I removed the wire from the spool gun and determined that the drive roller has the same speed changing issue regardless of wire presence.

And that is just exactly the problem, I can't get the stick-out I need to keep the tip from melting. Unless I turn the wire speed up ungodly high (I tried anywhere from 520 to 610), which I have not tried yet.

As for the tip size I will have to double check tomorrow what size the previous operator left on hand, I believe they are 0.035 but I think I saw some 0.045 somewhere.

Also I am using 100% Argon, 30-35cfh, there is always a slight draft on my end of the building.

[Ironken]

Is your run in setting set too long on the 251? 4-5 seconds is a long time for it to be the run in setting though.

[aametalmaster]

Is your run in setting set too long on the 251? 4-5 seconds is a long time for it to be the run in setting though.

I didn't think the MM251 had run in but it does and you can see how to set it here. Section 5 http://www.millerwelds.com/om/o1326p_mil.pdf ...Bob

[Cgotto6]

I was wondering about the run in setting also. With you describing a consistent time interval that makes me think it's an electronic setting or problem. If it was drag on the feed system I would think it would be more erratic.

[Boilermaker73]

spool

Had the same thing happen to me. Ending up being the wire wound to tight on the little spool. Loosen off the drive rolls grab the wire and pull it out by hand. It should be smooth with little resistance. First spool I ever had that did it. But it made my 30a act as you described.