Aluminum wire sticking to contact tips, bad.

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Hello,I bought a used miller spoolmatic 3, it seems to work fine.  I just keep getting the wire welded to the contact tips.  Sometimes I can't get the wire out.  I have only welded about 24" of weld and have had the tips stick about 12 times, two of them were fatal to the tips.  I am running a shopmaster 300 set on CV with arc control at 40, voltage at about 20.  The aluminum is cleaned with stainless wire brush and then was wiped down with Alcohol.  I am a first time aluminum welder, but my buddy is with me and he is experienced, just not with my gun.  Any advice or hints?  At first it seemed to be only on starting the arc that it would happen, but now it can happen during a weld.  Thanks
Reply:Do you have the correct tip size??? When wire welding al you have to use a tip that is larger then for steel because as the al wire heats up it expands and will weld to the tip. When using .035 wire .045 tip size is common... when buying a spay tip they may come over sized to start with.Could be other causes as well but this needs to be correct before you start.Ken
Reply:I have the correct size tip, it is for .035 wire and is oversized by miller, I was going to try and get larger ones, but I was afraid the wire would not arc correctly.  It doesn't matter if you have a little wire or a lot of wire out of the contact tip, it just burns down and welds itself to the tip.  Most of the time I can pull the wire through, but two times, the wire was so stuck that the tip ended up with wire inside with no way to get it out but a drill.
Reply:I have no experience with the shopmaster 300 so I can't comment on the arc control but the manual says that it increases voltage so you maybe start at 0 then play with it after you get rolling.Some questions??Wire feed speedWire typeMaterial thicknessJoint typeIf the spool gun is operating properly and you are just burning back to the tip you should check your volt vs wfs setup. If the wfs is to low for the volts it can burn back like you are describing.KenLast edited by KGIOR; 10-01-2010 at 06:16 PM.
Reply:Sorry I remembered I had started dealing with this gun in another thread, so I went there.  Here is the link, it will give you info.  I think the arc control only works on CC settings.http://weldingweb.com/vbb/showthread.php?t=37135
Reply:If you have made sure you are using a tip size larger than the wire diameter, then try increasing stick-out and wire speed.  If that doesn't solve your problem, turn your gas up a bit to help cool the wire.