DISCLAIMER: I cannot stress enough that what works for me may not be what works best for everyone. This is a “take it or leave it” thing!
If you do a lot of aluminium MIG welding like I did this past year, surely this has happened to you quite a few times:
Yup, that’s a melted contact tip for the spool gun. That happens most times when there’s an interruption in grounding (i.e. bad surface prep or total lack of fusion). The welding current has no choice but to return into the tip and this makes your aluminium wire melt into the tip itself.
Now, surely you’re saying that “Yeah, but they are not that expensive”. Let me tell you that if you can save them, every little bit counts! This is what true DIY’ers do! Here’s how:
First, unscrew the tip from the spool gun. Then press the trigger to make 8-10 inches of wire come out. This step is essential because when your wire fused at the tip, the spool gun has weakened your wire at the driving gears. If you don’t do this, your wire will jam and fuse again at your very next welding pass.
Second, put the tip in a vise. Then use one of your smallest punch in the set to make a dent in prep for drilling:
Next you need to use a drill bit of equal or slightly greater diameter than your welding tip. I use .030″ tips so the bit needs to be fairly small. Thus they are VERY FRAGILE! Be careful!
Slowly drill until you feel the drill “sink” without pressure. You shouldn’t have to drill more than 1/8″ deep. If you have to, be very wary, and let your bit cool down at regular intervals. If you break the bit into the tip, you’re done… throw it away and try again on the next melted tip.
If you do it right, you should be able to freely pull the wire out from the tip below. When that is done, use a small round file set (like the ones for acetylene torch maintenance):
As always, be careful and smooth. When you feel the file move through freely, your last step is to simply blow away any debris with compressed air:
…and bingo, you’ve just saved a contact tip!
Congratulations! Haha! I haven’t bought new tips in months. Saving money is good!
Now, I reckon that you could use the same process if you’d ever melt a tip for steel welding. It might be harder though. I’m not sure since I’ve never scrapped one.