Drill the base of the bat at each dent and ding that you want to remove from your aluminum bat. Be sure that you create the smallest possible entry point for the dent puller's retractable screw. This allows for easier closing of the holes created during the dent-pulling process.
Set the U-shaped dent puller so that the retractable screw is centered over the drill hole in the bottom of the dent. Loosen the retractable screw so that the screw becomes secured within the hole created during drilling. As the screw gets set into the dent, it will tighten. Once you can no longer tighten the screw into the hole, lock the screw in place so that you can begin to remove the dent.
Turn the handle to retract the screw back up to the top of the U-shaped dent puller. Slowly tighten the handle until you see the dent getting pulled back out of the bat. Because this works well on dents caused by hitting balls, only a limited amount of pressure should be needed to remove many of the dents in your aluminum bat.
Spot weld the holes that were created to pull the dents from your aluminum bat. After filling the holes with weld material, allow the bat to cool before grinding and polishing. Grinding the bat will remove the spot welds and even out the surface of the bat. When removing the excess weld, take your time in making the surface of the bat appear as it did when new. The process is time consuming, but if you want to keep using your favorite aluminum bat, you will need to take these steps to get it back in play.