Gearmotors from Cordless drills.

The Motors and gearboxes from cordless drill have long provided 12lb and even 30lb robots with a cheap drivetrain.  Originally these were mainly Handiwork 4.8v drills from Walmart but that source has almost dried up.  The Harbor Freight 7.2v drill looked like a possible replacement, but it too,  is no longer available.

Harbor Freight continue to make available a series of drills. There were 9.6v and 12v versions but now only the 14.4v and 18v versions are readily available. These are regularly on offer at $15 - $20 each.

Click on one of the options on the menu on the left to see how to strip down and modify one of these drills. Ready-to-go Gearmotors derived from some of these drills are available in the Kitbots section of my site. 

I wrote an article for Servo magazine on how to strip down and convert a cordless drill motor   page 1    page 2