Gearbox Internals
Motor Specs
Mounting Blocks

New Drill Motors

Note:   Regretfully the company making these went out of business before I could obtain any more than samples

In the past I got all my drill motors from Harbor Freight. I started by using 9.6v versions and as they became unavailable have slowly worked my way up through 12v, 14.4 and currently use the 18v ones in my 12lbers.  This leaves a couple of gaps for which there is no readily available solution. The first is a low voltage version like the original ones but with better speed when used with a 3S LiPo (11.1v) and a higher voltage (30 -40v) more powerful one suitable for use in 30lbers.

I have sourced some new drill motors directly from the manufacturer in China which fill these gaps.  Check www.kitbots.com for availability.

Motor Specs.      Solid models              Gearbox details          Mounting Blocks

The motors can be seen above.  On the left we have the Speed 700, 30v version, next are the Speed 500, 18v and 9.6v versions and finally I have a Harbor Freight 12v one for comparison. The gearboxs are very similar to those on the Harbor Freights but with a longer nose.  The gearbox can be locked in "drive" in the same manner as before.  Output speed is specified as 900RPM at nominal so performance with 3" or 4" wheels should be good. The gears all metal.

The motors all feature very good ventilation so overheating of the brushes in particular should be reduced versus the Harbor Freight design. Brush mounting look to be the same size on the 9.6v and 18v versions and look very similar to those on the Harbor freight. The Speed 700 30v motor has much larger brushes and brush mountings but of a similar design.

One big improvement is front air intakes so that cooling air will be pulled through the whole length of the motor. The rear of the gearbox is changed to allow air into these intakes.

The output shafts all use the same 3/8 thread with LH threaded screw as the Harbor Freights. The dimesions are a little different and perhaps not so strong. I've never managed to break one of the shafts on a Harbor Freight so I think these will be OK. The shaft is supported by two ball bearings that are spread further apart. I think my standard Colson hubs will fit without modification.

The gearbox front mounting  is more like a single D rather than the double D thats on the Harbor freights but the main dimensions are the same so a common mounting could be designed. 

The 9.6v and 18v versions weigh almost exactly 1 pound (the same as the harbor freight ones) and the 30v Speed 700 versions only weigh 1.125 lbs each.