Low Cost Planetary Gearbox Source...

[Joe Johnson]

While looking for some gearboxes for Robotic Amusements on ebay, I came accross the company BaneBots.



As it turns out, they make some pretty nice transmissions. AND they make some that are that the Fisher-Price and the Mabuchi motors will (pretty much) just bolt to (buy a gear or pull of the one that is on the stock motor, press the pinion on the FIRST legal motor, reassemble the gearbox, and mount it on your robot).

They come in a variety of ratios (5:1, 16:1, 20:1, 25:1, 64:1, 100:1, 256:1). The gearboxes have nice mounting points and beautiful 3/8" Dia output shaft that is long, easy to access (and support) and keyed w/.125 key.




I have 2 of these jewels on my desk right next to me.

Here is my thoughts.

They are sweet! But you are going to have to take the good with the bad.

The good:

• Reasonable Price (~$40)
• Nice mount points
• Nice output shaft (but it should be supported by an added bearing if you sideload it much)
• Compact
• Light
• Easy to use for the Fisher Price or Mabuchi Motors

The bad:

• Not exactly quiet
• I am skeptical that the transmissions can take the kind of torque we may be able to generate if you use a F-P motor and a high gear ratio (256:1 for example) if you stall the motors. I calc. that you could get over 50N-m out of the shaft if you really do use the 256:1 and a F-P motor -- that is alot of torque for a 3/8 shaft. I also have concerns about the face width of the last stage of the gearbox if you actually get to these higher torque outputs -- both the Globe gearboxes and the Dewalt transmissions have much beefier final gearstages than these gearboxes (this is just for comparison, not necessarily a criticism).

The Bottom Line:

• For the right application these gearboxes are AWESOME!
• I don't recommend trying to get 50N-m of torque output.
• I don't recommend using them as drive motors on a FIRST size robot.

FYI, I just talked to them the day before kickoff, they have 1000's in stock.

Good Luck,

Joe J.

Disclaimers:

• I have no ties (financial or otherwise) to Banebots, Inc.
• I have not field tested these on robots. All I can say is that my 11 years of FIRST experience leads me to believe that these gearboxes will be great in the right application on a FIRST robot.
• If you try this and it doesn't work out, I want to hear about it, but I don't want to hear things like "Dr. Joe, you are the reason we lost the Championship." As always, you mileage may vary.