for fun and boredom

[Jnadke]

Originally posted by ZACH P.
A place I know of to get such a differential is www.sciplus.com just go to drives, and then wheels.

The bad thing is that differential is only 21" long (axle). Unless you want to make your robot narrow, you'll want something longer.

It's not too hard to create a differential if you understand anything about gears and have the machining tools available. Just look at the page I provided. I gave some very basic instructions on how it can be done.

For gear ratios on the shifting system do it like this. Caculate a raw gear ratio (including wheels) such that your robot would move at 8 FPS. Then create a 2:1 and 1:2 option on the first shifter, and a 1:1 and 1:2 option on the 2nd shifter. You'll have options of 2:1, 1:1, 1:2, and 1:4, creating speeds of 16FPS, 8FPS, 4FPS, and 2FPS. I can see the advantage of this, because you can tailor your speed (and torque since they are proportional) to what competition you have.

You'll probabaly want to find the wheels first. Find something with major traction on the carpet, or something that is modifyable so that you can change the traction material. You'll need the wheels because you need them in calculating the overall gear ratios for calculating your torque and speed.