Custom Two Speed Gearbox

[Thad House]

Here is a gearbox calculator that i wrote. It takes wheel size and the gears and calculates the ratios and the speed. Is the 18fps the theoretical or actual speed that you want. The actual is usually about 80% of the theoretical, and the actual is what is calculated by my app. 18fps actual is VERY fast and very hard to control. I would also try using a 12 tooth CIM gear, which can help give some better ratios. Those can be found at Andymark.

Also dont count out some of the smaller gears from andymark. From andymark you can also get 14,16,19, and 24 tooth spur gears, in addition to a 28 tooth dog gear. You can also get a 50 tooth aluminum spur gear from andymark as well which will give you a weight advantage.

[Adam.garcia]

The 18 fps is actual.

I understand that this 18fps is a very fast speed, especially for FIRST robots. Essentially our team would like to have a proof of concept, with "swappable" gearboxes for our practice bots.

This "swappable" gearboxes will allow this drive train to be used as a very robust prototyping tool, come next build season.

Thank you, I will check out this gearbox calculator.

I'll keep you posted, as I inevitably will need more help from the CD community.

[Adam.garcia]

Do you have any sample gear ratios that your team has used in the past?

[Thad House]

We have never done a 2 speed in the past, but here is a picture of the ratio's team 254 did last year. They used 3.5 inch wheels, and they only weighed 100 lbs which allowed them to gear that high.

[Adam.garcia]

Oh wow, this is great!

Do you know of any other gear ratios that teams have released? (besides www.frc-designs.com where teams have posted their CAD models)

Thanks