Can a Mechanical engineer please explain how to calculate gearing ratio on planetary gears? I was wondering if electric drill / screwdriver boxes could be a cheap source of strong gearboxes.

Yours Simon M.

It's been done before, and if my plans go ahead it shall be done again very shortly

I'm quite sure that there is nothing new in this, I thought I spotted a site some where showing this with a 90° drive. But I wanted to know how the ratio could be calculated.
Yours Simon M.

Gear ratio is basically calculated by diameter of engaged gears. For torque from small to large, that is the 'amplification' you get when calculating.

The actual math is not quite this simplistic but first run gearing can be calculated this way.

I have been thinking over doing the same thing using drives from the newer battery drills with vari-speed controls.Some of the drills on the market place today are powerfull and cheap in price.The biggest problem is cutting them down to size and making a proper way to mount them in the hull.There are also very small and also cheap 90 degree drives that will seem to work for the drive shafts.
I think it may also be possible to use the exsisting triger speed control and reverse control with servo's,doing some moddifications to operate these with servo's.I have a non-RC Stuart on it's way to me and this is what I had planned on trying to use for it.
BIGMIG

P.S. Isn't figuring gear ratio just as simple as counting the amount of turns from the drive pinion gear it takes to turn the drive shaft one turn.(assuming you are trying to figure this on an existing gear box).?

He's asking about planetary gearing. Much harder to determine, as it depends on what part is stationary.

http://en.wikipedia.org/wiki/Epicyclic_gearing

D.

The more I look the more it hurts, [link=http://www.roymech.co.uk/Useful_Tables/Drive/Epi_cyclic_gears.html]Site 1[/link], [link=http://www.technologie-entwicklung.de/Gasturbines/TS-21/Gear_Box_Details/Gear_Calculation/body_gear_calculation.html]Site 2[/link]. Fourier transforms using laplace was about my limit.

Yours Simon M.

had thought of using these on a project before http://www.technobots.co.uk/acatalog/info_1452_007.html

Thanks for the link, I wonder how strong they are?

Yours Simon M.

not sure but the link to the whole site might provide an answer http://www.technobots.co.uk/acatalog...Motors_82.html

Regards Rob