pic: Sheet Metal Drive Module Idea

[MichaelBick]

Originally Posted by sentientfungus

Beautiful CAD. I love seeing sheet-metal designs, if only because our team doesn't have the resources to ever do one on the level that we'd like to (and I don't think we have the patience to CAD everything ).

I do have a question regarding the custom housing for the gear-box, namely, why? Don't get me wrong, I'm not criticizing the design-- I don't have nearly enough experience with custom gearboxes to offer anything constructive or unique there-- but I assume it's for weight? If so, then what are the actual weight savings over the original housing?

There are two reasons for repackaging a gearbox. The first reason is for form factor. Repackaging a gearbox means that you can make your frame adapt to it in any way you want. The second reason is weight. The repackaged gearbox has walls that are thin(comparably to the original housing). The Supershifter walls are .25" thick, the repackaged ones are at most .125" thick. Assuming that the sidewall sizes are the same, you basically just removed the weight of one AM shifter sidewall.

Andymark Shifter Sidewall = 5" * 5" * .25" * .0975 lbs/in^3(density of 6061 al) = .61 lbs

So you saved .61 of a pound if not more.

[cadandcookies]

Thank you very much for that response, Michael-- very helpful.

Team 2220 might have to consider doing custom gearboxes this next year (though we'll probably still be a 120lb robot anyway).

[Madison]

Originally Posted by MICHAELABICK

There are two reasons for repackaging a gearbox. The first reason is for form factor. Repackaging a gearbox means that you can make your frame adapt to it in any way you want. The second reason is weight. The repackaged gearbox has walls that are thin(comparably to the original housing). The Supershifter walls are .25" thick, the repackaged ones are at most .125" thick. Assuming that the sidewall sizes are the same, you basically just removed the weight of one AM shifter sidewall.

Andymark Shifter Sidewall = 5" * 5" * .25" * .0975 lbs/in^3(density of 6061 al) = .61 lbs

So you saved .61 of a pound if not more.

All of this is true, though the sheet metal shown is .060" rather than .120"

The real reason I did this, though, was because on a stock SuperShifter, the output shaft is 1.5" from the closest edge and, with 4" wheels, that leaves very little clearance between the Super Shifter (and its servo) and the ground. By repackaging it, I was able to increase the ground clearance -- though it seems to require pneumatic shifting rather than servo shifting.