Quote:
Originally Posted by chrisfl
So there are two different gear ratios both being driven at the same time. The gears on the output shaft spin freely and the dog moves back and forth to engage one of the output gears to the shaft?
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To be clear, when I say building your own custom gearbox, my assertion was machining your own plates to positions shafts and motors in a way that is advantageous for your application. There are way too many off the shelf options for shifting mechanisms and gears to even consider making your own.
The shifter shaft will largely define your geometry in a number of ways, so I'd start with that. Download a step file of whichever style shifter you want use and dissect that down the shaft. From there establish your geometric constraints and play with those shaft and motor positions until you get what you want.
A technique that has worked well for us is to draw a 2D sketch of the profiles of components, gears represented as a circle of the pitch diameter (remembering you need .001"-.003" additional space between centers on those). Make a sketch for each layer of the box. Turn them on and off to adjust things and verify clearance. Make sure things are constrained well from sketch to sketch. If you do all of this you can effectively figure all the geometry out without having to make actual models.
This tool may help:
http://www.wcproducts.net/how-to-gears/
Again, if you have specific questions, feel free to ask.