This FRC#33 instructable inspired us to look at other adapters.
The Milescraft adapter is slightly more compact than the DeWalt, and it uses bearings instead of bushings.
We unscrewed the main handle form the miter gearbox and pulled the snap rings to get to the internals of the mechanism. They appear to be sintered gears which are weak under impact, but for many FRC applications, this should be acceptable. There aren't any thrust bearings in this device so you shouldn't be pushing against either in the input or output features either.
This is the main assembly with the bearings held in with internal snap things.
Here is one of the gears and bearing pulled from the housing.
Here is a picture of both of the gears and one of the bearings.
Here we drilled a hole in through the input side of the housing to allow for perpendicular outputs.
Here is the final output with a 1/4" hex shaft going all the way through the input.
Also in this photo is a 1/2" hex tube with 1/4" hex internal bore from McMaster.
You would likely need to 1/4" hex broach the output of a gearbox for this to work in many applications but some application may only need hex to hex on both ends, and the McMaster tube can be used in those applications.
We haven't used this on a robot yet, but it's a useful tool to have in your design toolbox.
- Spectrum