pic: Team 2471's ball shifting spool
 

Re: pic: Team 2471's ball shifting spool
 

Did you guys manufacture that yourself? That's a legit piece of engineering! ;)

Re: pic: Team 2471's ball shifting spool
 

I second that. Looks completely professional, I would have guessed it was off the shelf. Care to share how you made it?

Re: pic: Team 2471's ball shifting spool
 

Thanks, I wish we had the machines capable of making that in house. Thankfully we have a mentor who has access to a really nice lathe and knows someone with a really nice wire EDM machine.
The assembly has three major parts: the spool, the ball carrier, and the shifter rod.

The ball carrier is turned to its outer shape on a lathe, the holes for the ball bearings and a key way are cut on a mill.
The shifter rod is turned to the correct outer dimensions then the end is threaded.
The spool is turned on a lathe and a profile for interacting with the bearings is wire EDM'd.