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Unread 16-02-2010, 16:57
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Joe Johnson Joe Johnson is offline
Engineer at Medrobotics
AKA: Dr. Joe
FRC #0088 (TJ2)
Team Role: Engineer
 
Join Date: May 2001
Rookie Year: 1996
Location: Raynham, MA
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Re: pic: 107 Teaser #1

Quote:
Originally Posted by Zanfardino2892 View Post
glad to see our thinking is on the same level being a team in the late 2000's. how did you deal with the issues of attaching the sprockets to the small diameter of the bike wheel hubs?
I don't know how team 107 does it but in 2004 using similar wheels we managed to find a way to interface to the hub that was pretty robust.

There was a section near the hub that was "cored out" in plastic injection molding speak. Basically they needed to install webs in the part to keep from having a big wad of hot plastic in the part (plastic parts like to have constant sections to help the flow of the molten plastic, but also to keep from having "sink marks" where the cooling (and therefore shrinking) inside of the part pulls in the outside of the part away from the wall of the mold. Anyway, this webbing made a perfect torque interface.

It looked a bit like this hub.

We had to lathe up a hub with the right dimensions then we made cuts in the hub that transferred torque to the webbing (and therefore the wheel).

It sounds harder than it was.

Joe J.
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