Originally Posted by Retmachinist
I'm not sure what you mean "to fit into a 3 piece bottom bracket?" Milling wouldn't be an option. There are ways to cut square holes, broaches, E.D.M.'s, lazers, water jet, also not sure why you need a tapered square hole? Explain.
yes what jim said....to fit onto the bottom bracket like the crank would....sorry for any confusion
edit:the idea was to make a piece for one side to mount 2 freewheels back to back and a piece for the other to mount the larger sprocket to the engine......both pieces would bolt onto a standard bottom bracket
but the idea revolved around making the square tapering hole like a crank arm has