Originally Posted by Creative Engineering
I think he's talking about the pedal crank shaft.
I've got the 3 piece set-up on my Spoilers. The shaft is square and tapered at the ends 2-3 degrees.
The hole in the crank has a corresponding square, tapered hole so that the crank is forced onto the taper for a positive fit. There is a bolt that draws the crank onto the shaft.
O.K. I am with you guys now. I thought at first he wanted to cut a tapered square hole through the bottom bracket, just tapered at one end. I couldn't figure out what you could use it for.
Got it now.