What is the best way to manufacture the spline shape in the crank?
Although at first it looks difficult to manufacture the spline shape in the crankarm, the quickest and easiest method is the same used for manufacturing the majority of tapered square cranks: a broaching operation followed by one or two coining operations. The broaching operation creates the straight-sided spline shape in the crank while the coining operation creates the 1 taper of the spline flute. The depth that the coining tool is pushed into the crank determines the amount of pre-load between the crank and spindle.
