We turned a 4-5" piece of 1/2" hex aluminum down to 3/8 or 7/16 but left a taper at the shoulder and threaded to accept a hex nut. We then drilled out the end to match the CIM shaft. Using a 3/32 slit saw in a vertical mill, we machined 4 slots to make a collet. The hex shaft fits a hub as shown. It works well and hasn't slipped so far.. In assembly it will have loctite. A bearing captures the other end of the shaft.
http://www.chiefdelphi.com/forums/at...d=13596734 16