Taper mounting collets are great for quick change over but it means you cant put anything down the spindle. It is worth having the flange collet chuck as well, I use both. It looks like your spindle has a 12 bolt flange and a register. Bore a peice of round to fit the register, decent sliding fit with zero play. Put transfer screws in the bolt holes, tap to mark and drill clearance holes and counter bore. Once its mounted on the spindle you can bore it out and shrink/press fit a smaller sized lump for the collet chuck, and then turn the collet angle and closing thread. I've made an Er40 and er32 like this, use them most of the time.