Two piece axle with bearing and captive nut.

I modified the gear side to be secured in two pieces with a bold and nut. I didn't like the idea of an M5 screw just embedded in the plastic and ultimately mine spun out. I tried a heatset but that didn't work well , so I came up with this. 

use one M5 x 40mm and a nut. 

Made the axle two pieces, put a hole for a M5 nut to drop into the screw portion.  easy to print in case of breakage.