A lot of the tightening problems people seem to be experiencing is actually caused by grub nuts, and poorly manufactured grub nuts. It's a bad design when it's made well! If your grub nuts do not all drop cleanly on the motor shaft to the same level, you have defective ones, ones not milled out all the way. And the collet can gall and not compress correctly on the grub nut. If you can apply a dab of oil to the arms of the grub nut before applying the collet and NOT getting any on the shaft, it works better. And if your grub nuts are not going on the shafts cleanly, you can ream them out carefully. If your outrunner motors have mounting screws on top, SERIOUSLY consider finding prop adapters so you can throw the grub nuts in the trash can where they belong.