Axle collars are a great alternative to using grub screws or a very effective way to stop axle movement when using 30mm axles.
These 2 piece axle collars are easy to use as you are not required to remove the axle to install them. The collars can slide over the top of axle keys if needed with the 30mm option having a milled section for both 6mm and 8mm axle keys.

AXLCK50
AXLCK30
AXLCK40
AXLC30------