Got my LR3 up and running, and had a few close calls with the Z axis dropping after powering down. I also need to frequently remove the gantry from the table in its current location, so I whipped this up in tinkercad:
Mine fit with just enough resistance to keep them from falling off, but are easily removed after booting and homing Z.
I have them on both sides. I home everything before shutting down, and the side with the router is the main offender, but having them on both is helpful when I pull the whole gantry off my table.