The relative humidity in my house is low and static electricity is an issue. I can go two steps from my PC to the CNC and get a shock that stings. I ground everything to protect the electronics from ESD. The bearings are conductive, so grounded the conduit at the ends with a small insert that fits in the ends of the conduit. I just stripped back a wire and ran it between the insert and conduit. The rollers have a wire from the bearing bolt, to the conduit, to the motor mounting screws. The middle assembly is grounding from bearing bolt to bearing bolt. The Z motor is grounded from the conduit, up the riser to the motor mourning screw (see pictures). I connected the ground to the negative terminal for one of the unused heaters.
Because of this problem, I didn’t want to use the exposed solderless connectors on the rollers. I made up two connectors by using male and female headers that I use for my Arduino projects. They are the same spacing as the stepper motor connectors that came with the kit. I just reverse one motor connection for the x and y motors so one of the motors run in reverse. The jumpers connect 3 male headers. I used the cables from the kit and put two female headers on each end of an extension (see pictures).