A lockable lateral adjuster mechanism comprises a platform with a channel carried by a base. A cam has an eccentric head that is pivotally disposed in the channel. The cam has a stem extending through the channel and into a counter bore in the base. The platform is laterally displaceable with respect to the base as the cam pivots. A countersunk interface is disposed between the eccentric head and the channel. A fastener extends through the cam to the base, and secures the cam, and thus the platform, to the base, and applies an axial load on the countersunk interface along an axis of rotation of the cam.