An adjustable friction brake assembly may adjust a variable amount of frictional force required to translate or rotate a shaft, rather than merely locking or unlocking the shaft. The brake assembly includes a housing for internally receiving the shaft, the external portion of the housing including external threading leading into circumferentially spaced fingers extending axially and oriented radially inward to engage the shaft. The brake assembly includes a rotatable adjuster having an internally threaded throughbore for engaging the housing and directing the fingers radially inward to engage the shaft, thereby increasing the required frictional force. For example, by rotating the adjuster clockwise, the required force can be increased; similarly, by rotating the adjuster counterclockwise, the required force can be decreased.