A precision apparatus (10) includes a constraint joint (256) having a contact (258A) and a contact engager (258B). The contact (258A) includes a contact region (268) that is rounded, and the contact engager (258B) includes a first wall (270A), a second wall (270B), and a third wall (270C). Further, the walls (270A) (270B) (270C) are arranged so that the contact region (268) simultaneously contacts only one location on each wall (270A) (270B) (270C) to create a true three point contact that provides three degrees of constraint. One or more of the walls (270A), (270B), (270C) includes a contact pad (274) that engages the contact (258A). Each contact pad (274) can be made of a hard, relatively low friction material with a low friction surface (273).