Abstract: A locking member is formed with a circular plate and an upstanding rim and is adapted to be pivoted between locked and unlocked positions beneath the head of an orbital sander. When in its locked position, the locking member holds the spindle of the sander against turning and permits the sanding pad to be unscrewed from the spindle. The plate of the locking member includes a dimple which engages the head and causes the locking member to rotate concentrically with the head when the locking member is in its normal, unlocked position. The rim of the locking member performs a fail-safe holding function in the event the dimple fails and also prevents the locking member from being improperly installed in an upside down position.

Abstract: A rubbing machine of the type in which a support is spaced from and overlies a rubbing shoe and in which the rubbing shoe is connected to the support by a drive mechanism operable to reciprocate the shoe. The rubbing shoe is rectangular in shape with the drive mechanism connected at the center of the shoe, and four flexible boots are connected between the support and the shoe at the corners of the shoe. Four pair of opposed, rigid studs are mounted between the support and the shoe to transmit thrust therebetween, and each pair of studs is mounted within a respective one of the boots with one of the studs connected to the support and one to the shoe. A tongue-and-groove connection between the opposing ends of each pair of studs confines the shoe for linear reciprocation in a straight path.