Abstract: A guide for a blade of a bandsaw includes a head and two molded, replaceable shoes that constrain the blade. Each shoe is symmetrical, having four side faces as a thick diamond-shaped frictional border for blade contact. The back of the shoe is a replica of the front. Internal sides of each diamond profile have a resilient web having strips that reversibly lock with grooves against a parallelogram raised from the head surface to retain the shoe carry rubbing forces from the blade. The shoe may be removed, turned through 180 degrees, or flipped over.

Abstract: Optical imaging apparatus and a machine vision camera system for an alarm protecting a person's hands when working at a motorized cutting or abrading machine, uses trains of sets of mirrors to define four spaced-apart viewpoints and transfer non-overlapping scenes on to an image sensor of a single camera. An optical axis from each viewpoint allows a cuboidal protected volume to be created. The cuboid may have vertical sides. Recognizable objects inside that volume cause the machine to stop, while objects near but outside the volume cause the apparatus to raise an alarm.

Abstract: An active safety apparatus adapted for a disk or circular knife or saw is based on optical surveillance apparatus. The apparatus provides a precise boundary for a protected volume surrounding the blade. The apparatus creates four corner edges for the protected volume, which is a cuboid or a right frustrum. Appearance of an operator hand, recognized by glove color, in the protected volume causes immediate, active stopping of a servomotor used to rotate the saw blade.