41 C.F.R. § 50-204.5 – Machine guarding.

(a) One or more methods of machine guarding shall be provided to protect the operator and other employees in the machine area from hazards such as those created by point of operation, in going nip points, rotating parts, flying chips and sparks. Examples of guarding methods are—Barrier guards, two hand tripping devices, electronic safety devices, etc.
(b) General requirements for machine guards. Guards shall be affixed to the machine where possible and secured elsewhere if for any reason attachment to the machine is not possible. The guard shall be such that it does not offer an accident hazard in itself.
(c) Point of Operation Guarding.
1. (1) Point of operation is the area on a machine where work is actually performed upon the material being processed.
2. (2) Where existing standards prepared by organizations listed in § 50-204.2 provide for point of operation guarding such standards shall prevail. Other types of machines for which there are no specific standards, and the operation exposes an employee to injury, the point of operation shall be guarded. The guarding device shall be so designed and constructed so as to prevent the operator from having any part of his body in the danger zone during the operating cycle.
3. (3) Special hand tools for placing and removing material shall be such as to permit easy handling of material without the operator placing a hand in the danger zone. Such tools shall not be in lieu of other guarding required by this section, but can only be used to supplement protection provided.
4. (4) The following are some of the machines which usually require point of operation guarding:
  Guillotine cutters. Shears. Alligator shears. Power presses. Milling machines. Power saws. Jointers. Portable power tools. Forming rolls and calenders.
(d) Revolving drums, barrels and containers shall be guarded by an enclosure which is interlocked with the drive mechanism, so that the barrel, drum or container cannot revolve unless the guard enclosure is in place.
(e) When the periphery of the blades of a fan is less than seven (7) feet above the floor or working level, the blades shall be guarded. The guard shall have openings no larger than one half ( 1/2) inch.
(f) Machines designed for a fixed location shall be securely anchored to prevent walking or moving.