What is the minimum distance required between machines to prevent bodily harm?

OSHA does not require a minimum distance between machines. However, the agency does say in 1910.217(f)(3), regarding mechanical power presses, that “the employer shall provide clearance between machines so that movement of one operator will not interfere with the work of another. Ample room for cleaning machines, handling material, work pieces, and scrap shall also be provided.” (OSHA has similar wording in its forging machine area standard, only adding in that the arrangement of machines shall be such that operators will not stand in aisles, per 1910.30(b)).

Otherwise, it would seem to be a case-by-case situation that depends on factors such as (but not limited to) the type of equipment, its application, and any additional operator safety concerns. If having the machinery near another machine poses a hazard, OSHA would expect measures be put in place to protect workers. The agency could potentially use the General Duty Clause or perhaps the machine guarding regulations in Subpart O, “Machinery and Machine Guarding,” to cite an employer.

Also, if the area is an exit access (see 1910.36(g)(2)) or if material handling equipment has to pass through the area (see 1910.22(b)(1)) then there are specific clearances that must be met.