Bolt Size Required
Q: There has been a question of whether or not we should be mounting the unit with M10 screws or M12 screws. We are proceeding with M12 screws as I stated in the earlier email below, but the question has been brought up. Please address whether M10 screws or M12 screws to mount your unit.
A: Highlighted in red to make it easier what would fit with what tolerance ( We would recommend a 3/8” or M10)
Drilled mounting holes called out in fractional size 17/32” = .53
This format is common in NFPA series 2A side lug air cylinder mounting where like Parker and others they give you a nominal size of the hole in fraction. We are not an air cylinder but we do use similar ideas to make mounting easy for installers who are familiar with them. As such the 78, 288, 298, as well as the 651/751 & 851 slide-a-mark series come in flange and side lug foot mount options. Below are some normal sizes machinist use when mounting items and choosing bolt sizes in (decimal equivalent).
M10 bolt tight hole 10.5 (.41) Med 11 (.43) Loose 12 (.47) M12 bolt tight hole 13.0 (.51) Med 14 (.55) Loose 15 (.59)
This link below is handy for clearance holes when using metric screw sizes. Note it give you close medium and loose fit.
http://www.draughtsman.co.uk/information_images/mechanical/clearance_holes.htm
The link below from Cal Tec is a handy chart, most machinist use something similar. It will give you the bolt body dimensions and closest metric size and the normal clearance hole
sizes.
