>> Wiki refs:
- " Phillips . . . purposely designed to
cam out when the screw is stalled,[
citation needed] to prevent the fastener damaging the work or the head, instead damaging the driver."
- "The
JIS B 1012 is commonly found in Japanese equipment. It looks like a Phillips screw, but is designed
not to cam out and will, therefore, be damaged by a Phillips screwdriver if it is too tight. " <<
Phillips design is certainly a worthy feature when
installing steel fasteners with a steel bit in an assembly line fashion as intended.
Unfortunately,
installation isn't the problem in this application. The broader head of the steel Phillips bit doesn't seat fully into the JIS-type screw causing it to ream out the head of soft brass or aluminum camera and lens screws
if they don't turn freely when unscrewing them -- which many don't as they're often corroded or a thread sealant has been used.
Once the cross point head of these tiny screws is damaged it's almost impossible to remove them with a screw extractor. If a JIS-type screw doesn't turn freely with a substitute Phillips bit you're better off to file a straight-slot type bit to a suitable point rather than risk reaming the head with a poorly fitting Phillips bit. Better yet, use the JIS bit with anything you plan to reassemble or repair.