Strange tool situation.

[Coach James]

Today I was using 1/4" machine screws to repair a spring board. The bolts were labeled as having 5/32 hex head drive.

My 5/32 Allen wrench, OEM brand, fit perfectly. My 5/32 Craftsman hex bit was too large, but my 4mm Craftsman hex bit fit perfectly.

Coach

 

[Derek420]

Just manufacturing differences just how it is check fitment with sockets of different brands on a bolt and you will see same goes for Allen/hex.

 

[APEowner]

There are standards that define the acceptable range of sizes for both the fasteners and the drive tools. If both are within spec. they'll fit. I'very seen other Craftsman tools that were outside of tolerance. I suspect that's the case here.

 

[MikeF2316]

Sounds like your mission is to measure the Allen keys with a micrometer. I, for one would be interested in the results.