Shaft pull question

I pulled this shaft out of a old Mizuno MP Flight-Hi cut muscle 2 iron

Never seen a shaft tip to have these marks on them before.

looking for some clarification and as to why it was done?

Have pulled a lot of these out of old Mizuno's. Can't remember if I have seen them from other OEMs. Always assumed that it was to crimp in shaft weight plugs so the shafts could be tip pre-weighted for faster assembly. Again that was just my best guess.

Those are called "dimples".

Standard practice for a long time when shafting irons. Helps create a snug fit in addition to the epoxy.

" Dimpling " ....It was a common practice back in the day , when shaft epoxy strength was

kind of hit or miss . I myself was using 2 part epoxies that targeted the RC model airplane

builders market . In theory the dimples added to the mechanical bonding of the shaft

to hosel surfaces. I would use a nail set to add dimples on some of my personal builds.

Thank-you!

Long after epoxies were sound, some manufacturers continued to use dimples as they force fit the shaft in the hosel allowing the club to be handled (meaning shaft not moving) during the build before the epoxy cured.

Long story short, it allows more "surface area" for epoxy to bond to shaft. In tight fits it will allow some more epoxy to remain on the shaft when inserted into the hosel.

> @JCAG said:

> Long after epoxies were sound, some manufacturers continued to use dimples as they force fit the shaft in the hosel allowing the club to be handled (meaning shaft not moving) during the build before the epoxy cured.

This is the correct answer I think. The dimpling doesn't increase bond strength, but the slight interference fit created keeps the shaft from rotating if the club is bumped/handled while the epoxy is drying. I believe Mizuno grips before gluing up the heads so assuring the shafts don't rotate while curing is critical.