A depth gauge arrived with a 3/8 inch = 9.5 mm mounting rod that fit one of my magnetic bases, but another base in my collection has a 5/16 inch = 7.9 mm clamp. Having recently rummaged through the aluminum rod stash, this happened:
The original rod at the top has an M6 thread, the drawer of random M6 screws provided suitable volunteers, and a bit of lathe work removed / shaped their heads accordingly.
The shorter rod has a blind hole, with a dab of epoxy holding the headless screw in place. Not that it matters, but the lathe held them in alignment for curing:
The longer rod got drilled all the way through, with more epoxy holding the screw, and, even with a relatively loose fit, no worries about alignment.
The longer rod gets the clamp away from the depth gauge’s base plate for better positioning:
They’ll surely come in handy along the way …