I wasn't sure where to put this question. I have a (mid 1970s American) winch/windlass - company is long gone. It has an unusual splined shaft (It's ~ 1" OD, inner shaft is ~ 0.75") and the splines are semicircular in cross section. Has anyone seen one like this, know the name it goes by or went by or in what context it was mostly used? I'm hoping to find or make a mate/socket for it. As for making a socket, I'm guessing the best approach would be to drill the six holes on the circumference of the ID circle, then bore the ID. Then harden. thanks!