Ah the RK05 (that was the DEC version of the Diablo drive). I used to have a replacement set of R/W heads for one but gave them to a friend who was restoring a couple of drives for a PDP-11 project. Fun times.

I've wondered what it would take to build a drive and its media from scratch. DEC used to do it all the time of course but given today's tools and tech. Could you build a 5MB removable platter drive? What sort of seek rate could you get on it? Clearly one of those projects that people that build their own vacuum tubes would get in to.