Ryan,
I did a modification to my 7x16 minilathe a few years ago extending the cross slide travel. As a part of this mod I purchased a new satin chrome cross slide micrometer dial from LMS. I bored a counterbore into the backside of the dial to accept a 1/16¡± cross section O-ring and sized it for a friction fit. I assembled it with a bit of white Lubriplate grease. It has been working out fine ever since final assembly.
I considered using a knurled screw and I am sure that would work well also, but didn¡¯t want the knob projecting from the side.
The 9¡± South Bend lathe used a slotted set screw that was flush and did not project although it required a small screw driver and was not convenient to use.
OldToolmaker