I do the same except with 1/4" Masonite. I machined the blocks with a slight taper so they easily drop in to the slot but go snug when at full depth. Vice lands close enough for what I do. There is no noticeable play. I've done the same for my 8" rotary table and for my indexing head & their foot stocks. Makes for much faster setups. I store them on wood bases with a sloppy groove for the blocks. I'd like to claim to be a tenths machinist but it ain't true. My DRO shows ,0002 but will flicker off that pretty easily. I'm lazy so I use the DRO for almost all positioning.
