The machined cast iron base in the four-jaw indepentent chuck - kinda "Poor man's surface grinder", tearing away near half of the 12 mm hardened ball bearings* (at 60-64 Rockwell C, a wee bit harder than the granite itself), just leaving them 1 mm proud of the bottom. The lathe just chugging along in slow back gear, while Hilda is screaming away at +12 000 rpm as I want the feet to be as flat, sharp-edged and big as possible, thus plowing away any remaining debris (rather than riding on top of it) from the surface plate. *Info on how to get these for free in "Dumpster Diving" folder.