The indicator tip has to sit on something to read the minute 0,001 mm/div movements from the pivoted measuring arm - hence a case-hardened bolt will do as an anvil, but has to be ground and honed as well. Hilda, my Chinese 400W butch dremel with a homebrewed 22 mm arbor for angle grinder disks sitting in the DIY-ed tool post holder ready to dig into some hardened steel. Lathe protected by sheet aluminium from grinding wheel/ case hardened dust, which is particularly grim to cast iron lathe beds and slides.