On a similar note, a set of plans for the Corliss I am building, had less that 5 parts with any tolerance, and all sizes were in fractions of an inch. Yeah, that 17/64 counter bore is real common-not, 9/32 can be found, now in the tool drawer. Piston, 1 1/4, cylinder bore 1 1/4, I'l make that work, but a few more would be nice. Drawings were done in 1978, based on a model done in 1947. A buddy of mine who worked as a draftsmen in the 50's said he never saw fractions on a machined part ever. In the shop manual the spec's for my 1934 pontiac, the crankshaft journals were listed as 1 11/32 diameter, as well as other fractions, but these were not intended as blueprints they were just specs.