The roto round is an adjustable fixture used to check concentricities, run-out, and or TIR of one or more surfaces to a basic diameter. Three precision bearings set the primary datum plane and support the weight of the part while 2 roller bearings mounted on the angled base define the circular datum. Indicators then contact the part as it is being rotated to determine various parameters. Dorsey also manufactures a line of heavy duty Roto Rounds with higher weight capacity and portable concentricity fixtures for use if your part cannot be placed on a CPF fixture. CPF fixture is for use with parts 1 - 5" (25mm - 130mm) in diameter. Contact us for details.