This is a locomotive wheel casting pattern for a 1:20.3 (F-scale) Climax Class A locomotive model. The pattern is 1.67" outside diameter by 0.50" thick. The pattern has additional material and 3 degree drafted walls for a finished wheel that is 1.59" diameter around the outer rim and is 0.375" thick. Ed Hume's book,
A Climax Class A Live Steam Locomotive, has detailed dimensions and provides a detailed workflow for making the wheels by CNC machining. There is more information on the book and locomotive design at
http://Model-Shop.net.