When the welds & shaft have cooled down it is set up in a lathe. Setting the shaft up in the four jaw chuck. Use of the test dial indicator to recreate concentricity of the shaft end held in the chuck. The steady is set up on another pre machined area to support the work while centre drilling. The crank pins were finish turned before being shrunk in place. Therefore there is no off set machining to do with this style of shaft construction.
