The shaft's diameter is 1" (25.4mm) which means that the blade must be installed with a bushing. the reason for using it is that I have it already, otherwise I have to produce a new shaft, pillow blocks and so on.that does look slightly overkill for the job but I guess if its what you have then it will have to do. What is the diameter of the shaft? most 300mm blades have a 30mm bore .