A fan wheel assembly includes at least three hub rings and a connecting member. A slit-shaped ejection hole is formed at the lower end of the nozzle for supplying a treatment liquid. A connection washer covers the lower neck portion of the connection head. A fastener assembly supports the support member between the first and second sides of the housing. The camera may be positioned to take a simultaneous picture of both the indexing surface and the part in order to evaluate the part using the picture by comparing an indexing surface image with a part image. Thus, only one portion of the ferrule of the present invention needs to be precisely defined.