Profile: Smithco Mfg., Inc. supplies air circulation propeller fans for lumber drying kilns and drying sheds. Our propellers include keyed taper lock bushings, stainless steel hardware and the blade pitch is easily set using the Smithco SMI-DG degree gauge. We produce 42" to 48" 4 blade propellers, 54" to 72" 4 blade propellers, 54" to 72" 6 blade propellers and 60" to 76" 8 blade propellers. Our 54" to 72", 4 and 6 blade propellers are used extensively in track loaded lumber kilns drying softwoods & airfoil blades, which are effective up to 1 1/2" w.g. of static pressure as measured across the kiln's fan wall & the maximum recommended fan speed is 925 RPM.