I also acquired a Radial Arm Drill from a line-shaft shop, without main or counter-shaft pulleys so rpm is unknown. It appears to be similar to the 1919 model so the original spindle speed was probably 300 rpm max. However as high-speed tools became available the max. spindle rpm soared to 1200 rpm and then to 2000 rpm in the following years. Does anyone know if I can select my counter-shaft pulley diameters for the higher RPM without abusing the spindle?