charles green wrote: > so the motor in, say, a small drill press or a _bench grinder_ is probably of > the resistive start winding type? > Yes, generally. Some of these may be capacitor-start, however. If it has a big rounded lump on the side of the motor, then it is cap start. > it would be nice to turn the rpms on a bench grinder way down for final > figuring of certain cutter edges, to reduce removal rate, reduce heat at the > cutter edge, and reduce innaccuracy from vibrations. > Well, get a 3-phase grinder and a VFD. With the stock single-phase motor, it can be done, but is very difficult. There are 2-phase VFDs, or you could use a Scott Tee to convert the 3-phase to 90 degree 2-phase. > brushed ac motors are easy to turn up and down, but have a large defect of > set point compliance with any loading, especially at lower rpms. (..and they > are noisy.) > Yes, you can use a closed-loop speed control, or convert the motor from series to shunt with a controller.
Jon ------------------------------------------------------------------------------ Virtualization & Cloud Management Using Capacity Planning Cloud computing makes use of virtualization - but cloud computing also focuses on allowing computing to be delivered as a service. http://www.accelacomm.com/jaw/sfnl/114/51521223/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
