it is a cost sensitive application, as always, and limited to single 115v phase mains supply. there are the sherline spindles/motors with decent speed controls, but sherline stuff is kinda spendy. i dont recall seeing any retail vfd pages, but i'm thinking in the many H$ to a K$ or so for a drive, and the smaller power motors i've come across replacing are a few hundred on their own. in contrast, a bench grinder from a home store or walmart can go as low as $40. ..hmm. i wonder how hard it would be to rewind one?
--- On Wed, 3/7/12, Jon Elson <[email protected]> wrote: > From: Jon Elson <[email protected]> > Subject: Re: [Emc-users] IRAMS Plan, FAN7382 with BUZ11 > To: "Enhanced Machine Controller (EMC)" <[email protected]> > Date: Wednesday, March 7, 2012, 10:38 AM > 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 > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
