The GS2 is a simple V/Hz control which is open loop. 208V @ 60Hz = 1800rpm simply scales 1/18 to 11.5V @ 3.3Hz = 100rpm. Nonlinearities will often cause problems at very low speeds in an open loop system. (Note: the GS2 might have some functions to boost the voltage at low speeds and such to help negate some of that. Read your manual to see if it can be programmed better.)
A higher end VFD (like a Hitachi 200/300/700) that can do sensorless vector control measures the current waveform shape and phase angle to try and accurately estimate rotor position(or speed). They have to be tuned though (just like linuxcnc feedback.) They will often have an 'autotune' feature. When enabled, it will go through a cycle of spinning the motor up/down and through a couple direction reversals to measure the motor parameters it needs. I think the Hitachi 700 even has a encoder/tach option where it can close the loop exactly for almost servo like performance. On Sun, Sep 13, 2015 at 10:40 AM, Drew Rogge <d...@dasrogges.com> wrote: > Hi Tom, > > What spindle motor are you using that can reliably get down to 100 RPM? MY > 3phase with a GS2 VFD and barely handle 400 RPM. > > Thanks, > Drew > > > On 9/12/15 8:39 AM, Tom Easterday wrote: > > On Sep 12, 2015, at 10:51 AM, Gene Heskett <ghesk...@wdtv.com> wrote: > >> I see that video, very impressive. But what sort of a threading tool > can > >> be driven at that high a side angle? None of the inserts I have, have > >> that sort of high angle side clearances. > > It is one of these, reversed in the turret (turning M3) with a 16ER A60 > insert: http://www.shars.com/catalogsearch/result/?q=404-1979 > > -Tom > > > ------------------------------------------------------------------------------ > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > -- > Drew Rogge > d...@dasrogges.com > > Phone: 8934OOO629OO4829631OOOOOOO > > > > ------------------------------------------------------------------------------ > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
