On 05/31/2015 11:46 AM, andy pugh wrote: > I just bought a new old lathe, as an upgrade to the Cheap Chinese > Lathe. The new lathe actually has a smaller between-centres distance > than the CCL, only 1" more swing, but weighs about 12x as much. > > The drive-train is a 900 rpm motor, then a Kopp Variator, and then a > 2-speed electrically-actuated gearbox. > > I am trying to decide whether to control spindle speed by setting up a > motor to twiddle the speed adjustment of the variator and leave the > VFD (which I need to synthesise 3-phase) at a fixed frequency, or > whether to leave the variator at a fixed setting and control speed > with the VFD. > > The advantage of the variator is that as you reduce the speed there is > more torque available, but that is not the case with a VFD.
My Hardinge HNC has a variable pulley system which I set to a fixed position and I use the VFD for speed and direction control. http://www.ebay.com/itm/111477002385 http://www.wallacecompany.com/cnc_lathe/HNC/00032-1a.jpg http://www.wallacecompany.com/cnc_lathe/HNC/00051-1a.jpg http://www.wallacecompany.com/cnc_lathe/HNC/ It works well for what I turn but I can imagine some parts that would need extra torque at low speed. I'm considering using both. It would be easy to hook up the vari-speed's stepper motor then set up an M code to set the position. The spindle encoder will come in handy to get the proper spindle speed with different vari-speed and VFD settings. One down side of the vari-speed is that it changes speed fairly slowly, but reversals with the VFD should be okay. > I suppose an alternative would be to swap the motor for a 240V > single-phase item and not have a VFD at all. Yuck. > The drive-train can be seen in this photo: > https://picasaweb.google.com/lh/photo/bXi9y-7WGDJSi8r0Rhr6XH69jlxvlrTD6CexboMrrBE?feat=directlink > > It is fairly substantial. > -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/ ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
