Hi Kirk Yes I've run several VFDs with EMC/EMC2. What you must understand is that there are vfds and there are VFDS. None of the inexpensive VFDs will handle low speed very well. Ones that will run full torque at zero speed use rather complex patterns of power pulses so that the rotor builds up full magnetic fields while not moving.
Many of the commercial lathes and mills will use a full AC servo system for spindle. That way they can command an oriented position and maintain holding torque. This is true of the spindle drive on the Mazak that I describe below. The orientation stuff that JMK and others worked out is pretty slick to watch. It starts counting a spindle rotation at the index pulse. This counts up to the maximum number of pulses in one rotation. We used a 360 ppr encoder on the spindle and a 1/1 belt so it counts to 1440 and resets. You can watch it count with Halscope. We picked up orient angle by watching the count while turning the spindle by hand and put that number in the INI file. When we switch from velocity to position mode in the spindle controller it ramps right down to the orient position and holds there. It didn't take many tweaks to orient position and we got a very clean tool change. HTH Rayh BTW -- I know that snips are dated but it would be kind to snip the Sourceforge added trailer on these messages when replying. On Sat, 07 Jul 2007 12:29:13 -0700, "Enhanced Machine Controller (EMC)" <[email protected]> said: >>From the videos on the lathe threading wiki page: > >http://www.linuxcnc.org/content/view/35/13/lang,en/ > >I can see that single point threading with a normal EMC lathe setup is >doable. But what about rigid tapping? It seems to me, tapping would >require being able to stop the spindle at a precise location. Can this >be done with: > >- A VFD or mechanical braking? >- Use a servo or stepper for the spindle? >- Forget the spindle and use a threading attachment? >- Use some sort of live tool? > >Has anyone used a VFD with EMC yet? I just put one on my manual lathe >and I am having troubles with starting at low speeds. Will low speed >torque always be an issue with VFD's? > >Kirk Wallace ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
