Gene Heskett wrote: > > The 3rd sensor, the index pulse generator establishes the start point on a > synchronized move, and works well as long as the spindle speed is steady. > Because of the acceleration delays in bringing the axis chosen up to speed > from its parking position, the spindle speed cannot be adjusted in the > middle of a G76 or G33.1 cycle without the thread moving sideways just > enough to muck it up. BTDT. :( > Not really true. I demo rigid tapping on my minimill, and run the spindle motor off a servo amp, but in open-loop mode. So, the spindle slows down when the tap goes in the hole. I believe it is at least a 20% speed drop during the tapping. But, it doesn't bind the 4-40 tap at all. The index pulse is only used once at the beginning of the spindle-sync operation, then only the quadrature info is used to synch the axis to the spindle. The encoder counter keeps a continuous count of the spindle rotations as a signed float (derived from an internal signed integer).
I think you can get away with two sensors on a lathe, one index pulse and one sensor that produces X pulses per rev., as long as your encoder counter scheme (hardware or software) can be set to count pulses as opposed to quadrature. Jon ------------------------------------------------------------------------------ LIMITED TIME SALE - Full Year of Microsoft Training For Just $49.99! 1,500+ hours of tutorials including VisualStudio 2012, Windows 8, SharePoint 2013, SQL 2012, MVC 4, more. BEST VALUE: New Multi-Library Power Pack includes Mobile, Cloud, Java, and UX Design. Lowest price ever! Ends 9/20/13. http://pubads.g.doubleclick.net/gampad/clk?id=58041151&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
