On Mon, Sep 26, 2016 at 12:24 PM, Greg Bentzinger <[email protected]> wrote:
> Chris; > > I only would request B-Directional as a time saver. I had a HAAS 5C > indexer which used stepper motors and it was reasonably fast - even so, > indexing often was the largest portion of total program run time. For small > indexers that most of us will make from small rotary tables, they will > likely be driven by low end steppers. These cheap rotary tables are also > notorious for having tight spots because the gear was not mounted perfectly > concentric. As the home builder/ converter we have to go to the lowest > common denominator and keep the max step rate down to where the motor has > excess torque at the tightest area. It's good to discuss this here because I get ideas I'd not think of on my own. You are right about there being a tighter spot in one place. But isn't this 100% repeatable? I don't have to go slow over the whole circle just because one spot requires it. Don't need to use lowest common denominator speed. Should be able to make the maximum speed a function of the table position. Actually my table is pretty good this way, light finger pressure on the crack works all the way around. If Linux CNC has a "Cycle Start" signal then I don't need to let LinuxCNC actually run the stepper motor. It can simply say "go to the next step" and my controller can push the motor up to the physical limits of the motor/table system. The cost to add "smarts" to a stepper driver is about 1/10th the cost of the typical stepper driver. The small computer costs about $3.50. Yes I know this feature could also go inside the FPGA on the Mesa card (if there is room left) ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
