>Thanks for the help on my zero motiion homing problem. I am using >Jeff's workaround and all is working better than expected.
My current project is converting a Derbyshire watchmaker's lathe to CNC by using a couple of tiny (1 inch diameter by 4 inch long brush servos on the cross slide (x/y) and a CMC servo (2 inch dia by 5 inch long) driving the headstock The lathe is a traditional watchmaker type lathe with type D or 10 mm collet holding headstock. I'm using Gecko servo drivers (step and direction from EMC2) I mounted the tiny servos on the removable cross slide and was going to use it just to do profiling with no control over the spindle when I got the idea that if I used a servo for the headstock drive (with positve drive through an XL 5 pitch belt drive) that I could set it up as an xyza configuration and do threading. That's why I came up with the question about zeroing out the accumulated rotary motion on the A axis for doing multiple pass threading. Well, tonight I got it all working and it is really neat to watch it do 10 passes threading a one inch 40 pitch thread and to have the thread start and stop at precisely the same point on each pass. I am getting a following error on the rotary axis quite often and I'm having a problem getting rid of it. I know that the number of steps per second is scale times velocity. In my case 13.3333 steps/degree x V where V is the number of degrees per second that I want to run the A axis. I also am pretty sure that a following error occurs when the step generator can't create steps fast enough to drive the axis at the desired velocity. What I am not sure about is how I take this information and my CPU speed or bus speed (whichever) and come up with the maximum practical speed to drive any axis I recently saw a really nice discussion of how to calculate base period, servo period, task period, etc. based on cpu speed and maximum steps/sec required. I'm pretty sure I could fix the problem by trial and error but I would rather have the technical basis for what is going on. I spent most of the evening trying to find the methodology but can't. If someone could point me to it I promise I will add it to my "Must remember" file and will never bother you again. Thanks, Cecil ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
