On Sun, 2007-10-14 at 18:00 -0700, Kirk Wallace wrote: > Last week I made my first thread on my lathe. It didn't take long to get > good threads, but I wasn't happy with the PID tuning, so I have been > doing battle with that. After some improvement, I tried another thread > and got a pronounced surge motion during the threading passes. This > happened last week, but turned out to be an erratic spindle encoder > signal. I checked all of my encoders, which seem to be fine. Then I went > back through some of my "known decent" PID settings and got the same > surging. The surge appears to be commanded. I have a feeling that the > increased acceleration times may be a factor. I wonder if synced motion > should have a ramp or buffer zone to allow it to lock gracefully. I have > a halscope graph of a spindle synced motion and my best tuning at this > link: > > http://www.wallacecompany.com/cnc_lathe/HNC/emc2/spindle_sync_surge-1a.png > > and the .ngc file is here: > > http://www.wallacecompany.com/cnc_lathe/HNC/emc2/spin_sync_z-1.ngc > > Any comments are appreciated. >
After looking at the graph for a while, it came to me that the slope of the Z0 to Z2 move intersects the vertex of the Z2 to Z0 move and the G4p0.2 dwell. Shown as line "A" my revised graph here: http://www.wallacecompany.com/cnc_lathe/HNC/emc2/spindle_sync_surge-1b.png Shouldn't the target slope have been line "B"? -- Kirk Wallace (California, USA http://www.wallacecompany.com/machine_shop/ Hardinge HNC lathe Bridgeport mill conversion pending Zubal lathe conversion pending) ------------------------------------------------------------------------- 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
