Kirk Wallace wrote: > On Fri, 2007-10-12 at 20:37 -0500, Jon Elson wrote: > ... snip > >>>So at 5k cpi on my lathe, I should be able to get similar results, I >>>hope. Thanks Jon. >>> >> >>Well, 5000 is a lot less than 128,000, and 4 times coarser than >>my 20,000 counts/inch. So, it would be normal to expect the >>best following error you could achieve may be worse. One >>encoder count is .0002" so you will never get better than that. >> >>Jon > > > Opps. It's really 50k cpi. I'm going to have to get a dog so I can blame > my mistakes on it. > Yes, 50 K will definitely work a lot better! > I have a plot for X here: > http://www.wallacecompany.com/cnc_lathe/HNC/emc2/p95i4d3ff1_1.png > > I started working on Z and totally missed it up. Hopefully, I'll be able > to fix it tomorrow. > Not too bad, but you might need more P. If you can't handle more P without oscillation, try adding or reducing D. If you can damp out the oscillation, then turn P up some more. When you get that as high as you can while still well stable, then turn up FF1 until the error at constant velocity is reduced to a small value. Now, you will have some errors during the accel and decel ramps, so increase FF2 until those are not much worse than the steady-speed error. You should be able to get the error on this routine down to maybe 100 uinch. Looks like you are rocking back and forth 1/2 inch in one second, including the accel-decel. Your velocity is peaking at 35000 counts a second, with 50K counts/inch, that would be 0.7 IPS or 42 IPM. Maybe I'll have to do one of these tomorrow and show you how good you can get it.
If the axes are similar (motors, amps, leadscrews, etc.) then the numbers that work on one axis can be used as a starting point for the next. Jon ------------------------------------------------------------------------- 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
