On Wednesday 23 January 2013 15:59:55 Bruce Klawiter did opine: Message additions Copyright Wednesday 23 January 2013 by Gene Heskett
> I am curious, how does LinuxCNC back off of a limit switch? > I have a bridgeport with hand wheels so it is easy for me, just > wondering how this is done on the big machines. > > Bruce As shown in the gfx on the wiki under homing, there is an implicit assumption that it is a mechanical switch, with a bit of hysteresis space between the close and the open going the other way. It's fairly well explained, but the lack of hysteresis in an electrical contact such as I am using, means I cannot set my backlashes for total compensations, because the backlash takeup move may reopen the contact, and its a show stopper error if the switch is already open when the backup move starts. I have x home working about 90% of the time by setting backlash to half a thou in the .ini file for x on my lathe, and around 3 thou less than real on my old sloppy z. When x works, it does all the motions in just a few milliseconds once the initial contact has been made. The old Z was the same except for the 300 milliseconds the backlash moves of 20 thou take. > ------------------------------------------------------------------------ > ------ Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, > CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills > current with LearnDevNow - 3,200 step-by-step video tutorials by > Microsoft MVPs and experts. ON SALE this month only -- learn more at: > http://p.sf.net/sfu/learnnow-d2d > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> is up! My views <http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml> Mollison's Bureaucracy Hypothesis: If an idea can survive a bureaucratic review and be implemented it wasn't worth doing. I was taught to respect my elders, but its getting harder and harder to find any... ------------------------------------------------------------------------------ Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. ON SALE this month only -- learn more at: http://p.sf.net/sfu/learnnow-d2d _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
