On Thu, 2013-01-24 at 18:51 +0200, Roland Jollivet wrote: > On 24 January 2013 18:27, Gene Heskett <ghesk...@wdtv.com> wrote: > > > On Thursday 24 January 2013 11:05:42 Todd Zuercher did opine: > > Message additions Copyright Thursday 24 January 2013 by Gene Heskett > > > > > Add a spring to your contact, to give it a degree of compression. > > > > > I did, in a previous design, mount the pcb on grommets so there was room > > for crush. but found it near impossible to get a consistent spring back. > > Or if off center, a consistent restoration to level. a 4 grommet mount > > would have solved that, but the frame of that gage didn't have room. So I > > wound up insulating the pcb being carved in a pocket of micarta, and > > g38.2'd the pcb I was carving, which worked very well indeed. > > > > Like T. Edisons & his light bulb, he found 10,000 ways it didn't work. > > > > All my current problems regarding this would go away if the switch > > hysteresis backup move would just do another 5 thou of back away anyway if > > it found the switch open when it checked instead of freezing in place and > > fussing with a big red error advisory because the switch was found to be > > already open as it started the back away move. HINT, HINT. IMO, the only > > error here is in the assumption that the home switch is mechanical, with > > several tens of thousandths on an inch, or in metric, possibly a whole mm > > of hysteresis. Perhaps even a per axis keyword to make it work either way? > > Would seem to give maximum flexibility at any rate. > > > > > > > How about using a proper travel limit switch. The contact operates well > within the first mm, and then you can press it a further 5mm or so with no > ill effect. And on release the hysterisis is very short... > > http://www.galco.com/buy/Eaton-Cutler-Hammer/E47BMS04 > http://www.galco.com/buy/NTE-Electronics/54-438-BP > > Regards > Roland Hi all, As Gene would say "there are many ways to skin this cat". a. manually run the carriage up against a stop and press home for that axis. Depending on the springiness of the mechanics probably good to about a thou.
b. use a home switch with a cam actuator i.e. ramp the switch on which guarantees it will stay closed with over-travel. Then you can either back off until it opens and use that as home or better yet back off to the index pulse. The homing method should match the repeatability of the machine. Like so many things measuring to .0001" isn't very valuable if the machine will only hold a thou. On my cinci I give up a couple of inches to have a homing setup that is easy. Someday I'm going to fix that. HTH Dave > ------------------------------------------------------------------------------ > 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 ------------------------------------------------------------------------------ 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
