Gene, Limit switches are normally wired up normally closed. The reason for this is if you cut a wire the machine stops.
That sounds like a strange way to put limit switches... on my BP mill for example there is a switch mounted to the X table and a bumpy thing mounted near each end so when the axis gets too close to the end the bumpy thing depresses the switch and stops all movement. I can take a photo of it you like. I suspect your over thinking this one. JT On 6/14/2014 11:38 AM, Gene Heskett wrote: > Hi all; > > Working on my micro-mill, putting ball screws in the x&y. > > I have now rigged the nut holders with microswitches to prevent the motors > from totally unscrewing the screws from the ball nuts. > > These switches are positioned so that the NO contacts are made in normal > service, eg the lever is held depressed by the side of the screw, until > the screw is within about 1/4" of the nut holder. The switch lever runs > up the side of the screw, so wear there should be minimal. > > I am inclined to wire them so as to disable that stepgen when the screw > clears the switch allowing it to open, as this seems like the safest way > to do it. Any open, or a broken cable should result in the safe action. > > Can I treat this as a simple current loop in plain 2 conductor wire, or do > I need to go get some of that foil shielded stuff we broadcasters use for > audio? > > And is the rest of my thinking correct? I believe I have two inputs left > yet, but with 4 axis's and a direction/speed spindle controller, I am out > of outputs on a std parport. > > Cheers, Gene Heskett ------------------------------------------------------------------------------ HPCC Systems Open Source Big Data Platform from LexisNexis Risk Solutions Find What Matters Most in Your Big Data with HPCC Systems Open Source. Fast. Scalable. Simple. Ideal for Dirty Data. Leverages Graph Analysis for Fast Processing & Easy Data Exploration http://p.sf.net/sfu/hpccsystems _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
