On Saturday 14 June 2014 15:35:15 John Thornton did opine And Gene did reply: > 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
Maybe John, but as there aren't any other switches for home or limit on it, my major concern was to keep the screw from clearing the nut and upchucking about 77 .0625" balls. I've unscrewed the x screw dozens of times now, its a pima requiring a long bar clamp to get it restarted. They are already placed & ready to wire up as of yesterday, so why not? I don't know if they would be consistent enough to function as homing switches until I get it all back together. I'm changing the drive coupling too, so the motor mount standoffs will need shortening about 3/4 inch as I re-assemble it. > 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 Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> US V Castleman, SCOTUS, Mar 2014 is grounds for Impeaching SCOTUS ------------------------------------------------------------------------------ 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
