If you're going to use micro-switches, rather use this <http://uk.rs-online.com/web/p/microswitches/1031645/?searchTerm=103-1645&relevancy-data=636F3D3126696E3D4931384E525353746F636B4E756D6265724D504E266C753D656E266D6D3D6D61746368616C6C26706D3D5E5C647B337D5B5C732D2F255C2E2C5D5C647B332C347D2426706F3D313426736E3D592673743D52535F53544F434B5F4E554D4245522677633D4E4F4E45267573743D3130332D3136343526> type;
Notice how the button is almost directly under the roller, as opposed to the 'normal' type of being near the lever pivot. The indicated type will have increased switching sensitivity and lower hysteresis. Regards Roland On 30 July 2015 at 13:02, Gene Heskett <ghesk...@wdtv.com> wrote: > On Thursday 30 July 2015 03:02:45 Marcus Bowman wrote: > > > On 30 Jul 2015, at 03:51, Gene Heskett wrote: > > > I bought a bag of small, roller tipped microswitches, and have a > > > couple mounts laid out but not carved yet. > > > > > > Going thru searches on ebay just now, for both inductive, > > > capacitative, and IR proximity switches, It sees like the majority > > > of them are needing 6 volts or more, and around 300 ma each to > > > function. Having seen some micropower capacitative switches in the > > > textbooks of yore, it seems like the ball has been dropped in terms > > > of being useful in a 5 volt logic circuit. > > > > > > Both the microswitch, and the inductive versions would seem to be > > > sensitive to collecting swarf, particularly if its a rare earth > > > magnet running a reed switch. > > > > > > My lathe seems to be relatively happy with a microswitch located > > > under the back edge of the bed for Z homing where swarf tends to > > > fall on past it, but x has to be kept swept clean because its > > > actually on top of the carriage. > > > > > > I see a whole passel of stuff drilled onto GO704's in the hits I can > > > get from google, but all of them preclude retaining the rubber swarf > > > shields, which I'd say was not worth the tradeoff. There has to be > > > a better way. > > > > > > So what sort of switches, and what swarf shielding to keep them > > > relatively clean & accurate are others using? > > > > > > PM's with pix appreciated if you have the time. > > > > Actually, this is a really interesting question. Having spent ages > > thinking about shielded locations for the mill, and about to do the > > same for the lathe, it would be useful if folks could put the pictures > > somewhere we could all see them. If anyone has any recommendations > > about makes and models of switches/sensors which provide better > > accuracy and repeatability than others, or useful ways of providing > > adjustment on mounting arrangements, that would also be very useful. > > > > Marcus > > > My thoughts exactly Marcus. In my googling, something like 3/4ths of the > sites that may have had helpful pictures, were behind a login requester. > Since I am not a member of any of those Mach oriented groups, thats less > than helpful. > > For X, I have considered removing the pointer which is also a mechanical > limit stop, and likely demolishable to an out of control move as there > are a couple OEM stoppers that would hit it. Once removed, then move > one of the stopper knobs (they are in a 'T' slot in the front edge of > the table) to someplace near the center of the table, and mount a switch > that it would close on the way by which would function as the home > switch. A similar setup is now on my lathe, with the switch under the > back rail of what passes for a bed, located to be activated when no tool > holder is mounted, and only 3/4" or so from the chuck face. X has > already been homed and parked about 1mm from its outside limit. Having > both switches well off center moderately well precludes its looking for > the switch in the wrong direction as its z is normally parked well away > from the work for gauge etc checking access to whats in the chuck. > > So this has worked well for a year for me. > > But I see no way to make certain that it looks in the right direction to > find home on a mill without physically locating the switch well away > from the center of the table. eg the switches trip point will need to be > toward the end of the travel, and a HOME_OFFSET then used to put zero > back at the center. From there, soft limits + & - would be used in > place of the existing knobs hitting the heavy centrally located pointer. > > There are not currently available, any such Y stops, so all of that will > have to be imagined and built. Again, off center far enough that from > any usual powerup location that it will search in the correct direction > to find the switch, then a HOME-OFFSET that establishes a zero on the > dro's at the center of travel, and again setting software limits from > this arbitrary home rather than actual limit switches. > > Z homing will either be completely arbitrary because of uncalibrated tool > lengths in an R8 spindle, or some sort of a pcb pad laying on the table > and a G38.2 move to find the top, sensitive side of the pcb. In that > case, how do I guarantee that I will remember to place the contact pad? > It needs to be automatic, and that gets complex. I often do that on my > toy mill, jogging down slowly till I get the probe tripped message, and > then home it after rising even slower to open the contact so I can home > it there, typically about .064" above the table. This would be more > accurately done IF I could home with the probe tripped, but LCNC won't > allow that. And I'm too lazy to put a switch in the probe lead. ;-) > > Or just sense someplace on the column & call it home. That doesn't seem > to be foolproof either, and I am absolutely the fool that will prove > it. :) > > Thats why I ask for ideas & pix. If you PM me pix, include perms to post > them on my web page, and they will then be available for others till I > fall over. > > > Thanks. > > > > > > 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> > > > > > > -------------------------------------------------------------------- > > >---------- _______________________________________________ > > > Emc-users mailing list > > > Emc-users@lists.sourceforge.net > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > ---------------------------------------------------------------------- > >-------- _______________________________________________ > > 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> > > > ------------------------------------------------------------------------------ > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
