As I tell the robotics students, design limit switches to survive missed detection & over travel. On a milling machine, I would recommend a roller type of switch, that would come in contact with a cam bar that is long enough to reach end of travel.
On my machine, I have two switches positioned about an inch apart, at the middle of travel. Then the are cam blocks, one positioned near each end of travel The roller rides up on the block, trips the switch, and the switch body is safely out of the travel path. I did my mill this way because I have sooo many pins available with the Mesa kit. On the school mill, I used one switch for each axis, and the cam block from either end of travel would trip it. So no failure (or other malfunction) will crush a switch! --J. Ray Mitchell Jr. jrmitche...@gmail.com "Good enough is the enemy of excellence"author unknown On Sun, Mar 31, 2019 at 7:03 AM Gene Heskett <ghesk...@shentel.net> wrote: > Greetings everybody; > > I think I've got the coolant pump starting problem fixed. Ignore that > faint knocking sound. > > Now I would like to use a teeny little pushbutton (6x6x2.5mm tall) > between two solid parts of this machine for home and potentially as > limit switches. > > However the amount of available overtravel after the switch has clicked > is quite limited unless this switch is mounted on something crushable so > that the getting stopped overtravel does not crush the switch like a > Coors can. > > Is there a way to determine how much overtravel vs approach speeds is > occuring? > > I ask because a wide open x or y move can do around 220 ipm on this > machine, and that stopping distance is not an ignoreable distance when > the switch only has maybe .010" of overtravel after its clicked. > > So I first would like to determine the maximum safe SEARCH_VEL I can use > for homeing, then from that, be able to set MAX and MIN LIMITS far > enough away from the crash stop to provide crash protection in the space > between the LIMIT set in the ini file, or how much crush room I have to > build into the switch mount? > > Also, in attempting to minimize this stopping distance, what or how can > one detect a motor step slip if the ACCEL's are stopping the motor > faster than it can stop? Hopefully without pounding a $90 dial into > junk. > > Thanks all; > > 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
