heh - Sorry. replied to wrong email.. oops (Boy that could have been really embarrassing...)
sam On 4/15/2013 1:28 PM, Gene Heskett wrote: > On Monday 15 April 2013 13:22:31 Viesturs Lācis did opine: > >> 2013/4/15 andy pugh <bodge...@gmail.com> >> >>> On 15 April 2013 11:00, Gregg Eshelman <g_ala...@yahoo.com> wrote: >>>> The crossover counters any offset push at one end of the gantry with >>>> an >>> equal pull in the same direction at the opposite end. The theory page >>> shows how it works. >>> >>> I have stared at the diagrams for long enough now that I have changed >>> my mind several times. I might have to build one to see. >>> >>>> Does LinuxCNC have H-bot support? CoreXY should drive identically. >>> Not built-in, but: >>> >>> http://www.linuxcnc.org/index.php/english/forum/38-general-linuxcnc-qu >>> estions/26302-cnc-avec-systeme-h-bot-ou-corexy >> Hmm, it is not the first time I see links to that Russian forum and with >> every time I get stronger and stronger impression that those LinuxCNC >> users that hang out there is a completely separate community... >> >> Anyway, I just cannot figure out, how to set up homing routine to home >> such a machine to some switches. > Use the sign of the HOME_SEARCH_VELOCITY to control which switch its > looking for. Then HOME_OFFSET with a sign can set home to any position. > Then in case the home switches are off in a corner someplace and you have > to jog the machine to a suitable starting position before invoking the > homing operation, run it to where the first switch is available quickly, > and use the HOME_SEQUENCE number to put all the home ops in the proper > order. > > On my lathe, a grep of the .ini for HOME returns this: > In [TRAJ] > HOME_ALL = 1 (one home all button in axis) > > In x [AXIS_0] > HOME = 1.250 (where it parks it when done) > HOME_IGNORE_LIMITS = YES > HOME_USE_INDEX = NO (if servo's, could be useful) > HOME_OFFSET = 0.01000000 (where it marks it as 0.0 from where its at) > HOME_SEARCH_VEL = -0.08 (in machine units, IPS IOW) > HOME_LATCH_VEL = -.008 > HOME_FINAL_VEL = -.1 > HOME_IS_SHARED = 1 (one logic signal is input for all homes) > HOME_SEQUENCE = 1 (second one to be done) > > > In z [AXIS_2] > HOME = 4.250 (where it marks it as being when finished) > HOME_IGNORE_LIMITS = YES > HOME_USE_INDEX = NO > HOME_OFFSET = 4.090 ( distance in this case from left face of gauge to face > of pcb on right face of gauge) > HOME_SEARCH_VEL = -0.08 > HOME_LATCH_VEL = -0.015 > HOME_FINAL_VEL = 0.25 > HOME_IS_SHARED = 1 > HOME_SEQUENCE = 0 (first to home) > > I place a gauge I made on the ways, backed up against the work piece as > chucked, place a cleaned cutting tool next to the pcb copper that is the Z > detector on the gauge, and hit the HOME_ALL button, It searches z for > contact, sets the home offset such that 0.0z is shaving the rust off the > chuck jaws, or if work is chucked, touching the face of the work. Then it > backs away a wee bit and searches inward to find the contact for the x > home, finds that piece of pcb, sets home to pretty close to the center of > the work (I'm still fine tuning that) then parks the tool back out of the > way till its needed. > > yerp, buzz, yerp, yerp, buzz, yerp, done in about 7 seconds. > > If the ways and base of my tool are lox clean, repeatable to under .001". > That however is a major problem for x as it tilts the gauge just for a good > coat of vactra on the ways. I need to make the rear, huge flat area into a > single point contact with the back in order to penetrate the oil film and > possibly leave a little room for dust, between it and the flat back way on > that toy lathe. > > The man page on homing could be clearer, but careful rereads will point the > way as there are many, many variations. And there are N! ways to screw it > up. :) > > The only fly in this ointment is that it all goes totally, absolutely to > hell if you have applied /any/ touch offs, and in my case I would call not > canceling the touch off in effect as the first thing the homing operation > does a bug. Ditto for trying to use position.txt, as that also > contaminates the zero's this sets. > > IMO its a BUG, and for me a BIG BUG, requiring that I first stop linuxcnc, > nuke the position.txt AND the linuxcnc.vars files before restarting > linuxcnc, so that it truly starts from scratch when homing. > > Touching the HOME button should first NUKE any touch off offsets in effect > at the time for the axis being homed. > > It does not, so home is then relative to the &^$#@ offset. I have broken > tools and wrecked nearly finished parts because of this, several times. > > Is there a valid reason for the current, save the offsets behavior? > > Cheers, Gene ------------------------------------------------------------------------------ Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis & visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
