Sorry for the lack of detail, I wrote the message too fast this morning when I just got up.
I'm planning to use 1 kw servos on each side with a max RPM of 3000. The idea is to gear down from the motor to the pinion 10 to 1 using the timing belts. The pinion I'm planning to use is a MOD 2 with 20 teeth. That would give a theoretical linear max speed of 37 meters/minute. I was thinking about making a custom component for offsetting the index pulse on the encoders but I don't know if this approach will be reliable enough. El mié., 3 oct. 2018 a las 10:17, Todd Zuercher (<to...@pgrahamdunn.com>) escribió: > I haven't really looked at the documentation for Master lately, but the > means for setting up a multiple joint axis (like a gantry) was documented > reasonably well last time I checked. > > My personal experience with rack and pinion driven wood routers is that > for stepper-motor drive you are going to want between 2.5-5 > revolutions/inch of travel. With a leaning towards the lower end of that > scale. With a 2.5 rev/inch ratio and half stepping the machine should be > capable of 600ipm rapids and about 0.001" resolution. If you are going to > run servo motors I would suggest a ratio probably double what you'd want > for a step-motor, but that will depend on the max rpm of your servo and > what you want your max feeds to be. > > The 10:1 ratio you mention doesn't tell us much without the pinion size, > is that motor revs to pinion revs, or motor revs per unit length? > > Todd Zuercher > P. Graham Dunn Inc. > 630 Henry Street > Dalton, Ohio 44618 > Phone: (330)828-2105ext. 2031 > > -----Original Message----- > From: Leonardo Marsaglia <ldmarsag...@gmail.com> > Sent: Wednesday, October 03, 2018 6:01 AM > To: Enhanced Machine Controller (EMC) <emc-users@lists.sourceforge.net> > Subject: [Emc-users] Yet another topic about gantry homing > > Hello to all! > > I'm building a CNC router for wood machining for a friend of mine and the > best way I found to drive the Y joint for this particular design, given the > size of the machine, is the following: > > One rack and pinion on each side of the longitudinal axis of the machine > and each pinion conected to a servo motor using two steps of reduction with > synchronous belts to achieve a 10 to 1 ratio. > > I've found several topics on the forum talking about the homing of an axis > arranged like this. I guess to have screw regulated home switches for each > Y joint is almost a must (in case you don't use linear scales). But I was > wondering if it's possible to use ,in conjunction with that, the index > pulse of an encoder coupled to directly to the pinion. > > My idea is to offset the index pulse on each encoder via HAL to make both > sides of the Y joint trip the index pulse together and stay squared during > homing. Is this a good practice? > > About how to drive both Y joints as one axis: I've read that there's a way > of simply adding two Y joints for the Y axis in the 2.8 master branch but I > don't know if there's documentation available already. > > But I was thinking about slaving one of the motors (using them as pulse > and direction at the beginning to make things easier) and use the encoder > on the pinion only for following error and homing. I don't like the open > loop approach a lot, but I don't know if it's that easy to use them as > servos in position mode without having too much trouble. > > Any thoughts? > > Thank you as always! > > Leonardo > > _______________________________________________ > 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 > _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
