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
