Directions of travel for CNC machines use the convention of how the cutting tool moves with respect to the workpiece. For a machine with a moving XY table and a stationary column holding the Z axis, and assuming the viewer is standing so that the X axis runs left and right, then positive X would happen when the table moves left. For other machine configurations this will vary, but the convention holds that you consider the motion of the cutting tool with respect to the workpiece regardless of what part of the machine is moving.
The convention for where Z axis is zero is less rigid. The more common method is to have Z zero with the cutting tool as far from the workpiece as possible. This helps the human to remember that -Z means plunging into the cut. Often the user sets offsets such that Z zero represents the top (or end, if a lathe) surface of the workpiece. There are other ways of doing this and it is a bit of a "religious" question. Steve Stallings > -----Original Message----- > From: [email protected] [mailto:[email protected]] > Sent: Saturday, June 06, 2009 9:38 PM > To: Enhanced Machine Controller (EMC) > Subject: [Emc-users] new pcb mill > > > > I am in process in setting up my little PCB mill. I have my > self confused. > > I am using stepper conf to get started with. The 3 axis work > fine under axis test. > > When I fire up EMC2 and run a small example program the Z > axis only moves about 1/4 inch though in step conf I have it > set for 3 inches and it travels the entire distance. > > > > My axis are 4 inches for both the X and Y axis and 3 inches > for the Z axis. Do most of you set the Z axis so it's 0 or > some positive number when raised fully and the goes to some > negative number as its lowered onto the work surface? i.e. > 0.00 - -3.250 I would like to stay with in convention. > > > > When in the home position, mechanical home uses a reamed hole > on the work table, the X axis is almost all the way right to > 1/4 inch of the end of travel. The gap to the far end is > 4.075 inches > > > > When the X axis moves left would you consider it going > positive or negative? > > > > Y axis moving towards the Z axis going positive? > > > > The Y axis in 13/16 inch away from being against the front > end of travel. The other end of travel is 4.375 inches > towards the Z axis. I am looking into installing some home > switches on all 3 axises > > > > How did you come up with the original axis travel > measurements? And what did you input into the. ini file for that? > > > > The stepper driver doesn't have much for specifications like > some others do. They only specify step pulse of 5 uS and > maximum step frequency of 40 kHz. The driver chip is an > Allegro A3977 though some other specs can be had from their > spec sheet.,however the BOB is using opto isolators or > similar devices. The drivers and bob are probotix sidestep > and their PBX-RF board. They seem to work ok I just want to > set it up properly. The lead screw is 1/2 inch acme 10 TPI > threads. Am using 260 oz in NEMA 23 motors.I did have a > defective driver but Probotix took good care of me and > exchanged it. :) Got it back yesterday. > > > > Looking around the Internet I come across many articles > telling about software and settings. I have not discovered or > don't know how to Google properly to find out how to take > mechanical measurements to the software and make the thing do > the circles etc I want it to do. > > > > Maybe someone knows of an article explaining all of this. > > > > Gary Fiber K8IZ > > -------------------------------------------------------------- > ---------------- > OpenSolaris 2009.06 is a cutting edge operating system for > enterprises looking to deploy the next generation of Solaris > that includes the latest innovations from Sun and the > OpenSource community. Download a copy and enjoy capabilities > such as Networking, Storage and Virtualization. > Go to: http://p.sf.net/sfu/opensolaris-get > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ OpenSolaris 2009.06 is a cutting edge operating system for enterprises looking to deploy the next generation of Solaris that includes the latest innovations from Sun and the OpenSource community. Download a copy and enjoy capabilities such as Networking, Storage and Virtualization. Go to: http://p.sf.net/sfu/opensolaris-get _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
