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Axis directions
« on: December 21, 2017, 07:05:30 PM »
Ok, I'm used to axis's being homed (0,0,0) in the front left corner with X axis increasing going to the right, Y axis increasing going toward the rear, and Z axis increasing going up.  Now I understand the Z-axis for CNC will work in reverse.  0 at the top and then negative values going down.  Is the same true of the X and Y?  Use rear right corner as home and negative values moving left/forward?  I'm in the process of setting up the software and want to do what is "common".
- Robert Beaubien
- Drone Plastics
-
“Dear Algebra, Please stop asking us to find your X.  She's never coming back and don't ask Y.”
Re: Axis directions
« Reply #1 on: December 21, 2017, 08:45:36 PM »
You had it right for X and Y  the first time and Z is positive up always.
Re: Axis directions
« Reply #2 on: December 21, 2017, 10:31:55 PM »
Excellent.  Thanx Gary.
- Robert Beaubien
- Drone Plastics
-
“Dear Algebra, Please stop asking us to find your X.  She's never coming back and don't ask Y.”
Re: Axis directions
« Reply #3 on: December 22, 2017, 12:11:57 AM »
Hi,
it is common practice to have the top of the Z travel to have machine coordinate of z=0. Therefore any Z axis move has machine coordinates of less than zero, ie negative.

A lot of new users baulk at such a thing. Under normal circumstances you have the machine set to display work coordinates. Thus the top of your material would be z=0,
above and free of the material positive z and bleow the surface, ie cut depth is negative z. But these are WORK coordinates, they are easy to understand and visualize.
MACHINE coordinates are a little different and especially so when all normal working z machine coordinates are negative.

With the Z axis at the very top of travel machine coordinate z=0. If you jog downwards 105mm say, to the top of your workpiece the machine coordinate would be z=-105.
If you were doing a 1mm cut the machine coordinate would be z=-106mm. It may look a little strange at first but it will make sense in the end. Mach tracks and operates
in machine coordinates its only us humans who need help with conveniences like work coordinates. Negative z machine coordinates are just fine for Mach and once you and
I get used to seeing negative z machine coordinates we too can derive good understanding of our machine.

Craig
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Re: Axis directions
« Reply #4 on: December 22, 2017, 09:28:52 AM »
Front left corner is a term that is relative to your location and perspective and has very little meaning when discussing axis following the right hand rule (which is the standard convention that allows the same Gcode file to be ran on any properly configured CNC (with the same abilities of course) to produce the exact same part). If the axis follow the right hand rule it will do so from any viewing position or machine orientation. If it is right it will be right if you spin the machine or mount it to the wall or upside down to the ceiling. What is important is that the axis travel in the correct direction relative to one another. You can reference (establish machine 0) for any or all axis in the positive or negative direction or anywhere in between (even in the middle). That is totally preference and the configuration settings allow for any of them. The following link may help.

http://www.machsupport.com/forum/index.php/topic,10308.0.html
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