I’m lost in what your trying to say i was incorrect in… Are you saying change zero to present position?
If that’s the case. Yes. Your right, incremental is based on present position and absolute is based on a specific position for the machine, regardless of the present position.
I’m reading other sources… so here I’m learning something, i always thought absolute meant the same. Looking at my macros i see g53 was used for those.
I think i got a simple explanation:
Absolute: a coordinate system that originates from your current 0,0,0 setting using that as an orgin as it measures out. Gcode compiled after your post processor utilizes the absolute coordinate system. Ex: x25y31, x24, y30, x25, y31 would make a square. G90 in gcode.
Incremetal: a coordinate system that is related to your present position. Ex: x25y31, x-1, y-1, x1, y1 would create a square.
Yeah. I feel more confident with that. Thank you, ya learn something new every day… i knew what they were, but absolutes orgin was what i thought i knew but was wrong. I had the right idea but the orgin wasn’t right. Made my macros a long time ago, and never looked at them since. thank you!
Hey Chris,
in order for others to understand what we are talking about, I quote your version 1.4:
Absolute Coordinate(s) (System) (Positioning): A coordinate system that does not take into consideration the position of any axis zero position. You should use the absolute coordinate system when you are having the machine travel to a set point as it will not move based on your XYZ zero point (example middle back, to move the machine out of the way so you can manipulate something on your waste board.) G90 in G-Code. See Incremental coordinate for the obverse.
Incremental Coordinate(s) (System) (Positioning): A coordinate system that is related to your axis zero point. G-Code compiled after your post processor utilizes the incremental coordinate system. (G91 in gcode) See Absolute Coordinates for the obverse.
So first, you write:
“Incremental Coordinate(s) (System) (Positioning): A coordinate system that is related to your axis zero point. G-Code compiled after your post processor utilizes the incremental coordinate system. (G91 in gcode)”
This is wrong. It is not related to your axis zero point. **Incremental distance mode (G91) just means that any subsequent axis value (e.g. “Z3” or “Z-3”) on the currently active motion command is relative to the position wherever the axis is at the moment. Negative values mean adding the value to current position by moving towards left, front, or bottom. Positive values mean adding the value to current position towards right, rear, or top.
Then you write:
Absolute Coordinate(s) (System) (Positioning): A coordinate system that does not take into consideration the position of any axis zero position. […] G90 in G-Code.
This is wrong. Here you mix up to completely different things, the machine coordinate system and the absolute distance mode, which have nothing to do one with the other. The fact that on the Buildbotics.com / Onefinity controller, the machine coordinate system is called Absolute in the “Absolute” column on CONTROL page, may have contributed to this erroneous assumption, because the correct term is machine coordinate, not “Absolute position”. So, to make it clear, the machine coordinate system is the one that is in effect after homing and before bringing into effect another coordinate system. If you want to move relative to the machine coordinates, while another coordinate system is in effect, you got to prepend G53 (Move in Machine Coordinates) command to the motion command. The machine coordinates always designate coordinates relative to the machine origin, which never changes.
This has nothing to do with G91 (Set absolute distance mode). This mode means, any subsequent axis value (e.g. “Z3” or “Z-3”) on the currently active motion command is relative to the zero point of the currently active coordinate system. This does say nothing about which coordinate system that is, it could be the machine coordinate system in case you did not yet probe/zero a workpiece, or an offset coordinate system that has the zero point at the zero position of your workpiece origin. The G91 command just means, the subsequent values are to be interpreted as a coordinate in the currently active coordinate system.
Note: I wrote this as reply to #61, before reading your answer one above (#62), just for the record.
Hey Chris,
This is wrong. G-code compiled after your post processor may, in the same way as any other g-code or even freely entered MDI commands, use any of all possible coordinate systems including machine coordinate system, and even define and put into effect any possible offset coordinate system, and switch between those.
Also it may freely change the meaning of motion commands between absolute distance mode and incremental distance mode on every new motion command, just to tell the interpreter how the subsequent values are to be interpreted.
I am sorry that I have to contradict you so much, but I appreciate you don’t seem to have teaching allergy 
(that rarely some people seem to have)
I encourage it. I always assume I’m not the smartest person in the room… and if i turn out to be, i find a new room.
My whole thing about not being human readable was partially along the lines of it being encoded or cryptic as you said and not in narrative form (that wasn’t what i was referring to specifically btw). You have decode it either by direct reference or subconsciously translate it, which was why i added the caveat it is possible to read in small parts…
the body of something really complex like 3d gcode was what i was referring to because like you mentioned reading music and hearing it is an example a non-english language… but I’ll say this again, i don’t think anyone can read the body of gcode and see what it will do/is without the use of a visualizer… that’s the context of not human readable i was referring to. If it was a simple shape with multiple passes maybe because of pattern recognition. Honestly if someone can read 1,000,000 lines and see what it is without computer help, they wouldn’t be doing this.
Do you have any relevant examples of pp that don’t though? I haven’t seen any at least because I’ve always heard that it’s hard coded in the CAD software to do that from the software to post processor. Never cared to investigate that internet factoid