OK thanks for the thread, that was a long read, and some good info but I’m not sure it really got to the bottom of it. There are really clear statements from @dan and @Tony that seem to suggest the following:
- The head is calibrated using the lid camera and this is sub-millimeter repeatable. See XY home position
- SVG coordinates are repeatable over time. See XY home position
But then contradicted by:
- “It does not appear that way in the UI”? See XY home position
- “what is being discussed as “0,0” - that is, the northwest most addressible corner - will change with the speed you use.” XY home position
So can someone please nail down the inconsistencies between the first two bullet points and the second two? There are seemingly six different explanations of what 0,0 is:
A: The absolute travel bounds of the gantry
B: The position of the head after calibration
C: The north/west most addressible point (i.e. the north/west most point that can be cut/engraved/lasered)
D: The 0,0 coordinate of the SVG file that I have uploaded
E: The 0,0 coordinate of the rulers in the GFUI
F: The places that D (and E) end up in on the final print
Importantly: A, B and F are physical coordinates, D and E are entirely logical. C is kind of both. Also, I understand why there’s no physical ruler on the GF itself - B is at best relative to the lid camera, but certainly not to any other part of the machine and definitely not the crumb tray.
- I can definitely verify that D and E are the same thing (when I upload an SVG vector that’s at 0,0 in the SVG file, it gets placed at 0,0 on the rulers).
- A isn’t terribly important other than to understand that it’s not the same as the others.
- B is calculated using the camera and is repeatable across time. i.e. it’s likely to be sub-millimeter the same physical position. This seems fairly unambiguous in the thread.
- C is print-dependent (i.e. speed and deceleration factor into this) (and operation dependent within one print)
So the question is: Is the relationship between D (and E) and F:
- Completely meaningless (
) - Print-dependent (i.e. F is based on C). (this would be understandable but
)
2.1. Different for every job, deterministic but competely unpredictable by the user.
2.2. Most jobs will be a fixed offset, but jobs requiring more “difficult” movement will sometimes cause this to be different. - F is a fixed offset from B (hooray!
)
3.1 C is always above/left of F no matter what is printing. (Woohoo! )
3.2 C may be inside F. i.e. sometimes I am prevented at cutting at 0,0 because of the artwork that I have placed there. (That’s cool, if the GFUI makes this clear) - Something else? (
)
(Edit to add 2.1 / 2.2 and 3.1 / 3.2 as two possible variations of 2 & 3).
@Tom_A it sounds like you’re saying it’s (2). This appears to be contradictory to my understanding of this post from @Tony. Additionally it goes against my reading of this post from @dan unless there’s a very subtle clarification required that he means “the same SVG file” (and the same operations from that SVG file).
Glowforge - can you please write this up somewhere easier to find than the forums?
All that said… I still don’t understand why I can’t place my artwork at 0,0 but 0.5,0.5 is fine.
Thanks