Posting in “Problems and Support” because I can’t post in Tips & Tricks yet (I think this would be a useful thing for other people?), but also I’d be keen to hear from Glowforge in regard to the questions at the bottom.
It doesn’t appear that my camera calibration is off enough to qualify for “Should you finish all of these steps, and find that you have an alignment error of more than 1/4”, please contact us so we can investigate.” but I was curious to quantify exactly how far off it is and how it varies across the work area. This way I can kind of correct for it manually when placing pieces. I realise this process won’t be accurate for all material thicknesses, but it’s a good start.
Anyway, I drew a 25mm grid on a sheet of card, and laid out cross markers in the GFUI according to the camera position, then did a shallow cut operation. (Yes laying out the markers was boring!). The result is that I now have a relatively good picture of how the calibration varies over the work area that I can reference.
I realise this isn’t quite good enough for accurately placing something on an existing piece (I can use a jig for that), but still it’s useful for other situations where the accuracy only needs to be ~1-2mm. (And now I know where the most accurate area is).
And here’s my handy reference card:
- Is this a “normal” amount of calibration error?
- It would seem that the error is exactly the camera distortion. Like it’s a continuous function over the area, it would be straightforward enough to describe mathematically – if only I could apply that function to the calibration data that Glowforge has for my printer.