Background:
I’ve found that the auto calibration process seems to not be applied when I run jobs from lightburn. I ran the on device auto calibration process, using the touch screen. I then tried sending a couple prints over to the machine with wifi as gcode exports from lightburn and then using luban to send to the machine. However, this process was onerous, and I know that lightburn can drive the machine directly (similar to an octopi driving it directly). I decided to hook into the machine using the USB cable.
From the auto calibration, it seems my bed height is 26mm (I have the laser beds taped to a destroyed 3dp bed, so that’s probably why it’s higher than you’d expect).
In lightburn, if move the head to e.g. Z29, it’s correctly just barely touching the surface of a 3mm piece of cardboard.
Original hypothesis:
If I start a job at Z29, I’m assuming the “auto calibration” would be doing the exact same of setting the Z to {bed height} + {material height} (e.g. 29), I would then expect to see similar cuts from running the job in lightburn as opposed to sending the gcode over, and then telling the machine to run the gcode.
The problem is that when I do this, the cuts don’t seem to be as good, using the exact same speed/power settings, I’m seeing extra burnout on the sides of the cuts.
Focusing attempts:
In lightburn, I set the Z to 28.5, then click “clear origin”, “set origin”, “set finish position”, and “focus z” (pretty sure only “set origin” is necessary, but just checking all the boxes).
I then went to Tools > Focus test, and attempted a test from 0 to 10 (again, 10 is probably way too high, but just seeing if things work).
When this test runs however, it seems to go ridiculously high (probably 20mm off the cardboard), and doesn’t actually burn anything.
Things I’ve tried:
- setting the “start from” to “absolute coords” and the “start z” in the focus test to e.g. 30
- Just runs the laser head into the bed, if you notice, when it does the moves, it drops the head down a bit, so I’m not sure if lightburn’s focus test will work at all, since the head should be basically right on the work piece, I’m not sure how that’s expected to work though. If I did manage to get it to turn the laser on at the right height, I’d think it’d try to move at the wrong (too low) height
- setting the “start from” to “current position”
- doesn’t seem to do anything different than “user origin”
- setting the “max power” in the focus test up to 99
- does actually output enough power to do something (I think it’s trying to write some numbers?), but since it’s so far away from the piece, it’s just a bunch of cryptic looking symbols
Question:
What am I doing wrong? I see other people on the forums saying they just “used the focus test to find the focus”, so I’m assuming I’m missing some crucial step. There must be some simple thing that I missed in the process of doing the focus test.
