Tried to set up my LightBurn camera today. I got through the process but it is not quite right. I can drop some text on a pencil and it looks good on the camera view, but the final burn is not where it looked like it was on camera. The pencil is horizontal on the honeycomb and my engraving starts from left to right. Final engrave is consistently too high on the pencil. So away from me, which is in front and towards the back of the machine. For the calibration of the lens I used the LightBurn camera option, 8MP and 85 degree lens. I also used a preset in lieu of going through the dotted card positions. I was not asked to measure the distance of the lens to bed, nor was I asked to input my bed size. So I do question whether that calibration is any good. The alignment I think is good, burned the 4 corners and placed crosshairs at each one.
The camera lens is mounted on the inner lid, fairly high and is angled slightly towards the front of the machine. Should the lens be pointing straight down? Any help would be greatly appreciated so I can have a good day tomorrow.
Having it straighter reduces the burden of the perspective correction and potentially gets your more usable resolution but it shouldn’t prevent you from getting a well usable solution. However, it’s more important that calibration and alignment be very close.
Presets are not going to be as good as a custom calibration but the deviance shouldn’t be so severe. If after additional tuning you find that you’re getting uncorrectable distortion then consider going through custom calibration.
How far off is the burn vs what you have on-screen?
If the deviance is slight it could be because of the difference in height of the material used for alignment vs what you’re burning to. Proper camera alignment is dependent on material height. Any difference from original alignment height will result in placement deviation.
If your deviance is consistent across the bed then you can use the controls in Camera window to fine-tune the overlay position and dimensions.
Thank you for the response. I will try again today but the process is more cumbersome that it should be. I would say that the distance my text is off is about 1.5 mm - 2.0 mm, that’s using a text about 6 mm high. As for the thickness of the material, if that is the issue, are you saying that one has to re-calibrate each time you use a different thickness? If that is the case, I do not think that this camera is worth the additional cost and effort. I can manually fit text in faster and better than by using the camera. Lastly, even the videos from Lightburn are not as complete and clear as they should be. Having to hand-hold the dot pattern card in various positions is fraught with inaccuracy, every time you move the card the lighting changes and you have to block out the light at times. Just needs to be more fool-proof.
Normally the idea is that you would change the z-height to keep the material at the height when alignment was done. Calibration is not a factor here. In other words, the distance from bed+material to camera would be held constant by moving the bed. If you’re focusing on the surface of the material during alignment and during job run this distance should already be the same. However, you should not change height of camera relative to laser. That relationship needs to be preserved.
How large is your bed?
Material height could very well account for that difference. Also, in general, with a well calibrated+aligned solution I think roughly sub 1mm placement accuracy can be expected, at least from what I’ve seen. I’ve seen posts from people expecting accuracy under .1 mm and being disappointed so perhaps temper expectations. I don’t think I’ve seen an official position on this though so take my view with a grain of salt.