Can't get print and cut to consistently line up

Hello

I’m loving Lightburn in general, but I am just pulling my hair out with print and cut to do larger pieces than my laser would do at once. I’ve watched a bunch of tutorials, practiced multiple times, and even written out a step by step checklist to make sure I’m doing things consistently every time. The problem is that I can never get it line up, and trying multiple times gives me different results every time.

Basics -
Ortur Laser Master 2 Pro
Lightburn 1.0.04
Windows 10

Steps I follow - very similar to the LB youtube tutorial on print and cut
Create a master file with the full image
Add crosshairs onto the image for alignment
Create a rectangle and use “cut shapes” to split the image in half, including crosshairs
Copy each half (including crosshairs on both images) into top half and bottom half files
Cut bottom half successfully
Open top half file
Use the LB move/fire functions to align to the first crosshair
Use print and cut wizard to set the first target point from the origin
Use move/fire to align to the second crosshair
Use print and cut wizard to set the second target point
Select the “align outputs to targets” option — I’ve also tried the “…(no scaling)” option, but I don’t think it should matter
Start the cut

Results:
I have the “top half” file redo the targets to ensure alignment before proceeding.
Usually one of the two targets lines up perfectly, but the other can be wildly off, the most extreme I’ve seen is 10mm. When I get a bad result, I stop the program and redo the print and cut wizard, sometimes I can get acceptably close on the second target (~.5mm), but no matter what I never get the same result twice in a row, and it’s never been exactly on.

See images below - in this case I tried three times and the top target was always on line. But as you can see, the bottom target misaligned by 6mm the first try and then 1mm the second try.


Any thoughts/tips/troubleshooting I can do in order to get better (or at least consistent) results? I really want to keep doing bigger pieces, but the effort required and the results right now are just not worth it to keep going.

@dotto Can we assume that you’ve been successful with other burns that don’t involve print and cut? Want to make sure we’re not dealing with multiple issues at once.

Based on what you’ve listed at a high level it seems like you’re doing the right things but the devil’s in the details. Have you set “Start From:” in the Laser section to “Absolute Coordinates”? I believe that’s necessary to do this reliably.

Otherwise, are you able to share the files that you’ve created so that people can take a look at your setup?

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Yes, I’ve had plenty of other successful burns. I’m open to thinking it’s a hardware issue, but I tend to think not because I can successfully go over the same area 2 or 3 times successfully without having any alignment issues when using “absolute coordinates” even with moving the head in between runs.

I am using “absolute coordinates”. Unfortunately, the file shown above is a purchased image so I won’t share it here, but I can say that it isn’t specific to one file. If you think it would be helpful, I can do up a test file and burn tonight and share it here.

I tend to think that if you are otherwise having perfectly aligned burns in other cases that this should be working.

OLM2 has basic stepper motors so can track reliably as long as it’s not missing steps. However, keep in mind that if the head is ever moved by hand after homing that the software can no longer reliably know where in space the head is.

As far as sharing files, the simplest design that can reliably reproduce the problem is your best bet. Someone should be able identify at least if your basic workflow is correct.

Sorry for the delay in responding. I’ve done further testing without any process changes and it is working more often than not now (maybe 1 out of 5 I have to stop and redo the alignment). I don’t know exactly what happened besides maybe a computer restart, a few choice words that the laser took personally, or more likely that problem exists somewhere between the chair and the keyboard.

One thing I have specifically noticed is that when I do get a misalignment, if I physically rotate the piece on the laser bed and then switch the order of the targets, it’s always been a perfect match the next try. I don’t have enough data to say that’s actually accomplishing anything, but at least it’s a workaround for me.

I’ll mark this as closed as I’m not sure what further steps to take.

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Good you at least have a workaround. Come back if you narrow this down further or eventually discover what the issue is. Might be useful for others.

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