Help understanding the Lightburn camera overlay image relative to material and graphic and framing

LightBurn Software Questions Tips and Tricks
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1

Hi’ya all,

I am new to Lightburn but not new to cnc machines, just Lightburn and its idiosyncrasies, namely the camera and its relation to the work area. I use other machines that use camera overlays. Some are diy lasers and some manufactured i.e. XTool.

Issue is between me, Ortur Laser Master 3 with extensions 40w, and Lightburn 2.x (Most likely I am the issue and I can learn, ish).

Okay I did the camera setup all 3 steps, no big deal after a bunch of error trials approaching Groundhog Day repeat-repeating until I uninstalled Lightburn and reinstalled it. I open my piece to engrave, get my work piece arranged in the bed, home, set home, use absolute origin, update the camera overlay image and align my graphic to be engraved. Easy-peasy! I preview the paths and then run the frame… The frame seems to occasionally and marginally correctly frame work piece. I proceed to return to origin, home, re-frame test again. Alas the frame doesn’t travel the same path as the 1st frame. Hence I return to origin, check for my 0,0,0,0 and home still 0,0,0,0. Yep again I frame! Nope, not the same path as the previous framing. Okay shutdown Lightburn and the laser machine, restart the engraving machine and then Lightburn and home and 0,0,0,0, load project, update overlay image, run the frame, it’s close but still not matching the placement of the material and the engraving image. Return to home, I move the material and re-run frame, closer and closer each time. Okay I think it’s gotta’ be this time after my latest material adjustment…frame again. Now I am silently screaming inside and laugh at the absurdity of it all. Try again tomorrow, go read up on the interwebs about Lightburn, camera setup and alignment, lens calibration and overlays again. This is where you can start part way through the second paragraph all over again; day three. Same pattern, same issue. I am tenacious and possibly stubborn. I checked the belts tension and alignments, it homes and zeros without issue. My machines home origin is lower left, as is my absolute origin. I triple checked my start position [green dot]; absolute 0,0,0,0; not user, not current and the laser moves and starts from the correct position, it’s the framing that seems to arbitrarily change; hence checking the belts, homing, and origins. I am baffled within my tunnel vision idea of overlay image + graphic + material + machine = framing disco party, all over the place. I am sure this could have been shorter, maybe next time, we’ll see.

Looking forward to the interwebs knowledge and experience.
A

2

Home the machine, then burn a 6" circle at fairly high speed. If the start and finish points of the circle meet exactly, you can eliminate backlash.

3

Use the classic test to verify the details:

Backlash.lbrn2

Scale it uniformly to fill the platform and run it as fast as the machine will go in Line layer mode with Enable optimizations turned off and power set to mark a sheet of cardboard. Any differences from the design will be informative; a crisp photo will let us look over your shoulder.

4

When I got my S30, the circle is what showed the backlash was present, and I never heard of the “classic” Backlash.lbrn2 file. :joy:

I consider the circle test a pre-diagnosis tool. :nerd_face:

5

Here is a diagnostic and method to check if the overlay image stays aligned.

First, (ignoring the camera), check the repeatibility/accuracy of your machine’s motion. After homing, mark a large square, home, run the same job again, home, run it again…are the marks perfectly aligned?

Now, ‘Update Overlay’, and check if the burn marks in the overlay image are aligned with your square graphic in LightBurn?

If not, redo your alignment, or adjust the overlay shift to fix the alignment.

Change the color/layer of the square graphic to ‘T2’ and File>Save as Template “Camera Check”.

Before you start a new job you can now go to File>Recent Templates and open ‘Camera Check.lbt’, ‘Update Overlay’ and check if the burn marks you made earlier still align with the T2 square in the template. This will provide you with a quick and immediate visual confirmation the image is still aligned. Frame the graphic to be extra sure.

6

I did the high speed 7 point star with a circle in it, I just mash some shapes together to see what kind of slop I get. The job completes, issue is that the same job, never moved just moved the material for another cut and the job starts in a different place. What I mean by a different place is that it returns to home after the job as to start from the same place as all the jobs 0,0,0,0 and the start of the cut or engrave is not even close to the 1st cut/engrave. Sometimes the X moves the wrong way and collides with the frame, not good. Other times it seems to start near the desired coordinates of the cut/engrave. I have a plasma cutter so I am familiar with home, user, current, object start points etc. and I also have an xtool metal fab cnc which ruined me outside of the abysmal 24x24 cut space. it needs a 5x8 cut space and a 1800w-20000w laser. I digress so this silly Ortur machine seems wonky; it’s two motors, 400x850mm and super basic. I will run a voltage and continuity test on the motor connections. I am starting to think it’s hardware communication related. I replaced the usb between the unit and the laptop and I did a factory reset of the machine, reloaded firmware, I don’t use wireless so it’s not configured. If I do a material cut test or a engrave test the laser works fine. It just wont get close to starting near the material, even with a simple tape border and square to line up material. It is like it is possessed and is neurotic when it comes to where am I going to move to start, here, maybe over here, is this where I am supposed to start, oh boy what’s over here, it’s nutz.

I think I am starting to feel crazy because I know what is supposed to happen versus what is happening :slight_smile: and I am okay with having conflicting thoughts rummaging around in my head but his is hardware not people.

7

I will give that a shot, optimizations is already off and lined layer mode. I will get you a photo, the cuts are fine *IF the machine moves to the correct start point from 0,0,0,0. I can cut and burn without slop or jig or wobble when it does cut and engrave. The issue is the moving from 0,0,0,0 to the job. If I fill the bed with a full piece of material 400mmx850mm of anything it’ll cut and engrave just fine, it is the movement to the job, not the job itself. Does that make sense. The same job object, graphic, cut lines, will not move on the Lightburn canvas. The job does not start near the point the object is on Lightburn canvas relative to the physical machines. It is NOT an origin issue because it return to home 0,0,0,0 after each job. Yet if I process the same job again it “should” move and cut or engrave very near the previous job and it does not. The location it moves to changes after each time I return the laser to home 0,0,0,0 and Lightburn verifies it as 0,0,0,0 when it arrives at the home and absolute origin. The star point is random, belts are tight, new as well, factory reset on the unit, USB only, no wifi, it cuts and engraves just fine when it does not randomly move to someplace that hits the frame. I have checked the Device Origin, device dimensions, job origin. The start location changes every time I run the same job and the start location is different every time. I recoded 25 start locations to see if there was a pattern, a rotation, a difference is x or y due to belt slop or missing teeth, the machine is new out of the box. I have a diy cnc plasma machine and xtool metal fab and diy 3d printer so I am familiar with “how this stuff works” and this isn’t working.

Imagine when you start a job the head moves to a random start location and starts, every time, never the same place twice. Even after home, reset, reconnect, set absolute, it is something between the unit and the job and that is lightburn or hardware.

8

When the machine is homed, is it at the same physical position on the platform every time?

You can determine that by firing a manual pulse into paper after homing: the machine should drop the pulse into the same hole every time.

The controller does not know the physical position of the laser head: all it knows is that the home switches were tripped. As a result, the reported (0,0) origin can be anywhere on the platform if the switches are misbehaving.

Does homing put the laser head at the same physical location on the platform every time? If not, then there is a problem to be solved.

Assuming it’s all good, then the symptoms suggest the maximum acceleration & speed are too high for the machine to handle.

The description “Ortur Laser Master 3 with extensions 40w” suggests the machine has a heavier (and possibly larger) laser head than the default GRBL configuration was intended for, plus a larger working area. It is possible for the guide wheels / rollers to be too snug on the rails, adding more mechanical load, but excessive acceleration / speed seems more likely to be the problem.

The Laser window has a speed setting controlling laser-off motions: what is that value now?

Set it to 500 mm/min (if you use metric units) or 20 in/min (if you use USA-ian units), which will be a crawl. Home the machine and see if that affects the results.

The permanent fix is to reduce the GRBL speed and acceleration values to match the machine capabilities, so that the G-Code cannot command speeds beyond the machine’s capabilities. That requires testing to verify the new settings, but knocking 25% off the current X and Y values might get the machine closer to its Happy Place.

9

Hardware issue. I took it apart, motors and all, tested each wire and found a poor solder connection for my Y motor on the receptacle, technically warranty but I didn’t want to go through the mess and time. Resoldered and its works as it should now. It now moves appropriately when I home and frame. It seems to have been an attenuation issue.

RESOLVED!

10

Thanks for telling us the rest of the story! :grin: