Doing a complicated project (Crib Wars). The design was done in Cut2d, carving was tried on a 3018 Pro. The design consists of 7 layers. 2 layers are carved and 5 layers are lasered. 7 different files. All the layers were designed as one project. Using the lower-left corner as my homing location and the center of the design as the origin. The file was exported as an SVG file so that it would be compatible with Lightburn. I opened the file in Lightburn and created 7 layers. I set it to laser all 7 layers. ( yes, I know 2 are meant to be carved, but I wanted to see if everything would line up properly). Lightburn proceeded and worked perfectly for the first 5 layers. Everything lined up perfectly. However, The last two, not so much. The last two are the holes (all 1067 of them) and the lines. the holes were aprox 10 mm to low as were the lines. What I discovered was that my XY Datum in Cut2d was at X150 and Y155; whereas in Lightburn it was X165 and Y183. How and why that is possible is beyond me. Also, why did the first 5 layers come out perfect and not the last two? Any input would be appreciated as I’m at wit’s end here. Thanks in advance. If the picture loads, this is the crib board that I’m talking about.
To confirm, were the layers aligned within LightBurn after you imported them?
What do you mean by the datum in LightBurn? Was this true for all layers or only the 2 affected?
What was the process of exporting the 7 layers? Was this done in a single file or as a separate file per layer?
Finally, is your primary question about alignment in LightBurn design or an issue with the alignment of the burn not matching the alignment in LightBurn?
Are you willing to share the .lbrn file for review?
Not to sure what mean by “Aligned”. It was opened in Lightburn and I created/retrieved the layers and set them up in Lightburn. I set the origin to be at the center of the work piece just as it was set in Cut2d. When I set Lightburn so that all layers would “show” they all are perfectly aligned with each other.
I guess I shouldn’t have used the word Datum. I mean the “origin” was not a the same coordinates.
The file was exported as a single SVG file. It showed all 7 layers perfectly aligned in Lightburn.
My issue is that not all 7 layers are aligned with each other. One would think that they should be, being that same origin position is used for all 7! The attached picture is what I first carve looked like. This is before I decided to do some laser work.
I’m still a bit confused. I can’t reconcile these two statements so can’t quite grasp where the problem is.
I think ultimately what you’re saying that the laser burn (that you did in LightBurn for the final 2 layers) didn’t align to the carving that you did (for the first 5 layers) and that it’s because the origin point was different between the carving and the burn. But that seems to be incongruent to other things you’ve said so want to make sure I really understand the nature of the problem.
All seven layers were lasered with Lightburn. I did that so that I could see if they all lined up. If they did, then I was going to try and carve the first two layers and laser the final 5. the first two would be the holes and the pockets. The last 5 would be the markers, the script, the lines, the advance lines, and the penalty lines.
Not sure what you mean by "stray node/short line segment. Do you mean open gaps in the lines/vectors?
Okay. This goes back to my initial understanding.
But sounds like they didn’t. So is the problem that the actual burn didn’t line up for the final 2 layers?
So going back to my original question:
The issue is really the latter, correct? The alignment of the burn for the final 2 layers does not match the alignment that you see in the LightBurn design?
Can you attach a full screenshot of LightBurn with the design loaded and a photo of the missed burn?
The last good burn was the dark patches. (these are penalty lanes). The next 3 didn’t line up. That is all the holes; the markers ( larger rings around the holes) and the lines.
Was this all run as a single job? Or you manually ran each layer one at a time?
I’ll bet the origin slipped during all that movement. You could test fire on a piece of tape then run the pattern without cutting then recheck origin.
One at a time. The first laser was the Pockets. That was perfect, but of course you have nothing to compare it to, because it was the first. Next was the advance lines. They were perfect. That’s when I let the machine do its thing. When I came back, the last three burns were all screwed up. I’m wondering whether the machine lost some steps somewhere? But, I have it running real slow, and this is a laser, it shouldn’t be losing steps!
Tomorrow, I’m going to try and “Save Gcode” and then run each file separately to see if there is any difference. Right now, I’m not saving anything, just running from the main file.
2 possibilities I can think of:
- Since you ran these one a time something in the alignment process was different on the 3rd run (sounds like you did all the remaining layers as one go?). Did you get enough of a peak into the 3rd run to know if it started correctly?
- As you say, lost steps. This is possible but if something happened it was likely sudden and jarring. Your setup is clearly capable of running some good burns so I doesn’t seem as straightforward as a loose belt.
I’m tending to think there must have been something different in the alignment process. Perhaps something like what @RalphU was referring to. If you have some stray parts in a layer outside your expected area that’s throwing off your center.
You could confirm that by trying to burn all 7 layers in one go. Probably would want to scale the image down and burn to paper or something as a test.
Just ran a quick test with the laser just doing the holes on a piece of thick paper. Ran it at 800 mm/min. About 15 mins in, I heard it lose steps. Stopped it immediately and reduced the speed to 500 mm/min. Ran it again and it so far is running perfect.
Awesome. Nice that you caught it in the act. Would be good if that’s all it was.
Just finished running the file. Still problems with the origin. The first three layers went perfectly. The last 4 only worked after I had to manually adjust the origin. One all four of the layers in question, when I opened them, I noticed that the origin (that little green square marker that shows where the origin is) had moved to a different location. Four layers, four different origins. Have no idea why this is happening. Will go back to Cut2d and export another SVG file, making sure that the origins are all in the same place, and then run Lightburn to see if the problem still persists!
Just had a brain fart after my last post. I’ve been doing this on my PC; I just decided to open it on my Mac to see if the same problem showed in regards to the origin. Didn’t. The origin remained at the same coordinates for all 7 layers. Will try a burn using my Mac in the morning to see what happens!
What coordinate system are you using? I assume current position?
Can you explain your overall alignment procedure?
Depending on how you’re doing this the actual SVG file may not guarantee you absolute position. Relative position of all objects in the file will be correct but they won’t necessarily be in the same absolute coordinates as your source.
What’s the difference between your PC and Mac? LightBurn itself should behaving the same.
What exactly are you referring to origin in this case? Do you mean the green square that indicates job origin position? That will be determined by your coordinate system, the choice of job origin position, location of objects in workspace, and selection of “Use Selection Origin”.
Or something else possibly?
Just a basic point about how theses machines work. I apologize if this is too basic. They are all open loop. Meaning that the actual position of the laser isn’t known to the controller. If the steppers slip then the pattern slips from then on.
Another point is Cut2d produces a vector file of your design. Once it’s imported into Lightburn then Cut2D can no longer cause a problem.
I also believe that layers remain locked in place in Lightburn. No possible way for layers to move relative to each other.
I still recommend: set origin and test fire into tape. Run a cold layer and let it stop and fire again. Do the same for every layer. If a layer moves then try slowing it down and retest. The origin should not move during any operation. Be aware that slipping may come and go. Steppers may behave different as they get warm.
I believe this is the underlying issue:
However, I don’t have experience with the gcode based lasers, but on the DSP/Ruidi based lasers, you’d typically have the start from position set to absolute coordinates or user origin. Especially when burning a bunch of a layers …
Hope this helps 