I have a few designs now which consistently lose their place during a run when optimised. Typically they shift a few millimetres horizontally. I think that the shift drifts 1 or 2 millimetres 2 or 3 times over the job. These are quite large intricate scores and cuts over an 800 x 600mm sheet.
If I turn optimisation off, it all runs fine and remains perfectly aligned from start to finish.
[EDIT: Optimise Cut Path setting]
I wondered if this was a mechanical fault, but running the same job at slow speed is also mis-aligned, rotating the whole job 180 degrees gives a slightly different mis-align. But again, turning off optimisation works OK.
These are jobs I have run many times before without problem.
This has recently started happening. Might be related to upgrading to v1.7.06
I started reading the topic to try to help in some way but I end up asking for clarification:
What do you mean by “turn optimization on” and “turn optimization off”?
Oh, okay. That optimization.
Can you put a print screen to see which selected options may interfere?
It also doesn’t seem to me that activating or deactivating the option would interfere, but it’s worth understanding what is actually being “optimized”
That’s the only difference. I run two jobs, one with optimise on, one without. The optimised cut loses alignment through the job so the end of the cuts do not lign up with the start.
If I do the same job without optimisation, then everything lines up/
To be better able to help please post a screenshot of the optomization settings, a photo of the result you’re getting and the lbrn2 file please. Also specify what machine you’re using.
On this image you can see where it is wrong. On the top section is a correct print, on the lower section is where the cut has lost alignment. (On the machine this is actually a left/right difference)
It looks like it is the “reduce travel moves” which is causing the problem. Disabling that seems top make it work correctly.
Looking closely, the top image doesn’t look correct either to me. It’s closer, but your inner lines aren’t aligning with the outlines of the casket. The tombstone isn’t closed at the bottom left corner. I can’t get in close enough on that area of the graphic in the Lightburn screenshot to see for certain, but it looks like all the inner lines are supposed to be contined within the outlines.
I think you have some backlash in your machine. It may be more prominent with optomizations enabled.
Load this file, sacle it proportionately to fit your bed and run it at high speed with optomizations turned off and just enough power to get a good mark on cardboard. Any discrepancies from the file will indicate machanical problems. Upload a photo of the results so we can look with you. BacklashTest.lbrn2 (68.8 KB)
You don’t have to go to the full bed size. I’d like to see it around 400mm wide. The larger and faster you go, the more likely it is to show any backlash. I recommend using cardboard because it’s free, think Amazon box.
By proportionately I mean don’t stretch it, keep the aspect ratio locked.
It looks good to me as well. I think we can rule out backlash. If you just engrave a portion of your project does it respond the same way or only when you engrave the full bed?
The only other thing I can think of at the moment is to check the PWM Rising setting.
It’s hard to tell, smaller jobs come out fine. Some large jobs, with very similar complexity also come out fine. It does seem to be design file specific. As I said before it is quite consistent, printing the same file generates the same discrepancy.
The gap in the corner is in the design - it’s a bridge to keep the pieces on the sheet.
Yes, you are right, there is a very slight discrepancy on the non-optimised version too.
I note the optimisation options include a “hide backlash” option - would that be useful in this context?
Another thing that just poped into my mind after @berainlb’s comment is sometimes the controller memory gets filled and things don’t behave as they shuld. Try deleting files from the controller and test again. Also, how are you running the job? Are you sending the file to the controller and starting there or are you using the start button in Lightburn? It is recommended to send the file rather than start, particularly on larger projects.
Comms issue seems less likely if on hard-wired ethernet. However, I’ve seen similar issues with consistent behavior that were indeed comms based.
If you don’t want to run a full test then perhaps do a binary diff of the stored file on the controller vs a newly generated RD file to confirm they are the same.
Also, are you able to see the misalignment on the Ruida display? Or does it look correct there? If display reflects error, then likely comms issue. If it does not then likely a mechanical issue… or possibly a configuration issue exposing a mechanical limitation.
Another test, save RD file, then import that same file back into LightBurn. Does the alignment issue show there? If so, then file is being generated incorrectly. If not, then something downstream such as comms issue or mechanical issue.
I do suggest purging files from the controller as suggested by @thelmuth if you haven’t already done so to rule that out.
