on this forum and have been pulling my hair out trying to solve a problem with my ortur/neje diode laser. I am getting wavy starts to lines on the x axis I have cleaned lubed tighten/ loosen belts adjusted eccentric Checked all grub screws slowed down accel values in grbl and still have a persistent wave at the beginning of cut. hoping someone can send me down the right path I have been testing using primitives in lightburn and can get some of the wave out if I really slow down accel values but it still shows. Longer lines start with a wiggle and then look really good as you can see in the picture I want to say thanks in advance for any thoughts
This is very likely a case where the laser module is not well secured to the gantry. With the amount of waviness you’re getting I’d expect you to be able to visibly witness this as the laser moves. Can you see the laser head bobbing forward and back on the gantry?
If so, identify the source of it. Try manually pushing/pulling the laser head forward and back against the gantry. Is there considerable movement there? If so, adjust the eccentric nuts to eliminate the gap between the wheels and the rail.
In my mind the module is well connected and I am not able to see the module move at all The photo I added is only a 2" square so the movement is slight. I have tried this in numerous locations on the bed with no change. I have pushed pulled twisted the gantry and cant manually feel any play I will try adjusting the eccentrics again as I have run out of other solutions
thanks so much for your reply I have seen your posts in many topics and they always seem spot on
Try taking a high speed video of the laser in motion. That should make any oscillations more apparent.
One other thing to check is to make sure the lens is well secured to the laser module. If it’s loose this type of thing can occur but this seems severe. Even at 2 inches I wouldn’t expect this level of motion.
Video is a great idea I went back thru eccentric /belts and really shook it around and can’t seem to feel any slip or slop and didn’t make any difference will shoot a video tonight. lens is pretty tight in the module might be something internal
If you can do it safely, I’d suggest checking to see if the drive belt is moving during those waves. That would let you know if the waviness is coming from the head or the stepper.
I am stumped did some slomo video shots today with my phone https://youtu.be/4bmF7DfwZ9U
[https://youtu.be/oL04OJHrIiU](February 13, 2023 - YouTube)
I cant really see anything that helps. I also rebuilt the mount for the neje thinking it might be the problem. It made absolutely no difference… tightened the crap out of belt no difference loosened belt still the same… tightened and loosened eccentrics still exact same result. I am running out of patience with this what am I missing?
Thanks to all for your help
Yeah, I checked for that in your original post. I would expect misaligned or misshapen wheels to have consistent waviness. Since yours are only occurring during acceleration/deceleration it’s unlikely to be caused by wheel issues.
You may want to setup some tests to help isolate the issue.
Create a filled rectangle with line interval of 1mm using horizontal scanning. Run this with job starting from top and from bottom
Repeat above but with scan angle at 90 degrees
Create a clockwise spiral and a counter-clockwise spiral
This may help identify where this is really happening.
Can you confirm if dramatically reducing speed reduces the artifact?
I dramatically dropped both the x and y accel speeds in grbl and it did reduce the wobble but didn’t eliminate it
I will run your suggested test when I get a chance and post results
Tried to set up test that you suggested but cant seem to figure out how to change start point in lightburn
I used the shape start point tool but in preview it seemed to have no effect not sure what i am doing wrong
I turned off optimize settings clicked off chose best start point without any effect I may try again tomorrow or throw the whole thing in the trash. I have a 60 watt co2 that runs perfectly but was hoping to use this for smaller jobs and engraving but wasting this much time is extremely frustrating and not productive
thanks all for your help and time
Figured out problem with shape start at least It only seems to work when object is in line mode then when i change back to fill W/ mutiple shapes it overides my shape start choices that I made while in line mode so I guess I can only do one at a time
Here are the results from what I could do with the test suggested I slowed it down to 30mm/s
wobble is still there on x axis startup Y axis looks pretty good. I will be able to work on it some more in coming days I may tear the whole x gantry down and rebuild from there
For reference the squares are 50mm spirals same
thanks
on the horizontal test, are the wavy portions at the start or end of the line burn? I’m a little surprised that every single line has them. I would have expected the first line possibly to not have the issue if this was just about a loose laser module. This potentially implies something else
the vertical test is also interesting. the left leaning heads and tails… are those at the start or end of the burn? I wouldn’t have expected any wobbles at all if the issue was isolated in the vertical orientation. Which size of the vertical test was the first line?
one thing about the vertical test is that it seems like it’s getting taller on the right. Is that just perspective or is the area not a rectangle?
The spiral tests show slight wobbles at the tops and bottoms of every curve.
I’m tending to think this is something more about oscillation… Is it possible that the laser head mount is oscillating when accelerating? The laser module seems to be mounted fairly low. I’m wondering if you’ve created a pendulum of sorts with a heavy lever arm.
Are you able to raise the laser module or otherwise increase the rigidity of the mount to see if the wobbles go away?
It appers the issue is in the X axis, I would physically grab the axis and feel for wobble in the diode mount, as well as tighten the grub screws on the stepper motor toothed pulley and ensure the end plates are fully tightened onto the extrusions.
If I wher to hazard a guess I think the issue may be on the Y axis, it looks to be almost all Y movement while travelling in the X direction, left and right belts are fighting each other and the Y stepper is trying to keep up, for a start Loosen and retighten the coupler on the cross shaft that connects the left to right belt. That will release any tension between the belts.
