Help with a setting

Hoping you guys may be able help…

I was running parallel lines to check the left to right position relative to each other for fills, and this is one I got. Let starting and stopping points line up nicely, but the lines look like hell.

One is at 100mm/sec and the other is at 200mm/sec.

Hoping it’s just a setting (using LightBurn.) The lens is seated fine, and the belts seem fine.

Thanks in advance.

That’s some kind of mechanical problem.
Loose belts, mirrors, lens, carriage is sloppy on the rails, gantry isn’t stiff enough and vibrates like a guitar string… etc.
Slowing down speed and acceleration will help mask/minimize the problem but the solution is to find out what’s wiggly and fix it.

Not doubting you in the least, but I can’t find anything loose or sloppy.

A guy in a group of FB said to try and pulse and move manually which I did, and I got an absolutely perfect line.

It’s such a text book example of a mechanical vibration.
I can see how the laser moved. From bottom to top it moves right to left (x-axis) along the red line then at the end of the line it takes a quick step in up in the Y-direction. That Y direction pulse “plucks the string” and sets up a vibration that continues along the X-axis (left to right now) until it dies out after a couple of cycles of oscillation. When it gets to the end of the line it makes that Y jump again and plucks the string and sets up the vibration for the beginning of the next line. Repeat as necessary…

That makes sense, so possibly more play in the Y axis, than the X?

Acceleration or speed too high could also cause this effect

That was my original thought (but I have an old old brain) and I couldn’t remember what it was called or where it is located. Can you possibly tell me a bit more? I am also still looking for slop in the mechanisms also.

Here is what I currently show. Just not sure which ones to mess with.

Max acceleration in cut parameters, either X and/or Y. I would advise making a note (or even better save) the current settings in case you go too far or the wrong way. Maybe a Ruida user could explain what the Acceleration factor is, changing this parameter may also have the desired result. Oh, Lower the values.

Acceleration isn’t the root cause of the problem, but slowing down speed and acceleration certainly helps to reduce the effects of the problem.
Your acceleration values already look very conservative.

I would probably turn down the idle speed some and see if that helps. Idle speed is the speed it travels between cuts (laser off) which would be those Y-axis jumps in your test piece. It’s set at 300 now which is not unreasonable, but try turning it down to 150 - 200mm/sec and see what happens.
It’s always a good idea to “save” your settings before you start messing with them in case you get lost and need to find your way back.

I agree @Hank it is mechanical, mine was gantry wasn’t still (EDIT: I meant stiff, told you I’m old) enough so the only workaround was to reduce the acceleration speed (I dont think I have idle speeds on my controller but could be wrong I’m also old! and may have forgotten :slightly_smiling_face:)

I tried reducing those numbers and then some of the others as well. Honestly other than getting the head into position where the image is, it had minimal effect.

Stupid question. Could my belts be too tight at this point? I can’t find any looseness anyplace…

Thanks again

Yes, it’s possible for belts to be too tight and make a problem worse.

If you move the carriage to the center of the gantry and grab the nozzle and gently try to wiggle it back and forth in both X & Y direction can you detect ANY play in any direction? Any flex in the gantry that might indicate it’s not stiff enough, or play in the bearings of the carriage on the rail?

Hi. Honestly no. I can’t detect any play whatsoever manually.

But that being said, I have the belts pretty tight, like to the point I am afraid they are going to tear or snap pretty soon.

I will try to loosen them a drop when I get in tomorrow and see if that makes any kind of difference.


Editing Idle speed etc won’t help with fixing problems in engraving or scans. Idle speed relates to movement when vector cutting while the beam is off.
You need to severely drop the line advance speed in Y engraving settings. Try a Line shift speed and Y start speed of say 2mm/s, and retest.

I had a similar problem and was fixed by tightening the screws on the X axis gears that tighten against the servo motor shaft (or the guide shaft in LM2 systems). If this screw is lose, it will tend to stay in alignment to a point if the shaft has a flat on it, but can still move a little also.

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