Wavey lines but only on angles with rotary

My problems persist. Let me update and see if anyone can give any further input. I am trying to set up a Piburn Chuck rotary and get consistent and repeatable wavey lines, only at angles/curves. Straight lines are crisp, such as 2 out of 3 sides of the triangle pictured or the square.

I have literally spent many hours with Piburn Mike from Lens Digital trying to help and we can’t figure it out. They have even sent a new rotary. This is why I’m posting here vs Piburn forum, the issue is with something outside the rotary.

Of course, I have checked the tightness and alignment of everything. I have tried slowing every jump off, acceleration, line shift etc speed I see in machine settings, tried changing pwm rising. To me it doesn’t seem if could be a belt or loose anything as it only occurs in angled lines and is very repeatable. I am using 12,800 steps which are set via dip switches and rotary setup; this is the number recommended by Lensdigital. In checking setup via distance test on mug, it is dead on.

In the photo, the top line is on the rotary and 2nd line is same settings flat, using x, y axis no rotary. The second photo is also on the rotary, the two perpendicular lines are crisp with the diagonals wavey.

OMtech 2028 80w Ruida controller & lightburn

there are no photos posted.

Oops, how about now?

So I don’t have your type of laser machine so my help is limited, others will have to jump in.
I can suggest a few things in the interim…
You seem to have isolated the problem to the rotary axis, either mechanical or a config setting.

  1. try a test cutting a straight diagonal line (which translates to a spiral on the cylinder). Use a line length equal to the hypotenuse of the triangle in first photo, same 45 degree angle from axis of rotation.
    Could be something to learn from the test, examine/post the gcode also if necessary.
  2. make a narrow rectangle of sufficient length to show 2 cycles of waves, and rotate it to 45 degrees. scan/raster that. adjust the scan angle to see how that changes results.
    examine/post the gcode.
  3. what are the rotary config settings, $103, $113, $123, $133 ? What is the cylinder diameter ?
    It’s possible the rotary steps/deg are too course for the scale of the graphic being scanned. I’ve run into that before but I don’t recall the result being wavy outline of scanned shapes, the problem was apparent before the scanning got that far.

I appreciate the input…gonna be completely honest here, you are gonna have to dumb it down a bit for me. I’ve only had this machine 2 months. I’m not familiar with posting Gcode etc, what do you want to see?

Run the tests suggested, analyze and/or report results.
You can save the gcode, the command stream that drives the CNC for motion and cutting, by pressing the “Save GCode” button in the Laser window below and left of “Start” button. Give the file a .txt file type and upload it to a post in this forum thread.

Some gcode reference info:
gcode command stream reference
Grbl v1.1 Realtime Commands · gnea/grbl Wiki · GitHub
Grbl v1.1 Configuration Commands · gnea/grbl Wiki · GitHub

Again, I don’t have or know specifically your machine model. I have a GRBL machine type/device. I don’t know how much of the gcode reference material will apply in your case, a lot of it I hope. Someone else will need to jump in that knows your machine model.

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