Issue with wavy lines on scoring operations

Wavy Line Laser Issue

I have an 80w CO2 laser. Yes, I clean the lens and mirror after every use.
The issue is scoring in a project results in wavy lines, every time.
I have been fighting this problem for quite a while now and have done all sorts of troubleshooting.
Scoring is where the issue comes up. Engraving and cutting don’t have this issue.
It doesn’t matter what the project is, scoring always does this.

Troubleshooting I have done:

  • Check the tightness of the belts
  • Checked all screws I can access
  • PWM settings and all the combos. I even made a chart :slightly_smiling_face:
  • Checked lens and mirrors for looseness
  • I even tapped on the various components of the gantry to see if anything rattled.
  • Send the file to the laser and start it from there.

This is the initial test project with just scoring done at 200 speed, 20 power.

In this photo is the test I performed - I have done several of these.

It looks like it will go away at certain speeds right? Well no. In this test it did, however, when I use the very same speeds that are ok in the test for a project, the issue still crops up consistently.

Very low speed and power help get rid of the wavy lines, around 25 speed, 11 power. With my laser, I can’t go much lower than that.
However, at that speed then the score lines and cut lines do not match up. In this photo, I marked that with red.

Still looks like belt problems.

You’re seeing the flexibility of a large gantry accelerating after direction changes. The wobbles occur after corners where the Y axis changes direction, so they’re most obvious on straight lines running generally parallel to the X axis.

Reducing the controller’s Y axis acceleration will reduce, but not eliminate, the wobbles.

On a Ruida, that value is in Edit → Machine Settings → Vendor Settings → Y Axis Settings → Maximum Acceleration:

Because the controller modulates the power based on the speed, you may find a lower acceleration requires a lower Min power level for more headroom.

The controller has several other acceleration limits that may also affect the outcome. I think:

  • Cut Parameters apply to motions with the laser on
  • Idle Parameters apply to motions with the laser off
  • Engraving Parameters apply only to back-and-forth engraved areas (duh)

Documentation on those parameters is basically nonexistent, so careful experimentation is the only way to fly. I think the Cut acceleration caps the X and Y values, but I haven’t done any careful measurements.

FWIW, that acceleration on my 60 W laser produces these results on 1 mm and 2 mm holes:

With these wobbles on the straightway sections:

They’re on the order of 0.3 mm peak-to-peak and don’t seem to bother anybody other than me. And, now, you. :grin:

2 Likes

I’ll have to mess with that tomorrow. Thanks.

I wouldn’t be surprised. But I’d have to think if I’m going to put more money and that much effort in to this pos. :joy:

Belt drives are inexpensive but there are tradeoffs for everything.

It seems like a complicated replacement though, right?