Hi all,
I wanted to follow up on a feature suggestion I submitted here as there’s been no discussion yet, and I believe this could be a really valuable improvement to LightBurn’s rotary support.
Problem:
When engraving wraparound designs on glasses with varying diameters—such as wine, tumbler, or pint glasses—the current rotary logic assumes a single uniform diameter. Even if the artwork is warped with the Taper Warp tool, LightBurn still slices the job into equally spaced splits based on that single value. This causes misalignment between slices where the diameter changes, especially over concave curves, because the same angular rotation results in different arc lengths. Gaps or overlaps form where each split begins.
Using overlap helps slightly, but since it’s applied uniformly across the axis, it only fixes part of the issue while causing excessive double-burning or shadowing in other areas.
Feature Proposal:
Add the ability to input both a top and bottom diameter in the rotary setup. LightBurn could then calculate the true circumference at each engraving height and taper the width of each split accordingly—effectively turning each slice into a trapezoid that matches the surface it’s covering.
This would keep the engraving perfectly aligned all the way around, even on curved or tapered glass.
Here’s a more complete visual explanation:
Why this matters:
Especially with the Omni 1 UV laser, the engraving quality on glass is incredibly clean and detailed when using a 0° or 45° scan angle. It closely mimics the appearance of sandblasted designs. This works best when using larger split sizes to reduce visible transitions—but that only works well on flat or cylindrical objects. On tapered glass, those same large split sizes introduce visible misalignments.
Most people compensate by using very small split sizes (like 0.1mm), but this introduces many fine lines into the design, breaking up detail and creating an unnatural look. A tapered split system would maintain both visual smoothness and alignment, allowing us to use the wider split sizes that give the best result.
Compatibility with Scan Angles:
This would work best at 0° or 45° scan angles, where the beam moves across or diagonally along the axis of rotation. At 90°, where the beam moves parallel to the rotary axis, diameter changes would still cause issues—but the 0°/45° case covers most users who want clean glass engraving.
Clarifications (for common responses):
- Taper Warp only warps the artwork. It doesn’t influence how the rotary moves or adjust step distances between slices.
- Overlap helps close gaps but does not account for variable arc lengths—overlapping too much in one area and not enough in others.
- Yes, you could manually compensate by warping and modifying the artwork by slicing ‘wedges’ from it, but this is tedious and doesn’t scale for production.
Machine details for context:
- Laser: ComMarker Omni 1 UV Laser
- Rotary: ComMarker R5 Rotary
I’m active in several groups and forums where people use the Omni 1 UV laser and others, and one of its standout capabilities is how well it engraves on glass. A lot of users run into this exact alignment issue, but I’ve yet to see anyone come up with a proper solution. Implementing a feature like this would definitely help a large number of users who rely on LightBurn alongside UV lasers for detailed glass work.
Would love to hear from the team or others if this is something technically feasible—or already possible in a way I’ve missed.
Thanks!
— Adam
