Step-by-step guide to glass engraving with the rotary unit - Part 2

Steve Opioka


Cleaning the glass: Ensure that the glass is clean to enable a clear engraving. Use glass cleaner and a lint-free cloth to remove dust, fingerprints, and other impurities.

Masking or protective coating: If necessary, you can cover areas of the glass that are not to be engraved to avoid accidental contamination (e.g., painted objects). Masking tape or special coatings can be helpful in this regard.

Inserting and connecting the rotary unit

Example LRA-KP58!! Pay attention to the jaw designation!!

When inserting the interchangeable jaws, make sure to insert the individual jaws in the correct order into the rotary unit. For this purpose, the individual jaws are marked with '1, 2, 3'.

Insert and connect the rotary unit

  1. Start the water cooling and laser
  2. Lower the work bed all the way down
  3. Move the laser head to the center of the work bed (where the rotary unit will later be placed)
  4. Disconnect the plug of the existing Y-axis
  5. Gently push the Y-axis with the laser head by hand towards the back so that the rotary unit can be inserted without causing any damage
  6. Place the rotary unit in the center of the work bed. Insert the object and ensure it sits horizontally. For conical glasses, the rotary unit can also be raised on one side to achieve a horizontal level of the object
  7. Manually move the Y-axis with the laser head back to the center of the work bed and position it above the rotary unit. Bring the work bed to the correct focus for the object. (Ensure that the laser head can swing freely over the rotary unit so that it is not damaged during a reset or restart.)
  8. Connect and secure the plug of the rotary unit to the available socket Clamp and secure the object, ensuring a tight fit, and secure it with the mandrel.

Set up the rotary unit in LightBurn

1. Menu Laser Tools Set up rotation

2. The stepper motor drives the chuck of the rotary attachment. As the name suggests, the rotation of this motor occurs in several discrete 'steps.' It is necessary to correctly set this number in the software so that it knows how many pulses to send to the motor to achieve precise rotation. Typically, a conventional rotary attachment requires about 10,000 to 15,000 pulses or steps for a complete revolution. If this number is not specified in the rotary attachment documentation, experimentation is required. For example, start with 10,000 steps, then place a piece of tape on the top of the chuck and press the TEST button in the LightBurn dialog box. LightBurn will then instruct the Ruida controller to send 10,000 pulses to the rotor. If the number is correct, the tape should end up in the exact same position as at the beginning. Otherwise, an adjustment to the step count is necessary.

Create design and set parameters

Load or create design in LightBurn -> Layer mode -> Fill!

Rotate the design to match the bottom and opening of the object to be engraved. In this case, positioning is done via camera.

At this point, I deactivate the 'Bidirectional Fill' as otherwise the thermal load would continue to increase. I have previously determined the values on a test glass.
I choose the line interval based on the size and intricacy of the design. For smaller designs, I use an interval of 0.07 mm (362 DPI) - 0.08 mm (318 DPI), and for larger designs, typically 0.09 mm (282 DPI).
Now, close the lid and start the engraving. Always monitor the engraving process and do not leave the laser unattended. If there are any jumps visible in the glass, the process must be stopped immediately!


Following the engraving, the glass and the engraving should be cleaned thoroughly. Regular dish soap and a sponge/cloth are sufficient for this.
Due to the thermal treatment, tiny glass flakes can break off from the glass, so it is important to work with gloves and safety goggles.
The finest glass shards (crisps or flakes) can be removed by subsequently treating the glass with a brass brush or #000 steel wool.