Cohesion3D Rotary, LaserBoard Configuration

Rotary Setup on LaserBoard

Rotary Setup on LaserBoard

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Rotaries from LightObject or Cohesion3D should work directly off of the board with the built-in drivers.

Plug it into the A motor port on LaserBoard, configure, enable, and setup in LightBurn.

Rotary types / settings will vary and need to be dialed in based on their specifications, but this guide can be used as a general starting point. For additional information on what is included with the Cohesion3D Rotary, refer to the release notes.

Determine Your Steps Per Millimeter

Check your specific rotary documentation for the needed data. Gather the following information to begin:

  1. Review the Stepper Motor Specs for the Step Angle and note the corresponding steps per revolution.
  2. All C3D drivers are set to use 1/16 microstepping. If you are using an alternate external driver for a custom setup, check the driver documentation.
  3. Determine the reduction ratio of the gears being used on the rotary. Divide the driven gear teeth on the motor by the drive gear teeth on the shaft. Example: 10 teeth on motor pulley / 20 teeth on shaft = 2:1 Reduction Ratio
  4. Plug in the previously gathered values: (Steps per Revolution × Microstep × Reduction) / 360 = Steps per Degree  Example: (200 × 16 × 2) / 360 = 17.77 Steps per Degree

Setup the Config File

  1. Power off the C3D Board, remove the SD card and access on your computer using an editor such as Sublime Text. Do not use Notepad++.
  2. Find the # A axis settings.
  3. Change the delta_steps_per_mm (Ex: 17.77 calculated previously as Steps per Degree).
  4. Reduce the delta_max_rate (Ex: 6000 mm/min)
  5. If needed, increase the delta_current to 0.8 or 1.0. The board’s per driver max is 1.2 amps. Do not exceed the stepper motor max. Ensure the motors are not overheating after increasing. For more info: Changing Stepper Motor Currents on the LaserBoard
  6. Decrease the delta_acceleration to between 50-200. Lower values prevent your work from flying off of the rotary or spinning too fast initially.
  7. Save your changes, safely eject the SD card, then reinsert into the board and turn everything on.

Test the Rotary

  1. Manually make sure your head has clearance over the rotary and home the laser before starting, to have room to put the device into the work area.
  2. Standard heads should be fine, but longer heads will require more clearance from the bottom.
  3. For roller type rotaries, refer to the rotary documentation or use a micrometer/calipers to measure the actual diameter of the drive wheels, including any rings, as thickness can vary.
  4. Adjust the rotary settings in LightBurn under Tools > Rotary Setup.
  5. Select “Chuck” or “Roller” under “Rotary Type”.
  6. Check “Enable Rotary”.
  7. Under “Rotary Axis”, select the axis which your rotary is connected to.
  8. For roller type, enter the previously measured wheel number into the “Roller Diameter”. (Ex: 54.25 mm)
    Note: For the Cohesion3D Rotary wheels, the large is approximately 50 mm and the small is approximately 28.15 mm, depending on what you have attached.
  9. Enter either the diameter of the object to be engraved or its circumference and the other value will automatically be calculated.
  10. Click “OK” to save the changes.
  11. In LightBurn, on the “Laser” tab, for the “Start From” setting, use “Current Position”.
  12. Go to the “Console” tab, next to the “Move” & “Cuts” tabs.
  13. Refer to the set screws on the pulley for the drive wheel as a reference for the rotation starting and stopping point.
  14. Once the laser connects, type G0 A360 in the command field and hit enter. Enter G0 A0 to return to zero degrees, testing in the opposite direction.
  15. The rotary should now make one full revolution of the wheel.
  16. Use a marker to mark the rotary drive gear on the motor and a corresponding mark on the motor bracket to gauge and tweak as necessary.
  17. If it falls short, follow the configuration steps above and increase the delta_steps_per_mm value in the configuration file (Ex: 19.77). If it overshoots, decrease the value.
  18. Send the console commands again to test the rotation or use the “Test” button in the Rotary Setup window.
  19. For full rotation testing, measure around the the test item and create a thin test rectangle with the height set to the circumference of the item you are engraving.
    Ex: For an item that is 2″ in diameter, make a rectangle that is 2″ (50.8 mm) by 0.1″ (2.54 mm) in the LightBurn work area to test with.
  20. Put the laser head over the item using the “Set laser position” pin icon on the left toolbar to start from the current position.
  21. Click “Start” to run the test.
  22. Make sure to disable the rotary and go back into whichever start mode you prefer (i.e., Absolute Coordinates) after you are done using the device.

General information on rotary setup in LightBurn and usage: LightBurn Software Documentation Rotary Setup

Troubleshooting

Movement

  • If you are not seeing any difference after updating the configuration file, make sure the changes were saved before ejecting the card safely from the computer.
  • Ensure that rotary is squared with the gantry if the rotation is skewed. Affix the device to the chassis / base using screws or strong magnets, or create a jig to get it into the same position every time.
  • If the item on the rotary is walking or shifting, try using the tension arm to secure it, putting weight inside of it (like a soft sand bag), and/or make the base of the item flush with the gear on the drive shaft.
  • For skipped steps, adjust the previously mentioned configuration settings and make sure the stepper motor has enough current.
  • For wheels turning in the opposite direction, rotate the connector on the A Axis so it is reversed. The item on the rotary will turn the opposite direction of the gears.

Output

  • For upside down images, rotate the image in the LightBurn workspace or rotate the rotary 180° in the bed area, to work in the preferred orientation.
  • Make sure you are not removing and reinserting the SD card with the power on to the board, otherwise you will need to Reset it to acknowledge any file changes.
  • If the power is not consistently outputting (resulting in dashed lines), try increasing the power from the laser control panel or in the job layer settings. If you still experience issues, you may need to increase the laser_module_minimum_power to 0.02 in the configuration file.
    Note: You may need to decrease your power settings on the laser control panel or in the layer settings for each of your files after making this change, as it will globally affect all of your output going forward.
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