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Rotary Mode (GCode)

Rotaries are used to turn cylindrical objects so that their surfaces can be marked by a laser. In order to use your laser with a rotary, you must first establish several important parameters in the Rotary Setup window that control the rotary's motion.

To open Rotary Setup, go to Laser Tools → Rotary Setup (Ctrl/Cmd+Shift+R), or click the rotary icon in the Modes Toolbar.

Rotary Setup

Click any option in the images below to jump directly to the relevant section for that option, or scroll down for a list of options and descriptions.

Rotary Setup for GCode (Chuck)

Rotary Setup for GCode (Roller)

Rotary Type

Select whether your rotary is a Chuck or Roller style rotary. Chuck rotaries have adjustable jaws that grab and hold objects, while Roller rotaries have revolving rollers or wheels that objects are placed on top of.

Enable Rotary

Tip

If Show rotary enable in main window is enabled in your Settings/Preferences, you can also enable or disable Rotary Mode using the switch in the Laser window.

Rotary Enable Switch

This switch controls whether Rotary Mode is enabled on the laser's controller. When enabled, the controller handles sending rotational commands to the appropriate axis and rescaling output.

When Rotary Mode is enabled, you'll see a status indication in the bottom right corner of your screen:

Rotary Mode Enabled

Mirror Output to Rotary

Enable the Mirror Output to Rotary switch if output to the rotary is inverted in the dimension of rotation.

Rotary Axis

Select which axis LightBurn will output rotational commands to.

Select Y Axis if you are unplugging your Y Axis stepper motor wire and plugging it into the rotary instead. Some lasers use the Y axis with a dedicated port and switch.

Select Z Axis or A Axis if you are plugging your rotary into a dedicated rotary axis. Consult your laser's manufacturer for help identifying the correct axis.

Rotary Settings

MM Per Rotation

Note

With a Roller style rotary, it is the roller or wheel driven by the motor that must make one complete rotation when you click the Test button, and not an object on the rotary.

Set the mm per rotation value to the distance of commanded movement in millimeters required to spin the rotary one complete rotation.

If this value is incorrect, output will be shrunk or stretched.

In most cases, mm per rotation will be provided by the manufacturer of your rotary or machine — consult the manufacturer if the mm per rotation value was not provided in the instructions included with your device.

Test

When the Test button is pressed, the rotary should turn a full 360 degrees, pause, then rotate back to the starting point. If the rotary turns too far, reduce the mm per rotation value. If it does not turn far enough, increase it.

Roller Diameter

This option is only presented for Roller style rotaries.

In most cases, Roller Diameter is provided by your rotary's manufacturer. If not, carefully measure the diameter of the roller or wheel driven by the rotary motor.

Once this measurement is accurately identified and set, it never needs to be adjusted again. If it is inaccurate, output will be shrunk or stretched.

Object Diameter

Tip

Use high precision calipers to guarantee the accuracy of your diameter measurement.

For Chuck style rotaries, carefully measure and enter the Object Diameter of the item on your rotary. This value must be updated every time you place an object with a different diameter on your rotary. If it is inaccurate, output will be shrunk or stretched.

For Roller style rotaries, Object Diameter does not affect output, but can be entered here to calculate the Circumference of your object.

If your object is tapered, check out our Taper Warp tool.

Circumference

Object Circumference is automatically calculated based on the value entered in the Object Diameter field. The converse is also true — Diameter is automatically calculated from Circumference.

Use this value to adjust the size of your graphics — for full wrap designs, the combined height of your graphics should be identical to the Circumference.

Notes for Smoothieware Users

Before configuring the above, you may need to set up the rotary axis on your controller. LightBurn sends rotary moves as angle values, and the GCode controller translates those angles into actual movements. To do this, it needs to know the correct number of motor steps to take for one degree of movement on the rotary motor.

If you have a Smoothieboard or other uncommon GCode-based controller, the number is usually 200 times your microstepping multiplier (usually 8 or 16) times any gear reduction, divided by 360.

For a Cohesion3D or HolgaMods rotary, this is usually

3200 steps (200 x 8 micro steps x 2x reduction) / 360 = 8.88888888 steps per degree 6400 steps (400 x 8 micro steps x 2x reduction) / 360 = 17.7777778 steps per degree

The steps per degree number, along with acceleration and maximum speed will need to be set in the appropriate location for the controller. With Smoothieware, those are the delta settings in the config.txt file on the controller.

Positioning

Tip

If your rotary is plugged into your laser's Y Axis, position the laser head toward the center of its work area before plugging in the rotary.

In most cases, [Current Position] is the best Start From mode to use when working with a rotary.

Align the object under your laser head in the X dimension. Output will be positioned on the object in the X dimension relative to the laser head and Job Origin selection. The Job Origin is indicated on your graphics by a green square. Parts of the graphic to left of the green square will output to the left of your laser head, and parts to the right will output to the right.

Turn the rotary or object on the rotary to determine where the engraving will output on the object in the dimension of rotation. Output in this dimension is also determined relative to your Job Origin selection — the rotary will turn to reach graphics positioned above or below the Origin.

See Coordinates and Job Origin for more information on the Start From mode and Job Origin settings.

Job Origin Rotary

In the above example, output will be centered around the starting position of the laser head.

Tip

To avoid having the rotary backtrack when making [Fill] engravings, select a top or bottom Job Origin.

Troubleshooting

  • If your output is shrunk or stretched in the direction of rotation, either mm per rotation, Object Diamater (if working with a Chuck style rotary), or Roller Diameter (if working with a Roller style rotary), is incorrect.
    • Use the Test button in the Rotary Setup window to check mm per rotation. The rotary should make one 360 degree rotation before returning to the start. If you are working with a Roller rotary, it is the roller or wheel driven by the motor that must make one complete rotation and not an object on the rotary. If it turns too far or not far enough, adjust mm per rotation.
    • Use high precision calipers to double-check the Object or Roller Diameter value.

  • If your controller returns an [Alarm:2], Soft Limits error, enter $20=0 in the Console window to temporarily disable Soft Limits. When you are done working with the rotary, be sure to enter 20=1 to re-enable Soft Limits in your machine's firmware.

    Additional Information

    This error is due to the amount of commanded travel on the rotary axis exceeding the Max Travel limit for the Y axis, as set in your laser's firmware. During flat engraving, this protects the machine from attempting to travel out of bounds and potentially damaging itself. Since the rotary can turn forever, it is ok to disable this setting when engraving with a rotary, but take care not to give the laser commands that could cause it to travel out of bounds in the X dimension.

  • If the object slips on a Roller rotary, try:

    • Wrapping the rollers with a non-slip material, or even rubber bands.
    • Placing weights inside the object, such as ball bearings or other small round objects, to help press the object against the rollers.
    • Going to Edit → Machine Settings and reducing the Acceleration value of your rotary axis, in your machine's firmware settings.
  • If you end up with a flat part at the bottom of the engraving, it means your rotary gear mechanism has backlash. Usually, tightening any belts in the rotary device will fix this, but, if not, you can place a small line a few mm below the bottom of your design, set to very low power (0.1%) and set it as the first layer to run. The rotary will spin to this position, then back up over that few millimeters of gap, and will take up the backlash with that movement.

For more help using LightBurn, please visit our forum to talk with LightBurn staff and users, or email support.