Controls & Operation

Once the software is installed, the entire printer is operated through the rotary encoder on the LCD display; there is no keyboard or mouse during normal use.

Input	Action
Rotate	Scroll through menu items, or adjust a value
Click (press)	Select an item, confirm a value, or exit a mode

Main Menu

On boot, OpenCAL displays the main menu:

> Print from USB
  Manual Control
  Settings
  Power Options
  About

Each option is described below.

Print from USB

Lists all .mp4 print files found on the inserted USB drive. Selecting a file:

1. If the filename encodes an RPM (e.g. part_9rpm.mp4), the motor speed is pre-set automatically (see Video File Naming Convention).

2. An RPM adjustment screen appears: rotate to change, click to confirm and start the print.

3. While in this menu the projector shows a black image; this is intentional, to avoid accidentally curing resin while browsing.

4. A Print Status screen is shown while the print runs. Click to stop.

5. If USB video prompt is enabled (see Settings), you are asked whether to save the camera recording to USB after stopping.

Note

Files with recording in the filename are hidden from this list (they are camera output files). Avoid using “recording” in your print filenames.

Tip

The camera saves recordings as .h264 (raw H.264 bitstream), not .mp4. To convert for playback on a computer:

ffmpeg -i recording.h264 -c copy recording.mp4

Manual Control

Direct hardware control without running a full print job.

Item	Action
Turn on LEDs	Turns the LED array on to the default red colour.
Turn off LEDs	Turns the LED array off.
Start stepper	Starts the stepper motor rotating (uses the last-set RPM).
Stop stepper	Stops the stepper motor.
Capture image	Takes a still image with the camera. Saved to USB with a timestamp filename if a USB drive is mounted, otherwise saved locally. The LCD shows “Image Captured” or “Image error”.

Settings

Item	Action
Calibration Images	Browse and display calibration images from the opencal/utils/calibration/ directory on the projector.
Show Alignment	Displays the cross-strut alignment tool image on the projector. Rotate the encoder to shift the image up/down for transverse alignment. Click to return.
Find Vial Width	Projects a white rectangle (a bar of light) onto the vial whose width you vary with the encoder, reporting that width in pixels. Used to measure the pixel size for calibration and to check that the projector is centred (even light on both sides). See the Calibration section of Printing Workflow.
USB video prompt	Toggles whether you are asked to save the camera recording to USB after each print. Shows the current state (“USB prompt: On/Off”).

Power Options

Item	Action
Kill GUI	Stops the OpenCAL application without rebooting.
Restart	Reboots the Raspberry Pi.
Power Off	Shuts down the Raspberry Pi.

About

Displays an animated scrolling credits screen with the project contributors. The LED array runs a blue/gold checkerboard animation while credits are shown. Click to exit at any time.

Video File Naming Convention

OpenCAL reads the RPM value directly from the video filename. Name your print files as:

<part_name>_<rpm>rpm.mp4

Examples:

• cylinder_9rpm.mp4 → motor set to 9 RPM automatically

• part_v2_12rpm.mp4 → motor set to 12 RPM automatically

If no RPM is found in the filename, the menu opens with the last-used RPM value.

Note

Print files (.mp4 videos) are generated from your 3D model using Tomo (or VAMToolbox directly). See Tomo — Print Preparation Software and VAMToolbox — The Projection Engine for how to create them.