Just to be 100% transparent - this is all AI generated code, I certainly do not have the capability to program something of this complexity. Even all of this documentation is AI generated, so there's probably a lot of mistakes. Please don't hesitate to submit PRs.

Point and Print - Camera Position Script for Klipper

Overview

This Python script (point_and_print.py) automatically inserts Klipper SET_SERVO commands into your 3D printer gcode files. It reads object definitions from the EXECUTABLE_BLOCK_START section, calculates the angle between your camera position and each object's center point, and inserts servo positioning commands before each EXCLUDE_OBJECT_START line.

The script is designed to be used as a post-processing script in your slicer software, where it will automatically process each gcode file after slicing.

⚠️ Critical Requirement

You MUST enable "Exclude objects" in your slicer!

The script requires EXCLUDE_OBJECT_DEFINE and EXCLUDE_OBJECT_START commands in the gcode. These are only generated when the "Exclude objects" option is enabled in your slicer settings.

• ❌ "Label objects" alone is NOT sufficient
• ✅ "Exclude objects" MUST be enabled

Location in PrusaSlicer/SuperSlicer/OrcaSlicer:
Print Settings → Output Options → ☑ Exclude objects

See SLICER_SETUP.md for detailed instructions for your specific slicer.

Camera Configuration

IMPORTANT: Before using this script, you must configure your camera's position and servo!

At the top of the script, you'll find the camera configuration section:

# ============================================================================
# CAMERA CONFIGURATION
# ============================================================================
# Define the camera location relative to the bed's 0,0 coordinate
CAMERA_X = 0.0  # X coordinate of camera mount (in mm)
CAMERA_Y = 0.0  # Y coordinate of camera mount (in mm)

# Define your print bed dimensions (in mm)
BED_WIDTH = 350.0   # X dimension of your print bed
BED_DEPTH = 350.0   # Y dimension of your print bed

# Servo configuration
# Set to either 90 or 180 depending on your servo's movement capability
SERVO_RANGE = 180  # Options: 90 or 180 degrees

# Klipper servo name (must match the name in your printer.cfg)
SERVO_NAME = "camera_servo"

# Servo angle that points camera at bed center
SERVO_CENTER_ANGLE = 90.0  # Manually calibrated center angle

# Invert servo angles (for upside-down mounted servos)
INVERT_SERVO = False  # Set to True if servo is mounted upside down
# ============================================================================

Configuration Steps:

1. Set Camera Position (CAMERA_X, CAMERA_Y)

   • Measure your camera's position relative to your print bed's origin (0,0)
   • Can be negative if camera is mounted off the bed

2. Set Bed Dimensions (BED_WIDTH, BED_DEPTH)

   • Enter your print bed's X and Y dimensions in millimeters
   • This is used to calculate the bed center point

3. Set Servo Range (SERVO_RANGE)

   • Set to 90 for a 90° servo (0-90° range)
   • Set to 180 for a 180° servo (0-180° range)

4. Set Servo Name (SERVO_NAME)

   • Must match the servo name defined in your Klipper printer.cfg
   • Example: If your config has [servo camera_servo], use "camera_servo"

5. Calibrate Servo Center Angle (SERVO_CENTER_ANGLE)

   • This is the servo angle where the camera points at bed center
   • How to calibrate:
     1. Use Klipper console: SET_SERVO SERVO=camera_servo ANGLE=X
     2. Try different angles (start with 90° or 45°)
     3. Find the angle where camera points directly at bed center
     4. Set SERVO_CENTER_ANGLE to this value
   • Common values: 90 for 180° servo, 45 for 90° servo
   • Can be any value if servo is mounted off-center

6. Set Servo Inversion (INVERT_SERVO)

   • Set this to true if for whatever reason your servo is turning the wrong way.
   • When inverted, angles are mirrored over the centerline
   • Example: 60° becomes 120°, 90° stays 90°, 120° becomes 60°

Usage

Running from Slicer (Recommended)

The script is configured to run automatically as a post-processing script in your slicer:

1. In your slicer, go to the post-processing scripts settings
2. Add this script as a post-processing script
3. The slicer will pass the gcode file path automatically
4. The script will modify the file in place

Example slicer configuration:

python /path/to/point_and_print.py

The slicer will automatically append the gcode file path as an argument.

Running Manually (For Testing)

python point_and_print.py <path_to_gcode_file>

Example:

python point_and_print.py /path/to/your/print.gcode

Running in Development Mode

If you want to test the script without command-line arguments, modify the script:

1. Open point_and_print.py
2. Change run_in_slicer = True to run_in_slicer = False
3. Set path_input to your test file path
4. Run the script without arguments: python point_and_print.py

What the Script Does

1. Parses the EXECUTABLE_BLOCK_START section (around line 190)

   • Extracts object names and their center coordinates
   • Example: NAME=object1 CENTER=150.5,200.3

2. Calculates bed center from configured bed dimensions

3. Calculates servo angles for each object

   • Determines the angle from camera to bed center (reference position)
   • Calculates angle from camera to each object
   • Computes the angular difference
   • Converts to servo position (0-90° or 0-180° depending on servo range)
   • Assumes servo midpoint points camera at bed center

4. Finds all EXCLUDE_OBJECT_START lines

   • Identifies which object is being started
   • Example: EXCLUDE_OBJECT_START NAME=object1

5. Inserts Klipper SET_SERVO commands with calculated servo angles

   • Adds a servo positioning command before each object start
   • Uses the configured servo name from SERVO_NAME
   • Example: SET_SERVO SERVO=camera_servo ANGLE=74.50

6. Saves the modified file

   • Overwrites the original gcode file with the modified version
   • Creates a backup is recommended before running

Expected GCode Format

The script expects your gcode to have:

EXECUTABLE_BLOCK_START Section

; EXECUTABLE_BLOCK_START
EXCLUDE_OBJECT_DEFINE NAME=part1 CENTER=100.5,150.2 POLYGON=...
EXCLUDE_OBJECT_DEFINE NAME=part2 CENTER=200.3,180.7 POLYGON=...

EXCLUDE_OBJECT_START Lines

EXCLUDE_OBJECT_START NAME=part1
; ... printing commands for part1 ...
EXCLUDE_OBJECT_END NAME=part1

After Processing

SET_SERVO SERVO=camera_servo ANGLE=90.00
EXCLUDE_OBJECT_START NAME=part1
; ... printing commands for part1 ...
EXCLUDE_OBJECT_END NAME=part1

SET_SERVO SERVO=camera_servo ANGLE=74.54
EXCLUDE_OBJECT_START NAME=part2
; ... printing commands for part2 ...
EXCLUDE_OBJECT_END NAME=part2

Klipper Printer Configuration

Before using this script, you must configure the servo in your Klipper printer.cfg file.

Add Servo Configuration to printer.cfg

Add this section to your printer.cfg:

[servo camera_servo]
pin: PB6  # Change to your actual servo control pin
maximum_servo_angle: 180  # Or 90 if using a 90° servo
minimum_pulse_width: 0.0005
maximum_pulse_width: 0.0025
initial_angle: 90  # Start at midpoint (45 for 90° servo)

Configuration notes:

• pin: Set to the GPIO pin connected to your servo signal wire
• maximum_servo_angle: Must match your SERVO_RANGE setting in the script (90 or 180)
• initial_angle: Set to servo midpoint (90° for 180° servo, 45° for 90° servo)
• name: The [servo camera_servo] name must match SERVO_NAME in the script

Common Pin Assignments

Check your printer's documentation for available GPIO pins:

• Raspberry Pi: gpio17, gpio27, etc.
• SKR boards: PB6, PE5, etc.
• Octopus boards: PB6, PB7, etc.

Testing Your Servo

After adding the configuration, restart Klipper and test the servo manually:

SET_SERVO SERVO=camera_servo ANGLE=90
SET_SERVO SERVO=camera_servo ANGLE=45
SET_SERVO SERVO=camera_servo ANGLE=135

The camera should rotate to point at different parts of the bed.

Servo Angle Calculation

The script calculates servo positions using SERVO_CENTER_ANGLE as the reference point where the camera points at bed center.

How It Works:

1. Calculate angle from camera to bed center (reference)
2. Calculate angle from camera to object (target)
3. Find angular difference: target - reference
4. Add to servo center angle: servo_angle = SERVO_CENTER_ANGLE + difference
5. Clamp to valid servo range (0-90 or 0-180)

Why Manual Calibration?

Different servo mounting positions may result in different center angles:

• Centered mount at 90°: SERVO_CENTER_ANGLE = 90
• Off-center mount: SERVO_CENTER_ANGLE = 75 or any other value
• 90° servo centered: SERVO_CENTER_ANGLE = 45
• 90° servo off-center: SERVO_CENTER_ANGLE = 50 or any other value

By manually calibrating, you get precise control regardless of how your servo is physically mounted.

Example Calculation:

Configuration:

• Camera at (0, 0)
• Bed center at (175, 175)
• SERVO_CENTER_ANGLE = 90

Results:

• Object at (175, 175) [bed center] → servo angle = 90° (no offset from center)
• Object at (85, 85) [lower-left] → servo angle = 90° (nearly at center in this example)
• Object at (250, 85) [right side] → servo angle = 74.54° (15.46° right of center)
• Object at (85, 250) [top side] → servo angle = 108.69° (18.69° left of center)

Requirements

• Python 3.6 or higher
• No external dependencies required (uses only standard library)

Configuration

Inside the script, you can modify the run_in_slicer flag:

• run_in_slicer = True (Default): Script expects a file path as a command-line argument (for use in slicer post-processing)
• run_in_slicer = False: Script uses the hardcoded path_input variable (for manual testing/development)

This mirrors the behavior of other popular gcode post-processing scripts.

Notes

• Always backup your gcode files before processing
• Configure the camera position (CAMERA_X, CAMERA_Y) at the top of the script before first use
• The script will overwrite the original file
• If object names in EXECUTABLE_BLOCK_START don't match those in EXCLUDE_OBJECT_START, a warning will be displayed
• The script preserves all original gcode content, only adding camera commands

Verification

After slicing a file, check that the script ran successfully:

1. Open the generated gcode file in a text editor
2. Search for SET_SERVO
3. You should see lines like:

   SET_SERVO SERVO=camera_servo ANGLE=90.00
   EXCLUDE_OBJECT_START NAME=object_name

Console Output Example:

Program point_and_print.py initiated
Processing file: print.gcode
Read 9316 lines
Camera position: (0.0, 0.0)
Bed size: 350.0x350.0 mm, center: (175.0, 175.0)
Servo range: 180° (center angle 90.0° points to bed center)
Found 3 objects:
  GoPro_Shaft.stl_id_0_copy_0: center=(84.9995, 84.9989), servo angle=90.00°
  GoPro_Shaft.stl_id_1_copy_0: center=(150.001, 84.9989), servo angle=74.54°
  Threaded_Ball.stl_id_2_copy_0: center=(84.9987, 171.874), servo angle=108.69°
Inserted 19 SET_SERVO commands
Successfully saved modified gcode to: print.gcode

Customization

If your gcode format differs from the expected format, you may need to adjust the regular expressions in the parse_executable_block() function to match your specific format.

Troubleshooting

"No objects found in EXECUTABLE_BLOCK_START section"

• MOST COMMON CAUSE: "Exclude objects" is not enabled in your slicer!
  • Go to Print Settings → Output Options → Enable "Exclude objects"
  • Re-slice your model
  • Verify EXCLUDE_OBJECT_DEFINE commands appear in the gcode
• "Label objects" alone is NOT sufficient - you need "Exclude objects"
• Check that your gcode file has an EXECUTABLE_BLOCK_START section
• Verify the format of object definitions matches the expected pattern
• The script may need adjustment for your specific slicer's output format

"Object 'xyz' not found in EXECUTABLE_BLOCK_START section"

• Object names in EXECUTABLE_BLOCK_START and EXCLUDE_OBJECT_START don't match
• Check for typos or formatting differences in object names

Servo moves opposite direction from expected

• Your servo may be mounted upside down
• Set INVERT_SERVO = True in the script configuration
• This will mirror all angles over the centerline (60° ↔ 120°, 90° stays 90°)

Servo doesn't point at objects correctly

• Verify physical alignment: calibrate SERVO_CENTER_ANGLE properly
• Use SET_SERVO commands to find angle where camera points at bed center
• Check CAMERA_X, CAMERA_Y, BED_WIDTH, BED_DEPTH settings
• Ensure SERVO_RANGE matches your servo (90 or 180)
• See SERVO_CALIBRATION_GUIDE.md for detailed calibration steps

Servo name error in Klipper

• SERVO_NAME in script must exactly match servo name in printer.cfg
• Example: [servo my_cam] requires SERVO_NAME = "my_cam"