/mainboard

OAMS (Open AMS) Configuration Setup Guide

Introduction

This guide provides step-by-step instructions for setting up the configuration for the OpenAMS (OAMS). An OpenAMS is an AMS which electronics have been switched to make its mechanicals compatible with Klipper. OAMS supports Klipper only.

Prerequisites

  • Access to the shell of the Raspberry Pi connected to your 3D printer.
  • Basic understanding of command line usage.
  • Access to the internet for downloading necessary files.
  • Familiarity with 3D printer components and their functionalities.
  • A 3D Printer
  • An extruder / toolhead with a filament bump cutter (such as Filametrix. It is also recommended the extruder is a dual hobbed gear extruder, since loading filament requires the gears to pull on the filament and overcome the spring force of a loaded extruder. It is critical for any extruder that the path from the PTFE tubing all the way down to the extruder gears is smooth and unimpeded. Any blockage, roughness, or constriction between the PTFE and the top of the extruder gears will cause nothing but problems with the OAMS.
  • A CANBus setup is mandatory; however, the ACE FPS board can be used as a canbus bridge (USB -> CANBus) for Klipper to communicate with the ACE mainboard. Hence, there is no additional cost to setting up CANBus for the printer. If CANBus is already installed, the ACE FPS board may be operated directly as a CANBus node (instead of a CANBus bridge)
  • It is mandatory you thoroughly familiarize yourself with Klipper's excellent documentation on CANBUs

Making the AMS compatible with klipper printers

OAMS uses one (or multiple AMSs) and the following custom components:

  • 1x ACE (Automatic Color Exchange) filament pressure sensor (FPS) board per printer
  • 1x ACE (Automatic Color Exchange) mainboard per AMS installed
  • Printed parts (STLs and CAD are provided)
  • 4mm outer diameter / 2mm inner diameter PTFE tubing to reach between the FPS and the toolhead extruder (4mm ID / 3mm PTFE must only be used in the filament path ONLY after the toolhead extruder)
  • Optionally, one might need some of these spring to balance the friction in the PTFE tubes when they are very long (300mm bed printers and longer, specially for printers with flying gantries such as a Voron v2.4)

Principles of operation

It is important one understand the working principle of the AMS and how it operates in order to tune and troubleshoot any possible problems with the system. Here is an excellent introduction.

Prime amongst the components, it is the filament pressure sensor (i.e. filament buffer). The filament pressure sensor (a hall effect sensor) and its spring loaded slide magnet (hereafter referred as FPS) is the most critical of systems to have a properly working OAMS. Without a properly working FPS, the rest of the system will simply not work.

The FPS measures the amount of compression in the filament being fed into the toolhead extruder, and makes part of the feedback mechanism to inform the OAMS about how fast to feed the filament to the extruder, maintaining always pressure within a specified range. The OAMS cannot operate without this feedback mechanism.

The FPS also acts as a limiting switch while loading filament onto the toolhead extruder. Once the filament hits the top of the gears of the toolhead extruder, the pressure on the system increases until the OAMS turns off the follower motor and detects that it is bottomed out. It is important to understand this concept, since if the FPS slide reaches its maximum value before reaching the top of the gears of the toolhead extruder, it will instruct the follower motor in the AMS to stop, and the loading sequence will fail since the extruder will not have the filament available to pull.

Long reverse bowden tubes (collectively referred in this text as bowden tubes) necessarily produce more friction; hence, in order for the FPS to work properly, one must choose the number of springs to use together to get the right amount of pressure in the FPS to balance the friction of the tube. For example, empirically, a Voron v.24 350mm will need two spring to balance the friction from the long PTFE tube. A RatRig 3D Printer V-Core 500mm might need as many as three springs.

Flashing the Boards

There are two boards that will need flashing, the ACE FPS and the ACE mainboard.

Setting up the FPS Board

  1. Without the ACE-FPS board being powered, place a 2.54mm jumper across the boot jumper.
  2. Connect the USB-C cable from the board to the Raspberry Pi.
  3. Verify the board is in DFU mode by issuing the following command in the command line: lsusb.
  4. Clone the Katapult repository and navigate to the directory: 
    sudo apt -y install git
git clone https://github.com/Arksine/katapult
cd katapult
  5. Configure the bootloader for the FPS board: 
    make menuconfig
(Hit Q, then Save)
make clean && make
  6. Install dfu-util and flash the bootloader: 
    sudo apt -y install dfu-util
dfu-util -d 0483:df11 -a 0 -R -D ~/katapult/out/katapult.bin -s0x08000000:mass-erase:force
  7. Remove the BOOT jumper from the physical board and disconnect and reconnect the USB cable.

Setting up the AMS Board

  1. Connect the USB-C cable from the AMS board to the Raspberry Pi.
  2. Repeat steps 3 to 7 mentioned above for the FPS board but using the appropriate filenames and directories.

Configuring Klipper

  1. Stop Klipper service: 
    sudo service klipper stop
sudo service moonraker stop
  2. Clone the Klipper and Moonraker repositories: 
    cd ~/
mv klipper klipper-original
git clone https://github.com/OpenAMSOrg/klipper
mv moonraker moonraker-original
git clone https://github.com/OpenAMSOrg/moonraker
  3. Activate the Klippy virtual environment: 
    source ~/klippy-env/bin/activate
  4. Start Klipper and Moonraker services: 
    sudo service klipper start
sudo service moonraker start

Setting up CANBus

  1. Enable the can0 interface in the Raspberry Pi's network configuration: 
    sudo nano -w /etc/network/interfaces.d/can0
  2. Enter the following configuration: 
    allow-hotplug can0
iface can0 can static
    bitrate 1000000
    up ifconfig $IFACE txqueuelen 1024
  3. Unplug and replug the FPS board.
  4. Check for the presence of the can0 interface: 
    sudo ifconfig

Finding UUIDs for FPS and AMS Boards

  1. Stop Klipper service: 
    sudo service klipper stop
  2. Find the UUID for the FPS board: 
    ~/klippy-env/bin/python ~/klipper/scripts/canbus_query.py can0
  3. Find the UUID for the AMS board by plugging it in and repeating step 2.

Updating Klipper Code (Optional)

If you've already installed the Klipper code, update it with the latest version from the OpenAMS repository:

cd ~/klipper
git pull

Additional Resources

The conversion

Converting an AMS to an OAMS system involves replacing its mainboard (located under the plastic tray inside the AMS enclosure), and and tuning the FPS, provided you already have an extruder with a filament bump cutter. Steps are given below, along with pictures on how to make the conversion.

Limiting Factors

  • Users have reported encountering errors related to maximum extrusion during filament changes. This error message, such as "Move exceeds maximum extrusion (2.745mm^2 vs 1.440mm^2)," may appear due to settings in the slicer or firmware configurations.
  • To address this issue, users have experimented with adjusting the max_extrude_cross_section configuration option. For instance, one user set max_extrude_cross_section: 100 under the [extruder] section. However, it's essential to verify the impact of such changes and understand their implications on print quality and printer performance.
  • Another limitation relates to maximum extrusion distance. Errors may occur when attempting to extrude filament beyond certain thresholds, as indicated by the "max_extrude_only_distance" setting in the printer.cfg file. Adjustments to this setting, such as setting it to 1001 under [extruder], may alleviate the issue. However, users should ensure proper tuning and calibration to prevent extrusion-related errors.

Follow these instructions carefully to ensure the successful setup of the OAMS configuration for your 3D printer. For any further assistance or troubleshooting, refer to the provided resources or reach out to the OpenAMS community.

OAMS (Open AMS) Startup Checks Guide

This guide will walk you through the steps to set up the startup checks for the Open AMS (OAMS) custom 3D printer multi-material system. At this stage you should already have all the code, oams.cfg, and all of the macros in this repository installed. From mainsail or fluidd you should be able to see both the ACE FPS and the Mainboard.

Available OAMS commands

Here's a summary of the OAMS commands and their options:

  1. OAMS_LOAD_SPOOL: Loads a spool of filament.

    • Options:
      • AMS: Index of the AMS (0 to 3).
      • SPOOL: Index of the spool (0 to 3).

  2. OAMS_START_UNLOAD_SPOOL: Initiates the unload sequence for the currently loaded spool.

    • Options: None. This is an internal command and should not be used. For unloading spools, please use the SAFE_UNLOAD_SPOOL macro instead.

  3. OAMS_CONTINUE_UNLOAD_SPOOL: Continues the unload sequence for the currently loaded spool.

    • Options: None. This is an internal command should not be used. For unloading spools, please use the SAFE_UNLOAD_SPOOL macro instead.

  4. OAMS_LOAD_STATS: Queries load statistics.

    • Options: None.

  5. OAMS_CHANGE_CLICKS: Changes the number of clicks for loading filament.

    • Options:
      • SET: Number of clicks (integer, minval=0).

  6. OAMS_LOADED: Resumes loaded state.

    • Options: None.

  7. OAMS_CHANGE_FILAMENT: Initiates a filament change.

    • Options: None.

  8. OAMS_CALIBRATE_CLICKS: Calibrates the number of clicks needed for loading filament.

    • Options:
      • OAMS_NAME: Name of the OAMS (e.g., oams1, oams2, etc.).

  9. OAMS_CALIBRATE_HUB_HES: Calibrates the hub switches.

    • Options:
      • AMS: Index of the AMS (0 to 3).
      • SPOOL: Index of the spool (0 to 3).
      • OAMS_NAME: Name of the OAMS.

  10. OAMS_SPOOL: Retrieves information about a specific spool, such as its type, percentage of filament remaining, and number of clicks. It can also be used to set the PERCENTAGE remaning when switching or loading new filament, the command following parameters:

    • AMS: Specifies the AMS (Advanced Manufacturing System) index.
    • SPOOL: Specifies the spool index.
    • TYPE: Optional parameter to set the type of spool.
    • PERCENTAGE: Optional parameter to set the percentage of filament remaining.
    • CLICKS: Optional parameter to set the number of clicks.

These commands allow for various operations related to filament loading, unloading, calibration, and status querying.

Configuration Setup Steps:

  1. Adjust Schmitt Trigger Ranges:

    • Determine the optimal upper and lower ranges for the Schmitt trigger based on sensor readings.
    • Example values: Trigger_lower = 0.4, Trigger_upper = 0.65.
    • Add the option pressure_sensor_bldc_schmitt_trigger_reverse_lower: 0.4 to control BLDC unloading pressure.

  2. Restart Klipper:

    • After adjusting trigger ranges, restart Klipper to re-read the new values.

  3. Calibrate PTFE Tube Length:

    • Run the calibration routine OAMS_CALIBRATE_CLICKS to determine the number of clicks before filament reaches the toolhead.

  4. Save Configuration:

    • Use the SAVE_CONFIG command to save the PTFE tube length value for motor speed adjustments.

  5. Test Spool Loading:

    • Use OAMS_LOAD_SPOOL and OAMS_UNLOAD_SPOOL macros to test loading and unloading for all spools.

  6. Configure Macro Variables:

    • Adjust variables such as retract_before_cut, extrusion_reload_length, extrusion_unload_length, and hotend_meltzone_compensation in macros based on your setup and preferences.

  7. Test Filament Loading:

    • Use macros T0, T1, T2, and T3 to test filament loading, unloading, and cutting functionalities.

  8. Manually Extrude Filament:

    • Manually extrude filament to ensure it reaches the tip of the hotend for printing readiness.

  9. Adjust Slicer Settings:

    • Ensure slicer settings only issue T0, T1, T2, and T3 commands without any other special operations.
    • Enable the "prime tower" feature in the slicer (e.g., Prusa Slicer or Orca) to facilitate multi-material printing.

Additional Notes:

  • Monitor filament extrusion to ensure it reaches the hotend tip properly.
  • Adjust extrusion and unloading lengths to prevent overloading motors and ensure smooth operation.
  • Test and adjust settings as necessary for optimal performance.

By following these steps, you should be able to configure the OAMS multi-material system successfully for your 3D printer. If you encounter any issues or need further assistance, refer to the provided conversation transcript or seek help from the Open AMS community.