Stealthburner BTT SB2209 CAN Bus Toolhead System/Filament Cutter

Revisions

2024-03-26 Revised Main Body to incorporate Straightened Latch.  Replaced corresponding Motor Plate as well.

Overview

This group of objects implements a CAN based Toolhead for the Voron 2.4r2 3D Printer.  The design uses a slightly modified version of Voron Clockworks 2 extruder in which a BTT SB2209 Toolhead PCB is mounted in place of the Hartk 2-piece PCB.  Stealthburner parts not modified by the changes in this compilation are not included.  See https://github.com/VoronDesign/Voron-Stealthburner  and https://github.com/sorted01/Filametrix for the remainder of the parts.

The design includes the necessary parts to mount a CAN Bus umbilical cable between the Toolhead and The Z axis Cable Chain.  This eliminates the X & Y Cable Chains and relocates the X & Y end stops.

The Z Cable Chain is reoriented from the vertical to horizontal below the gantry.  This is necessary to eliminate interference between the Z axis Cable Chain and the CAN Bus umbilical.

The Aft Right Z axis belt closeout was modified to allow the CAN Bus umbilical to be routed at the right aft corner rather than the center.  This is necessary to accommodate the Z axis Cable Chain reorientation.

Phaetus Dragon Hot End was chosen for this design.  The appropriate Hot End enclosures were included.

Voron TAP is assumed and includes a mount for the X Axis end stop.  Either the ABS printed TAP or the Chaotic Libs Metal CNC version may be used.

Finally, filament cutter Filametrix was incorporated into the Stealthburner to improve filament change reliability.

Other Design Considerations

SB2209 Toolhead PCB connection to the RPi 4B running Klipper is through a BTT U2C USB to CAN adapter.  Although it is possible to configure the BTT Octopus 1.1 to output CAN signals, in practice the U2C adapter was found to be more reliable at communication speeds of 1MHz.  

Design Details

• The CW2 extruder is a modified version of the Filametrix ERCF modification.  The CW2 main_body included with ERCF v2 has mounting screws for the Toolhead Sensor that were very difficult to install.  The version included here has the mounting screws accessible from outside the part, otherwise the part is unmodified. The version included contains ECAS PTFE connector, Extruder Entry Sensor and the Toolhead Sensor (below Extruder Gears). The ECAS connector is necessary for ERCF or other filament auto loaders in order to provide positive PTFE Bowden Tube retention,
• The Y endstop was relocated to the aft right gantry above the A stepper motor,
• The X endstop was moved to the X axis belt attach part (TAP) and connected to the SB2209 Toolhead PCB,
• The X axis Cable Chain attach bracket was replaced with one from the EBB SB2240_2209 CAN “Custom Printed Parts” Github subdirectory.  This bracket provides strain relief for the CAN Bus and USB cables,
• Rear CAN Bus Cable attach point was added to the A motor area near the Y axis endstop.  The cable was routed to the reoriented Z axis Cable Chain and routed through the new Z axis belt cover on the right side of the printer to the U2C USB to CAN adapter,
• Finally, the U2C adapter was connected to a freed USB port on the RPi.
• Fusion 360 models are included for reference and remixing.

Configuration

Klipper was reconfigured per instruction supplied with the BTT SB2209 Toolhead PCB.  A copy has been attached for convenience although it is highly suggested that the latest version be downloaded from BTT's Github site.

Wiring Details:

The following lists the Port assignment used for this particular configuration.

Pin   Function

PA2 SB2209 Board Temp

PA3 3950 Analog Chamber Temp

PA4 MAX31865 Hot End Thermistor 

PB5 Extruder Entry Endstop

PB6 X Axis Endstop

PB7 Toolhead Endstop

~!PB9 Probe Endstop (CNC TAP)**

PB13 Hot End Heater

** The input requires a Pull Up (~) resister and inverted signal (!) so that a broken wire will not cause the nozzle to impact the bed but rather cause Z axis Homing to halt the toolhead vertical movement

BOM

See Description for modifications.