Voron Stealthburner Toolhead — Complete Build and Setup Guide

Toolhead Stealthburner Build Upgrade

The Stealthburner is the latest official Voron toolhead, designed to replace the Afterburner. Released in late 2022 after extensive community beta testing, it improves cooling, reduces weight, simplifies filament loading, and adds support for modern hotends and toolhead PCBs. If you're building a new Voron or upgrading from an Afterburner, this guide walks you through the complete assembly, wiring, and Klipper configuration process. Last updated: May 2025.

The Stealthburner is not a single part — it's a modular system. The extruder (Clockwork 2), the fan duct (standard or LED), the hotend carriage, and the probe mount are all separate subassemblies that bolt together. Understanding how they interact is the key to a clean build.

What is the Stealthburner?

The Stealthburner is Voron Design's third-generation toolhead. Compared to the original Afterburner (2019) and the Mini Afterburner (V0), the Stealthburner offers:

• Improved part cooling: Dual 4010 blower fans in a self-contained duct, delivering directed airflow from both sides of the nozzle. The standard fan duct achieves ~40% more airflow than the Afterburner's single blower.
• Clockwork 2 extruder: Replaces the Clockwork 1. The CW2 uses a single BOM-gear (bonded drive gear) on the motor shaft and a matching idler bearing, eliminating the gear train of the CW1. This reduces complexity and improves extrusion consistency.
• Hotend compatibility: Interchangeable hotend carriages for Dragon (standard), Revo Voron, Rapido UHF/HF, and Phaetus BMS. No more printing adapter brackets.
• Integrated probe mounting: Built-in mounts for Klicky, Voron Tap, and Euclid probe systems, with wiring channels in the body.
• CANBus-ready design: Internal routing channels for toolhead PCB cables (SB2040, EBB36, EBB42) with strain relief points.
• Lower weight: Approximately 280g fully assembled with a Dragon hotend and standard fans, vs ~320g for the Afterburner with equivalent hardware. Lighter means less ringing at high accelerations.

Parts List

Before starting, gather all components. The Stealthburner requires 3D-printed parts (PETG or ABS), hardware, and electronics. You can source the printed parts from your own printer or from China-direct vendors.

Printed Parts

• Stealthburner body (main shell, left and right halves)
• Clockwork 2 extruder body and tension arm
• Fan duct (choose standard, LED, or touchscreen version)
• Hotend carriage (match your hotend type)
• Probe mount (Klicky or Euclid depending on your setup)
• Toolhead PCB mount (if using SB2040 or similar)

Hardware Kit

• M3x8, M3x12, M3x16, M3x20 BHCS screws
• M3x8 FHCS screws (for hotend carriage)
• M3 heat-set inserts (type depends on plastic — brass knurled inserts for PETG, brass threaded for ABS)
• M3 washers and M3n nuts
• 2x 4010 axial fan (hotend cooling) — 24V, 0.1-0.15A
• 2x 4010 blower fan (part cooling) — 24V, 0.15-0.25A
• NEMA14 stepper motor (for CW2 extruder) — LDO 36STH20-1004AHG or equivalent
• BMG gear kit — one drive gear + one idler bearing + shaft + circlip
• Hotend (Dragon Standard, Revo Voron, Rapido, etc.)
• Heater cartridge (standard 24V 50W or 60W ceramic)
• Thermistor (NTC 100K 3950 or PT1000 depending on needs)

Electronics

• Toolhead PCB: SB2040 v1.0 or v1.1 (recommended), EBB36, or EBB42
• Pre-crimped JST-XH and JST-SH wire harnesses or custom-cut wires
• CANBus transceiver if using SB2040 over CAN
• PT100 amplifier board if using PT1000 thermistor

Assembly Sequence

Build in this order — each subassembly connects to the next, and going out of sequence means disassembling work you've already done.

Step 1: Insert Heat-Set Inserts

All printed parts have designated holes for M3 heat-set inserts. Use a soldering iron at 230-260°C (for PETG) or 280-300°C (for ABS). Press each insert straight down, holding pressure for 3-5 seconds after it seats. Do not tilt — a crooked insert will strip during screw installation. Install all inserts before any other assembly step.

Step 2: Clockwork 2 Extruder

The CW2 is a direct-drive extruder with a single drive gear pressed onto the NEMA14 motor shaft and an idler bearing on the tension arm. Filament is pinched between the drive gear and the bearing.

• Press the drive gear onto the motor shaft. The gear must be flush with the end of the D-shaft — use the flat spot on the shaft as a guide. If the gear is too high, filament will ride on the smooth part of the shaft. Too low and it hits the body.
• Insert the motor into the CW2 body. The motor screws secure through the body into the motor face — M3x12 BHCS.
• Install the idler bearing on the tension arm. The bearing screws onto an M3x12 screw with a spacer washer. Do not overtighten — the bearing must spin freely.
• Assemble the tension arm onto the hinge pin. The spring pushes the arm against the filament path. Tension is adjusted by turning the M3 thumb screw on the back of the CW2 body.
• Filament path check: Insert a piece of filament into the CW2 from the top. It should drop straight through the drive gear/idler gap and exit the bottom of the extruder body cleanly. If it catches on a printed edge, sand the inside of the filament path with 400-grit paper.

CW2 gear reduction note: Unlike the CW1 which used a 7:1 planetary gear reduction, the CW2 is direct-drive — the motor shaft is also the drive gear shaft. This means one motor revolution = one gear revolution. The BMG-style gear pair (drive gear + idler bearing) provides the effective gear ratio through the difference in gear diameters, giving approximately 3:1 mechanical advantage. This is more than sufficient for 1.75mm filament extrusion and reduces the total gear train friction significantly.

Step 3: Hotend Carriage and Installation

The hotend carriage is a printed block that mounts the heat sink, heat break, radiator, and nozzle. Different carriages exist for each hotend type.

• Slide the heat sink into the carriage from the top. The heat sink should fit snugly — if it's loose, add a thin shim of Kapton tape. If it's too tight, lightly sand the carriage slot.
• Install the heat break into the heat sink. For a Dragon Standard hotend, the heat break is press-fit. Apply thermal paste (boron nitride or similar) to the heat break threads before insertion.
• Attach the radiator block to the bottom of the heat break. The nozzle threads into the heat break from below.
• Critical dimension — nozzle protrusion: The nozzle tip must extend exactly 1.5mm ± 0.1mm below the bottom face of the hotend carriage. This ensures the nozzle clears the fan duct and aligns correctly with the part cooling airflow. Use a digital caliper to measure. If the protrusion is wrong, adjust by adding or removing the copper washer between the heat break and the heat sink.
• Secure the hotend carriage to the Stealthburner body using M3x8 FHCS screws from the front. The carriage slides into a dovetail slot on the body.

Step 4: Fans and Fan Duct

The Stealthburner uses two separate fan systems: a hotend fan (axial) that cools the heat sink fins, and two part cooling fans (blowers) that direct air at the printed part.

• Hotend fan: Mount the 4010 axial fan on the left side of the Stealthburner body (looking from the front). Airflow direction is into the body, across the heat sink, and out the rear. The fan label (usually an arrow) should point toward the heat sink. Secure with M3x16 screws through the body into the fan.
• Part cooling fans: Mount each 4010 blower fan into the fan duct housings. The blowers sit vertically, with the outlet aligned to the duct channel. Secure with M3x12 screws. The two blower fans are wired in parallel — both positive wires to the part cooling fan output, both negative wires to ground.
• Fan duct selection: Three options exist — standard (no frills), LED (includes 2x WS2812 LEDs for lighting the print area), and touchscreen (larger body with capacitive touch button). The standard duct is lightest at ~8g. The LED duct adds ~3g but is worth it for print monitoring.

Step 5: Probe Mount

The Stealthburner supports multiple probe systems:

• Klicky: A probe mount is printed that slides into the left side of the Stealthburner body. The Klicky probe uses microswitches to detect the bed surface. It's cheap (~$3 in parts) and reliable. The mount includes a dock station that attaches to the bed frame.
• Voron Tap: Tap uses the entire toolhead as a probe — the nozzle itself triggers a microswitch when pressed against the bed. Mount Tap between the Stealthburner body and the X carriage plate. Compatible but requires removing the Klicky mount if switching.
• Euclid: Docks on the gantry and attaches to a mount on the Stealthburner left side. Similar to Klicky but uses a magnetic coupling instead of servo actuation. Heavier but more durable.

Wiring — SB2040 and CANBus

The SB2040 is Voron's recommended toolhead board. It mounts inside the Stealthburner body and connects all toolhead components to a single CANBus or serial cable back to the mainboard. This eliminates the heavy cable bundle that the Afterburner required.

SB2040 Wiring Map

SB2040 Connector Pinout:
- MOT0 (Extruder): 4-pin JST-XH — A+/A-/B+/B- to NEMA14
- H0 (Heater): 2-pin JST-XH — heater cartridge (+/-)
- TH0 (Thermistor): 2-pin JST-XH — NTC 100K thermistor
- FAN0 (Hotend fan): 2-pin JST-SH — 4010 axial fan
- FAN1/FAN2 (Part cooling): 2x 2-pin JST-SH — blower fans (parallel)
- PROBE: 3-pin JST-SH — signal, GND, VCC (for Klicky or Euclid)
- RGB: 3-pin JST-SH — 5V, GND, data (for LED fan duct)

CANBus vs USB vs Serial: The SB2040 connects to the mainboard via a single 4-pin JST-GH cable for CANBus. This carries both power (24V) and data over the CAN protocol. Alternatively, connect via USB-C (direct to the SBC) or UART serial (to the mainboard). CANBus is the cleanest option — one slim cable replaces 8-12 individual wires. The trade-off is that CANBus requires a transceiver on the mainboard side (USB-to-CAN adapter or integrated CAN on the mainboard).

Wiring sequence:

1. Mount the SB2040 on its printed bracket inside the Stealthburner body
2. Screw in the toolhead PCB bracket with M3x8 screws
3. Connect the extruder motor wires to MOT0 — match wire colors to the motor datasheet
4. Connect the heater cartridge to H0 — polarity doesn't matter for resistive heaters
5. Connect the thermistor to TH0 — polarity doesn't matter for NTC thermistors
6. Connect the hotend fan to FAN0, part cooling fans to FAN1 and FAN2
7. Route all wires through the strain relief channels in the Stealthburner body
8. Secure the CANBus cable with the included clip to prevent connector strain

Klipper Configuration for Stealthburner

Once the hardware is assembled, the Klipper config needs to be set up for the Stealthburner-specific components.

Extruder (CW2)

[extruder]
step_pin: SB2040: MOT0_STEP
dir_pin: SB2040: MOT0_DIR
enable_pin: !SB2040: MOT0_EN
rotation_distance: 7.53  # BMG gear set value
microsteps: 16
full_steps_per_rotation: 200  # Standard NEMA17
nozzle_diameter: 0.400
filament_diameter: 1.750
heater_pin: SB2040: H0
sensor_type: Generic 3950
sensor_pin: SB2040: TH0
control: pid
pid_Kp: 21.527
pid_Ki: 1.063
pid_Kd: 108.987
min_temp: 0
max_temp: 300
pressure_advance: 0.040  # Start value, calibrate per filament

Rotation distance for CW2: The standard value for a BMG gear set is rotation_distance: 7.53. This corresponds to the effective circumference of the drive gear. If you're using an aftermarket gear set, calibrate this value by extruding 100mm of filament and measuring actual extrusion — adjust proportionally.

Fan Configuration

[heater_fan hotend_fan]
pin: SB2040: FAN0
heater: extruder
heater_temp: 50.0
max_power: 1.0

[fan_generic part_cooling_fan]
pin: SB2040: FAN1
max_power: 1.0
shutdown_speed: 0.0

Note: If using two separate part cooling fan ports on the SB2040, wire both fans to FAN1 (use a Y-splitter cable). FAN2 can be repurposed for chamber exhaust or an additional hotend fan if needed.

Probe Configuration (Klicky Example)

[probe]
pin: ^SB2040: PROBE
x_offset: 0.0
y_offset: 20.0  # Adjust based on probe mount position
z_offset: 0.0
speed: 10.0
samples: 3
samples_result: median
sample_retract_dist: 5.0

Cooling Performance and Weight Comparison

How does the Stealthburner stack up against other toolheads?

The Stealthburner strikes the best balance for most Voron users. The Dragon Burner is lighter (better for high-speed printing on V2.4) but lacks the integrated probe mounting and CANBus routing that the Stealthburner offers. The Afterburner is bulkier and uses an outdated worm-gear extruder that introduces backlash. For 95% of Voron builds, the Stealthburner with CW2 is the right choice.

Final Checks Before First Print

1. Verify nozzle protrusion is 1.5mm — measure with calipers
2. Manually rotate the extruder gear — should spin freely with no binding
3. Turn on hotend fan via Klipper — verify airflow direction (toward heat sink)
4. Test part cooling fans — both blowers should spin freely with no scraping
5. Heat the hotend to 200°C and extrude 50mm of filament — verify consistent extrusion
6. Run PID_CALIBRATE HEATER=extruder TARGET=240 — the Stealthburner's airflow changes thermal behavior, and the default PID values may need tuning
7. Print a first-layer test to verify Z offset with the new toolhead weight distribution

Building the Stealthburner is a satisfying upgrade that improves both print quality and reliability. Take your time on the CW2 gear installation and nozzle protrusion measurement — those two details cause the most post-build issues. Once dialed in, the Stealthburner will run for thousands of hours with minimal maintenance.