BigTreeTech SFS V2.0 mounting holder on Creality Ender 3 V3 KE print head

What's new in v2.0

Second revision of the bracket, printed and installed on my own Ender 3 V3 KE. Three real changes over v1:

• Coaxial filament path in both X and Y. The head-side filament offset (head_filament_offset) was tightened from 13.5 mm on v1 down to 13.2 mm on v2 — a 0.3 mm correction in X that brings the head-mount filament reference into alignment with the fixed sensor-internal filament axis (sensor_filament_offset = 12.8 mm, a property of the BTT SFS V2.0 itself that can't be changed from outside). In Y, the whole sensor block moved 1 mm rearward (closer to the print-head face) to complete the alignment. The net effect is that filament exiting the sensor now sits essentially directly above where it enters the extruder — no lateral or forward nudge along the way, and the motion signal from the sensor is correspondingly cleaner. This coaxial alignment is also what makes the simplified v2 filament routing practical (see "Filament path" — no bottom fitting, no PTFE stub, just an open air gap between the sensor output and the extruder inlet).

• Rigid closed-frame body, no ribs. v1 was an L-shaped plate with two stiffening ribs on the ends. v2 is a closed rectangular frame with a window cut through it — the sensor still bolts to the frame with the same M3 holes from the BTT drawing, but the load path around the window is a continuous full-thickness wall instead of a plate + ribs. Stiffer against extruder-pull deflection, cleaner to print, and no thin-rib overhangs to worry about.

• Mounting holes: same pattern, doubled up. All screw hole positions are essentially unchanged from v1 — same 3-hole BTT SFS V2.0 pattern for the sensor (two upper holes at sensor_holes_x = 24.7 mm pitch + one side hole from the official BTT drawing), same 2-hole head_pitch = 33.5 mm for the H6 clip screws into the print head. Only micro-offsets were tweaked to line up with the new coaxial geometry. If you have v1 installed, the same screws fit v2 without any change.

Everything else — wiring, Klipper config, materials, print orientation, slicer profile — is identical to v1. The filament path is also simplified on v2 (bottom fitting + Capricorn stub dropped, see "Filament path" below). If you already have v1 installed and wired, swapping to v2 is a 5-minute mechanical job with the same screws and the same cable.

Designed parametrically in FreeCAD 1.1.1, same spreadsheet-driven approach as v1.

TL;DR

A 2-in-1 bracket that replaces the stock Creality flat-cable clip ("H6") on the Ender 3 V3 KE print head. It still acts as the flat ribbon-cable strain relief (same two H6 screws, same mounting holes), and adds a dedicated mount for the BigTreeTech SFS V2.0 filament motion sensor — now with coaxial filament alignment and a stiffer rigid-frame body. Result: accurate runout AND jam detection without drilling, modifying or adding any new hardware to the print head.

Print info

Geometry (parametric — FreeCAD spreadsheet)

All dimensions live in a single spreadsheet inside the FreeCAD file. Edit any of these, hit recompute, re-export STL. Constraint names below match the sketch exactly.

The sensor_filament_offset (12.8 mm) is a fixed internal property of the BTT SFS V2.0 sensor itself — measured to a different reference face than head_filament_offset, so the two values don't compare directly. What changed between v1 and v2 is only the bracket's own head_filament_offset (13.5 → 13.2 mm), a 0.3 mm tightening that pulls the head-side filament trajectory into alignment with the sensor's internal filament axis. After that correction the filament drops from the sensor's output straight down into the extruder inlet with no lateral load, and the open-air routing described in "Filament path" becomes practical.

What you need

• This printed bracket (1 piece)

• BigTreeTech SFS V2.0 filament motion sensor — BTT product page

• The 2 screws that originally held the stock Creality flat-cable clip ("H6" part) on the print head — you re-use them, no new screws needed

• The 3 mounting screws that come in the BTT SFS V2.0 box — these go into the three sensor holes (2 upper + 1 side) per the BTT manual

• 1× PC4-M6 push-fit fitting on the input (top) side of the sensor for the bowden tube from the drybox (comes with the BTT SFS V2.0). The output (bottom) side of the sensor is left open on v2 — no fitting, no PTFE stub. See "Filament path" below.

• A fine needle or a 0.5 mm flat jeweller's screwdriver for popping ferrules out of the BTT and Creality connector housings (see "Wiring" — no crimping tool needed, the BTT cable ferrules are the same standard size as the Creality housing's pins)

• A permanent marker / masking tape / sticky note for marking the green-block end (+5 V) and the far end (+24 V — KEEP EMPTY) of the Creality 4-pin housing before re-pinning (see "Wiring" — the big green 24 V terminal block on the mainboard is the only physical reference that survives every mirror flip, and getting this wrong is what fried my first sensor)

• Optionally a multimeter — useful for double-checking the BTT pinout if your sensor batch differs from the manual, or if you just want to be sure before plugging in

Installation overview

1. Power down the printer and disconnect the stock filament runout sensor cable from the print head.

2. Unscrew the stock Creality flat-cable clip — it is a small black plastic part marked "H6" with two screw lugs. Keep those 2 screws, you will re-use them. The clip itself becomes obsolete.

3. Mount this 3D-printed bracket to the print head using those same 2 screws into the same threaded holes (into the two lower holes on the bracket, head_pitch = 33.5 mm apart). The flat ribbon cable now routes through the bracket's cable pass-through — it keeps the strain-relief function of the old clip.

4. Mount the BTT SFS V2.0 to the bracket using the screws that came in the BTT box, into the three upper sensor holes (2 top at 24.7 mm pitch + 1 side) per the BTT manual.

5. Install the PC4-M6 fitting (from the BTT box) into the input (top) threaded hole on the sensor only. Leave the output (bottom) hole open — no fitting on v2.

6. Route the filament through the sensor (see filament-path section below). Thanks to the coaxial alignment of v2, filament exits the sensor's open bottom hole and drops straight into the extruder inlet through a short air gap, with no PTFE stub in between.

7. Wire it up by moving 3 of the 4 BTT ferrules into the original Creality 4-pin connector housing (see wiring section below — no crimping needed, but pay attention to the pinout: the pin of the FILA connector nearest the green 24 V screw-terminal block on the mainboard carries +5 V (BTT red wire); the pin farthest from the green block carries +24 V and must stay empty; the BTT runout-signal wire stays unused).

8. Configure Klipper so the printer actually reacts to the new motion sensor (see "Klipper configuration" below). Without this step the sensor is wired correctly but the printer doesn't know it exists — no runout/jam pausing will happen.

Filament path

On v2 the filament path is deliberately simpler than v1:

Why no fitting or PTFE piece on the sensor output?

On v1 I ran a short Capricorn PTFE stub with a PC4-M6 fitting between the sensor output and the extruder — the idea being to guide the filament through the small gap and keep the motion signal clean. In practice, that bottom fitting + stub made manual filament handling awkward: threading a new filament, cutting a fresh tip on load, or feeling for a jam by hand — all needed clear finger access to that spot right above the extruder inlet. The bottom fitting + stub was in the way.

On v2 I dropped both the bottom fitting and the stub. The top PC4-M6 fitting stays — it sits well above the extruder, out of the way of the load zone, and it's needed to anchor the bowden tube from the drybox to the sensor. What was in the way of finger access at the extruder inlet was specifically the bottom fitting + stub — removing them clears that whole zone. From the sensor output down to the extruder there is now just an open air gap. Two things made this practical:

1. v2's coaxial alignment (0.3 mm in X, 1 mm in Y). Filament exits the sensor perfectly on-axis with the extruder inlet directly below — no lateral guidance is needed and the air gap is short enough that the filament simply can't buckle over that distance.

2. Direct finger access to the load zone. Without the bottom fitting or stub, I can now grab / cut / thread the filament by hand right where it enters the extruder, and reach the extruder's load lever without any obstruction.

So on v2 the routing is: generic white 2.5 mm ID PTFE from drybox continuously up to the top PC4-M6 fitting on the sensor → through the sensor → free air → extruder. This is what I run today on my own printer and it works completely reliably — no false jams, no bowden-side load on the sensor, and full finger access at the extruder inlet.

Note: The air gap between the sensor output and the top of the extruder is intentional — it also leaves room to operate the extruder's filament-load lever / clip. On v2 nothing needs to fill that gap.

Wiring — IMPORTANT, READ BEFORE PLUGGING IN

The Ender 3 V3 KE's stock 4-pin filament-sensor connector has 24 V on one end and 5 V on the OTHER end. Putting the BTT sensor's +5 V wire on the wrong end — the 24 V end — will destroy the sensor the instant you power the printer on, AND it will fry the mainboard's filament-sensor input circuit at the same time. The damage is not limited to the sensor: on my own printer this mistake required replacing the entire mainboard, because the runout-input on the board got latched permanently in the "filament present" state and could no longer read any sensor at all. Total cost: one BTT SFS V2.0 + one full Ender 3 V3 KE mainboard. I personally got this wrong on my first attempt. Read the geometry section below before re-pinning anything.

How the BTT SFS V2.0 cable is laid out

The BTT SFS V2.0 ships with two cable connectors on the sensor side, 4 wires in total:

• One small connector carries +5 V plus one of the two signal outputs

• The other small connector carries GND plus the other signal output

On the batch I received, the wire colours are:

The pairing inside the two BTT housings is: red + blue together (power + runout switch), and black + green together (GND + motion). This matches the BTT documentation and the typical Sprite-extruder wiring guide. If your batch has different colours, double-check with a multimeter on the BTT sensor side before re-pinning — colours have been consistent across batches I've seen, but BTT does occasionally rotate suppliers.

The BTT SFS V2.0 has two independent signal outputs — one is a simple end-stop switch (filament present/absent, the blue wire), the other is a motion pulse that fires while filament moves through the sensor (the green wire). You will use only the motion signal on this printer (see "Why MOTION and not RUNOUT" below).

What you see after removing the bottom cover

With the printer powered off, remove the bottom cover of the Ender 3 V3 KE base. You are now looking at the top side of the mainboard (the component side). The features that matter for this job, all clustered close together, are:

• A big green screw-terminal block with two terminals marked + and − — this is the 24 V power input for the board. It's the largest green terminal block in this area and impossible to miss.

• Right above it (in roughly the same row), another smaller screw-terminal block marked BED + / BED − — the heated-bed output. Useful as a secondary visual landmark.

• Just next to the green 24 V block, a small 4-pin vertical header — this is the FILA filament-sensor connector. This is the socket you will plug your re-pinned cable into.

• Surrounding it are the X / Y / Z / extruder motor connectors and a few small headers (LED, etc.) — none of those concern us here.

The FILA pin labels themselves (+5 V, GND, SIG, +24 V) are printed on the bottom side of the PCB as silkscreen — meaning you will not see them with the bottom cover removed, because they are on the opposite face from where you're working. That is fine. Do not flip the board to look for them, and do not rely on any silkscreen photo found online — both are mirrored relative to the side you're plugging into, and that mirror is exactly how filament sensors get fried on this board.

Instead, use the green 24 V terminal block as your one and only reference. It is a chunky physical object that looks the same from every angle and cannot be mirrored away.

FILA pinout — referenced to the green 24 V terminal block

Looking at the top of the board with the green 24 V terminal block visible to the right of the FILA connector (the same view as the photo I have of my own board), the four pins of FILA read — left to right — as follows:

In plain words:

• The pin nearest the green 24 V terminal block carries +5 V — BTT red wire.

• The next pin outward is GND — BTT black wire.

• The next pin is SIGNAL — BTT green wire (motion signal).

• The pin farthest from the green 24 V terminal block carries +24 V. Keep this pin empty. Anything you plug into it sees 24 V the moment power comes on.

In the stock Creality runout-sensor cable, only the three pins closer to the green block are populated (+5 V, GND, SIGNAL). The +24 V pin farthest from the green block stays empty in the stock cable, because the stock sensor doesn't need 24 V — and the BTT SFS V2.0 doesn't either.

⚠ WARNING — how this destroyed my sensor AND mainboard (my own mistake)

What killed my first sensor was not a wrong cable or a wrong connector — it was a mirror flip in my head while re-pinning. I had been looking at an online photo of the bottom-side silkscreen pinout, and when I went to actually plug things in (from the top side, where the FILA connector is), left and right swapped in my head. I knew the 24 V end existed and meant to leave it empty, but I lost track of which end was which after the flip and put the +5 V wire into the slot that was actually 24 V. The instant I powered the printer on, the sensor died.

And it wasn't just the sensor. The 24 V back-feed into the mainboard's +5 V rail killed a component on the board itself — specifically, it latched the stock runout-sensor input into the "filament present" state permanently. The printer continued to run otherwise, but:

• The stock runout sensor became useless — it was stuck reading "filament present" no matter what.

• The same input could no longer be used to read the new BTT SFS V2.0 either — the input circuit was fried, not just the sensor.

• In other words, the only filament-sensor input on the board was destroyed.

The only fix was to replace the entire mainboard, not just the sensor. Total cost of one mirror-flip: one BTT SFS V2.0 + one full Ender 3 V3 KE mainboard. That is why this warning sits this high in the document and why this guide identifies each FILA pin by its distance from the green 24 V terminal block rather than by silkscreen labels, photos, slot numbers, or any "left/right" scheme.

Why this is so easy to do:

• The Creality housing has power pins on both ends — +5 V on the end nearest the green block, +24 V on the end farthest from it. They look identical, no mechanical key.

• The FILA pin labels are printed on the bottom side of the PCB — invisible from the working side. Any photo of them (yours, mine, or someone else's online) is mirrored relative to how you actually plug things in. Trying to use that photo as a reference is the single most common way people fry filament sensors on this board.

• The BTT cable doesn't come pre-labelled with which end is which on the printer side — you have to map it yourself.

• The fix: identify the FILA pin to leave empty by its proximity to the green 24 V screw-terminal block — the empty pin is the one farthest from the green block. The green block is a big physical object on the top side of the board, sitting right next to FILA. It looks the same from any viewing angle, so the reference cannot be mirrored away.

How to avoid the mistake

1. Anchor everything to the green 24 V terminal block. With the bottom cover off, look at the top of the mainboard and locate FILA right next to the green 24 V terminal block. The FILA pin closest to the green block is +5 V — where the BTT red wire goes. The pin farthest from the green block is +24 V — must stay empty. The two pins between them are GND (next to the +5 V pin) and SIGNAL (next to the +24 V pin).

2. Mark the housing the same way. Before re-pinning, hold the empty Creality 4-pin housing in the orientation it will sit when plugged into the FILA socket. With a marker, sticky note, or tape, label one end as "green-block end — +5 V" and the opposite end as "far end — +24 V — KEEP EMPTY". The labelled "green-block end" stays unambiguous no matter how you rotate the connector.

3. Insert one ferrule at a time, starting from the pin you most care about. Put the BTT +5 V ferrule (red wire) into the green-block-end pin first. Verify visually it's in the marked end before moving on. Then GND (black) into the next pin out. Then the motion-signal (green) into the next. The far-end pin stays empty.

4. Ignore any silkscreen photo you might find online. The FILA labels are on the underside of the PCB, so every photo of them is mirrored relative to the side you're plugging into. Don't try to mentally un-mirror it — just trust the green-block anchor.

5. Multimeter cross-check (optional but cheap). Before plugging in, you can probe the FILA housing from the back with a multimeter while the printer is off, then very briefly power the printer with nothing connected to verify the green-block-end pin reads 5 V to GND and the far-end pin reads 24 V to GND. 10 seconds of measurement removes all doubt.

Re-pinning procedure (no crimping needed)

The BTT cable ferrules are the same standard size as the Creality housing's pins. You don't need to crimp anything — just pop the ferrules out of the BTT housings and the Creality housing, then slot the BTT ferrules into the empty Creality 4-pin housing.

1. Identify which BTT wires you need. From the 4 BTT wires you will use 3: red (+5 V), black (GND), green (motion signal). The blue wire (runout signal) stays unused — there is no spare pin for it in the Creality 4-pin housing without occupying the +24 V pin (the one farthest from the green terminal block), which would instantly damage the BTT sensor's signal pin. Just leave the blue ferrule sitting in its original BTT housing — the housing stays unplugged on the printer side, so the wire is safely isolated by the plastic itself. No heat-shrink, no cutting, no fiddling.

2. Pop the needed BTT ferrules out of their housings. Each BTT housing has a small plastic locking tab inside each slot — press it gently with a fine needle or a 0.5 mm flat jeweller's screwdriver while pulling the wire backward. The ferrule slides straight out, fully intact.

3. Pop the ferrules out of the original Creality 3-wire cable. Set the Creality cable and ferrules aside — you only need the empty Creality 4-pin housing.

4. Mark the green-block end and the far end on the empty Creality housing using the green-terminal-block anchor (see "How to avoid the mistake" above).

5. Insert BTT ferrules into the Creality housing, working from the green-block end outward: - Green-block end pin (+5 V) ← BTT red wire - Next pin (GND) ← BTT black wire - Next pin (SIGNAL) ← BTT green wire (motion) - Far-end pin (+24 V) → leave empty - BTT blue wire (runout) → stays in its original BTT housing — that housing simply remains unplugged. The plastic itself isolates the ferrule, no extra work needed.

Each ferrule clicks in audibly. Pull on each wire afterward to confirm it's locked. 6. Plug the assembled connector into the printer's stock filament-sensor socket on the print head. No mainboard or firmware changes needed.

If you have never popped ferrules out of a connector before: search YouTube for "how to remove pins from JST connector" or "depin Dupont connector" — it's a 2-minute skill, no special tools, just a needle and patience.

Why MOTION and not RUNOUT?

The Ender 3 V3 KE's stock filament-sensor input is a single signal pin — you only get to pick one of the two BTT outputs to feed into it. The motion signal is strictly more useful: it triggers the print to pause both on filament runout AND on filament jam (extruder pulling but filament not moving — clogged nozzle, ground-out drive gear, broken filament between sensor and extruder). The runout switch only fires on the first of those. Choosing motion makes the runout output redundant on this printer, which is why we ignore it.

Klipper configuration

Because you wired the motion signal from the BTT SFS V2.0 into the printer's filament-sensor input (see Wiring section), the Klipper module you want is [filament_motion_sensor] — NOT [filament_switch_sensor]. The difference matters: a motion sensor pulses while the filament moves and goes quiet when it stops, while a switch sensor just reports present/absent.

Using the motion signal catches failure modes that a simple switch would miss:

• Jams — filament is present but not advancing (clogged nozzle, ground-out extruder gear)

• Stripped filament — extruder gear chews a hole in the filament, no forward motion

• Filament breakage between the sensor and the extruder

• Plus the obvious end-of-spool runout that a switch sensor would also catch

This is why we ignored the BTT's runout-switch output and only routed the motion signal: the motion signal already covers the runout case (filament stops moving when it runs out) AND covers the jam cases that a switch sensor can't detect at all. One signal, all four failure modes.

Klipper configuration is mandatory — the hardware install alone does nothing. With only the wiring done, the printer has a working sensor but no code reading it. You must add (or replace) a [filament_motion_sensor] block in your printer.cfg, restart Klipper, and verify with QUERY_FILAMENT_SENSOR before the first real print. If the Ender 3 V3 KE stock firmware already configured a [filament_switch_sensor] on the same pin, you must change it to [filament_motion_sensor] — leaving the switch type won't trigger on jams (the whole reason for installing the BTT SFS V2.0).

For the exact working [filament_motion_sensor] block: see the BTT SFS V2.0 manual and the Klipper filament_motion_sensor documentation — both have working example blocks. The pin name will be whatever the stock runout sensor was wired to on your Ender 3 V3 KE mainboard — re-use the same pin name in the new config.

After a night of debugging, my configuration looks like this:

[filament_motion_sensor filament_sensor]
switch_pin: ^PC15
detection_length: 3.0
extruder: extruder
pause_on_runout: true
runout_gcode:
  M117 Filament jam/runout detected
insert_gcode:
  M117 Filament inserted

Material

• PETG is the recommended material. Tested in orange — the print on the model photos is the one currently running on my printer.

• ASA is also fine and gives better temperature tolerance near the heatbreak.

• PLA is not recommended — too brittle for parts that get tightened with screws on a moving toolhead, and softens at chamber temperatures inside an enclosure.

Orientation and supports

• Print flat side down (the side that mates against the print head face).

• No supports needed when oriented this way.

• No raft needed.

OrcaSlicer settings (tested profile)

Profile name: *0.16 PETG sensor_holder 0.4 — the actual profile currently running on my Ender 3 V3 KE with a 0.4 mm nozzle and generic PETG. Unchanged from v1: the bracket is a compact rigid mounting part loaded by screws and toolhead vibration, so the profile is just a beefed-up standard PETG strength profile.

Quality

Walls

Shells

Infill

Speed

Changelog

• v2.0 (this version) — closed-frame body replaces the L-plate + ribs of v1; coaxial filament path achieved by tightening head_filament_offset from 13.5 mm (v1) to 13.2 mm (v2) in X and shifting the sensor block 1 mm rearward in Y. Screw hole patterns unchanged from v1 (3-hole BTT drawing for the sensor, 33.5 mm pitch for the H6 head screws). Filament path simplified: only the top PC4-M6 fitting on the sensor remains (anchoring one continuous generic 2.5 mm ID PTFE tube from the drybox); the v1 Capricorn stub and bottom PC4-M6 fitting are dropped so the filament crosses from sensor to extruder through a short open-air gap — mainly to keep finger access to the extruder inlet for manual load / cut / jam handling. Same H6 clip screws, same wiring, same Klipper config as v1.

• v1.0 — original L-shaped bracket with stiffening ribs. Superseded by v2 and no longer distributed on this listing (v2 uses the same screws, holes, wiring and Klipper config, so there is no reason to prefer v1 for a new build or a reprint).

License. Released under CC BY-NC-SA 4.0 — print, remix and share for non-commercial use, with attribution.

Feedback. If you install this, I'd love to see photos in the "I made one" section — especially of the wiring and any cleaner approaches to the 24 V / 5 V pinout problem.