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Slide in motor 4 and fasten Loading 3D view…
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Take the motor you labelled 4. src servos.yaml · follower/wrist_flex — ID 4 · STS3215 1:345 · Feetech STS3215 servo, 7.4V, 1:345 gear (C001) F-002 · check — Each motor answers on its own ID 1–6, bottom joint = 1, gripper = 6; leader and follower motors are labelled and kept apart. Slide it into the wrist motor holder. src Fix it with 4 small self-tapping screws, Self-tapping screw. A screw that cuts its own thread into the plastic as you drive it. These are the smallest screws in the kit and hold each motor in its printed bracket. No public source confirms the exact size yet (D-001).Source: lerobot/docs/source/so101.mdx#joint-1 · waveshare.com src lerobot/docs/source/so101.mdx#joint-4 — "Slide in motor 4. Fasten motor 4 with 4 M2x6mm screws." check — Motor 4 held by 4 motor-tab screws, two per side, each side one into the forearm and one into holder 4; its cable connects to motor 3. instructions — The four screws are horizontal: on each side one passes through the forearm and one through holder 4, so they also lock the holder to the forearm. Connect motor 4 to motor 3 with its cable. src check — Motor 4 held by 4 motor-tab screws, two per side, each side one into the forearm and one into holder 4; its cable connects to motor 3. Done when Motor 4 is held by 4 screws and its cable goes to motor 3.
lerobot/docs/source/so101.mdx#joint-4 "Slide in motor 4. Fasten motor 4 with 4 M2x6mm screws." waveshare.com Follower step 11 SO-ARM100/STEP/SO101/SO101 Assembly.step placement check (viewer/public/geometry/placements.json): servo 4 sits in Motor_holder_SO101_Wrist (44% enclosed) SO-ARM100/STEP/SO101/SO101 Assembly.step placement check (pipeline hole test): per side one screw through an Under_arm_SO101 hole and one through a Motor_holder_SO101_Wrist hole Notes: The four screws are horizontal: on each side one passes through the forearm and one through holder 4, so they also lock the holder to the forearm.
Check: Motor 4 held by 4 motor-tab screws, two per side, each side one into the forearm and one into holder 4; its cable connects to motor 3.
Motor slot: wrist_flex · ID 4 · STS3215 1:345 ·
7.4V servo on a 5V supply; 12V servo on a 12V 5A+ supply (optional variant);
How we placed it: Part role confirmed by placement in the upstream assembly STEP: servo 4 sits in Motor_holder_SO101_Wrist (44% enclosed).
You need STS3215 motor, 1:345 gear, code C001 Feetech STS3215 servo, 7.4V, 1:345 gear (C001) servo-sts3215-c001-345 approximation3D stand-in Stand-in shape: the 3D geometry or placement is not measured from the real part.
Qty 7 is the two-arm build (6 follower + 1 leader). A 12V variant with 30 kg.cm stall exists for the follower only and needs a 12V 5A+ supply (README). Includes two horns and a 3-pin cable per the assembly texts; kit contents are not itemised upstream. Geometry: the upstream repo's own simplified body `STEP/SO100/STS3215_03a.step` (Apache-2.0, single solid drawn to the datasheet, D-007 for where they differ) with its fused horn plates cut off and the datasheet ø6 x 3.4 output boss added, posed on the embedded vendor model's transform; the vendor mesh is not redistributed.
details Wrist motor holder Motor holder (wrist side) motor-holder-so101-wrist details Small self-tapping screw (motor screw) Motor-tab screw, M2-class self-tapping motor-tab-screw unverifiedno source yet Not checked yet: no public source confirms this. Treat it as a best guess and report what you find.
Sources disagree and no kit has been measured (D-001, open). Upstream default = the assembly STEP, which models 24 positions per arm: 22 x "Type I Cross Recessed Fillister Head Tapping Screw ANSI B18.6.4 1-42 x 0.1875 Type AB" (≈ ø1.9 x 4.8 mm) and, for the two screws that enter motor 1 from above, 2 x "0-48 x 0.1875" (≈ ø1.5 x 4.8 mm). Vendor/doc variants: LeRobot "M2x6mm screws (smallest screws)"; Waveshare "pointed screws". The Feetech datasheet gives no tab screw and ships "No Accessories". Qty = count used across the LeRobot steps (24 + 21 positions); a kit inventory settles the spec and count. Seating per screw is read from the STEP by the pipeline (shank through a hole of which printed part) and drives what the 3D view shows at each step.
×4 details Phillips screwdriver #0 · PH0 tool details Phillips screwdriver #1 · PH1 tool details Cables in the 3D view motor 3 → motor 4 elbow flex → wrist flex cable-elbow-flex-to-wrist-flex approximation3D stand-in Stand-in shape: the 3D geometry or placement is not measured from the real part.
Sources (4) How we placed it Part role confirmed by placement in the upstream assembly STEP: servo 4 sits in Motor_holder_SO101_Wrist (44% enclosed).