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Seat motor 1 in the base Loading 3D view…
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Lower motor 1 into the base. src Fix it with 4 small self-tapping 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-1 — "Place the first motor into the base. Fasten the motor with 4 M2x6mm screws (smallest screws). Two from the top and two from the bottom." check — Four motor-tab screws in: two from the top, two from the bottom. Motor 1 cable reaches the base opening. orientation note — Two screws from the top, two from the bottom (LeRobot). Let the motor's cable come out through the opening in the base. src check — Four motor-tab screws in: two from the top, two from the bottom. Motor 1 cable reaches the base opening. Done when 4 screws in, two from above and two from below, and the cable reaches the base opening.
Upstream numbers the follower's steps; this leader step is the same build step (extends F-011).
lerobot/docs/source/so101.mdx#joint-1 "Place the first motor into the base. Fasten the motor with 4 M2x6mm screws (smallest screws). Two from the top and two from the bottom." waveshare.com Follower step 1 SO-ARM100/STEP/SO101/SO101 Assembly.step placement check (pipeline hole test): 2 screws up through the base floor, 2 down from above the servo, all in Base_SO101 holes; the base motor holder has no hole at these positions Orientation: Two screws from the top, two from the bottom (LeRobot).
Notes: Placement check in the upstream assembly STEP: the lower pair enters from under the base floor and the upper pair from above, all four through holes in the base into the servo tabs; none of them touches the base motor holder, which comes next. The STEP draws the upper pair one size smaller (D-001).
Check: Four motor-tab screws in: two from the top, two from the bottom. Motor 1 cable reaches the base opening.
Motor slot: shoulder_pan · ID 1 · STS3215 1:191 ·
7.4V servo on a 5V supply;
You need STS3215 motor, 1:191 gear, code C044 Feetech STS3215 servo, 7.4V, 1:191 gear (C044) servo-sts3215-c044-191 approximation3D stand-in Stand-in shape: the 3D geometry or placement is not measured from the real part.
Geometry: the upstream repo's own simplified body STEP/SO100/STS3215_03a.step (Apache-2.0, D-007) with its fused horn plates cut off and the datasheet ø6 x 3.4 boss added, posed on the embedded vendor model's transform; the vendor mesh is not redistributed.
details Base Base base-so101 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 Sources (3) Upstream numbers the follower's steps; this leader step is the same build step (extends F-011).
lerobot/docs/source/so101.mdx#joint-1 — "Place the first motor into the base. Fasten the motor with 4 M2x6mm screws (smallest screws). Two from the top and two from the bottom." waveshare.com (retrieved 2026-09-07) — Follower step 1 SO-ARM100/STEP/SO101/SO101 Assembly.step — placement check (pipeline hole test): 2 screws up through the base floor, 2 down from above the servo, all in Base_SO101 holes; the base motor holder has no hole at these positions