Frequently asked questions
Which servo goes at which joint?
Follower: STS3215 1:345 at all six joints. Leader: 1:191 at shoulder pan and elbow flex, 1:345 at shoulder lift, 1:147 at wrist flex, wrist roll and gripper. Servo IDs run 1 to 6 from the base up.
See: /servos/
Which power supply?
5V for the standard 7.4V servos on both arms. 12V (5A or more) only if you bought the optional 12V follower servos. The leader is always 7.4V on 5V.
See: /servos/
Sources (1)
- SO-ARM100/README.md#sourcing-parts — IMPORTANT note on 7.4V vs 12V
Which screws are which?
M3x6 machine screws hold horns and attach printed parts to horns (datasheet-confirmed thread). The small screws that hold each servo in its bracket are M2-class self-tapping; sources disagree on the exact part (see D-001), so check what your kit shipped.
Sources (2)
- lerobot/docs/source/so101.mdx#joint-1
- mantech.co.za (retrieved 2026-09-07) — section 9 drawing
Should I set servo IDs before assembling?
Yes. Every source configures IDs first; Waveshare warns it is troublesome to reach the cable after assembly.
See: /follower/002-follower-set-servo-ids/
Sources (2)
- lerobot/docs/source/so101.mdx#2-set-the-motors-ids-and-baudrates
- waveshare.com (retrieved 2026-09-07)
Where do the cable clips go?
There is no separate clip part. The wire grooves are cut into the SO-101 brackets; the eleven "Wiring_holder" components in the upstream CAD are empty placeholders (D-003).
See: /parts/
Sources (2)
- SO-ARM100/STEP/SO101/SO101 Assembly.step — zero-solid Wiring_holder components
- waveshare.com (retrieved 2026-09-07) — SO-ARM100 Installation Instructions item 3
Why does motor 5 get only one horn?
The wrist-roll motor is fitted with one horn only; LeRobot and Waveshare agree.
See: /follower/051-follower-joint5-horn/
Sources (2)
- lerobot/docs/source/so101.mdx#joint-5
- waveshare.com (retrieved 2026-09-07) — Follower step 15
Where sources disagree
Six recorded discrepancies between the upstream repo, the LeRobot page, the Feetech datasheet and vendor wikis are kept in discrepancies.md.