Issue 02 · Physical AI
The body is a reducer
Precision reducers in the humanoid robot supply chain
Harmonic Drive in Tsu and Nabtesco in Hotaka hold about 75% of precision strain-wave and RV. Twenty to forty reducers per humanoid. The ceiling is Mie, not Sand Hill.
30 Aug 2026 · 7 min · 1:01 listen · /industries/precision-reducers.md
Assembler is not the industry. The reducer is. Sit Tsu and Hotaka, then sit the qualification calendar.
Desk view · cite the URL
Listen
Night briefing
Eve · 1:01 · not a keynote
The chain
Feedstock to fleet
09 steps
I · Now
Allocation
II · 2026–28
Qualification
III · 2027–30
Park velocity
IV · After 2030
Second source or no industry
X desk
It broke there first
The map lands on X. The missing column usually sits in a reply. We sit both, then write the view.
Shawn @smsehy
Break
The binding constraint is not the assembly line. It is the actuator supply chain. Each humanoid needs 20 to 30 precision reducers. Nabtesco and Harmonic Drive control 75% globally. At 100,000 units a year you compete with every industrial robot OEM on earth.
27 Aug
Shawn @smsehy
Comment
The $16k unit cost gets the attention. The number that matters more is the actuator and reducer bill of materials inside that $16k. The race to $16k is a race to secure volume from those suppliers.
27 Aug
Shawn @smsehy
Comment
The second hurdle after sourcing is the qualification cycle. Thousands of continuous cycles under thermal load and functional safety before plant safety managers sign off on un-caged deployment.
28 Aug
Milk Road AI @MilkRoadAI
Source · Picks and shovels
The $7.5T physical-AI stack into 2050 is a picks-and-shovels map: Harmonic (HSYDF), Nabtesco (NCTKY), Schaeffler, Nidec, Ambarella, Yaskawa. The names that do not trend until the assembler does.
Aug
Still open on this chain
Inbound. Not yet a sitting.
13 Oct · 10:52 · @droidhuntSource · Open · @wireSankai Mechatronics closed a nine-figure RMB Series B to scale humanoid joint reducers — its parts already power Beijing's Tiangong robots, and a 1M-units/yr plant is under construction. State industrial funds led.
@droidhunt · Thread had no replies. Post of 13 Oct 2026 names the Series B close, state funds, existing Tiangong supply and the plant under construction. No further plant clock in the thread.
Sankai Mechatronics closes a nine-figure RMB Series B and builds a 1 million unit per year plant for humanoid joint reducers that already power Beijing's Tiangong robots.
Sources
Short
Nine by sixteen. One line.
0:13
20 to 40 reducers per body. The ceiling is Tsu and Hotaka.
Notebook
Pack for NotebookLM
Google does not give the desk a generate-overview pipe. Copy the pack, drop it in a notebook, and let their voice sit beside ours.
House
Sit the next issue. Print the chain.
A house underwrites one map — electrification, physical AI, the picks that do not trend until the assembler does.