Koch v1.1 parts list
Dynamixel-based leader and follower arm pair, the first LeRobot reference arm; pricier than SO-101 but uses ROBOTIS servos.
Robot armsintermediate by Jess Moss (after Alexander Koch's low-cost robot)
Exploded view
Tap any part to see where to buy it. Diagram is schematic, not to scale.
Every part you need
| Part | Qty | Spec | Where to buy |
|---|---|---|---|
| Dynamixel XL330-M077-T leader arm servos | 6 | 5V class, low-torque, high-speed XL330; official BOM lists $24/unit at ROBOTIS US Light and easy to backdrive, so the leader moves freely by hand. | ROBOTIS: check price (unverified) Generation Robots: EUR 40.20 RoboSavvy: GBP 22.19 |
| Dynamixel XL430-W250-T follower arm servos (shoulder, elbow) | 2 | 12V class XL430; official BOM lists $50/unit Stronger joints near the base carry the follower's weight. | ROBOTIS: $27.50 Generation Robots: EUR 36.00 RoboSavvy: GBP 27.20 |
| Dynamixel XL330-M288-T follower arm servos (wrist, gripper, base) | 4 | 5V class XL330, higher torque than M077; official BOM lists $24/unit Smaller joints of the follower. | ROBOTIS: check price (unverified) Generation Robots: EUR 40.20 RoboSavvy: GBP 27.20 |
| ROBOTIS FPX330-H101 hinge frame and idler set (4 pcs) servo frames | 2 | 1 set for the leader, 1 for the follower Hinge frames the printed parts bolt to. | ROBOTIS: check price (unverified) 4 pcs Generation Robots: EUR 12.03 4 pcs |
| ROBOTIS HN11-I101 idler set XL430 idlers | 1 | Follower only Idler side support for the two XL430 joints. | ROBOTIS: check price (unverified) set Generation Robots: EUR 8.60 set |
| Waveshare Serial Bus Servo Driver Board servo bus controller | 2 | 1 per arm; same board as Waveshare Bus Servo Adapter (A) USB to TTL half-duplex bridge for the Dynamixel bus. | Waveshare: $4.99 Amazon: check price Akizuki Denshi: JPY 1,280.00 |
| 5V power supply leader power | 1 | 5V barrel supply for the XL330-only leader XL330s run at 5V; 12V will destroy them. | Amazon: check price |
| 12V power supply follower power | 1 | 12V barrel supply for the follower Feeds the XL430s directly and the XL330s through the voltage reducer. | Amazon: check price |
| 12V to 5V DC-DC converter follower voltage reducer | 1 | Buck converter so the follower's XL330s get 5V Lets one 12V supply run both servo types on the follower. | Amazon: check price |
| Jumper wire set 3x40 pcs (M-M, M-F, F-F) wiring | 2 | 1 per arm Bridges the Waveshare header to the Dynamixel cable. | Amazon: check price |
| Table clamp mounting | 2 | 1 per arm (EU list uses a 4-pack instead) Holds each base to the desk. | Amazon: check price |
| 1.5 mm star / cruciform screwdriver 2-pack tools | 2 | 1 per arm in the BOM Fits the small Dynamixel screws. | Amazon: check price |
| USB C-A or C-C 2-pack USB cables | 2 | 1 per arm in the BOM Board to computer. | Amazon: check price |
Quantities follow the official Koch v1.1 docs: https://huggingface.co/docs/lerobot/koch. "Unverified" prices come from search listings or older BOMs that we could not confirm on the seller's product page.
Kits (fewer orders, check what they leave out)
| Kit | Price | Includes | Leaves out | Buy |
|---|---|---|---|---|
| Koch arms (US) PartaBot | check price | Listed in the SO-ARM100 kit list as also selling Koch robots | Store link only; product and price not verified | PartaBot: check price |
3D printed parts
Needed. PLA+, ABS or PETG, 0.4 mm nozzle max, about 30% infill. Print each leader and follower STL once; the leader platform is optional but lets the follower reach the floor. Files: https://github.com/jess-moss/koch-v1-1/tree/main/hardware
Mistakes builders make
- Never power XL330 servos from 12V. One builder burned a set of XL330s by scanning them on the 12V follower supply; use the 5V supply or the reducer.
- The Waveshare header does not take the Dynamixel plug directly; the jumper wires bridge D, V and G to the servo cable.
- BOM says FPX330-H101; the assembly video shows FPX330-S101, which you can also print. Either works.
- Either of the two connectors on a Dynamixel can be used; they are daisy-chain ports.
- Firmware recovery for XL430 through the Waveshare board failed on Mac and Windows for some builders but worked from Linux.
FAQ
How much does it cost to build the Koch v1.1?
About $477 to $560 in parts at current prices, Leader ($199) plus follower ($278) per the official US BOM; high end allows for higher current Dynamixel pricing and tariffs. Excludes printing, computer, cameras, shipping..
Do I need a 3D printer for the Koch v1.1?
Yes. PLA+, ABS or PETG, 0.4 mm nozzle max, about 30% infill. Print each leader and follower STL once; the leader platform is optional but lets the follower reach the floor.
Is there a kit for the Koch v1.1?
Yes: PartaBot. Check what each kit leaves out before ordering.
Buying guides for this build
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Last checked 2026-10-25. Sources: github.com · github.com · github.com · github.com · github.com · github.com · www.generationrobots.com · www.generationrobots.com · www.generationrobots.com · robosavvy.co.uk · robosavvy.co.uk · robosavvy.co.uk · www.generationrobots.com · www.generationrobots.com · www.waveshare.com