How to build PingTi Arm
6-DoF desktop robot arm · Beginner
Build PingTi Arm, a larger human-scale take on the SO-100 for LeRobot with two STS3250 shoulder servos and six STS3215s, about $261 in parts per arm.
Mostly printed parts and plug-in servos. Good first build.
Our estimate, part-time
≈$261 per arm excl. PSU and prints (source BOM)
Apache-2.0
What is PingTi Arm?
PingTi Arm is nomorewzx's scaled-up take on the SO-100, closer to human arm proportions but still built on cheap Feetech serial servos. A small bridge package keeps it LeRobot-compatible.
The big change is the shoulder: two high-torque STS3250 servos share that joint to carry the longer links, and six STS3215s handle the rest. The source BOM comes to about $261 per arm, not counting the power supply or printed parts.
Versions and forks
- SO-100 / SO-101
PingTi Arm specifications
- Servos
- 2 × STS3250 (50 kg·cm) + 6 × STS3215 (30 kg·cm), 12 V
- Shoulder
- Dual-servo (IDs 2 and 3)
- Interface
- Feetech USB board
- Model
- URDF provided
- Software
- LeRobot via bridge
Figures as published by the project. See Sources below.
Bill of materials
| Part | Qty | Notes |
|---|---|---|
| Feetech STS3250 | 2 | ≈$74 each |
| Feetech STS3215 (12 V) | 6 | ≈$14 each |
| Feetech USB board | 1 | |
| Table clamps | 1 pair | |
| Dupont wire | — | |
| 12 V PSU and printed parts | — | Not in total |
Where's the full bill of materials?
The full BOM, with exact quantities and vendors, lives in the project's own files. Prices change often, so treat $261 as a ballpark from the project. Start at the project repository.
Tools you'll need
- 3D printer
- Small screwdrivers
Step-by-step build overview
Electronics & wiring overview
One Feetech bus to the USB board, powered at 12 V. Two servos drive the shoulder, so their calibration has to match.
Software
LeRobot through the PingTi bridge package.
Tips from the bench
- ☕ Check the shoulder servo directions before putting load on the joint.
- ☕ Use a beefier supply than an SO-100 needs.
PingTi Arm FAQ
How is it different from the SO-100?
It's larger and has a two-servo STS3250 shoulder.
What does it cost?
About $261 per arm before the PSU and printed parts.
Sources
Written by Bots n' Beans from the project's own documentation. Check the sources for the latest revision before you buy parts.
Related builds
Robot deals
All deals →
Get dealDeal · Everblog
10% off
ShopShop · CircuitMess
DIY robot kits
Robot and gadget kits you build yourself.
ShopShop · GRABO
Cordless vacuum lifter
GRABO Pro Brushless: the original cordless vacuum lifter for pavers, stone, glass and panels.
Like what we do? Buying through these links supports Bots n' Beans. We earn a commission at no extra cost to you. Thank you!