AR4 (MK5) vs SO-101 (SO-ARM101)
Cost, parts and difficulty side by side.
| AR4 (MK5) | SO-101 (SO-ARM101) | |
|---|---|---|
| Cost | $1,200 to $2,300 | $230 to $330 |
| Difficulty | advanced | beginner |
| Parts | 94 | 8 |
| 3D printing | yes | yes |
| Kits available | 8 | 5 |
| Made by | Annin Robotics (Chris Annin) | TheRobotStudio and Hugging Face |
| Full list | AR4 (MK5) parts list | SO-101 (SO-ARM101) parts list |
AR4 (MK5)
Desktop six axis arm with machined aluminum links, geared closed loop steppers and a Teensy controller, built from kits or self-sourced parts.
SO-101 (SO-ARM101)
Low-cost 3D printed 6-DOF arm pair (leader plus follower) for teleoperation and imitation learning with LeRobot.
The short answer
SO-101 costs less to start: about $230 against $1,200 in parts. SO-101 has the shorter parts list (8 lines against 94). AR4: The AR4 manual gives conflicting motor part numbers (BOM vs DIP switch table). Check the motor list in Mistakes builders make before ordering.
Motors and servos
AR4
- 1 x StepperOnline 17HS15-1684D-EG10-AR4 geared stepper
- 1 x StepperOnline 23HS22-2804D-YGS50-AR4 geared stepper
- 1 x StepperOnline 17HS15-1684D-EG50-AR4 geared stepper
- 1 x StepperOnline 11HS20-0674D-EGS16-AR4 geared stepper
- 1 x StepperOnline linear stepper for J5 (17E19S1684MB4-200RS-AR4 in the current package)
- 1 x StepperOnline 14HS11-1004D-EGS20-AR4 geared stepper
SO-101
- 7 x Feetech STS3215 7.4V, 1/345 gear (C001)
- 2 x Feetech STS3215 7.4V, 1/191 gear (C044)
- 3 x Feetech STS3215 7.4V, 1/147 gear (C046)
- 2 x 5V power supply, 5.5x2.1 mm barrel