NEMA 17 stepper (17HS4401)
The cheapest repeatable motion you can buy. 1.8° per full step, 200 steps per revolution, no feedback — it either works or it silently skips and ruins the part.
The role it plays
An actuator turns electrical power into motion. The useful unit is never the motor alone — it is motor + reduction + encoder + driver loop, and most of the engineering is in the last three. The number that decides a design is continuous torque at the joint, not the peak figure on the datasheet. Peaks last milliseconds; gravity lasts all day.
Typical use: 3D printers, small CNC, belt-driven axes, lab automation.
What the numbers actually mean
The headline figure is 0.4 N·m (holding torque), with 1.8° (200 steps/rev) as the next most load-bearing number (step angle). At $12 in the actuators tier it sits cheap enough to prototype with and replace without regret, which is the correct way to learn a new subsystem.
How it compares
Same subsystem, closest alternatives. The primary spec column is usually the one that decides it.
| Part | Price | Primary spec | Second spec |
|---|---|---|---|
| NEMA 17 stepper (17HS4401)Open-loop stepper | $12 | 0.4 N·m | 1.8° (200 steps/rev) |
| Feetech STS3215Serial-bus servo | $17 | 30 kg·cm (2.94 N·m) @ 7.4 V | ~0.222 s / 60° |
| Feetech SCS0009Micro serial servo | $8 | 9 kg·cm (0.88 N·m) @ 6 V | ~0.1 s / 60° |
| Dynamixel XL430-W250-TSmart servo | $50 | 1.5 N·m @ 12 V | 59 rpm @ 12 V |
| Dynamixel XM430-W350-TSmart servo | $260 | 4.1 N·m @ 12 V | 46 rpm @ 12 V |
Where it shows up
It is a component-level choice rather than a defining part of a named platform — pick it for the subsystem it serves, not to match a reference build.