Choose servos by torque, backlash, power draw and duty cycle before you choose by headline speed.
Robot arm servos fail when the arm is designed around price instead of torque. The shoulder and elbow carry the whole load, so those joints need the strongest motors. Wrist and gripper joints can usually be cheaper and lighter.
For a small desktop arm, metal gear hobby servos are fine if the links are short. For better repeatability, move the base and shoulder to steppers or smart servos and leave hobby servos for the gripper.
Largest torque requirement, usually the first upgrade
Handles payload and link weight
Lower torque joint for tool angle
Stable multi-servo PWM from ESP32 or Arduino
Prevents brownouts and jitter
Use stronger servos only on shoulder and elbow.
Use stepper reduction on base and shoulder, hobby servo on gripper.
Treat the generated output as a prototype plan, not a certified product. Body-adjacent, high-voltage, optical-energy and mobility builds need qualified review before real-world use.
Estimate payload plus link weight times distance from the joint, then add a large safety margin.
Weak power, backlash and poor internal control are the common causes.
For feedback and repeatability, yes. For a first low-cost arm, regular servos are enough.
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Start with this prompt prefilled, then let RoboHub generate the live parts list, wiring plan, CAD and firmware.
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