Developer diaries

Making fixing parts for SG90 series servo motors


Standard robot parts: Servo motors

A robot is composed of various elements.

Robots are systems that sense, plan, and act.

NEDOロボット白書2014 1-11 (in Japanese)

Sensors are responsible for the “sense” part. On the other hand, actuators are responsible for the “act” part.

There are many variations of actuators used for this motion part. However, servo motors are used commonly in robots.

In general, a servo motor is a motor that, when given a control signal, rotates the motor to the angle or position implied by the signal and has a mechanism to hold that angle or position.

江崎徳英・石井モルナ, 二足歩行ロボット 工作&プログラミング, p. 10, 2015 (in Japanese)

Unlike ordinary DC motors, servo motors have a twist: they can adjust their position and speed. Inside the servo motor is a DC motor, which is part of the servo motor. In addition, a variable resistor called a potentiometer is often installed. This detects the angle and adjusts the position.

There are various types of servo motors, but the one I will be using this time is the Tower Pro SG90.

Cheap! Light! Powerful! Servo Motor SG90

There are various types of servo motors, but the one we will use this time is the “Inexpensive! Lightweight! (Surprisingly) powerful!” servo motor SG90.

It is often used in hobby and craft applications because it is inexpensive, lightweight, and yet powerful to a certain degree.

Tower Pro SG90 Servo motor

I will now use a 3D printer to make the parts that hold this servo motor in place.

SG90 and its derivative series

There are several similar derivative series of SG90 with different performance.

SG90 and some of its derivative series

SG92R has higher torque than SG90. On the other hand, SG90-HV is a continuous rotation servo, which does not control the angle like SG90, but keeps rotating. SG90, SG92R, and SG90-HV have the same shape. (Some datasheets have slightly different dimensions, and there are some variations depending on the source of information, but it is safe to assume that they are approximately the same.)

The MG92B seems to have a slightly different shape. It is slightly larger. It is even higher torque than SG92R because of that.

Size comparison between SG90 and MG92B

This servo motor is a product of the brand Tower Pro. Is this the right place for the original homepage? Tower Pro official website

In the online store here, it says something like, “When you buy from other sites, please check because there are many counterfeit products.”

I often use these servo motors when I make robots, so I am planning to make fixed parts for them.


I created it! I also distribute stl files. Click here to read the article.