motor frame size guide

The frame size of motors is used for both stepper motors and brushless DC motors. The length of the motor will vary but the frame size simply refers to the diameter of the motor face. Frame sizes are split up into NEMA (National Electronic Manufacturers Association) ratings which are a useful shorthand for motor sizes.

Don’t forget that within these frame sizes it is possible to have various motor lengths (sometimes known as the stack length). Changing the stack length will generally not impact on the speeds that you can get but it will have a major impact on the torque (turning force) that you are able to achieve. See the table below for an overview of frame sizes. Some such as NEMA 17 and NEMA 23 are very commonly used (these have been highlighted in orange). Others are generally available but less common.

Frame Size

Diameter

Typical Torque Range (Stepper)

Typical Speed Range (Stepper)

Typical Torque Range (BLDC)

Typical Speed Range (BLDC)

NEMA 8

20mm

0.01-0.04Nm

0-1000rpm

  

NEMA 11

28mm

0.06-0.12Nm

0-1000rpm.

  

NEMA 14

35mm

0.05-0.5Nm

0-1000rpm

  

NEMA 16

39mm

0.1-0.25Nm

0-1000rpm

  

NEMA 17

43mm

0.2-1Nm

0-1000rpm

  

NEMA 23

57mm

0.5-3Nm

0-1000rpm

  

NEMA 24

60mm

1.2-4.6Nm

0-1000rpm

  

NEMA 34

86mm

3-12Nm

0-1000rpm

  

NEMA 42

110mm

12-20Nm

0-1000rpm

  

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