NEMA17 stepper motor selection guide: Mounting dimensions, applications, selection and problem solving

 

You may often encounter the term “NEMA17” when selecting a stepper motor. NEMA17 is not a model number indicating performance; rather, it is a standard that specifies mounting dimensions. There are a wide variety of products within NEMA17 category, and their capabilities vary significantly depending on the specific model. This article provides a systematic explanation of what the NEMA17 standard entails, the key factors to consider during selection, and how to optimize your choice for various use cases.

NEMA17 is a standard specifying physical mounting dimensions with a flange size of approximately 1.7 inches

Much like NEMA23 and other NEMA sizes, NEMA17 refers to standardized dimensions such as flange size and mounting hole positions. These standards are collectively known as NEMA sizes.

NEMA (National Electrical Manufacturers Association) is a U.S. standards organization and stepper motor standards are specifically defined in the publication NEMA ICS 16‑2001. In this context, NEMA17 corresponds to a 1.7-inch (approx. 42 mm) square flange size, ensuring compatibility in mounting dimensions.

NEMA size standards define not only square flange dimensions but also round flange diameter, mounting hole size and position, pilot diameter and depth, and other physical dimensions.

The following table outlines example inch‑based dimensions defined in NEMA ICS 16‑2001, taken from “Table 2 — Shaft number designation” and “Table 4 — Dimensions for mounting flanges for inch dimension motors.”

NEMA standard: “Motion/Position Control Motors, Controls and Feedback Devices” 

Example of an external view drawing of the ASPINA stepper motor STA-42D series. The elements enclosed in the square are specified by the NEMA standard.

Performance is not defined by NEMA17

It is crucial to understand that NEMA sizes dictate only mounting dimensions, and they do not define performance factors such as torque, electrical characteristics, step angle or motor length. Consequently, performance varies significantly among NEMA17 stepper motors depending on their motor length and winding specifications.

To understand how to properly choose a NEMA17 stepper motor, here is a concise overview of stepper motor fundamentals.

Stepper motors differ from other motor types in the following ways.

These fundamental elements are essential to understand when selecting the appropriate NEMA17 stepper motor for your application.

NEMA17 stepper motors are widely used in various applications. The following table shows ASPINA’s NEMA17 stepper motor series and typical applications.

The information in this table is current as of the publication date of this article.

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The most important point is that requirements differ greatly by application. NEMA size alone does not provide sufficient criteria to determine the appropriate motor for a specific project.

ASPINA provides customized stepper motors optimized for specific design requirements, as well as standard (off-the-shelf) stepper motors available in small quantities.

Specifications beyond physical dimensions are critical

To answer the question “Which NEMA17 motor should I choose?”, you must consider not only the NEMA17 physical standard but also performance specifications, such as:

When selecting a stepper motor, users often misunderstand the equation “NEMA size equals performance”, or they fail to sufficiently evaluate torque requirements, drive conditions and surrounding specifications. These issues commonly occur with both standard (off‑the‑shelf) and custom motors, leading to inappropriate motors selection.

Below are typical oversights that frequently occur when choosing a motor based solely on a NEMA size such as NEMA17.

Selecting only by flange dimensions and failing to achieve required torque

Motor selection often begins by choosing a NEMA size that matches the flange pitch on the equipment side. However, NEMA size does not represent output performance, and even within the same NEMA size, the available torque range varies greatly depending on the motor’s axial length. Consequently, if the available axial space is limited, you may be unable to find a NEMA17 stepper motor that meets the required torque. This can force an upgrade to a larger NEMA size, necessitating physical modifications to the mounting structure of the equipment.

Inaccurate torque calculation leading to incorrect choices of motor length or drive method

If the required torque is not accurately calculated, the following mismatches can easily occur:

These issues apply to both standard (off‑the‑shelf) and custom‑designed stepper motors. Since the essence of motor selection lies in matching the required torque with the motor’s specifications, any mismatch becomes very difficult to correct in later stages of development.

Overlooking compatibility with drive conditions

Motor selection requires not only evaluating the motor itself but also ensuring compatibility with the driver. Common issues include:

These issues occur not only when using a standard (off‑the‑shelf) stepper motor but also with custom motors if the drive conditions are incorrectly configured.

Overlooking shaft specifications, mounting requirements and environmental conditions

When the focus is primarily on torque and NEMA size, the following elements may be overlooked until the implementation stage:

Although these elements are not directly related to performance, they can lead to serious problems such as an inability to assemble the motor into the device or premature failure after assembly.

Example of torque ranges (pulse frequency: 1000pps) by step angle, NEMA size, winding type, and axial length for ASPINA stepper motors

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In stepper motor selection, many factors such as torque, drive conditions, and mounting specifications interact in complex ways, and these cannot be evaluated based on NEMA size alone. As a result, it is common to encounter challenges during the evaluation process, such as uncertainty about which model meets specific requirements or concerns that NEMA17 may not provide sufficient performance.

These situations are by no means unusual and can occur with both standard (off‑the‑shelf) and custom stepper motors.

One effective solution is to consult specialists who possess in‑depth knowledge of motor technology and can also evaluate the equipment-side requirements and drive control conditions to determine the optimal solution. ASPINA has a comprehensive support system precisely to help customers overcome these types of selection stage challenges.

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See ASPINA 2 phase hybrid stepper motor lineup

ASPINA supplies not only standalone stepper motors, but also system products that incorporate drive and control systems as well as mechanical design. These are backed by comprehensive support that extends from prototyping to commercial production and after-sales service.

ASPINA can offer solutions that are tailored to suit the functions and performance demanded by a diverse range of industries, applications, and customer products, as well as your particular production arrangements.

ASPINA supports not only customers who already know their requirements or specifications, but also those who are facing problems at early stages of development.

Do you struggle with the following concerns?

Motor selection

Motor and associated component development

Unique requirement

Seeking answers to these problems? Contact ASPINA, we are here to help.

Author: Corporate Strategy Office (ASJ-CS), ASPINA