The Spectrum of "Computerized" Sewing Machines

Focus on STEPPER MOTORS and how they are used on your sewing machine.

The vast majority of sewing machines being manufactured today are “computerized” machines, opposed to mechanical machines.

Now, the word “computerized” or “electronic” carries a very negative connatation for some sewists, and I understand why that might be. If you aren’t a computer person, it is fair to assume that you wouldn’t be a “computerized” sewing machine person either.

With that said, today I want draw a dividing line of sorts and introduce the idea of computerized sewing machine spectrum. For example, both the Baby Lock Jubilant and the Bernina 990 fall under the same “computerized sewing machine” umbrella, but they are one opposite sides of the spectrum. The latter truly blurs the line between sewing machine and computer, while the former is more comparable to a microwave or a digital clock.

With a top-of-the-line sewing & embroidery combination machine, you are getting product infused with state of the art technology: an iPad-type screen, pinpoint laser seam guides, wifi capability, compatibilty with with smartphone applications, search function (like Google), projectors, laser seam guides, and other modern features. Certain machines are even equipped with a built-in camera that can scan the fabric to the screen so that it underlays with the stich design, allowing to sewist to see exactly how the design will look prior to the stitch-out. Now that is a capital “C” Comuterized sewing machine. But the type of person who buys a machine of this sort is not the type of person who is concerned about computerized machines.

When it comes to buying a normal sewing machine — let’s say, a sewing machine for less than $3,000 — the electronics aren’t all that exotic. There is a digital screen similar to a microwave or clock. There is a motherboard. However, the majority of “computerization” that causes some folks concern resides mostly in the integration of stepper motors into the sewing machine design. I believe that if sewists better understood what stepper motors are and how they are used in your sewing machine, then perhaps we can quell fears concerning machine computerization.

So. . . . what is a stepper motor?

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A stepper motor is a type of electric motor designed to move in seperate steps rather than moving continuously like traditional motors do. With each electrical pulse it receives, the motor rotates a specific angle—called a "step. Because of this step-by-step movement, stepper motors are widely used in applications that require precise control of position, speed, and torque, making them incredibly useful in the design of sewing machines.

Circled in Red: Stepper Motor on a Janome Skyline Sewing Sachine

Here are some of the functions that stepper motors perform on a sewing machine:

Control of Stitch Patterns
Stepper motors control the needle's position and movement to create intricate stitch patterns. By rotating in precise steps, they move the needle in different directions (left, right, up, and down), allowing the machine to switch between stitch types like zigzag, decorative, or straight stitches.

Needle Positioning
A stepper motor can accurately control the needle's stopping position, ensuring it stops at the top or bottom of the fabric when the machine halts. This feature is useful for tasks like pivoting corners while sewing.

Feed Dog Movement
Feed dogs are the small metal teeth under the fabric that pull the fabric through the machine. A stepper motor can control their movement to adjust the fabric's feed rate. This allows for more precise stitching, especially when switching between different fabric types or stitch lengths.

Automatic Thread Tension Adjustment
In some sewing machines, stepper motors adjust the thread tension automatically based on the fabric and stitch type. This ensures consistent stitches without the user needing to manually adjust tension settings.

Embroidery
In sewing machines with embroidery capabilities, stepper motors control the movement of the embroidery arm. This allows for precise positioning of the needle and fabric, enabling the machine to sew complex embroidery patterns.

Why do sewing machine engineers use stepper motors in place of mechanical parts?

One, it allows the engineers to equp sewing machines with the aforementioned functions, some of which are not possible with purely mechanical machines: needle up/down, automatic thread trimming, hundreds of stitch patterns, machine embroidery, etc.

Two, it’s more efficient and arguably more reliable that tradional mechanical parts. Stepper motors operate using electromagnetic coils instead of traditional motor brushes, which increases their longevity. The absence of mechanical wear-prone parts makes stepper motors durable and reduces the need for maintenance. Also, since stepper motors don’t rely on friction-based components like brushes, they tend to last a long time when operated within their rated parameters. Minimal wear on internal parts results in low maintenance costs and efforts over the motor's life.

Think about it like this:
Let’s say a sewing machine has 20 different stitch patterns. Each pattern requires the needle to move left to right at varying widths. In conjunction with the needle movement, the feed dogs will feed the fabric forward and backward at varying lengths. On a mechanical machine, there are 20 differently shaped cams within the machine that correspond with the 20 stitch patterns. In addition, there is an entire stitch-selection assembly that is composed of different mechanical parts (think of selecting stitches with a knob). There is an assembly that connects the cams to the needle bar to achieve the needle left-to-right movement. There is an assembly that connects the feed dogs to the stitch selection assembly so that the feed dog movement properly correspeonds with the stitch pattern we’ve selected. Meanwhile, on a comuterized machine, a stepper motor controls the needle bar movement and a stepper motor controls the feed dog movement. We are now depending on a few stepper motors to perform the function of many different mechanical parts. In a certain sense, fewer individual parts means there are fewer things that can go wrong.

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Thank you for reading.

Stepper motors play a massive role in the function of modern sewing machines, and I think it’s helpful to draw a line between computerized machines that use stepper motors to perform useful everyday functions, versus computerized machines that truly blur the line between sewing machine and computer.

-Cale

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