3. Sewing machine

During sewing, the needle moves up and down. When it moves downward, it pierces the material and pulls the upper thread through it. This thread passes to the underside of the fabric together with the needle, forming the basis of the future stitch.

As the needle begins to rise, the upper thread does not follow it perfectly. As a result, a small loop of thread forms behind the needle, which is crucial to the entire sewing process.

Next, the hook, which rotates beneath the stitch plate, catches this loop of the upper thread and pulls it around the lower thread located on the bobbin. This movement causes the upper thread to wrap around the lower thread.

In the next stage, both threads are tightened, and the point where they interlock is pulled precisely into the center of the material. This is the moment when a classic lockstitch is formed—strong, neat, and durable.

At the same time, as the needle completes its movement, the feed dogs located beneath the fabric rise, move the material forward by a set stitch length, and then lower again so they do not block the next needle penetration.

This entire process happens in a fraction of a second and is repeated hundreds or thousands of times per minute, allowing the sewing machine to create an even, consistent, and highly precise seam.

A post-bed sewing machine differs from a classic flat-bed machine in that its working area is raised in the form of a vertical column. This design allows the material to be freely rotated around the needle, which is essential when sewing three-dimensional shapes such as sneaker uppers.

At the top of the column is the needle, which moves up and down and carries the upper thread through the material. Directly above it operates the presser foot, whose role is to stabilize the leather or fabric during sewing. Post-bed machines often use roller presser feet so they do not restrict movement when working on curved parts.

Inside the lower section of the column are the hook and the bobbin with the lower thread. The hook rotates in sync with the needle movement and catches the loop of the upper thread, wrapping it around the lower thread. This is where the lockstitch is formed and locked inside the material.

Beneath the presser foot, in the upper part of the column, the feed dogs move the material forward by one stitch length. In post-bed machines, their construction allows precise control of the leather even when sewing tight curves and small radii.

At the rear of the machine there is a handwheel, which allows manual control of individual needle penetrations—extremely important when working on precise details. The drive is provided by a motor (most commonly a servo motor), which enables smooth speed control and very slow sewing when handling difficult sections.

The system is completed by the thread tension assembly, thread guides, and feeding mechanisms, all of which ensure that the stitch remains even and consistent, even when sewing thick leather and multiple layers of material.