Development of an active low-cost thread tensioning system for a crochet machine

As part of an earlier project, a crochet machine, “CroMat”, was designed and built, and a patent was filed for it. An essential part of this crochet machine is an active thread tensioning device, which is needed to regulate the thread tension on the machine’s crochet needle. Until now, a special supplier with an integrated thread return system has been used for this purpose.

However, such commercially available supplies are very expensive and are also designed for knitting machines, whereas the newly developed crochet machine has slightly different requirements. In addition to retracting yarn, a thread tension system for the crochet machine must be able to dynamically adjust and regulate thread tension during stitch formation, which requires communication with the machine’s microcontroller. This is complicated by the fact that each type of stitch that can be formed by the crochet machine requires different lengths of yarn.

The current project focuses on developing a thread tensioner tailored specifically to the crochet machine. Key components include a wrap brake, a return spring as a thread storage device, a driven wrap wheel, and a stepper motor controlled by an Arduino via a driver board. The thread tension is measured to control the motor using a load cell with a strain gauge.

The poster shows the newly designed and built thread tensioner and provides an outlook on further improvement possibilities.