Gymnast Report post Posted October 20 In connection with my experiments with making a DC motor drive, I had the opportunity to measure the motor current consumption for a sewing situation. For DC motors, the current is close to proportional to the delivered shaft torque. I'm fine with getting some measurement results with numbers on some situations to get a better understanding. But for normal users I don't think it has any relevance. Maybe the knowledge can be useful if you want to experiment a bit with which motor you want on a sewing machine. The curve below shows the DC motor current over time for just above one stitch. The driver electronics ensures a very constant motor speed. This video shows the current situation used when the power consumption was recorded: https://youtu.be/N-FB2jHYyuw The measured mean torque here is approximately 0.5 Nm, while the maximum torque is approximately 2.3 Nm. This corresponds to a peak pressure on the sewing needle equivalent to 145 N (15 kgF or 33 lb). For these slightly more powerful household sewing machines, I use as a general rule to limit the torque to 3.5 Nm. My guess is that industrial sewing machines for leather can generally withstand a significantly higher torque. At higher speeds of the sewing machine, you will be able to get help to penetrate the material by taking the energy from the inertia of the motor and flywheel, which then briefly reduces speed. At low speeds of the sewing machine, there will typically not be enough rotational energy for it. I guess that for larger leather sewing machines you will also see a correspondingly large variation in the torque that the motor must supply to the sewing machine at low speeds. If you want to know more about the specific setup with this Pfaff 230, there is more information here: Quote Share this post Link to post Share on other sites
