Gymnast Report post Posted October 17 I bought a Pfaff 230 about a year ago. It is a somewhat heavily built household sewing machine and can be considered a bit like a little sister to the Pfaff 138. Where household machines have typically been sold with motors with a maximum shaft power of 40 W, the Pfaff 230 was sold in Denmark with a larger motor with a shaft power of 80 W, which could make them sew at a maximum speed of approx. 1900 stitches/minute. According to German sources, the machine can withstand speeds of up to 2500 stitches/minute. Today's typical servo motors for industrial sewing machines have an input power of 550 W and a maximum shaft power of around 350 W. Since I don't have room for a fixed table with a regular servo motor, I decided to build a smaller motor drive from scratch as a little DIY project to see what could be achieved. But at the same time cheap components were used. The idea was to achieve a wide speed range, and the result was that the difference between the lowest possible speed and the highest speed became a factor of approx. 600. Lowest speed was 2-3 stitches/minute and highest was 1780 stitches/minute. Most available servo motors that you can buy have a minimum to maximum speed ratio of about 50. Most users here will probably think that the speed ratio of 50 is good enough, but maybe they haven't tried anything else. The reference may be the old clutch motors, which were more difficult to control. Here, for example, a seller who describes the sewing machine's lowest speed as super low: My assessment would be that the lowest speed here is far too high. At the same time I don't like how the machine jump-starts with no warning. This is a video with a demonstration of my DIY motor drive: I have now tried using the machine for a few projects, and I think the low possible speed is an advantage. This means that you get full control of the needle position via the pedal. A good pedal is also necessary to be able to achieve this. At the same time, the sewing machine can also sew quite fast. Quote Share this post Link to post Share on other sites
kgg Report post Posted October 17 4 hours ago, Gymnast said: I bought a Pfaff 230 about a year ago. I viewed your video and would be interested in seeing the motor and pedal setup. kgg Quote Share this post Link to post Share on other sites
Gymnast Report post Posted October 17 9 minutes ago, kgg said: I viewed your video and would be interested in seeing the motor and pedal setup. kgg Hello kgg My YouTube channel got some more videos with this sewing machine. This is a speed test with some remarks using the original motor: https://youtu.be/VLU_s1RGasA This is more about the mechanics regarding the new DIY motor drive: https://youtu.be/Ig69cM_0w7Q The pedal is like you see and attached to an air pressure sensor. Some electronics and an Arduino microcontroller is involved as well, but I have not yet made any "nice" documentation of that yet. To my knowledge, the important thing about the pedal is, that you need to have a large range of pressure applied from minimum speed to maximum speed of the machine. I use a pressure of 4 Newton (0.9 pounds) for minimum speed and 40 Newton (9 pounds) for max speed. So you got a factor 10 in pressure needed that allows for precise and fast control by the foot. The possible length of compression of the pedal have much less importance. When you using air as I do, you will have have a pressure change due to temperature changes (ideal gas law). Therefore a zero point adjustment are needed by some manual setting or by some software (I use software here). Furthermore the software implement some unilinear function, so you can get more accurate low speed control. I use parts of a parabola function. You are welcome to ask for more specific details, and I shall try to provide them. Quote Share this post Link to post Share on other sites
