Slowing down my servo.

[dikman]

I'm with Constab. I've fitted speed reducers (home-made and all different) and/or larger pulleys in lieu of handwheels to all of my machines and it gives me all the control I want. They compensate for the inadequacies of cheap/generic servos.

[Gymnast]

I have tried to look in more servo motor specifications, and I think it is hard to find what the lowest constant speed is. Normally you cannot find it or it is hidden very well. I guess it is because leatherworkers and other users seldom ask for this specification. Sometimes the machine got a ramp up function from start, but it do not help much. Perhaps most servo motors are designed for garment high speed machines, that do not need a bigger variation in speed.

Normally the display shows the speed as Costabulary write. But I should think that 41 should mean 4100 RPM and 16 should mean 1600 RPM. But in general you do not know how these numbers translate to RPM. If the lowest speed is 1600 RPM, it is a very high low speed, and I newer heard of that before. Something could be wrong as reported in this video from 2012:

https://youtu.be/X6CCxv3i4No

This problem was discussed in more threads of this forum back 2012. This is one of them: 

I use my domestic sewing machine for many different jobs, and it have got a DIY speed control with a factor of about 68 between highest and lowest speed. Furthermore the construction of the pedal make a fast and easy control of speed:

https://youtu.be/uTB8DnyYAlA

 

I think it would be no problem for a servo motor manufacturer to make a similar speed control with very limited extra costs, if they got the demand for it.

[toxo]

6 hours ago, Gymnast said:

I have tried to look in more servo motor specifications, and I think it is hard to find what the lowest constant speed is. Normally you cannot find it or it is hidden very well. I guess it is because leatherworkers and other users seldom ask for this specification. Sometimes the machine got a ramp up function from start, but it do not help much. Perhaps most servo motors are designed for garment high speed machines, that do not need a bigger variation in speed.

Normally the display shows the speed as Costabulary write. But I should think that 41 should mean 4100 RPM and 16 should mean 1600 RPM. But in general you do not know how these numbers translate to RPM. If the lowest speed is 1600 RPM, it is a very high low speed, and I newer heard of that before. Something could be wrong as reported in this video from 2012:

https://youtu.be/X6CCxv3i4No

This problem was discussed in more threads of this forum back 2012. This is one of them: 

I use my domestic sewing machine for many different jobs, and it have got a DIY speed control with a factor of about 68 between highest and lowest speed. Furthermore the construction of the pedal make a fast and easy control of speed:

https://youtu.be/uTB8DnyYAlA

 

I think it would be no problem for a servo motor manufacturer to make a similar speed control with very limited extra costs, if they got the demand for it.

Yes, I believe 1600 would be too fast for me but I've brought the speed down some by fitting the 40mm pulley. It's still a little too fast so I'll be taking a trip to the pulley shop soon for a replacement hand wheel. I might go as big as 250mm. I know it's a bit sticky outy with no guard on it but there's only me and the dogs here and the dogs can't reach. Have to cut a longer slot for the longer belt and move the bobbin winder but I think it'll be worth it. I'll still have up to No 41 if I want a bit more speed.

I don't Know if  the Jack motors have the gradient thing in em. I'll check before I do anything drastic.

[dikman]

Personally, I think those numbers that are quoted in the manuals are pretty meaningless, just something they come up with to sound impressive! You have to experiment with the settings and various pulleys to get something that works for you.

[toxo]

I've just ordered a 250mm pully with the corresponding taperlock bush with a 15mm bore. Total cost inc vat =£23+ the new belt. The only variable is the size of the new belt. I'm aware that if I could get the servo to start at 1 instead of 16 I wouldn't need such a big pulley but I can always change the size of the pulley and use the same taperlock bush. Another factor in going for a big pulley is weight. I might even add more weight to make up for the heavy factory handwheel.

[toxo]

Update. Turns out the shaft on my Adler is 14mm not 15mm so will be exchanging the taperlock bush later. Also the center set screw that holds the nylon bush for the synchroniser isn't long enough for the thickness of the bigger pulley but it looks like College Sewing has that covered with a kit. I did bodge it together with a torx bit in the keyway and a leather strip for a belt andthe result looks really good. I'll try to do a video when It's done. 

[toxo]

Another update.

Pulley now secure but belt too small, changing it tomorrow. Made a leather one to test.

https://youtu.be/fCRqWdEqTeM

[dikman]

[Gymnast]

20 hours ago, toxo said:

Another update.

Pulley now secure but belt too small, changing it tomorrow. Made a leather one to test.

https://youtu.be/fCRqWdEqTeM

When I you see max speed in the video, is it with the pedal pressed to max speed? Is the max speed limited by a setting?

It seems to me, that the lowest speed is about 1 stitch per second and max speed is about 3 stitch per second.

[toxo]

1 hour ago, Gymnast said:

When I you see max speed in the video, is it with the pedal pressed to max speed? Is the max speed limited by a setting?

It seems to me, that the lowest speed is about 1 stitch per second and max speed is about 3 stitch per second.

You set the speed on the panel. The pedal then gives you from zero to max . In the video the set speed was the lowest I can get it which was 16. On that setting I can stop at half a stitch. If I set the speed to 41 (the highest it will go) the machine will still go from zero to max but at a faster rate.

Finished the fettling today. Put on the new belt but had to extend the slot in the table. Had to make a new bracket for the needle synchroniser because of the bigger diameter of the pulley but all done now. I know it's gonna be a joy to use now once I attempt to fine tune it. :)