my new consew 206RB-5 premier 550 variable speed servo motor-speed control

[dikman]

Don't run yourself down, you did pretty good on your purchase, they're a very good machine to start with and should be more than adequate for your current needs. Fit the smaller motor pulley (hopefully there should be enough adjustment to use the existing belt) and then experiment with the settings on the servo, who knows, it may be fine as it is.

[wydfuqnopn]

well I returned the pulley I bought bevause there wasn't a place to set it to the bore so then tonight I bought this one https://www.walmart.com/ip/Grizzly-G5436-Single-V-Groove-Pulley-6-Pitch-Dia-1-2-Bore/134318402 it has two places for the screws like the one that came with it and it is a little under two times the size. any bigger and I would have to move the bobbin winder around. (musnt do that) hahahahaahah. just gonna run with it. thanks again gentleman

[dikman]

That's the one that myjtp used in the link that R8R posted. Should work fine.

[Gregg From Keystone Sewing]

11 hours ago, dikman said:

And if you want to take it to the next level -

large wheel + speed reducer, gives me 1 stitch every 2.5 secs! Yes, I know, it's a bit extreme, but........

Seriously, a 2" on the motor and a 6 - 8" on the head unit (as in R8R's link) should give you the control you want.

Wow, now that's slower than slow.  I would fall asleep behind the needle with that setup.  Very nice, I'm sure it works great.  Like Dikman said, Consew 206RB series machines are great and one of our most popular machines that we offer.  We've been selling them since they came out in the 70's and never stopped.  

Edited November 6, 2018 by Gregg From Keystone Sewing

[dikman]

It's probably too slow to be practical, but it was done to compensate for the servo as I found the pedal transition from stop to max was too sudden for my liking.

[Gymnast]

I just noticed this topic, and I hope it is in order to revive this thread about slow speed control.

I have noticed some recent youtube videos showing the speed control of servo motors. And I was not impressed by the slow speed control. Then I found these two 7 years old threads here dealing with the same problem and making a simple modification to some of the motors.

https://leatherworker.net/forum/topic/41916-having-problems-with-servo-motor-speed-control/?tab=comments#comment-260742

https://leatherworker.net/forum/topic/41483-servo-motor-mod-diy-easier-speed-control/?tab=comments#comment-258131

Did the servo motors on market improve regarding slow speed control the past 7 years?

[dikman]

I think you'll find that they've changed the design of the motors since that was written and many of them no longer use the optical method of speed control.

[Gymnast]

13 hours ago, dikman said:

I think you'll find that they've changed the design of the motors since that was written and many of them no longer use the optical method of speed control.

Thanks for your reply

It seems like the old findings from 2012 is not referenced any more. The funny thing is about the case in 2012 was, that it was a new man in the busines that started sewing and was unhappy with the disign. Most others would just accept the servo motor and "that you just need to pratice" to get better - its is not the machine that has a problem.

I can confirm one called Yuma 550 watt, with another design shown here:

https://www.youtube.com/watch?v=w7sh972qqmk

It uses a magnet and a hall element magnetic field strength sensor. So the movement of the magnet changes the field at the hall sensor. However it cannot be a perfect system either. The earth magnetic field is about 50 micro Tesla, and it may somewhat disturb with the speed depending of the position in the World and direction of the table. However I do not know its performance regarding low speed.

What I see is, that the lowest possible speed of the machines seems to be quite high (in my opinion). I would not be satisfied unless you could reach below 30 stitches/min. But it seems to me, that the speed jumps up from zero speed to a quite high low level speed. I know something about Electronics and Electric motors, and a well designed servo motor should have no problem in operating with a factor 100 in speed from lowest speed to maximum speed. And you should be able to control that with a good pedal as well. So I cannot figure out why this is not done with servo motors for sewing machines.

This video from 2012 show this good low speed control with a modified servo motor: https://youtu.be/-h5U32SDZ38

I noticed these two recent videos from 2018 with quite high low speed of about 120 stitches/min. It is a Ho Hsing G60 servo motor on Pfaff 1245:

https://www.youtube.com/watch?v=oJVlq_L16ew

This other kind have the low speed limit of about 60 stitches/min with Sewpro 1100 NPFL:

https://www.youtube.com/watch?v=UT2CRg2HiYY

You have many more videos out there, they all seems to have this "to me strange" low speed limit. And many of them do only have a span of about a factor 5 from their controlable lowest speed to their max speed.

Perhaps I should make a new thread here asking about this.

[Gudmundur]

This is a interesting topic to me, because I just bought a servo motor from a polish company. The motor is Texi ac 750 SM with a synchronizer for up or down needle stop. I installed the motor on my old Singer 132K6, so far I understand the motor has a lower limit of 300 rounds pr. minute. And a upper limit of 3000. It took five days to reach my home address, with a weekend counted in. 

Best wishes

GK

[Wizcrafts]

I really detest the brushless servo motors that start at 100 or more rpm. They cause the machine to start and stop with a jerk. The last one I had (and replaced) was on a Techsew 2700 I bought second hand. When I first set it up, the motor caused such a mechanical jolt that the bobbin thread unloaded in the bobbin basket. I replaced it with a Family Sew FS-550s that starts at zero and smoothly increases in speed. That is the only way I go, other than regular clutch motors.

More slow speed torque is achieved by installing a speed reducer. My machine came with an unattached 2:1 reducer which is now installed. I can start sewing at a few rpm and ramp up to about 1800 with the reducer installed. It starts and stops without a jolt.