Servo Does Not Vary From Top Speed.

[FoxyD]

I have just replaced a clutch motor on Brother B755-mkIII with a servo. The make has been over-labelled but model is WR561-1 and has awful instructions translated from Chinese. If I set the top speed to 1000 RPM or more, then the speed will vary with the treadle depression but with a lower top speed the treadle acts like an on/off switch, delivering the chosen top speed with no variation with treadle travel. The accelerator control is a magnetic wiper moving near to a 3-lead electronic sensor. Can anyone suggest how I can get variance at lower speeds?

[Colt W Knight]

I could be wrong -

Do you think this problem is because your motor doesn't have enough torque to turn the pulleys at the lower speeds when you are feathering the pedal? A lot of machines need different sized pulleys to run at slower speed with adequate torque to sew.

You can try pressing he pedal and helping the pulley get started to check.

Edited April 3, 2015 by Colt W Knight

[FoxyD]

Thanks for your reply. I don't think it could be torque because there was no leather under the needle when it does this.

[biglew]

look at this... maybe it will help. It made my motor run a bit of smoother curve

[FoxyD]

Thanks so much for that. Unfortunately the servo in that video runs on an optical sensor. My servo is magnetic so the adjustments suggested in that video cannot be applied...

[Gengle100]

Foxy D I just acquired the same servo motor, but I did not come with instructions. Any way you could send those my way?

[TomG]

There is a servo motro out there - I think it's a Consew 500 - That uses a Hall Effect transistor. These are actually a semiconductor that energizes with a magnet. So, it's either on or off. You can't do variable speed with those via the foot pedal.

The ones with the optical controller, like the one on the video, are able to be variable speed. I Think the COnsew motor I got to replace the hall effect one is a 550 or 1000? I'd have to look.

I will tell you that the paper vane didn't work super well. It was fine at first, but as it sagged over a short period of time, it's range and control points changed. One of the isses is that the light on the optical interruptor is way too bright. It makes the control of how much light hits sensor very touchy. And it is so bright that a piece of paper with pencil marks doesn;t work. I used a piece of plastic gift card I cut into a ramp and played with that with some success.

I ordered a couple of replacement vanes and did some cutting and filing, but although I did get a variable speed, it was still too touchy for my tastes. But it at least made it consistent and I didn;t have to worry about the paper sagging.

Still better than the clutch motor.

[Constabulary]

My preference is the 750 Watt JACK Servo that College Sewing in the UK sells but I use it in combination with a 3:1 speed reducer. The lowest motor speed is 200 rpm but the SR slows it down very well. For my purposes they work very well. AFAIK they are also magnet controlled.

I have 2 of them and I´m quite pleased. But I admit - the instructions manuals are a pain!!!

[FoxyD]

Foxy D I just acquired the same servo motor, but I did not come with instructions. Any way you could send those my way?

Soon as I find it amongst my junk I will post it up for you.

[Trox]

Hi, I once had the same problem with my 600 W (220v single) Cobra servo motor. Then they sent us an fix, a small black tape piece in an envelope. I put the tape bit in place and the servo worked just fine. Very good low speed control, but I lost some of the top speed. That must have been a couple of years ago now, but it still work fine; no changes yet. The Cobra motor looks very similar to the motor in the video (different color only). I remember it was very sensitive to the color shades on the paper modification I tried before the fix arived. With lighter color, more top speed and less low speed control. So the best fix for the optical sensor is something dark that reflect less light.

I just wanted to mention that the fix worked fine for me. However it will not help for the motor in question here, with the magnetic speed control. Perhaps posting some pictures will help, there might be similar motors out there of other brands that work fine (or worse). That's likely since it's a Chinese product. It will also help others to know what to stay away from in the future. We should have a topic about different motors, where we could compare them to each other. That would be very helpful for the future. Thanks

Tor

[Trox]

My preference is the 750 Watt JACK Servo that College Sewing in the UK sells but I use it in combination with a 3:1 speed reducer. The lowest motor speed is 200 rpm but the SR slows it down very well. For my purposes they work very well. AFAIK they are also magnet controlled.

I have 2 of them and I´m quite pleased. But I admit - the instructions manuals are a pain!!!

Hi Constabulary, Thanks for your review of the Jack servo. But do not forget to mention what machine type you use it on. 750 Watt together with a speed reducer will normally create enough torque for an heavy stitcher. But Watt is not the same as torque (Nm), but an top speed measurment, effect. In my case the Cobra motor is used on a Pfaff 345 (medium tripple feed machine) and in action to a 3:1 reducer too. Then it's actually to strong for the machine, because it has no safety clutch and can knock it out of timing when a accident happen.

It do not matter if the Jack servo don't have lower max top-speed setting than 200 rpm, if the low speed control on the pedal is good. It should be more than enough motor for an medium machine of the upholstery class with out the use of an speed reducer, is it? It comes both with and without needle position, does it not.

Tor

[Constabulary]

I have the JACK JK363A-1 with needle positioner with 40mm custom pulley (original wa 75mm). This one runs on a 111G156 triple feed upholstery type machine with safety clutch and the 3:1 SR as mentioned above. I have disconnected the synchronizer for the NPS because it seems not to work in combination of with speed reducer. I don´t care because I have enough slow speed control. I figured I just don`t need the NPS - dead topic for me.

Manual says it has 2.5 N.m torque. But the manual over all is a pain in T.A..

I once have written a review:

http://leatherworker.net/forum/index.php?showtopic=56445&hl=%20jack%20%20servo&page=1

The other JACK servo I have is the 750 Watt JK361A w/o NPS with 75mm standard pulley (I had the 550 Watts motor with 40mm custom pulley earlier but have updated the entire motor and speed reducer setup recently - I will add a 40mm pulley again one day.) This one runs on Singer 133K3 heavy sewing machine and also has a 3:1 speed reducer.

All I can say that the 750Watts Jack Motor in combination with a 3-1 reducer meets my requirements and I can work with this setup. I never did any math regarding torque or so. Usually the seller of servo motors don´t even provide this information. The only dealer I know who provides these informations is Universal Sewing for their ENDURO SERVOS. The the orientation for the end consumer is the number of Watt.

Edited July 24, 2015 by Constabulary

[Captayne]

WR561-1 Controller on heavy machines

I have purchased a  chinese brand HMC WR561-1 controller for my old Claess/Pfaff/Textima 8346 (which is still continued by CL-Maschinenbau), in Germany.
It is a Shoe-maker, Leather-patcher or universal strong and durable machine, which I bought last year and it came with a work destroying clutch motor! I wonder how anybody can use this @all. No chance to have a slow harmonic sewing with it. So I did all by truning the handle myself.
But now the time had come to exchange the ancient clutch motor with a servo motor! Searching the web I found sewtex.de and they had some models.
The HMC WR561-1 was advertised as:  For extra heavy machines, 0- set max RMP by foot pedal, needle upper or lower stopping!  For 180€.
That's exactly it! I thought, and bought it.

After some Installation work on my machine, it turned out that most relevant features do not work!
Frankly speaking for me the complete offer appeared to me to be a kind of a lie.
See Photo of the complete thrown together setup after my first try.

1. The speed was in no manner adjustable by foot pedal, only from the controller setting -by pressing buttons repetively. What I absolutely did not want, facing away and taking hands away from the workpiece. When pushing the lever/pressing the pedal, the Machine made a jumpstart to the set speed.  This was exactly not what I wanted. No way!

2. The needle positioning did not work either. 30-50% of the cases the Controller threw Error E-06 Needle positioning error after releasing the pedal. Restarting the controller took tooo many seconds.

The support from Sewtex was somehow fobbing me off with citiations from the awfull manual.

But never the less:

I was able to figure out a fantastic solution.
To make the story short, here is the result first, and later how I did it:

1. The Machine now has variable speed using the foot pedal. Somehow the controller seems to support only steppings in speeds up to the set speed. And it does not start from 0 rpm, but something around 200.... maybe more. Still not as promised but it is OK!

2. The needle now can stop  in upper AND lower position, depending on the position, where the pedal is released. If there is enough way to stop at the next needle up postion, then the needle will stop in the up-postition, same for lower postion! This is awesome! Even more awesome is the new usecase: with hits to the pedal, you can move the needle stepwise to up, down, up, down .... positions and work through critical areas of a seam. You can draw letters with a seem now, using motor drive!  Or work through other complicated (pre-drawn) paths on a piece and have boths hands free for your piece.
And when pressing the pedal, the machine runs with respect to the pedals positions speed  (with steps in speeds) and the max settings within the controller! This is really great with such a big machine!

Now the explanation:
1 st, why the controller seemed to have no variable speed:
The sensor for this is a Hall-Sensor, which is able to detect a magnetic field. Inside the Pedals sensor box, a magnet is attachted to a small lever, which moves the magnet over the hall sensor. This sensor seems to be rather sensible, and runs through its entire ananlog sensing range in only some angular degrees! So if you turn the lever by hand, and very carefully, you can see the motors speed beeing adjusted. For me it was not possible to reproduce this with my foot, when the lever is connected to the pedal.
Now I pulled the internal lever with the magnet attached/integrated some Millimeters out on its shaft. So that the plane of motion is now 2-3 mm away from its former plane. This flatens the ramp of the magnetic gradient and the sensors output ramp now covers a much wider area of motion of the input lever.
This helped!  See Photo, where my final position of the internal magnet holing lever is visible.

I found out, that the variable speed is only available, if the max speed is set so something above 900 rpm. Below this it still behaves digital. ON or OFF. For my Claess 8346 I have a setting of 2000, so it is nice.

Background information: My machine has installed an intermediate timing-Belt gear, which might have a reducing ratio of 3. So when the Servo turns three times, the Handle turns one time. This makes more than sense to keep.  Becasue it reduces the minimum speed and increases the torque on the handle. I like both!
But:
This caused E-06 Position-Sensor Error. Because. After releasing the pedal, the controller reduces speed and then waits ~ maximum one turn plus some extra way for the needle sensor. If the needle sensor does not detect the needle position, then the controller fires the error and quits working. Depending on the phase, when the pedal was released, in my case the motor had to turn possibly almost 3 more spins, to reach the needle up position! Too much to think everything is ok, from the perspective of the programmers of the firmware. What a pitty.

So the controller firmware software is just too inpatient, to wait for the needle trigger, in cases of an additional gear between motor and Handle.
Now I have checked, how the position sensor works exactly, and I found, that there's also a hall sensor inside. Above it spins a disk with two magnets in, which have opposing mangetic fields. One magnet faces with the northpole to the hall sensor, and the other with the south pole. With this, the Sensor can detect, if the needle is in upper or lower position, and with respect to the customers setting can  stop at either position.
Now my idea was, if the path to my desired needle position is too long for the controller, so that it fires the error, I can reduce the path, if I flip one magnet around. Then with every half revolution the hall Sensor fires.  But it fires only one event very half revolion. Needle up or needle down every half revolution (depending on which magnet was flipped around). .. but that's not a bug! Its great!
 See Photo Position Sensor.
I had to adjust the needle setting in the controller, to detect the position, which my magnets indicate now. Otherwise it fires E-06 Error at all time, because no magnet indicates it.
And the result is, what I have described above:
Depending on the position, when the pedal is released it goes to either needle up or down, depending on what is the next possible.
And the really fantastic thing is:
Small Hits to the pedal moves the needle to the next clear position. Two hits are one complete revolution and stitch. This allowes a) turning the leather, with needle inside the leather and foot up, and also moving the leather by hand, when the needle is up. GREAT!

So guys, please let me know, if this was helpful for anybody!
Sorry for my english, I am not a native speaker.
Andreas.
 

Edited August 14, 2016 by Captayne

[Captayne]

I have to add something!

After I had switched the controller off and on again the controller checks, if it can find northpole AND southpole, but in my config only one was found of cause, and again it fired Position Sensor Error E-06.

Come on!
But no problem: I just added the missing two poles by adding two other magnets half way between the existing magnets. Two tiny 5mm disk magnets are needed and a 5mm drill. Its easy to install. See the new, updated photo.
Now half a revulution of the handle is recognised to be one complete revolution. And this shortens the path to a needle event.

Same as before, I had to adjust the shaft connection of the postion sensor relative to the handle, so that the machine stopps in either upper or lower position and not in between.
Now my controllers software impatience was resolved, the remaining path to the next needle trigger is much shorter than before now. It comes earlier now and no E-06 was fired since then, as the controller still finds both poles, but twice as often per revolution.
Thanks.

 

[Dannyjoe]

I just bought the same motor for my Pfaff 417.
I figured out i need rpm's between 200 and 1000.
If i set my maximum Speed to 1000 i cant begin with a speed of 200. It starts with an average speed of ~800 rpm.

Did anybody fix it without changing the gear wheel?

[Oliver76]

Captayne , sent you a PM