What does a needle position servomotor do on leather sewing machine?

[CowBoyOUTLAW]

What does a needle position servomotor do on leather sewing machine? See below video link on YouTube.

 

[Wizcrafts]

48 minutes ago, CowBoyOUTLAW said:

What does a needle position servomotor do on leather sewing machine?

Facts only answer

As the video demonstrated, it allows the operator to precisely stop with the needle either fully up or fully down, no matter the speed you were sewing at. This means that whether you are sewing 1 stitch per second or 30, pressing down with your toe or heel in the designated manner will cause the machine to come to a dead halt with the needle up or down. This would be a useful combination for an operator who lacks good foot control (medical or injury causes).

Editorialized answer

I have the same type of machine in the video; a Cowboy cb4500. It has a 3:1 speed reducer and an analog servo motor with a simple rotary switch to limit the top speed. It ramps up smoothly from zero to the maximum speed as set by the knob. I can easily operate my machine at less than one stitch per second, then floor it on straightaways to sew at 10 or 15 stitches per second. As I approach corners, turns, or the end of the stitch line, I simply back off the speed pedal until I reach the end, then either reverse into the previous few stitches, or move the stitch length lever to the zero movement position and double tap it to lock in the threads. In my learned opinion, there is absolutely no need for a normal user, with good foot muscle control, on this type of machine (Juki 441 clone), to install a needle positioner and more expensive digital servo motor if it has a 3:1 reducer between the motor and machine.

[Constabulary]

Well, nothing really new in this video. However - does the needle positioning work in combination with a speed reducer?

[kgg]

4 hours ago, Constabulary said:

does the needle positioning work in combination with a speed reducer?

Great question, as some people have had problems in the past when trying to combine a speed reducer with a needle positioner on a electronic controlled servo motor. I didn't see one on the second machine with the speed reducer. 

8 hours ago, CowBoyOUTLAW said:

What does a needle position servomotor do on leather sewing machine?

Since price is always a factor what is the price of the servo motor and needle positioner?

kgg

[GritMercantile]

We have on our Techsew 4800 Pro. The EPS is invaluable for us and speeds up the process. I would agree that if you have good treadle control and EPS may not be needed. Is it nice to have? Yes, Have to have? No. Would we purchase another machine without it? No.

[CowBoyOUTLAW]

On 10/6/2022 at 10:22 PM, GritMercantile said:

We have on our Techsew 4800 Pro. The EPS is invaluable for us and speeds up the process. I would agree that if you have good treadle control and EPS may not be needed. Is it nice to have? Yes, Have to have? No. Would we purchase another machine without it? No.

“How many times a day you need to remove your hand from workpiece to the hand wheel for lifting needle, then remove the material?”EPS great for time saving, also avoid losing stitch when you turn material for changing direction.  

On 10/6/2022 at 7:07 PM, kgg said:

Great question, as some people have had problems in the past when trying to combine a speed reducer with a needle positioner on a electronic controlled servo motor. I didn't see one on the second machine with the speed reducer. 

Since price is always a factor what is the price of the servo motor and needle positioner?

kgg

Price is higher than other motor, due to its high performance. 

[CowBoyOUTLAW]

On 10/6/2022 at 11:41 AM, Wizcrafts said:

Facts only answer

As the video demonstrated, it allows the operator to precisely stop with the needle either fully up or fully down, no matter the speed you were sewing at. This means that whether you are sewing 1 stitch per second or 30, pressing down with your toe or heel in the designated manner will cause the machine to come to a dead halt with the needle up or down. This would be a useful combination for an operator who lacks good foot control (medical or injury causes).

Editorialized answer

I have the same type of machine in the video; a Cowboy cb4500. It has a 3:1 speed reducer and an analog servo motor with a simple rotary switch to limit the top speed. It ramps up smoothly from zero to the maximum speed as set by the knob. I can easily operate my machine at less than one stitch per second, then floor it on straightaways to sew at 10 or 15 stitches per second. As I approach corners, turns, or the end of the stitch line, I simply back off the speed pedal until I reach the end, then either reverse into the previous few stitches, or move the stitch length lever to the zero movement position and double tap it to lock in the threads. In my learned opinion, there is absolutely no need for a normal user, with good foot muscle control, on this type of machine (Juki 441 clone), to install a needle positioner and more expensive digital servo motor if it has a 3:1 reducer between the motor and machine.

Thank you!!

 

[CowBoyOUTLAW]

On 10/6/2022 at 2:14 PM, Constabulary said:

Well, nothing really new in this video. However - does the needle

On 10/6/2022 at 2:14 PM, Constabulary said:

Well, nothing really new in this video. However - does the needle positioning work in combination with a speed reducer?

work in combination with a speed reducer?

Thanks for your great question. We just tested, the needle position could not working well, but it is not about the synchronizer, but about mother board, we will upgrade the system ASAP

[CowBoyOUTLAW]

On 10/6/2022 at 7:07 PM, kgg said:

Great question, as some people have had problems in the past when trying to combine a speed reducer with a needle positioner on a electronic controlled servo motor. I didn't see one on the second machine with the speed reducer. 

Since price is always a factor what is the price of the servo motor and needle positioner?

kgg

Kgg, we fixed the problem, now the Kinedyne needle position synchronizer can work perfectly with speed reducer.

[Constabulary]

So how much speed reducer reduction will this motor / needle positioner now accept? 1:2, 1:3 or even more?

Does it matter how big the motor pulley is? Usually these motors comes with ~75mm pulley but most LW swap it to 40-50mm pulley.

I´m just a user but not an electronics geek so this question may sound stupid (maybe not).

Is there (probably) a way to adjust the "reduction acceptance" (I have no other word, sorry)  in the motor management menu? That would be a great feature.

 

Edited October 13, 2022 by Constabulary

[Cumberland Highpower]

Is there any particular reason why every servo and clutch motor made comes with such a large pulley on the motor shaft?  Generally, the first thing I do is toss the original pulley and replace it with a smaller diameter one just like Constabulary does.

 

Edited October 13, 2022 by Cumberland Highpower

[CowBoyOUTLAW]

14 hours ago, Cumberland Highpower said:

Is there any particular reason why every servo and clutch motor made comes with such a large pulley on the motor shaft?  Generally, the first thing I do is toss the original pulley and replace it with a smaller diameter one just like Constabulary does.

 

Large pulley most definitely avoid slipping

[CowBoyOUTLAW]

17 hours ago, Constabulary said:

So how much speed reducer reduction will this motor / needle positioner now accept? 1:2, 1:3 or even more?

Does it matter how big the motor pulley is? Usually these motors comes with ~75mm pulley but most LW swap it to 40-50mm pulley.

I´m just a user but not an electronics geek so this question may sound stupid (maybe not).

Is there (probably) a way to adjust the "reduction acceptance" (I have no other word, sorry)  in the motor management menu? That would be a great feature.

 

Thanks for your idea, users might be not happy to adjust some parameters in motor management menu, so we set wide range ratio in motor board, acocording to HT-SP03 Bearing drive Speed Reducer, the gear ratio is 1:3 (https://www.cowboysew.com/slow-speed-sewing-machine.htm)

[kgg]

14 hours ago, Cumberland Highpower said:

Is there any particular reason why every servo and clutch motor made comes with such a large pulley on the motor shaft?  Generally, the first thing I do is toss the original pulley and replace it with a smaller diameter one just like Constabulary does.

A good example of the belt contact surface would be:

i) a 75mm diameter circle would allow a belt to contact with half of the circle at any given time. That means the belt actually contacts 117.81mm of the pulley surface

ii) a 50mm diameter circle would allow a belt to contact with half of the circle at any given time. That means the belt actually contacts 78.54mm of the pulley surface

iii) a 40mm diameter circle would allow a belt to contact with half of the circle at any given time. That means the belt actually contacts 62.83mm of the pulley surface

A 40 mm circle would only have 53.33 percent of the contact surface as a 75mm circle.

kgg

[Cumberland Highpower]

On 10/13/2022 at 10:01 PM, kgg said:

A good example of the belt contact surface would be:

i) a 75mm diameter circle would allow a belt to contact with half of the circle at any given time. That means the belt actually contacts 117.81mm of the pulley surface

ii) a 50mm diameter circle would allow a belt to contact with half of the circle at any given time. That means the belt actually contacts 78.54mm of the pulley surface

iii) a 40mm diameter circle would allow a belt to contact with half of the circle at any given time. That means the belt actually contacts 62.83mm of the pulley surface

A 40 mm circle would only have 53.33 percent of the contact surface as a 75mm circle.

kgg

 

I guess I should have just said "I don't know why an Engineer with any real world experience in actually using servo motor of this type, would draw up (as an OEM) a large drive pulley on a servo or clutch motor?" rather than just posting it as a rhetorical, slightly sarcastic question.

 

Edited October 15, 2022 by Cumberland Highpower

[kgg]

3 minutes ago, Cumberland Highpower said:

I think we all understand the physics of a "larger" pulley/belt friction/contact surface area and drive speed KGG

Personally I have never had a much of a problem with belt slippage on any of my machines and haven't needed to fiddle with the servo motor pulley size. When belt slippage has happened I was asking/hoping it would punch through something that was beyond the machines sewing limits. In those cases the belt slippage was a good thing and prevented possible damage to internal parts. lf I were to consider putting a speed reducer on or changing the servo motor pulley size it would be just to gain lower speed control not for extra punching torque.

In the end I guess the Engineers who design the machines have to take into account the stress that can be placed on internal parts and what size of motor / pulley sizes that would best accommodate the majority of users for a particular machine.

kgg