Development of best servo motor for leather sewing machine

[Wizcrafts]

9 hours ago, CowBoyOUTLAW said:

Yes Kinedyne HM-750SH low speed high torque servo motor is ideal for leather sewing machine.  
At least, the motor can greatly improve the performance of our leather sewing machine.

Is this motor optically controlled? If so, there were people printing variable density optical filters that users could install inside their digital motors. These filters smoothed out to speed variations so the motor started at zero rpm and steadily increased as the operator pushed down on the speed pedal. Stopping the foot motion left the motor at that speed until one backed it off or pushed down further. I had this modification on a motor that came with my Cowboy cb4500, in 2011 or 2012. I would compare the action to the analog motors that replaced it.

[dikman]

15 hours ago, CowBoyOUTLAW said:

Only for your information, before we sell our industrial sewing machine with cheap servo motor arround Au$ 140, too many troubles, that's why we start to make servo motor. In Italy and Sweden, they use Effka motor before, now use Kinedyne, saving a lot, instead of spending more..

That's commendable that you make your own motor, although if you had so much trouble with the original motors you supplied why not just change supplier? It would be interesting to know the failure rate of the motors used by other sellers - Cowboy, Techsew etc. In general modern electronics are pretty reliable but ANY circuit board can fail at ANY time, often for no discernible reason, although surges/spikes are often the main culprit.

Wiz, interesting thought but I'd be surprised if they use optical sensors, everyone seems to have gone to Hall Effect sensors now.

[GerryR]

My opinion, from a mechanical standpoint, is to start with a servo that has an integral 5:1 gear reducer.  This automatically increases torque and allows the servo to start at a higher speed.  This is easier on the motor and the drive electronics.  Also, a dual pot foot pedal, one pot sets the max speed and is hand adjustable, the other is the foot-operated pot so you always have the full range of the foot pedal for whatever your max speed is set to.  I have this on my system which utilizes a variable frequency drive (VFD).)  You might even consider offering an AC-servo system (VFD controlled) instead of a DC system.  The electronics are inexpensive, especially for 1 HP and less, however, they require a 3 ph motor to operate, but they can be had with integral gear boxes.  As you are designing from scratch, you can spec your own motor.  I have had two systems with AC servos and two with DC servos and personally prefer the AC units.  Also, a needle position sensor can be implemented with a proximity sensor and metel "flags" put at appropriate locations and you can have multiple flags to stop at various needle positions.  If this is implemented along with a jog button or heel pedal switch, you can control all your stop positions quite easily.  Just some food for thought. 

[CowBoyOUTLAW]

16 hours ago, nejcek74 said:

I learnt sewing with modern servo motor with needle positioner. I am buying them in Europe from a big reseller, Strima, they are around 300 euros. They start at 100 rpm minimumspeed I think, 750 we. 

Thanks to needle positioner I don't miss lower speeds. I do needle up, needle down and I can go step by step when I want. And the needle is always in the right position (locked stitch or open tensioner etc) so working is easy and precise. I don't need and don't want a speed reducer under the table. 

A jog dial would be useful to limit upper speed which I need to do on the controller. I also miss more robust needle positioner with better and easier fixing to different types of machines.

For me a middle priced servos with good documentation and support would be interesting. Efkas prices are too steep, the cheapest Chinese imports are undocumented and have often strange quirks that are difficult to solve 

Needle positioner is necessary, most servo motors with it. In Italy, Kinedyne HM-750SH is replacing Efka servo motor, that's why our price is higher than other Chinese cheap motors.

[CowBoyOUTLAW]

2 hours ago, dikman said:

That's commendable that you make your own motor, although if you had so much trouble with the original motors you supplied why not just change supplier? It would be interesting to know the failure rate of the motors used by other sellers - Cowboy, Techsew etc. In general modern electronics are pretty reliable but ANY circuit board can fail at ANY time, often for no discernible reason, although surges/spikes are often the main culprit.

Wiz, interesting thought but I'd be surprised if they use optical sensors, everyone seems to have gone to Hall Effect sensors now.

We have been looking for over 6 months, we have contacted all motor supplier include HO HSING and ISM....
Even ingnore durbility and perfomance, no servo motor can directly drive CowBoy CB4500 if without speed reducer.

 Kinedyne HM-750T and HM-750L Energy-saving Motor use Hall Effect sensors, HM-750SL and HM-750S servo motor use optical sensors

[CowBoyOUTLAW]

2 hours ago, GerryR said:

My opinion, from a mechanical standpoint, is to start with a servo that has an integral 5:1 gear reducer.  This automatically increases torque and allows the servo to start at a higher speed.  This is easier on the motor and the drive electronics.  Also, a dual pot foot pedal, one pot sets the max speed and is hand adjustable, the other is the foot-operated pot so you always have the full range of the foot pedal for whatever your max speed is set to.  I have this on my system which utilizes a variable frequency drive (VFD).)  You might even consider offering an AC-servo system (VFD controlled) instead of a DC system.  The electronics are inexpensive, especially for 1 HP and less, however, they require a 3 ph motor to operate, but they can be had with integral gear boxes.  As you are designing from scratch, you can spec your own motor.  I have had two systems with AC servos and two with DC servos and personally prefer the AC units.  Also, a needle position sensor can be implemented with a proximity sensor and metel "flags" put at appropriate locations and you can have multiple flags to stop at various needle positions.  If this is implemented along with a jog button or heel pedal switch, you can control all your stop positions quite easily.  Just some food for thought. 

Thank you very much for sharing, we have already achieved all the points mentioned above😁😁

[CowBoyOUTLAW]

8 hours ago, Wizcrafts said:

Is this motor optically controlled? If so, there were people printing variable density optical filters that users could install inside their digital motors. These filters smoothed out to speed variations so the motor started at zero rpm and steadily increased as the operator pushed down on the speed pedal. Stopping the foot motion left the motor at that speed until one backed it off or pushed down further. I had this modification on a motor that came with my Cowboy cb4500, in 2011 or 2012. I would compare the action to the analog motors that replaced it.

WOW, are you servo engineer?
Few people can talk about optical controls deeply. Now we use 600 line encoder, the minimum speed on CB4500 is about 10 stitch per miniute. If use 1200 line encoder, in theory the speed can down to 5 SPM.

[CowBoyOUTLAW]

13 hours ago, Cumberland Highpower said:

It looks to me that you've just drummed up a thread on this forum to make sales of what you already market, Right? 

You're asking for input on "designing" a new servo, yet debate every time someone mentions a point or suggestion contrary to what you're already marketing/selling.  For example when a member suggests options for supply voltages, you just jump to market your "Kenedyne" motor as it's available in both.  You should have said, that's a great idea, we'll incorporate that into the worlds best heavy servo motor that we're working on, maybe we'll make it a dual voltage, plug and play unit!

If you're looking to design a servo for leatherworkers to use on heavy stitchers, follow our collective advice and be open minded.

If you want to add all these features including a ridiculous "jog dial"  you're not really going to get anywhere.   ISM in the Republic of China already has the best servo going with all those "other" features we don't really need.   The ISM SV-71 650w servo is around $300. I bought mine from College Sewing machine for 189GBP ($258). Those units are light years ahead of any of the lower cost PRC made units and not all that inferior to a Ho Hsing unit.

Maybe I'm a little too skeptical, I don't know.  It could be something innocent like a mistake in translation from English to Chinese, or maybe a cultural communication mismatch?   

The members here buy Servos for 2 reasons.  1)  Better low speed control  2) Needle Positioning  

Those are the only major advantages they have over a clutch motor and yes, clutch motors are very much still a thing.   They're nearly indestructible, basic, easy to adjust, and power machines along all day, every day.  I actually like the faint hum they make, you know the machine is on.   Yes, they do consume a little more power, but unless you have a shop floor with 100-+ machines running, it's not an issue.   If you factor in maintenance/repair/replacement of burned units as well as electricity consumption over a 10 year span, servos could and probably do, carry a higher cost.

I have 21 clutch motors operating on my shop floor, the oldest date on one is 1967, the newest is dated 1993.  (Most all are made in Taiwan/ROC back when that wasn't really a great thing quality wise).  I seriously doubt any brushless servo would last 30-50 years?

It may be a cultural difference. We need the hand-on experience from leather workers to improve the quality of the motor, so  we carefully analyze and explain these suggestions. Is there anything wrong?
We tested ISM SV-71 650w servo motor, it can't directly drive extra heavy duty leather sewing machine like CB4500, if without speed reducer

[dikman]

So your motor has an internal 5:1 gear reducer? That's what you just said, and if so that would explain the high cost.

You say that an NPS is "necessary". Who says it's necessary, it's the considered opinion of some of the more experienced on this forum that it is not necessary. I think we need to clarify exactly what your intended market is, on the one hand you're emphasizing extreme slow speed control (without needing a speed reducer) for the likes of a 441-class machine and then you're talking about the necessity for NPS, jog dials, needle up/down position and 1/2 stitch adjustment (?). For a decent servo to run a 441 sewing heavy leather you only need to keep it simple, as has been pointed out - slow speed and easily adjusted variable speed, nothing more is needed. All the other "extras" are more suited to higher speed sewing.

[CowBoyOUTLAW]

33 minutes ago, dikman said:

So your motor has an internal 5:1 gear reducer? That's what you just said, and if so that would explain the high cost.

You say that an NPS is "necessary". Who says it's necessary, it's the considered opinion of some of the more experienced on this forum that it is not necessary. I think we need to clarify exactly what your intended market is, on the one hand you're emphasizing extreme slow speed control (without needing a speed reducer) for the likes of a 441-class machine and then you're talking about the necessity for NPS, jog dials, needle up/down position and 1/2 stitch adjustment (?). For a decent servo to run a 441 sewing heavy leather you only need to keep it simple, as has been pointed out - slow speed and easily adjusted variable speed, nothing more is needed. All the other "extras" are more suited to higher speed sewing.

The minimum speed is 50 RPM only, and the torque of motor is enough to drive any extra heavy duty sewing machine, why with gear reducer? For the high price, easy to explain: other 800W and 1000W servo motor in today market cannot drive CB4500 withour speed reducer, but our 750W motor can; Other motor use Hall Effect sensor, we use optical sensor; If you tight the machine belt, other motor frame maybe bend, our motor frame will not....
For the NPS, I might be wrong, in China we mainly sell to manufacturers who need high speed, all motors to them must be with needle positioner. 
Jog dials, needle position and 1/2 stitch adjustment, they are optional for people who need it. 
"For a decent servo to run a 441 sewing heavy leather you only need to keep it simple" -- thank you, really appreciate it!