Recommendation - Jack Jk-561A-1 Servo Motor

[VanRhodes]

amuckart -> what does your sensor look like internally? I am trying to get my NPS to work but I'm not having much progress yet even though I do hope to find out. Thanks to the very nice gear ratio of my current setup I get a 1:10 ratio so its still _very_ manageable, but I would very much like to have the NPS working properly as it will make the W-W patterns so much easier.

[VanRhodes]

Here's the system I am currently working on, showing the NPS mounted to the shaft of the head and the gears used to achieve the desired gear ratio.

[amuckart]

Ho-Hsing are for sure higher end quality motors and are more expensive afaik. But I´m very please with my Jack servo. I don´t really need the NPS but would have been a nice feature though. Still a huge improvement compared with the freaking high speed & energy consuming clutch motors.

The new ones are expensive. This one came on a Pfaff 441 that I bought second hand for NZ$200. I didn't have space for the machine itself, so I sold that but kept the motor.

[amuckart]

amuckart -> what does your sensor look like internally? I am trying to get my NPS to work but I'm not having much progress yet even though I do hope to find out. Thanks to the very nice gear ratio of my current setup I get a 1:10 ratio so its still _very_ manageable, but I would very much like to have the NPS working properly as it will make the W-W patterns so much easier.

Sure, here they are. The unit has three optical sensors, and a set of disks. Once has regularly spaced tiny holes that tells the motor how many RPM the actual machine is doing (as opposed to how many RPM the motor is doing), and the other two have a chunk out of the rim and can be rotated to set the needle up/down position.

Bear in mind that this is quite an old unit. Ho-Hsing haven't made this motor for several years. I don't know if more modern motors use hall effect sensors or still use optical ones.

I made the aluminium bracket that prevents the sensor from rotating.

[Trox]

Thanks for a good topic, very good reviews of the motor.

I just want to clear up what I said about Needle position and speed reducers. It only applies to the new Efka motors DC 1200, DC 1250, DC 1500 and DC 1550 with control boxes. These motor systems do not adjust the needle position on the synchronizer head any more (like on older Efka motors). Adjustments are all done in the control box and the head are just there to calculate belt slippage. Without a belt drive as on VanRhodes cl. 20 (has to be) gear drive, you would not need this head at all using an new Efka.

Anyway, Efka assure their motors would be strong enough for any known lock-stitch machine without use of a speed reducer (I never had any problems with mine, using just half of the rated torque settings on a 441). That said, there are always special solutions than need a speed reducer. Then you can mount the head on the speed reducer itself to avoid these errors.

HohSing, uses the"old" type adjustments in the sync. head on most of their motors, if not all. Several/most of their motors are AC position motors, not DC as Efka uses. So if the motor has the same style head as on Amuckart`s HohSing, it should be working well with a speed reducer.

It could be many other reasons for getting "NP" errors on the Jacksew motor. The actual adjustment timing could be wrong, needle down and needle up are set to close together or to far (from 0 to 360 degree). The head could be mounted wrongly on the shaft, jumps on the shaft or turns a little with the shaft. Or it could be a control box error. There are many Chinese "NP" motors on the marked having these errors, its very common. Then of course the lack of a good manual and support will make problems too (you get what you pay for).

Overall, this Jacksew motor looks to be a good alternative. The next step up would be an HohSing G series "NP" motor; the G60 is not that expensive (even here in Norway) and it has 600 watt, no errors and good low speed control. Made in Japan for around 300 $ (Check with Gregg @ Keystone) http://www.hohsing.com/index.php/en/ac-servo-motor-en/142-g-series-en This motor will not allow any extra attachments such ar foot lift, thread trimmers etc.. If you are looking for such options you must by a more expensive motor system.

Thanks

Tor

[Constabulary]

There are for sure better motors than the Jack but as TROX said - you get what you pay for. As an hobbyist I´m please with mine and don´t need all these features but if someone does he should buy a HoHsing or an EFKA. I basically needed s/t that spins my machine

[VanRhodes]

amuckart: Thanks alot! My NPS is pretty much the same inside minus the third disc for counting the RPMs. This atleast confirms my suspicion that the NPS is simply checking the need up and down pos and nothing else, meaning the amount of gears or pulleys in between the motor and machine shaft doesnt matter one bit.

Trox: Thanks for the clarification! I've been eyeballing on of the newer Efka units but I'm afraid its a little bit pricey right now, besides the Jack-motor with the timing belts and gears does offer plenty of control and power as it is, but I'll have to see if I can figure out why the NPS won't work as intended. When the NPS is activated and I turn on the control box, the servo moves a small bit, 1/4 or similar tops, and then stops and display the E5 error. I'm not sure why it does this but I will have to test and see what I can come up with.

[Trox]

amuckart: Thanks alot! My NPS is pretty much the same inside minus the third disc for counting the RPMs. This atleast confirms my suspicion that the NPS is simply checking the need up and down pos and nothing else, meaning the amount of gears or pulleys in between the motor and machine shaft doesnt matter one bit.

Trox: Thanks for the clarification! I've been eyeballing on of the newer Efka units but I'm afraid its a little bit pricey right now, besides the Jack-motor with the timing belts and gears does offer plenty of control and power as it is, but I'll have to see if I can figure out why the NPS won't work as intended. When the NPS is activated and I turn on the control box, the servo moves a small bit, 1/4 or similar tops, and then stops and display the E5 error. I'm not sure why it does this but I will have to test and see what I can come up with.

Hi,

I do not know these Jack servomotors. The Error guide is as expected for these Chinese motors; translated with Google I guess.

With an Efka, you can call them on Skype video call and show them the problem. They will sit down with you until your machine sews, as it should. That’s free, included in the package. If it takes one day or four, that do not matter. That is necessary when time is money.

Like I said before, if you share a machine revolution (360 deg.) in two parts, each 180 deg. Needle-up position inside one part and needle-down pos inside the other. If one is adjusted to close to the other window, it sometimes will return to the wrong position. Rotate backward or not at all. These two positions must be correct timed otherwise this might happen; the motor gets no clear start/stop signal. Same thing will happen if you take off the head and try to start the motor.

Perhaps something happens in your gear reduction; perhaps it is too many gears. Perhaps it will work better if you position the pos-head on another gear wheel. I do not know, it’s hard to tell without seeing it my self. However, if this motor works with normal speed reducers. I think this has a logical solution, map it down on a piece of paper and count rotations in the drive. Perhaps you will see what’s wrong with the setup (or has it worked with this setup before?)

Otherwise, check that the head are well connected to the hand-wheel; stays still when the Hand-wheel rotates (does not follow the shaft around). If there is an IR beam inside, check for dirt on the lens and false light etc. Then take an all reset if necessary and time the two positions all over again.

Remember that needle-down position will be a bit after BTC, when the needle it’s on its way upward again (when the hook has grabbed the thread loop). The thread take-up lever should have traveled half its way up.

In Needle-up position, the thread take-up should be all the way up. I do not know if this applies to the Jack servo, however the motor has to get its start/stop signal from the head (if constructed like mention in the other post’s) If this do not help you contact the dealer and ask for help or make a complain.

Good luck

Tor

[VanRhodes]

Trox: Thanks for the intel, I will have another look at everything and properly inspect it as soon as time allows for it, at the moment I have some pressing matters that I need to finish up so there's really not alot of time for troubleshooting but I do greatly apprechiate your efforts in helping me out! Thanks alot!

[Constabulary]

Thanks for sharing this. I was eyeing those up the other day and it's nice to read some experiences with them.

I'd love to know more about your speed reducer. The one that came with my 441 clone is a POS and I need a better one.

Sorry - seems I missed this.

My speed reducers are custom made and have 2 ball bearings.

http://leatherworker.net/forum/index.php?showtopic=53689&p=351899