What servo motor setup to get?

[CowboyBob]

On 3/27/2023 at 2:22 PM, kgg said:

I would be interested in knowing what the class 441 machines with a dealer supplied speed reducer installed actually get.

We always use the 45mm & no one has ever complained they run too fast.LOL

Edited June 9, 2023 by CowboyBob

[Mekanic]

22 hours ago, dikman said:

Is the needle synchroniser working ok? Some servo/synchronisers don't work when using a speed reducer.

It's "consistent"...adds an additional stitch. Raises needle to UP when pedal is back-tapped.  I'm still learning/tweaking setup.

[Trox]

On 6/9/2023 at 11:49 PM, Mekanic said:

It's "consistent"...adds an additional stitch. Raises needle to UP when pedal is back-tapped.  I'm still learning/tweaking setup.

It's an option on all motors if you want the needle to stop down or up when you heel the pedal, it must be down. But you won't get this to stop where's supposed to with a speed reducer. It's bases on a 360° rotation with a belt direct to the machines pulley. Expensive position motor controllers can account for belt slippage, but no system will calculate for an extra belt and two pulleys. There aren't any motors that can do that. I've seen some have put the synchronizer head on the speed reducer instead of the machine handwheel. But still it will not be accurate. Luckily these motors will work without the syncro head. Expensive motor systems like Efka won't run without a synchronizer. But on Chinese cheap motors the syncro head is just a 15$ extra. Most of these systems aren't accurate anyway.  It's important that these systems are accurate, it has to stop at exactly the same place/degree of the revolution every time. It's when the needle has past it's lowest position and picked the bobbin thread. If it stops earlier and you raise the foot to turn your work a stitch will be skipped. To late and the needle is out of the work. I know the earliest Chinese designes wasn't any good, but they should have been able to figure this out by now. German motor brands have use this system since the 1970 ties. The problem is that accurate servo systems are expensive to make. Accurate speed controls too.  There are enough power in these motors, people put speed reducers on them to get better speed control.  With the price of the reducer and motor combined your not far from what a proper motor system costs.

[Sauls]

Thank you for those details @Trox  very helpful.  I’m debating in my mind if I need a speed reducer since I do prefer to have the needle position sensor active.  Just picked up a used Juki 1341 and starting to run a few test pieces, but so far I don’t think I need a reducer.     Enduro SM645-1P seems to be okay.  

[toxo]

On 6/9/2023 at 12:23 AM, dikman said:

Is the needle synchroniser working ok? Some servo/synchronisers don't work when using a speed reducer.

I was waiting for this question to come up. As you know I have big pulleys on two of my machines and the NPSs work fine but my new machine has a box style reducer and it the NPS won't work properly. It's not a rail crash because I can start and stop really slowly (and speed up in the middle) so with some practice I should be able to needle up/down without the NPS.

This did get me thinking and I wondered if anyone had tried putting the NPS directly on the motor pulley?

[GerryR]

I seem to favor AC servo systems.  They are 3-phase motor systems (with 1-phase power input) using a variable frequency drive (VFD).  I have built a couple of different systems.  They are more expensive than the Enduro DC drive systems, and you need an "Inverter" rated motor to run at low speeds (to handle the extra heat).  I mention this because using a proximity sensor and a metal flag on the hand-wheel, for example, they can be made to stop in any position, depending upon the location of the metal flag, regardless of the speed reducer used.  They, generally speaking, are very reliable systems, as well.  A general DC servo system can be made to do the same, however the systems made specifically for sewing machines do not seam to have this option.  I'm just tossing out another option when considering motor drives for sewing machines.