Can anyone help me with a running a 3-phase Juki at home?

[Quade]

Quote

VFDs don't put out a clean 3 phase like you would get from your utility, as mentioned by 480volt the motors connected should be inverter rated. mines not, so researching what that meant I learned a non inverter rated motor on a VFD can actually get bearing damage over a very long time of operation, something about the way the VFD feeds it.

A VFD lets you change the frequency of the AC in order to change the speed of the 3 phase motor.  An "Inverter rated" motor is built to run at variable speeds.  A standard motor might overheat when run at a non-standard frequency.  So you can run a standard motor on a VFD as long as you're just putting out 60 hz and running the motor at the rated speed.  The benefits of the VFD in this case would be slow start and braked stopping.  Also you can remote control the VFD.  I use the VFD on both the lathe and drill press to change the speed of the motor. It saves me from belt changes. 

Not knowing this box and motor, I had second thoughts about recommending the VFD.  If the box simply turns the AC into DC and runs everything including the motor on DC, then a VFD would work fine.  On the other hand if the box does tricky things with the AC, the VFD might not be a good idea. As someone else pointed out, the VFD doesn't like switches and such between it's output and the load. 

Easiest thing would be to just install a cheap servo. 

[williaty]

15 hours ago, Quade said:

I run my 3 phase lathe and drill press off a $200 VFD

https://www.amazon.com/HKS-Variable-Frequency-Controller-Converter/dp/B09Q8JVTVN/

Here's a cheap one. 110v single phase to 220 3 phase. 

Instead of that, I'd install a 750 watt servo motor and simply not use the servo the machine came with. 

https://www.amazon.com/Consew-CSM3000-Sewing-Machine-Electric/dp/B01N1L1P7G/

It's a relatively simple install. 

I tried this with the equipment listed in the first post.

 

It doesn't work.

 

Getting a computerized sewing machine to run turns out to be more finnicky than getting a basic electric motor to run.

[kgg]

15 minutes ago, williaty said:

Getting a computerized sewing machine to run turns out to be more finnicky

The computerized machines are good at doing a lot of fancy stuff but when you see Juki dealers shy away from repairs and factories replacing them on a schedule it tells me that you should just strip the computer controls off and install a servo motor as Wiz previously mention.

kgg

[dikman]

I agree - unless you're a masochist and like to punish yourself!

[Handstitched]

Well, this has turned into something quite educational  . Here in Oz, our standard single phase voltage is 240v and 3 ph is 415v. 

HS

[hamradio]

This is a somewhat old thread that I found while searching for something adjacent, but I have direct experience with what looks to be the same servo, and thought I’d chime in.

In the engineer’s manual for these older Juki servos, it states that for single-phase applications, one may just omit one of the legs of the 3ph wiring for the motor and proceed as usual. If I recall, it did specify which wire to omit. In my case with all of the factory wiring intact, this was the black wire. Red and white are hooked up to the source. Obviously, read the documentation for your own application and look at how your own machine is wired up before attempting any of this.

 I’m running two DLN-5410-6 this way with no issues whatsoever, and also tried it out on an older Brother servo and it seemed to work fine, until the controller began having issues a year later. The same issues were present with a static phase converter, so I’m not sure if they were related or not to the power source. It seems like a lot of the power supply circuits for these just rectify each leg of the power individually and then it goes into a transformer, and some of these designs are kind of agnostic to whether all three or only two of those legs have power.

IMO, it’s worth the hassle to get this stuff running versus swapping in a generic servo motor and losing all of the nice automatic bits, thread trimmer, foot lift, etc. Even just the factory servos themselves just work so many leagues better and smoother than the retrofit motors ever do.

Edited August 4, 2023 by hamradio

[williaty]

5 hours ago, hamradio said:

In the engineer’s manual for these older Juki servos, it states that for single-phase applications, one may just omit one of the legs of the 3ph wiring for the motor and proceed as usual. If I recall, it did specify which wire to omit. In my case with all of the factory wiring intact, this was the black wire. Red and white are hooked up to the source. Obviously, read the documentation for your own application and look at how your own machine is wired up before attempting any of this.

I am willing to bet this only works for a very narrow production time range. My machines, which have newer computers on them than what you show there, would shut down with an Open Phase error when I tried that. They were too smart to put up with simple fixes like that. The various manuals for them also never mentioned anything about being able to get away with it.

 

Still might be a good option for the people with the really old machines.

[MarlinDave]

I bet the control circuit is single phase. Might try swappIng the 3 wires because sometimes converters leave one pole out of balance/phase. 

[shoepatcher]

if he replaces the motor, he loses the auto functions on the machines.  Both motors are -7 which means they have toys.  I would go the route of a phase converter like Uwe said so you do not lose those functions.

glenn