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Spindle motor or controller?

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Groundhog

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#1
The motor for the spindle of my Syil X4+ CNC mill quit last night. I'm not much with electronics and am not sure how to trouble shoot this. I'm a mechanic, not an electrician.

The motor will make a revolution or 2 then rattles something awful and quits. I can hit "spindle stop" and "spindle start" and it does the same thing again. I forgot to try it in the reverse direction - I'll go try that in a bit. It sounds like a bearing is out but the motor turns easy by hand without any roughness or binding.

I've attached a short video so you can hear the rattling sound.

Any knowledgeable help would be greatly appreciated.

spindle mtr 1.jpg


P1040039.MOV
 

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JimDawson

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#2
You know two things at this point: 1) it doesn't work, and 2) the bearings seem to be OK.

It could be a bad winding, a bad Hall sensor, a loose wire, bad encoder (if equipped), or a bad controller.

I would first check the wiring for any obvious connection problems. Tug on the connecting wires at the terminals.

Then if that's OK, then do a quick winding ohms check to ground (motor case) and winding to winding. The winding to winding should be maybe 2 ohms or so, but more importantly should be about the same between all of them. To ground should be infinity.

If that checks out OK, then I would take the motor and controller to the local motor shop and see what they have to say.
 

Groundhog

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#3
Jim,
Thanks.
I've checked wiring and connectors everywhere but at the controller. I'll move the mill tomorrow and check there.

All fields check "OL" to ground.
blk-red = 0.9 ohm
blk-blue = 0.9 ohm
red-blue = 1.8 ohm

Is that enough to cause problems?

I can get it to keep running (either direction) if I keep it below 800 rpm. However it makes a terrible noise (sounds like a bearing missing a few balls). With no power to the mill I can turn the motor by hand. It feels like there is a magnetic, pulsed drag bit otherwise it feels smooth.

The cover over the wire entrance (and the hall effect cover?) is cracked and shows a tiny bit of coolant or condensation along the crack. I don't see any moisture on the motor, wires or hall effect components though. One screw for the cover is a lot longer than the others and was gummed up with old coolant. As you can see from this picture someone has been in here before (buggered screw heads). There is an intact seal in the motor housing though. (I bought the mill used.)

Even though I live in a town of 45K the only motor shop only does pump motors. There might be a control electrician but I'll have to wait until Monday to start making calls.

Again, thanks for your help. If you come up with any other ideas please let me know.

motor wire end.jpg motor wire cap.jpg
 

JimDawson

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#4
All fields check "OL" to ground.
blk-red = 0.9 ohm
blk-blue = 0.9 ohm
red-blue = 1.8 ohm
OL to ground is good.

The winding to winding numbers are not so good. red-blue is 2x the other two. The problem is that I don't know if they should all be 0.9 or 1.8. I assume that this test was done with the motor leads not connected to the controller.

EDIT: I just checked a new, just out of the box, 1.8 KW servo motor and the winding to winding was 1.00 ohm across the board.

The resistance you feel when turning the motor by hand seems normal.

It could be that you have a shorted winding, and the drive is current limiting and shutting down above 800 RPM. If there is an indicator of some kind on the drive, maybe you can see an error condition (blinking LED, or even a text display if equipped)
 
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Groundhog

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#5
No, the motor wasn't connected to anything when I did the tests.

There is no error message when it shuts down. There is one display that I neglected to look at that may show a light for an error. I'll have to re-install the motor and try it. However, even when it is running (below 800 rpm) is is no where close to right or normal.

I sent an email to the Jeff at Syil America (the dealer - just down the road from you in Coos Bay). He has always been extremely helpful with parts, but we may still have a problem figuring out what to replace. I'm sure I'll hear from him Monday. If the motor isn't too expensive I might have to just start replacing things one at a time until it runs?
 

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#6
Hi Mike,

I've just watched your video, the noise you are hearing is the rotor hitting the stator. I think the bottom bearing has failed ! If you use a pointed tool in the shaft center at the bottom, you might be able to move it from side to side. If so its new motor time.
 

Groundhog

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#7
Nope - doesn't seem to be a bearing. I took it apart enough to be able to spin each bearing and they feel good.

It doesn't look like Syil America has a motor. My mill is 110v and the new mills have been 220v for a long time. But it doesn't seem that they are willing to try to get one either. They gave me the email address of Syil in China and told me to try there. In all fairness I didn't buy the mill from them, but they are the only North American dealer.

But now I'm stuck without a working motor, not really sure what is wrong and not well enough versed in electronics to trouble shoot it. And it seems that I can't buy a direct replacement either (I would like to be sure that it is bad before I replace it though!).

I think I can replace the motor and controller, but I don't really know what I'm doing when it comes to the cnc's electronics. I would need some step by step instrictions. Are there any good videos or web sites to help with that?

Does anyone know of somewhere I can send it to be tested and rebuilt if needed? Or would that be cost prohibitive?

Anyone with suggestions of what I can do please chime in. I'm lost.
 

BaronJ

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#8
Hello Mike,

That motor appears to be a BLDC, (Brush Less Direct Current) one. In the picture of the bottom the shaft looks to be slightly off center.
So I'm not convinced that the bearing at the bottom is OK. Since you have it apart are there any signs of rubbing or abrasion on the rotor or stator.
 

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Groundhog

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BaronJ -
Thanks for the heads up!

I glanced at the PJM Tech web site earlier but didn't pay a lot of attention. The 123 frame you linked to is close, but not quite right.

I've learned that the "123" is the distance between the mounting holes in millimeters. I searched their site some more and found a motor with the same specs as my motor. However, part of the motor designation is different and I don't know what that means (BLM-92GM-KHB5N4 compared to my MLB-92IM-KHB5N4). All of the specs they list are the same so I don't know what the difference is - if any.

I plan on going to the local motor shop this morning. I don't think they work on stepper brushless motors, but maybe they can give me some advise (since I am clueless). I'll take a print-out of that web page with me.
 

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#11
Hello Mike,

The first part of the number is the motor distributors designation, that last part corresponds to the numbers given in the PJM listing. Knowing the physical dimensions and the motor power, you should be able to find the correct one.

I would Email PJM and give them the numbers that are on the ratings plate asking if that motor is one of theirs and if they will supply you with one. Also ask for a price along with carriage charges. You may be surprised !
 

Groundhog

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#12
Update Monday, Aug 20th

I have a question that maybe someone can shed some light on.

I still haven't pinned down the problem with the spindle motor on my Syil X4+ CNC mill. In other words I still don't know if it is the motor, the control board or the wiring/connections. But it really doesn't seem to matter because there don't seem to be any replacement components anyway. I am going to have to replace both the motor and controller with a 220V set (the mill is now 110V).

First off, I can easily supply the 2 different voltages. But can you foresee any problems running the spindle with 220V and the X, Y, Z axis and other components at 110V? The suppliers I've been talking too don't seem to be concerned.

Second, I've found have a system usiing a motor with the exact physical dimensions as the one I have. But theirs is less powerful and slower turning;

AC Servo Drive - H01 Frame
0.75~1.0kW servo motor pair
0.75kW AC servo motor Rated 3000rpm, Rated torque: 2.9Nm, Peak torque: 7.2Nm

while my old motor is labeled:
300V DC
4.3A
1100W
3.14Nm
3500r/min

Is that something I need to be concerned about (or is it likely my old motor label is just a bit over rated)? My actual top speed was 3470 by hand-held tach and of course I don't know about the torque. I really was hoping for a bit more speed, not less.

(Note: Syil Corp. in China has offered to put together a similar package - but they haven't responded for my request for pricing and specs in almost a week. They might have a more powerful / faster set or a better price but I don't know??)

Any thoughts you have would be greatly appreciated as I am totally uncertain what I should do.

Thanks,
 

JimDawson

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#13
I answered this in your PM to me, but I'll post it here also for the benefit of others.

There shouldn't be any problem running the spindle at 220 and the rest at 110. I would just bring in 220 with the neutral and split off the 110.

I can't find that motor in the DMM specs. That would be a 92mm frame, and all I see is a 86 and a 130, no 92. Is this something you inquired about directly to them? The 0.75KW motors seem to have a 3000 RPM base speed with a 5000 RPM max speed.
 

Groundhog

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#14
Jim, PM replied to - thanks

In short; yes, I've been talking to Michael Tien at DMM. He is very helpful.

I think I will order the goodies from DMM tomorrow. He said a week or so to delivery. I'll keep this forum (and Jim) up to date!
 

BaronJ

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#15
Did PJM reply to your Email ?
 

Groundhog

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#16
I never did email then because it was looking likely that it isn't the motor. I just went with DMM (who Syil said would be the best route for help).

Speaking of which, I was under the imperssion that it would take several days before they could ship. I placed the order this morning and received a shipping notice to look for it Thursday!
 

BaronJ

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#17
OK. Keep the forum updated.
Thanks:
 
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