Never is a wire to the Ground pin #4 Chinese seem to forget. I took the picture into an editing program and lighted it a lot, it looks black but no windings??
Never is a wire to the Ground pin #4 Chinese seem to forget. I took the picture into an editing program and lighted it a lot, it looks black but no windings??
1000x750 Workbee CNC - Mach4 - PMDX USB - Windows 10 Pro
A little lost. The windings should be in the motor body correct? This picture is just the connector cap. I'm not sure how to get the motor housing apart. Best I can tell a special tool is needed on the chuck end.
Over current or voltage running at 12k rpm drawing 2 amps? I was taking a 1/8” depth of cut using a half inch carbide ball mill at 120 IPM. Would that really overload the spindle cedar wood
I stripped a working hy 2.2kw water cooled spindle recently to get a close look. Not something i would buy!
That is normal for these spindles not to have the Ground connected, you are expected to connect it which almost all spindle users check this before they run it, they normally connect it with a ring terminal to where one of the cover mounting screws go, remove a piece of the plastic from the cover to clear the Grounding terminal and you are done
They are easy to take apart the nut / bolt on the back, it is left hand thread, and yes you need custom made wrenches so you don't damage any of the parts
Mactec54
Mactec54
You got lucky that you where not touching your machine when it failed, or you could of been electrocuted, that is why they have electrical codes
There is no warranty with any of these spindles, in most cases they ask you to send it back which will cost you more than buying a new spindle
Buy a New Spindle, you VFD Drive may be damaged also
Mactec54
Braking resistors are used.... well they are only used when braking. Not back EMF and we were talking about EMI? FYI and others .... just one reference. https://www.fortressresistors.com/pr...ing-resistors/
This is also to educate about EMI > https://kebblog.com/electromagnetic-interference-vfds/
By the way I agree with Mac, your screwed. Buy a new one from a USA vender and get a new VFD they recommend as a package deal. Or I have used Automation Tech for the the spindle motor and purchased a Japanese Hitachi drive from a USA vender. I got two instruction manuals with the drive (and DVD) and a 800 number to call If I had questions. Sure it cost maybe $100 or so more than the Chinese made ones or a knock off of a good Chinese drive.
Last edited by wmgeorge; 09-10-2019 at 10:00 AM.
1000x750 Workbee CNC - Mach4 - PMDX USB - Windows 10 Pro
Only EMI since when, you need to know and see the whole picture not just one part of it
None of the information you posted applies to a 400Hz spindle they only know what works for a 50 /60Hz motor, you are in a different place when you start dealing with a 400Hz 24,000 RPM spindle the back EMF if the drive DC bus capacitors can't handle it they are smoked, if the DC bus capacitors have a over voltage sensor then it blocks the over voltage then makes IGBTs fail
Breaking Resistors are used to absorb this Back EMF and protect the VFD Drive
Over Voltage VFD Drive Fault is caused by Back EMF you see these Drive Faults posted on here all the time
Mactec54
Your answers are typical for you, made up. The viewers here can do their own search for EMI and back EMF and get the truth. Braking resistors are only used when stopping the motor.
So your contending that a un-shielded supply power cord from the VFD to the Spindle motor caused the motor to fail?
Last edited by wmgeorge; 09-10-2019 at 01:06 PM.
Why would it have shown continuity between ground and the other poles if disconnected ground. Will check tonight
Since your ground pin is not hooked up to the metal on the frame I don't understand. If you get any reading to motor frame ground from a winding its bad. Winding to winding should read the same, pretty low 1 or 2 ohms.
No reading from winding to winding= bad. Your not touching the meter leads with your fingers are you?
1000x750 Workbee CNC - Mach4 - PMDX USB - Windows 10 Pro
That is what you are saying it is not what I said
What is happening when a Breaking Resistor is installed, please tell everyone your uneducated guess
Electromotive force (EMF) refers to the voltage generated by a spinning motor. Measuring this voltage in order to determine the rotational speed of a motor is commonly called Back-EMF since the voltage tends to "push-back" against the circuit driving current into a motor's windings.
Mactec54
It means you have a short somewhere
When you test you should check like this, when checking for a shorted Pin check to the body of the spindle not the unconnected 4th Ground Pin
Pin 1 to Pin 2=
Pin 2 to Pin 3=
Pin 3 to Pin 1=
Then check all to Ground the spindle body
IF you have a short to Pin 4 then you have a wiring problem in the plug, or the plug is damaged
This is the most basic of tests to do but will give an idea of what is happening
Mactec54
Back EMF reduces the voltage and therefore current in the motor windings. A motor has coils turning inside magnetic fields, and a coil turning inside a magnetic field induces an emf. This emf, known as the back emf, acts against the applied voltage that's causing the motor to spin in the first place, and reduces the current flowing through the coils of the motor. Since it reduces current flow, how can it burn the motor out??
Once again a Braking resistor on a VFD can NOT be in the circuit when the motor is running, its impossible! Only used when stopping the motor. This applies for all VFD's not just 50/60 Hz but all! When is Dynamic Braking Resistor used in VFD?
I am sure the readers here can figure this all out with a few simple Searches. Try https://www.google.com/search?client...UTF-8&oe=UTF-8
1000x750 Workbee CNC - Mach4 - PMDX USB - Windows 10 Pro
The first part that you where able to copy from some where that is correct, the below video will help you understand what happens when a motor stalls and has no Back EMF, this is what burns out motors
No one said it was
Yes I'm sure they can, some will already know this from there highschool physics on motor operation
Very basic Highschool Physics here is a video just for you, this demonstrates what happens when a motor stalls and why it fails
https://www.youtube.com/watch?time_c...&v=5mf4NmmLWnE
Mactec54
I hope you where able to check your motor, I would do the check from the back side of the plug, I had a thought that seeing you where getting some odd reading the motor may not be damaged, and it could be just the wiring of the plug that is the problem as others have had this problem as well with plug wiring being faulty, and the plugs in general being bad so worth a good look at
Mactec54
mactec54 posted on #27 No confusion here, that is why they install Braking Resistor to absorb the Back EMF
Mac I am done posting on this Thread, you change the Subject to get attention away from your mistakes. The Readers here on CNC Zone can sort it out if they read the info and links I have put up and ignore your errors. Even this might help you understand > https://forums.mikeholt.com/forum/ac...stor-operation
Last edited by wmgeorge; 09-12-2019 at 07:47 AM.
1000x750 Workbee CNC - Mach4 - PMDX USB - Windows 10 Pro
No mistakes with what I posted, the Highschool Physics video tells you the same thing
What I posted is correct, when a motor is running normally and you have a Braking Resistor installed the first voltage it will see is Back EMF with any sudden change in speed, so you have no understanding of how it works ,
A Braking Resistor is not only to help stop a motor fast, but to protect the VFD Drive from over Voltage spikes with normal running, ( decelerating or a stall Etc.) The Back-EMF from the Motor is being monitored by the VFD all the time
Mactec54