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IndustryArena Forum > MetalWorking Machines > Fadal > Rumbling sound from the spindle motor area vmc15
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  1. #1
    Join Date
    Aug 2010
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    33

    Rumbling sound from the spindle motor area vmc15

    Hi guys,
    My machine makes a mysterius rumbling sound from the spindle motor area.

    The machine is:

    Fadal VMC-15
    Model #: 914-15
    Year of mfg: 1997
    Serial #: 9708670
    Baldor Vector Drive, the sticker says: INV-0045
    Drive, Baldor FVF1915C; 10HP VMC1
    7500 RPM, 10HP, Y/D VMC15

    Spindle motor: Baldor 10HP, 3ph
    Spec.: 37F71800073 X073 X173
    Frame: 215TC,
    Volts: 230/460
    There is no mechanical transmission on this machine.

    Line voltage readings are:
    A12 - B12 : 231V
    A12 - C12 : 245V
    B12 - C12 : 233V
    DC readings are confirmed to be 5V, +12V and -12V.
    I disconnected the regen. resistor and it reads 13 Ohms.
    The temperature in the room where the machine is used is 70 - 85 deg.F.

    The machine was bought used six years ago.
    I had no problems in running it in any range of speeds or rigid tap from 2-56 to 1/2-13 TPI.
    The spindle load during cutting as observed on display rarely exceeds 30 - 35%.
    As I use frequently small tools most of the time the spindle will run between 5000 - 6500 RPM @ 15% spindle load.
    I mostly cut aluminum, brass or plastics.
    I only use pure MOBILMET 404 as coolant and Vactra oil #2 for lubrication.
    The machine may run for 20 hrs straight for a day or two and then it may be not used for weeks before the next run.

    All the videos I mention in this post and some more info can be found on: http://www.flex-mount.com/fadal/fadal.html

    A few weeks ago I noticed a strange rumbling sound while the spindle was decelerating to stop. It happened after running the machine that day only for about 30 min.

    When attempting to start the the program, during acceleration the rumbling appeared again and then disappeared before the spindle reached 4000 RPM and the spindle stayed quiet all away to 6000 RPM.

    The rumbling was getting louder for each tool change, and always occurring only on deceleration and acceleration.

    After a few more minutes the spindle developed hesitation during orientation and during start. (video 02_203.wmv and 03a_212.wmv)

    I had to shut down the machine as it was impossible to run it.

    After about 2 hours I started the machine again to show to a friend of mine the symptoms and see if he had some suggestions.

    To my surprise the machine started without any problems and could be run on any spindle speed without any unusual sound. (video 01_210.wmv)

    So I started the job and after about 30 min. the symptoms gradually repeated to exactly what I experienced earlier forcing me to shut down the machine again.

    I repeated this cycle a few times and predictably had the same results.

    After while I noticed the following regularities:

    Shutting down the machine for 20 min. gave me 11 min of work before the symptoms forced me to shut it down.
    For 30 min. break I was getting 14 minutes of working time.
    For 40 min. break - 17 min. working time.
    For 2 hrs break and more - also only 17 min. working time.

    In each event the spindle load indicator was climbing from about 25% at the beginning to over 60% at the end of my working time.

    In each event the spindle and the motor stayed quiet during it's cutting time at about 5000 RPM without any RPM fluctuation.

    Interestingly I noticed that merely turning the main power to the machine ON without turning ON the controller (not pressing the green "CNC Power ON" button) and waiting for about 10 to 15 minutes causes the rumbling problem to show up.

    So it looks like it does not matter if the motor is energized or spindle is spinning - the problem will show up after the magical 10 to 15 minutes.

    I also noticed that I was able to run the machine on 5000 RPM for about 45 minutes with only one tool without stopping the spindle.

    I re-wrote my programs so I would use only one tool for all the pieces without stopping the spindle (I used G4P66000 instead of M1) and then shut down the machine for about 1 hour and then do another operation again using one tool at a time and taking another hour break until I finished the job.

    The longest time I used "one tool run" was over 3 hours with 6000 rpm with no unusual sound or vibration however, because I was afraid to damage something during normal stopping of the spindle I shut down the machine by cutting the power using main disconnect.

    To my surprise the spindle coasted down to 0 RPM in about 80 seconds without any unusual sound or vibration.

    The situation started deteriorating gradually until finally on Aug. 8th I was not able to run the machine at all because:

    1 - terrible rumbling on low RPM (two bangs per revolution of the motor) ---See the linked video: 07_244.wmv
    2 - The spindle refused to accelerate to higher RPM and the load indicator was fluctuating up and down between 40% and 80% --- ( video: 08_245.wmv)
    3 - The spindle was hesitating during start sometimes even kicking backword before it started in the right direction.
    4 - The spindle would not orient properly. (video: 06_241.wmv)
    5 - The machine runs on low RPM with constant rumble. ----(video 04_213.wmv)

    As an additional information:

    I used a stethoscope to listen to the motor and spindle bearings rotating the spindle manually and while the spindle was coasting without detecting any abnormality.

    At the end of my 3 hours continuous run, using IR thermometer I measured the temperature of the top portion middle section and bottom portion of the motor as well as the spindle. The motor upper section was 95 F. middle section 101 F lower section 96 F. Spindle was 85 F.

    I also checked all the components in the space where the Vector drive resides looking for overheated components.
    All components and connections were about 85 F. Vector drive was 89 F and the transformer 90 F.

    I suspect that what seems as a mechanical noise may really be of an electrical origin such as bad pair of windings in the motor or misenergized winding. Or perhaps the vector drive goes bad. The encoder seems to be OK because I can run the spindle (with bangs) at any very low RPM without change in its speed.

    I am completely lost.

    Is there any good soul that could help me to solve the mystery?

    Again, all the videos I mention in this post and some more info can be found on: http://www.flex-mount.com/fadal/fadal.html



    Voytek1

  2. #2
    Join Date
    Mar 2010
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    0

    spindle noise

    It sounds like a bad motor with some bad windings,or possibly the drive or encoder going out. you should go up to were the electic box is buy the motor and disconnect the wires to the motor and ohm them to ground,there should be no current to ground and if you connect the legs and go leg to leg it should be around .05 to .3 ohms .also listen in back buy the drive to the wye/delta relays and see if they are clicking causing interupted current to the motor.start here and repost results.

  3. #3
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    Aug 2010
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    33
    Sorry for the late reply, I had a family emergency.
    Thanks Alex for your input.

    I checked some stuff and these are the results:

    Wye/Delta relays seem to function OK. They are activated after the green CNC Power button is pressed and click decisively.
    I also examined all eight contacts and cleaned them to make sure there are no burned spots.

    I checked the motor windings for shorts. No shorts.
    The resistance between legs on the motor is 0.3 Ohm for each pair of legs.

    I disconnected and took apart the resolver on the top of the motor. It is clean. Just in case I wiped the disk with the lint free cloth (the one used in cleaning fiber optic components) as well as the detector.
    I put it back together.
    This did not change the machine behavior.

    I also managed to run some more tests (described below) to look for some regularities.

    Test 1:
    I turned the machine on and set the spindle speed (in MD) to 4000 RPM.
    I activated the spindle (M3) and the motor started with some rumbling which quickly disappeared on it's way to 4000 RPM.
    I increased the speed all away to 5500 RPM without any unusual noise.
    The spindle was then left running for about 3 minutes.
    I shut the motor down with M5 and the rumbling sound appeared right before the stop.
    The spindle stopped in about 3 seconds.

    Test 2:
    I turned the machine on and set the spindle speed (in MD) to 2500 RPM.
    I activated the spindle (M3) and the motor started with much more rumbling than before which again quickly disappeared on it's way to 2500 RPM.
    I started manually reducing the spindle speed slowly and the rumbling began at about 1800 RPM.
    The more I decreased the speed the louder the rumbling became.
    At about 1550 RPM it became unbearable.
    Then as I was increasing the spindle speed gradually the rumbling gradually was disappearing until I reached almost 1900 RPM at which speed the rumbling was gone.
    I repeated the same procedure without stopping the motor about a dozen of times. Every time with exactly the same results.

    Test 3:
    I turned the machine on and set the spindle speed (in MD) to 150 RPM.
    I activated the spindle (M3) and the motor failed to start right away.
    It kept kicking on for several times but finally started with distinct bumping sound and stayed that way on 150 RPM for about 5 minutes then the machine went into emergency stop by tripping the motor overload relay.
    I think the message was Error #8.
    I shut down the machine.
    I reset the relay (White button see new picture 264b.jpg) and I noticed that two terminals (T1 and T2) on that relay were very hot and one (T3) barely worm. Actually the hot part was the center portion of the relay.

    After these tests the spindle had difficulty to both: start and stop decisively.

    I shut down the machine and after about 10 minutes I was again able to start the motor and run it at 2500 RPM. With same results as in test #2.
    This time however the spindle had difficulty to start. (See new video: Post2.wmv)

    I looked at the explanation of an Error #8. Where is the spindle magnet sensor?

    I also checked all terminals inside the vector drive for loose wires and visually checked for any burned components.

    The new video and some more pictures can be found at: http://www.flex-mount.com/fadal/fadal.html

  4. #4
    Join Date
    Jul 2006
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    142
    What is the possability that a magnet is coming loose in the spindle motor itself?

  5. #5
    Join Date
    Feb 2008
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    547

    Red face Smitty your to young for a senior moment! - Grin

    Quote Originally Posted by smittys800 View Post
    What is the possability that a magnet is coming loose in the spindle motor itself?
    ??? Sorry smittys there are no magnets in the spindle motor. Voytex the spindle magnet sensor sets just under the fan on top of the motor. (I think that what your asking for) Hummm... maybe I the one having the senior moment!
    Steve

  6. #6
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    Quote Originally Posted by scadvice View Post
    ??? Sorry smittys there are no magnets in the spindle motor. Voytex the spindle magnet sensor sets just under the fan on top of the motor. (I think that what your asking for) Hummm... maybe I the one having the senior moment!
    Steve
    Right, there are no magnets in the spindle motor.
    I also do not see any magnets on the top of the motor under the fan ( or I am just to old ?).
    I believe the spindle rotation sensor is the one marked by me as Sensor #2 on the second set of pictures at http://www.flex-mount.com/fadal/fadal.html
    The magnet is right under it.
    I am assuming that the spindle rotation sensor works just fine since it causes Error #8 when the spindle (or motor) refuses to start after M3.

    Any other suggestions?

    Voytek

  7. #7
    Join Date
    Mar 2003
    Posts
    900
    voytek1--
    The error #8 is indicating a problem with the spindle orientation circuit. It could be the Hall effects sensor looking at the embedded magnet in the spindle pulley. This is the usual cause of the error. Also the cable down to the 1010 spindle controller card or possibly, but highly unusual, the 101 controller card itself. An error of #10 would indicate the spindle motor encoder having an issue.
    To verify this:
    1. At Enter next command enter DI
    2. enter DS
    3. this will display some sensors and switches ion the screen.
    4. Look at the center column and the top item-ORIENTSP
    5. This is orientation sensor
    6. manually rotate the spindle 360 degrees slowly several times.
    7. Each time the magnet passes under the hall switch the display should turn to a value of 1 and then return to 0 as the magnet moves awaay.
    8. If this does not change state or is erratic in changing state then you have verified the that circuit is having an issue.
    9. To remove the switch display from the screen press the letter X.

    Hope this helps clear things up.

    Neal

  8. #8
    Join Date
    Feb 2008
    Posts
    547

    Add on to Neals post...

    When doing what Neal suggest, clean the area around the hall sensor (Shaft Mag. and sensor area) Sometimgs goo and chips can get in there. I've seen a few machines where the little can like cover is missing or loose, allowing this to happen. Also a loose connection. Sometimes people mickymouse an after market auto air filter up there and that can push on the sensor and cause problems.
    Steve

  9. #9
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    Aug 2010
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    I verified that the ORIENTSP goes from 0 to 1 while magnet passes under the sensor.

    I think that because the motor refuses to start rotating the spindle on time,
    the sensor properly reports it to the controller and the machine goes to the emergency stop with Error #8.
    I am in the process of running extra tests to look for more specific events that would occur in predictable manner.
    I will post it as soon as I get it done.
    I will also update the material on the my web page.
    Meanwhile, thanks guys for your involvement in trying to solve this puzzle.

    Voytek

  10. #10
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    spindle noise

    I think the spindle drive may be the problem.check the voltage going to the motor while running and then while it is acting up see if it is jumping around,if the drive is bad the noise can sound just as bad as a bad bearing.I did have an encoder also cause similar issues before especialy the us digital one you have ,the new ones are sealed one pc. units.they are around $300 or so.and are the cheapest part to try first,and in my opinion are just plain a good idea to replace i have seen so many issues caused by the old ones during my time in field service that they are one of the first things i try with an oddball issue like this.you can just run the cable on the outside to test with,if you get one be aware 2 wires have changed( the thick black goes to shield,and the white goes to blue).you also can check the control input voltage to the drive,check pins 4+6 on the 6 pin molex for dc voltage,between 0 and 10 vdc check for steady voltage.there is also the possiblity of a bad motor bearing showing up under load.if you have another fadal now would be a good time to swap the drives and see if it follows.

  11. #11
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    Aug 2010
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    33
    I checked the voltage between pin 6 and 4 on molex connector.( See: molex.jpg)
    The voltage is steady on each speed regardless if the motor rumbles or not.

    Maintenance manual (page 271) says :

    “ On a standard machine a 1.3 volt DC signal will result in a speed of about 300 RPM in low range. ”

    I set each speed with Sxxx, so I was in the low range and these are my readings:
    150 RPM: ------- 0.21V
    200 RPM: -------0.27V
    300 RPM: ------- 0.41V
    500 RPM: ------- 0.68V
    950 RPM: -------1.3V
    2500 RPM: ------3.38V
    What am I missing?

    Another thing I noticed was that the rumbling noise on the low range disappears at about 2000 RPM of the motor sped but on the high range disappears at about 3400 RPM of the motor speed.

    This would mean, if my logic is right, that it could not be of a mechanical origin (like a bearing) from the motor which should stay at the same RPM of the motor regardless of the low or high range of setting. (See. Video: Low_High.wmv)

    I disconnected all the wires at the motor from lines T1, T2, T3, as well as from lines 4, 5 and 6.
    I measured a resistance and these are the results:
    Between the wires that were connected to the line T1, T2 and T3 all readings show an open circuit
    Testing to the ground shows an open circuit.

    Between the wires that were connected to 4, 5, and 6 all three readings show an open circuit.
    Testing them to the ground also shows open circuit.

    Between wires that were connected to 4 and T1: 0.16 Ohm.
    Between wires that were connected to 5 and T2: 0.16 Ohm.
    Between wires that were connected to 6 and T3: 0.16 Ohm.

    And finally between 6-2, 6-1, 5-3, 5-1, 4-3 and 4-2 shows an open circuit

    During each measurement I manually rotated the motor shaft 360 Deg. to make sure that the readings do not change. No change detected.

  12. #12
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    My apologies. I made a mistake in taking the measurements of the resistance between the motor leads.
    I just edited my last post to give corrected readings.
    Sorry I guess I am just getting old.

  13. #13
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    When Ohming a motor check from T1 to T2, T1 to T3, and T2 to T3. Your reading with a standard Ohm Meter should be bewteen .05 an .8 ohms for a spindle motor.
    NOTE: make sure that the output wires (T1,T2,&T3) from the vector drive are disconnected from the drive. Checking from each wire to ground should be OPEN.

    Neal

  14. #14
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    Quote Originally Posted by Neal View Post
    When Ohming a motor check from T1 to T2, T1 to T3, and T2 to T3. Your reading with a standard Ohm Meter should be bewteen .05 an .8 ohms for a spindle motor.
    NOTE: make sure that the output wires (T1,T2,&T3) from the vector drive are disconnected from the drive. Checking from each wire to ground should be OPEN.

    Neal
    In this configuration all three are 0.3 Ohm.
    The results of readings for other configurations are in my previous post.
    Some of them are also with wires from Wye/Delta relays disconnected in the motor junction box.
    I re-traced wiring of Wye/Delta. It is shown on included WyeDelta.jpg
    It looks like Wye/Delta relays in neutral (power OFF) state connect (4-10), (5-11), and (6-12) together.

    Some larger files and videos are constantly updated at http://www.flex-mount.com/fadal/fadal.html
    Attached Thumbnails Attached Thumbnails WyeDeltaL.jpg  

  15. #15
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    spindle noise

    The motor sounds good and the signal voltage is normal.most of the time when the encoder goes out the load meter will bounce around or max out at medium speeds,and the control will read that it is going full programed speed (ie.7000rpm) but is really not going more than 4000rpm,you can tell if you program 1/2 of max speed and move the override pot around and listen to the motor ramping if the sound does not change over 100% then there is an issue.By all the testing you have done i am 90% sure that your drive is going bad.another test you can do is to use a battery to input the dc voltage to the drive and different battery combos to test different speeds. the drive uses 0-10vdc.10 for full speed.the encoder is wired into the drive directly and can still have the effect listed above.I think the next step is to get the drive swapped out with a known good one,if you can get a loaner from someone.

  16. #16
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    Aug 2010
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    Well, I still have a a problem and it is getting worse.
    Now it is almost impossible to shut down the machine in a normal fashion without terrible noise.
    It sounds like a rock crasher and I am concern with an integrity of the entire frame and the motor.
    So I have to use a main disconnect to stop the spindle (motor).
    This way the motor and the spindle coasts quietly to stop.

    I've tried to apply direct DC voltage (1.5V) to pin 4 and 6 on Molex connector but the motor did not start at all.

    I checked the voltage on the output from the vector drive to the motor while running it @ 2500 RPM.
    These are the reading between:
    T1 and T2 ----- 520V
    T1 and T3 ----- 520V
    T2 and T3 ----- 482V

    Does anyone have a clue if these readings are normal?

    I found an excellent manual describing operation and functions of the keypad located on my vector drive.
    It is at this link: www.baldor.com/pdf/manuals/718-599.pdf
    I am sure it may be useful to many of you.

    This is some of data I pulled out from my drive using keypad's diagnostic mode:

    1 – Bus voltage --- 333V
    2 – Total drive running time ---- 4627 Hrs 42 Min.
    3 – Software version ------- S18-2.18 FA5

    I also managed to run the motor on different speeds using the keypad's LOCAL mode.
    The rumbling is very pronounced while starting the motor but once it gets to about 2500 RPM the rumbling disappears.
    What's very strange is that when I stop the motor using keypad's STOP button the motor sometimes stops dead in about 2 second, but sometimes it just coasts to stop and sometimes breaks aggressively just to release at about 1000 RPM and then just coasts to stop.
    So the symptoms are the same while running the motor under the control of the motor's control card and from the LOCAL mode of the vector drive.
    I think it would be logical to at least eliminate the control card as a culprit.
    Well, I am running out of ideas.

  17. #17
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    Mar 2003
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    900
    All three legs should be within a few volts of each other. Your have one leg that reads 42 volts lower than the other two.
    Also the readings of 520 volts concern me. That just doesn't click right with me.

    Neal

  18. #18
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    Aug 2010
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    Although the problem is still there I think finally I am getting some more meaningful data.
    I removed the belt and it turns out when I use the keypad in the LOCAL mode the vector drive does not see the magnetic spindle rotation sensor so there is no longer 3 seconds limit.
    I am able to run the motor without the spindle and have all the time I need to take some voltage measurements without the spindle interference.
    The rumbling is still there, and it looks like it is of purely electrical nature.
    I attempted to rewire output from the vector drive to the motor to see if the difference in voltage follows the output of the vector drive or the windings on the motor.
    The connections are shown in attached file CrossConnections.jpg .
    It looks like the lower voltage follows the vector drive regardless which winding is energized so the conclusion would be that the motor probably is OK.
    For some reason I could not run the motor on one of combinations that's why I said “probably”.
    The next test I am planning to run is to find out if the bang that occurs every 180 deg of the rotation of the motor shaft will change its location in relation to the shaft while the power from vector drive is connected to different windings.

    I also managed to access a Fault Log of the vector drive.
    All 32 entries are attached in the file Fault_Log.pdf.
    There are 3 different faults:
    PWR Base FLT,
    Over Current FLT,
    and Current Sens FLT,
    The last one suggests a problem with a current sensor and/or it's connection to the control board.
    I just wish I new where that current sensor lives, is it in the vector drive enclosure?
    The first and second fault points, among other things, to the encoder to motor coupling.
    But why the symptoms are so predictable and regular (cyclic)?
    One would think that the coupling or electrical noise would create rather random rumbling.
    Any thoughts?
    Attached Thumbnails Attached Thumbnails CrossConnections.jpg  
    Attached Files Attached Files

  19. #19
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    Feb 2008
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    547

    Question Just wondering...

    Do you have the ability to High pot the motor? Otherwise, I suspect the VF drive. I'm not an expert though...
    Steve.

  20. #20
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    I would like to thank every one who tried to help me to solve the problem and pinpoint to the specific device.
    I think I definitely narrowed it down to the Baldor's vector drive.
    In my attempt to confirm my conclusion I contacted Baldor and was given a name and address of a company that is an authorized Baldor repair center and deals specifically with their vector drives.
    I was hoping to to get a suggestion as to either a board or a component that is failing.
    So I removed the drive from my machine, drove 130 miles and left the drive for a bench test.
    In about a week I was called and told that they could not test it because Baldor could not supply them with any schematics for this particular drive type.
    The guy was trying to be very helpful and devoted at least 1 hour of his time to talk to me, however because a lack of documentation he could not make any definite diagnosis.
    So I drove the drive back (130 miles) home and re-installed it on the machine.
    I used the machine for last month in it's limited capacity (only on 2500 RPM and without stopping the motor between operations).
    I also totally took apart the drive several times looking for something indicating obvious failure of some component but with negative results.
    Every day the usability of the drive became more and more limited.
    Each time I stopped the machine I had to wait longer and longer for the drive to actually start working and allow me to turn the CNC controller on.
    Initially the waiting time was just about 15 minutes or so but then got several hours before I was able to fire up the machine again.
    If I pressed the “Start CNC button” while a keypad on the vector drive was not showing anything the spindle load indicator was showing a light bar pulsating from zero load to about 40% every second or so.
    As of today the drive refused to start after six hours of waiting so I think I should finally declare it legally dead.
    I am ready to replace it with the new H2 type of a drive.
    The irony is that I am still not really 100% sure that this is going to solve my problem.
    I want to thank again every one and in particular Alex Gitzel who spent a lot of time with me on the phone and Neal as well as Steve (scadvice) whose hints were very helpful in narrowing down possible causes of symptoms of what started as “Rumbling sound from the spindle motor area”.
    Because your advices I was able to eliminate the spindle, the motor, the motor control board and other components leaving the vector drive as a final culprit.
    Even though I could not get to the single component within the drive I consider it as a great learning experience.
    I hope all the 1147 readers of my post also found it interesting and useful.

    Thanks

    Voytek1

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