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  1. #1
    Join Date
    Jun 2008

    Meldas 520AM, Touble with Spindle Orientation

    Run into a new problem with my ”new” Feeler / Meldas 520AM VMC:

    When I have the machine in Manual mode and I want to orient the spindle (rotate it to the tool change position), most of the times it will not orient properly. It starts to rotate fast but then slows down to really slow creep before it stops at the orient point. When I grab the spindle when oriented it is possible to move it a little back and forth (spongy feeling) before it gets stiffer.

    My other Feeler orients much quicker and does not allow any spongy moves after oriented. It is quite stiff when oriented.

    Does anyone know which parameters that affect the spindle orientation?

    I have checked the cable from Magnet Sensor and Spindle drive’s CN6 port and it was OK.
    I have also checked the cable from Spindle motor’s built in Pulse Signal Generator and Spindle drive’s CN5 port and it was OK.

    Maybe it is an encoder problem, a magnet sensor problem or parameter problem?
    The machine has produced a lot, so maybe the parameters worked OK and lately some encoder or magnet sensor problem has occurred?
    What do you think?

    This is the kind of orientation setup I have on both machines.

    On the newer (1998) Feeler FV-800A with the orientation problem there is a SJ-N 7.5A Spindle motor.

    On my older (1996) Feeler FV-800 with working orientation there is a SJ-7.5XW8 spindle motor.

    Should some parameters differ due to the different motors used?

  2. #2
    Join Date
    Oct 2005
    Parameters might vary between machines. There should be several that affect the spindle orientation. Sensor might be a magnet on the spindle pulley with the sensor attached to the head. All the Mitsubishi machines I've seen have that spongy feel when the spindle is in the oriented position. Some wiggle is normal.

    I think the parameters you would adjust are on page 6 of the spindle parameters.
    Attached Thumbnails Attached Thumbnails image.jpg  

  3. #3
    Join Date
    Aug 2009

    Meldas 520AM, Touble with Spindle Orientation

    Hi CNC Viking,

    Nice to learn that the RS232 problem is solved.

    Regarding orientation, please ref. the attached document for your reference.

    I believe the Orientation is done by Megnasensor (if with gearbox), the other options are Motor PLG (If no gear box) or External Encoder(if with Gearbox).

    This can also be confirmed from Spindle Par. SP037,
    i.e. SP037, Bit 0 = 1 (External Encoder),
    Bit 1 = 1 ( Magnasensor),
    Bit 2 = 1 ( Motor PLG)

    If PLG or External Encoder, then PGE (SP002) need to be increased to increase the servo rigidity, else if it is Magnasensor, PGM (SP001) need to be adjusted.

    You can adjust this parameter in combination with CSP (SP006) as per the table in section 2) of 1st page, as per the phenomenon observed on machine.

    You can further optimize with the next parameters to get best performance.

    Bet Regards,

    Attached Files Attached Files

  4. #4
    Join Date
    Jun 2008
    Thanks a lot for the info...

    The parameters you mention must be SP005, SP006 and SP007 and they are all mentioned in Girish' PDF as well.

    Both my machines have spindles driven by toothed belts and ratio is 1:1, so no gearbox. No encoder on spindle.

    They both have a Magnet Sensor reading a rotating magnet attached to the spindle.

    Both have a built in Pulse signal generator (PLG) in the Spindle Motor.

    Present parameters from the 2 machines.

  5. #5
    Join Date
    Jun 2008
    I also saw a note in the Instruction Manual on page App.1-116, that SP125 should have 1/2 of SP124 value.

    Look below for my present parameters. It is a bit mixed up for FV-800A, don't you think? It seems obvious that I should swap values between SP124 and SP 123?

  6. #6
    Join Date
    Feb 2012

  7. #7
    Join Date
    Jun 2008
    Dear slamet,

    There is little chance that your need will be seen as you have rised your question in a thread adressing "Trouble with Spindle Orientation".

    You will most likely receive more answers if you start a separate thread for your boards.

    Just my 2 cents...

  8. #8
    Join Date
    Jun 2008
    OK, today I have been playing a little with spindle parameters.
    Now it orients more often than not. There are however occations when it doesn't.

    I changed to the yellow ones, the old ones can be seen on the right side.

    The new values for SP124 and SP125 made the oriented position a lot stiffer.

    Then I did some full tool changes in MDI mode. It went well, but then suddenly the arm hit the spindle dogs when spindle was not oriented.
    How come, that there was an OK signal to let the arm do that. What gives the "oriented" signal anyway, and how can I check for any bad component?

  9. #9
    Join Date
    Apr 2007


    hi there, had a problem with a Feeler simular to what your looking at
    you might want to look at the belts , (might half to feel in side the houseing and see if the belts have lost teeth, what can happen is the senosor reads right placement but inertia swings the spindle a few degrees off so it hits the dogs

    hope it help

  10. #10
    Join Date
    Jun 2008
    I will take a closer look at it, but I think that the arm comes in too quickly, before the spindle even reach oriented position. Or the spindle overshoots the point and get hit by the arm. Maybe i can record on video and look at it in slowmotion?

    Also, there are a lot of switches that can be stuck or not acknowledging position for tool pot down/up, arm start, arm half way, arm end positions, etc...
    I will look at those too and their cable paths all the way back to the boards.

  11. #11

    Re: Meldas 520AM, Touble with Spindle Orientation

    dear all,

    Recently I purchased Hartford HV-35 with MELDAS 500 milling machine. It was sitting in some ware house for some time, battery died and machine lost parameters. In addition seller did not provide me with documentation.

    It has M520AMR control and Italian Hartford distributor managed to provide me with some parameters for that machine model and I managed to read in.

    In this moment only thing that is not working on machine is M19 or tool change. I can see from portal that you are experienced with Mitsubishi controls.

    when M19 command is given, message emerge "MDI running" but spindle is not rotating or blocked in position.

    spindle motor has built in encoder and spindle module is MDS-A-SPJ-75

    is there any way you could help me or any idea how to resolve machine issue?

    thank you in advance!

  12. #12
    Join Date
    Jun 2008

    Re: Meldas 520AM, Touble with Spindle Orientation

    Very long between updates, but this machine has been a little in the back seat the last 10-12 years.

    Anyway, in 2021 I changed the spindle drive, servo drives, power module etc to the newer C1 versions. After that I got the 018 alarm because the C1 servo drives did not like my OSE 253 encoders! It wanted high speed OSE 104's or OSE 105's. Recently I bought 4 brand new OSE 105 S2's (1000 000 pulses per rev) and installed those. After some initial servo parameter changes the system is now up and running.

    So now I could continue to check on the orientation issue again and play around with the parameters in the documents in post #3 again and it responded immediately! Now I have fast orientation and it is rigid. Tool changes are fast and accurate.
    Problem solved! I put those early orientation problems down to my old faulty spindle drive.

  13. #13
    Join Date
    Jun 2008

    Re: Meldas 520AM, Trouble with Spindle Orientation, SOLVED

    Hi, now re-labeled as "SOLVED"

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