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    Default Bridgeport 760 VMC

    Hi all , I wonder if somebody could advise on my problem . I have a Bridgeport 760 VMC , I had a few issues starting to occur , namely the spindle started to struggle when accelerating , especially at low revs and first thing in the morning when cold . Also the machine would bomb out when stopping or decelerating . I was advised it was probably the spindle drive ( siemens ). I managed to locate a refurbished one and fitted it , using the memory card from my old unit to transfer the relevant parameters across . The machine started up ok and the spindle ran perfectly with no struggling to get going . so far so good . I then went to stop the spindle and to my horror it bombed immediately . I now obviously assume some other fault is at play other than the spindle drive . Any ideas Please.....Many Thanks in advance .

    ps . I did read on another thread ( from 2008 )about altering a parameter in the drive to increase the ramp up / ramp down speed as a possible fix , although it did say this was a just worth a try option and not really addressing the actual fault itself .

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    Thread bumpity,

    What year is your machine ?

    Is it an XR or older / different "Bridgeport 760 VMC".

    Nice you swapped out drives pretty neatly and transferred parameters.


    When you say "Bombs" the spindle locks out or just power / VFD just cuts out ?

    Curious what manuals you also have for the machine ?

    I'm wondering if there might be transformer/ surge/ ground issues.

    Machine has been running good for a number of years where you currently have it ?

    There may be parameters / various setting that might baby the spindle more but maybe that's more of bandaid than a fix - or maybe the setting / parameters could be wrong ?

    Wondering also if the spindle motor windings are burning through their insulation - lower resistance - less impedance / time for a spindle motor replacement (maybe) ?

    If cold and lower end start up and insulation on the spindle motor windings are burning through then there's a bigger surge / too lower resistance (tending almost towards a hard short circuit) that would trip out various breakers , relays and other "Protection" circuitry. More fused copper less inductive impedance, lower static resistance.

    Are there nominal resistance (test) values for the various windings of your spindle (in the tech manual ?).*

    __________________________________________________ __________________

    * Disclaimer for safety / electrocution etc.

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    Thanks for reply
    1987 is the year , when I try to stop the spindle it knocks out the simo drive 611 which sits next to the main spindle drive , which in turn gives a z axis fault as the head drops before the brake grabs it . It all resets after main power is turned off and back on again . On very low revs sometimes this dosn't occur , but anything over 500 rpm is a definite . I'm not very electrically competent myself but have gleaned that all the excess power is thrust back into the 611 from the main spindle drive on deceleration . My local bridgeport engineer seems to be scratching his head and guessing , but did suggest sending the 611 drive off for a repair , but as you stated there could be anything causing a spike and I feel i'm throwing good money after bad . Shame to scrap it but the bills are mounting .

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    YOu have not given enough info
    what control?
    how long have you had it?
    running on real 3 phase?
    Is it the lineup of siemens drives on a common DC bus? CHeck voltages

    Accel decel errors on spindle drives are common with phase converters, because the drive cannot sink voltage back into the grid. This makes me think of power supply issues as does the z drive error

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    Thanks for reply ,,,Its a 2500 control , while I've had the machine since new , its been in its present location ( new unit ) for 2 and a half years , problems started in the hot summer of last year . The spindle drive was getting very hot before it failed , but as said , this has been replaced with a refurbed one . Not sure what you mean by "real" 3 phase . All comments will be investigated and any further comments all greatly received .

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    Quote Originally Posted by I.Barnesy View Post
    Thanks for reply ,,,Its a 2500 control , while I've had the machine since new , its been in its present location ( new unit ) for 2 and a half years , problems started in the hot summer of last year . The spindle drive was getting very hot before it failed , but as said , this has been replaced with a refurbed one . Not sure what you mean by "real" 3 phase . All comments will be investigated and any further comments all greatly received .
    Problems started during the whole five minutes of the British Summer ? ;-),

    So simple question before things get super complicated,

    What is your machine plugged into for it's source of electrical power ?


    [US vs. U.K. power phasing is different .]. And if you are using a phase convertor or different / modified transformer.].

    U.K. single phase is 240V ...

    How to Get 3-Phase Power in Your Home | TNR

    ^^^ Just a quick snap shot overview of true three phase power in the U.K.


    If memory serves me right there is domestic U.K. split phasing for 480V (2 phase) for electric cookers and the like.


    480v Split Phase, new workshop, VFD's required | ElectriciansForums.net

    ^^^ It might get a little complicated if a special phase convertor or transformer is sought or needed.

    __________________________________________________ __________________________________________________ __________________________


    Could be weird for example if someone bought a US VMC off a US air base (in the U.K.) and tried to run it off "British electricity" . <- not very likely scenario but Gustafson's suggestion of wrong phasing and wrong type of phase convertor / transformer can explain some of the troubles you might be experiencing. Or if the machine was moved from an industrial environment to a more domestic environment - electricity wise.

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    So heidenhain TNC 2500
    check the voltage taps on the transformer are at the same voltage as what you are actually seeing on the line.
    Real three phase, as in are you running a phase converter.

    Check the voltage into the machine and the DC buss voltage on the Seimens drives


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