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  1. #1
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    Default New Milll....VFD

    We did a bit more spending today at 600 machinery buying a new Clausing mill to compliment the 40 year old Bridgeport that we bought brand new so many years ago. The question that this raises is on the machine there is a plate specifying speeds at 50 or 60hz and it occurred to me that we could hook it up to a VFD for infinite speed control and braking which might be useful when running heavy cutting heads at the same time running it at 60hz. Has anyone done this and found it to be advantageous? I wouldn't know if it is an advantage as I don't use the machine only some of the stuff that comes off it and the operator has not got a clue what a VFD does apart from what I have described to him.
    CHRIS

  2. #2
    BobL is offline Member: Blue and white apron brigade
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    Default

    Not sure what your question is Chris. Are you asking about the issues involved with adding a VFD specifically to a Clausing Mill or to a mill in general?

  3. #3
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    Quote Originally Posted by BobL View Post
    Not sure what your question is Chris. Are you asking about the issues involved with adding a VFD specifically to a Clausing Mill or to a mill in general?
    Mills in general, I think I know how to do it. Is a VFD on a mill worth doing as most more expensive mills have stepless spindle speed already. Is the increase in speed a worthwhile thing? The only real advantage I can see is far quicker traverse speed on the table.
    CHRIS

  4. #4
    BobL is offline Member: Blue and white apron brigade
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    Quote Originally Posted by Chris Parks View Post
    Mills in general, I think I know how to do it. Is a VFD on a mill worth doing as most more expensive mills have stepless spindle speed already. Is the increase in speed a worthwhile thing? The only real advantage I can see is far quicker traverse speed on the table.
    If the mill is multiple motor (main spindle, feeds and coolant pump) mill you can't usually drive the mill with one VFD as spindle and feed speeds really need to be independent so will need seperate VFDs.

    If you already have 3 phase then it's far less likely to be worth the effort.

    If you don't have 3 phase and are hoping to use a 240V 3P VFD to just drive the spindle motor then whether it's worth it depends on the motor - some mills have built in motors (ie cannot be replaced) and if these are delta then nothing short of motor rewires will get these back to full power.

  5. #5
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    Quote Originally Posted by BobL View Post
    If the mill is multiple motor (main spindle, feeds and coolant pump) mill you can't usually drive the mill with one VFD as spindle and feed speeds really need to be independent so will need seperate VFDs.

    If you already have 3 phase then it's far less likely to be worth the effort.

    If you don't have 3 phase and are hoping to use a 240V 3P VFD to just drive the spindle motor then whether it's worth it depends on the motor - some mills have built in motors (ie cannot be replaced) and if these are delta then nothing short of motor rewires will get these back to full power.
    This mill has a single three phase power lead and its own onboard power distribution including breakers. It is sold in other parts of the world for 60hz use as is.
    CHRIS

  6. #6
    BobL is offline Member: Blue and white apron brigade
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    Quote Originally Posted by Chris Parks View Post
    This mill has a single three phase power lead and its own onboard power distribution including breakers. It is sold in other parts of the world for 60hz use as is.
    That's pretty standard and does not change my above comments above, especially the issues regarding multiple motors.

  7. #7
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    Bob, they use this same mill at 60hz for the entire machine. If I put a VFD on it at 60hz what is the difference to plugging it into a 60hz power supply without a VFD.

    PS....I see your point.
    CHRIS

  8. #8
    BobL is offline Member: Blue and white apron brigade
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    Quote Originally Posted by Chris Parks View Post
    Bob, they use this same mill at 60hz for the entire machine. If I put a VFD on it at 60hz what is the difference to plugging it into a 60hz power supply without a VFD.

    PS....I see your point.

    A multiple motor mill typically has a contactor for each motor each with a built in safety switch. Lets say the table feed jams where by the load on the table motor goes up exponentially before it's own inbuilt safety switch kick in and cuts the power to the motor. Doing this to a VFD will blow chips and caps.

    All the VFD manuals I read say the the safest way to use a VFD is to have them directly connected to a single motor and then setup the VFD up to suit and protect that motor. This means one VFD to one motor and use the VFD to switch the motor on/of. I know some guys have one VFD driving a bunch of motors - I just don't reckon its safe to do this. One member here is experimenting with using one 240V VFD then a step up transformer to convert to 415V to drive a mill with multiple motors and relying on the transformer to protect the VFD - I haven't commented on this but I still wouldn't do if for the reasons above.

    On my small mill with just two motors I'm using two VFDs, a 2HP for the spindle and a 0.5HP for the coolant pump.

  9. #9
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    Quote Originally Posted by Chris Parks View Post
    We did a bit more spending today at 600 machinery buying a new Clausing mill to compliment the 40 year old Bridgeport that we bought brand new so many years ago. The question that this raises is on the machine there is a plate specifying speeds at 50 or 60hz and it occurred to me that we could hook it up to a VFD for infinite speed control and braking which might be useful when running heavy cutting heads at the same time running it at 60hz. Has anyone done this and found it to be advantageous? I wouldn't know if it is an advantage as I don't use the machine only some of the stuff that comes off it and the operator has not got a clue what a VFD does apart from what I have described to him.
    Does your Clausing have a mechanical variable speed drive and a mechanical brake? If it does then the main advantage of the VFD would be the 60Hz frequency for a slightly higher top speed... am I understanding correctly? PS I recently bought a mill from 600 too.

  10. #10
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    Chris do a youtube search for Doubleboost he has one fitted im sure

  11. #11
    BobL is offline Member: Blue and white apron brigade
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    Quote Originally Posted by wheelinround View Post
    Chris do a youtube search for Doubleboost he has one fitted im sure
    I don't doubt that lots of folks have fitted them without knowing of the issues in that and the first time they overload a motor they risk damaging their VFD.

  12. #12
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    Quote Originally Posted by BobL View Post
    I don't doubt that lots of folks have fitted them without knowing of the issues in that and the first time they overload a motor they risk damaging their VFD.
    Guess that is why thoughourly checking out all specks is parramount.

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