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  1. #1
    topari is offline Aluminum
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    Question difference between universal & semi-universal dividing head ?

    Can someone explain the difference between a universal dividing head and a semi-universal dividing head ?

  2. #2
    Malc-Y is offline Aluminum
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    Quote Originally Posted by topari View Post
    Can someone explain the difference between a universal dividing head and a semi-universal dividing head ?
    My understanding is that a universal dividing head comes with a full set of change gears to enable differential indexing and spiral milling to be undertaken. Spiral milling is used for machining flutes in drills etc and uses a drive from the milling machine leadscrew to the dividing head using the gears supplied. The start of the spiral is decided by the gear ratio between the leadscrew and the dividing head. The semi-universal dividing head does not have this facility. Both types are capable of being tilted about 100 degrees from the normal position (parallel to the bed).
    I have an Elliott 5" centre height universal dividing head that I bought on ebay and it is complete with the full set of change gears, tailstock and 8" 3 jaw chuck. I have used it on my Bridgeport with a horizontal attachment for gear cutting but havn't tried spiral milling with it yet.

    Malc.

  3. #3
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    gwilson is offline Diamond
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    Agreed.The semi tilts,but no gear train.

  4. #4
    Damien W is offline Stainless
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    Quote Originally Posted by gwilson View Post
    Agreed.The semi tilts,but no gear train.
    George, without wishing to foment ill-feeling or to incur your wrath I hope you will accept my substituting the word pivotting as applied to both the universal and semi-universal dividing heads. To me tilting conjures an image of sideways movement whereas the heads are designed to pivot in one axis within the dividing head's frame.

    And as I understand it, to achieve full functionallity a Bridgeport will not have the features required. A machine like a universal milling machine only has the swivelling table to allow the machining of helical shapes.

  5. #5
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    gwilson is offline Diamond
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    Since you and I have always been in favor of correct speech,o.k.,pivots.

  6. #6
    Malc-Y is offline Aluminum
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    Quote Originally Posted by Damien W View Post
    And as I understand it, to achieve full functionallity a Bridgeport will not have the features required. A machine like a universal milling machine only has the swivelling table to allow the machining of helical shapes.
    While the Bridgeport doesn't have a swivelling table, it does have a swivelling head which together with a horizontal attachment can be used to machine helixes provided that you can adapt the end of the leadscrew to carry a gear instead of a handle.

    Malc.

  7. #7
    Damien W is offline Stainless
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    Mal,
    Yet more proof that one is a risk taker to be too dogmatic in anything one says.

    I assume you mean that the ram of the bridgeport can be swivelled? Tilting the turret head would not be comparable to swivelling the table on a universal mill.

    Thanks for the magnanimous gesture George. I had to refer to the dictionary. I had the second n and m reversed in my first spelling attempt.

  8. #8
    Malc-Y is offline Aluminum
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    Quote Originally Posted by Damien W View Post
    Mal,
    I assume you mean that the ram of the bridgeport can be swivelled? Tilting the turret head would not be comparable to swivelling the table on a universal mill.
    Yes, the ram and head can be swivelled 360 degrees. The head can also be tilted but this is not necessary, or indeed possible, when using the horizontal attachment as the back support for the horizontal arbor wouldn't line up with the end of the arbor if the head was tilted up or down.

    Malc.

  9. #9
    3t3d is online now Titanium
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    However, if you use a stub arbor held vertically, you can tilt the head from vertical, and thus achieve the same results as swiveling the table on a universal horizontal milling machine.
    You would at that point have made the swivel in the headstock orientation instead of the table travel.
    But the cutter can be situated at the required angle relative to the travel of the helix on the work. It is just angle in another plane than on a universal horizontla setup.

    In this case no horizontal attatchment is needed or desired for the helical work.

  10. #10
    Malc-Y is offline Aluminum
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    Quote Originally Posted by 3t3d View Post
    However, if you use a stub arbor held vertically, you can tilt the head from vertical, and thus achieve the same results as swiveling the table on a universal horizontal milling machine.
    You would at that point have made the swivel in the headstock orientation instead of the table travel.
    But the cutter can be situated at the required angle relative to the travel of the helix on the work. It is just angle in another plane than on a universal horizontla setup.

    In this case no horizontal attatchment is needed or desired for the helical work.
    Yet another example of the versatility of the Bridgeport!

    Malc.

  11. #11
    topari is offline Aluminum
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    Is vertex a well know brand ?
    Attached Thumbnails Attached Thumbnails vertex01.jpg   vertex02.jpg   vertex03.jpg  

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