home made 5c chuck done! - Page 4
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  1. #61
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    Did anyone answer the what's wrong with a draw-tube question?

    Answer: Plus side is a nice ever so straight co-axial pull on the collet. Down-side the draw tube eats up valuable real-estate in the spindle.

    Cyclotronguy

  2. #62
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    Quote Originally Posted by Cyclotronguy View Post
    ...Down-side the draw tube eats up valuable real-estate in the spindle.
    You answered your own question.

  3. #63
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    Quote Originally Posted by Cyclotronguy View Post
    Did anyone answer the what's wrong with a draw-tube question?

    Answer: Plus side is a nice ever so straight co-axial pull on the collet. Down-side the draw tube eats up valuable real-estate in the spindle.

    Cyclotronguy
    Valuable ? Both of the draw tube closers I have pass the same diameter work piece as the collet does at the thread. There are collets with larger acceptance bores, but that size only goes back to the pull threads. Good for short work only.

    So I don't see any compromise with a draw tube, none at all.

  4. #64
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    Quote Originally Posted by CalG View Post
    Valuable ? Both of the draw tube closers I have pass the same diameter work piece as the collet does at the thread. There are collets with larger acceptance bores, but that size only goes back to the pull threads. Good for short work only.

    So I don't see any compromise with a draw tube, none at all.
    No shortage of "short work" in the world.

    Several collet systems that could use a drawtube would need a 2-piece or awkward from-the-nose insertion because the threaded portion is larger than a 10EE bore. 2J for example. My ones are in the form of Sjogren 2J and Hardinge "loop" closer 2J.

    Other collet systems are not ordinarily seen with drawtubes anyway, and are also too large for the bore. My Rubberflex uses the rotary-hammer closer, my Burnerd Multisize has the "loop" type. My ER and TG use spanner wrenches.

    No, not all sizes of stock can extend through the bore. I did say "precuts"? But even precuts can at least make use of part of the space the #12 jarno spindle-bore taper leaves when there is no drawtube blocking it.

    Not to forget - some of these closers also sit well-forward of their D1-3 mount, too.

    For sizes well-above conventional 5C max [1], that combination allows stock considerably longer than 5C, nose to threads.

    All that said?

    - Drawtube closers nearly always consume the least "daylight", TS-ward of the spindle. Which can matter on the 10EE mere 20" ration.

    - Drawtube systems are also USUALLY lower-cost (think handwheel, rather than hand-lever) than most any of the other options

    - the only nose-only closers that are cheaper to implement than drawtube (ER-XX) are far slower to cycle than even a simple handwheel drawtube.

    - "Loop" nose-closers are fast. Very. Also expensive. Very-very.

    - More expensive yet, power closers at the nose, rather than off the arse-end of a powered drawtube.

    Trade-offs. Drawtube advantage is there's usually more money left unspent so one has collets to put ONTO it..

    The two shop-fabs show in this thread? Go and price-out store-bought ones, new.

    Not only was clever thought and good workmanship shown, there was a serious payback off the "sweat equity" invested. Which was "non-trivial", both cases.

    TANSTAAFL

    Bill

    [1] The Hardinge pot & step chuck closer I have is also sans-drawtube - pin-spanner operated - and allows clear-up to 7" diameter. But those ARE short-short...

  5. #65
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    Very nice!

    Roger


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