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Thread: Best way to "go oval"?

  1. #1
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    Best way to "go oval"?

    SUBTITLE: Not elliptical orbits, but the 'orbiting' of things elliptical

    Stu's new Escoulen eccentric chuck and the recent discussion about ferrous metals (cast iron vs steel) have somehow "spun" me off on a couple of converging tangents. My brain took in "eccentric", chewed on it for a bit, and eventually spat out "elliptic"...

    ... which reminded me of a neat-o section in David Springett's 1994/95 book called [Adventures in Woodturning]. My copy has a price sticker of $24.95 on the back, but according to the link it is now available at the low, low price of anywhere from $61 to $390!

    The last section of the book deals with Elliptical Turning. Mr. Springett dedicates an entire 16-page chapter (pp. 181-196) to the construction of an "oval chuck" and its mounting to a regular lathe:



    The "Slide" spins in place, centered on a "boss" that's turned with a Morse taper and held tight to the spindle with threaded rod that passes through the headstock. The "runners" ride on the "cam", which can be offset by different amounts to vary the "oval-ness" of the cuts made in the spinning project (which is attached to the "faceplate").


    The remaining 28 pages of the book are dedicated to several projects that can be made with such a chuck:




    Pretty cool stuff!

    Before I get around to my questions, I need to note a couple things:
    1) The "bed" of the lathe pictured in the book is a single round tube, as opposed to the parallel, flat ways on most of the lathes I've seen.

    2) The "headstock housing" shown in the diagram above is just that ... a wooden box that is built up around the headstock (such that it "hugs" it firmly) and anchored to the lathe stand with clamps.




    Now for my questions:
    A) On a "normal" lathe with flat ways, could the wooden headstock housing be replaced by a stiff piece of L-iron (or similar) ... firmly fastened between the ways, up against the headstock?

    B) Would it be reasonable to replace the threaded rod & drilled boss arrangement with a threaded boss ... made with one of Lee Valley's [Lathe Spindle Taps]??

    C) Do any of the oval chuck parts seem like they would be better executed in metal than in wood? (And would Travis or Randy be willing to machine them for a fee? )

    D) Would I be better off just looking for a manufactured oval chuck setup? Does anyone make such a thing?
    Last edited by Kerry Burton; 01-11-2008 at 07:06 PM. Reason: Updated URLs for iamges

  2. #2
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    Kerry, I read your story with a lot of interest.
    In the first place it looks to me very complicated.
    I understand the whole system, how it works as well.
    Not any doubt about using wood (hardwood) for such a construction, my own build lathe is build up of hardwood, including my tailstock and tailstock barrel. So my experience with hardwood constructions are good.
    In my opinion better than using sheet metal.
    I think that it is possible to find a more simple solution, maybe they excist.

  3. #3
    Looks complicated to me as well, but heck I'm still working on bowls!

    In case anyone wants to look at the book before buying, don't overlook Google Books

    http://worldcat.org/wcpa/oclc/32970899

    Just put you own zip code in and reload

    Jay

  4. #4
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    Quote Originally Posted by Ad de Crom View Post
    So my experience with hardwood constructions are good.
    In my opinion better than using sheet metal.
    Thanks for the feedback, Ad.

    Well, I was thinking of something more substantial than "sheet metal" ... something fairly hefty indeed. Perhaps 1/8" (3mm) steel or thicker? I figured that if hefty steel can be welded up at right angles (like Stu does all the time) and bolted or otherwise attached to the ways, I could get away without having to build a "headstock housing". That might be tricky if the spindle has little or no overhang away from the headstock. (The bracing material might interfere, and reduce the swing available for the chuck and/or projects.)

    I agree with you that nice, dense hardwood should work well for the moving parts. Using metal for the slide and runners would almost require some kind of ball bearing construction, it seems to me.


    Quote Originally Posted by Ad de Crom View Post
    I think that it is possible to find a more simple solution, maybe they excist.
    We can always hope!

    Have you ever seen an oval chuck in use? I remember watching an episode of The New Yankee Workshop where Norm visited the Old Schwamb Mill in Arlington, Massachussetts. The (water-wheel-powered?) shop specializes in assembling, turning, and gilding oval picture frames. (Hey - I just found a cool link! Check out "How the Lathes Work" [HERE])

    In the show, the operator stood in front of a "whirling dervish" of a workpiece ... but the line along which they applied their turning tools was "quiet".

    Anyway, I don't know if there is a much simpler arrangement for the moving parts. I was mostly hoping for a less involved (and stronger?) way to attach it all to the headstock.

  5. #5
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    Check out this site. All you ever wanted to know.
    http://www.volmer---ovaldrehen.de/englisch.htm

  6. #6
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    Thanks for the link! Section 4 of that website contained a reference to an American named Dan Bollinger who has created a LARGE "oval lathe". A quick Google search turned up [THIS PAGE].

    Check out the two videos about halfway down that page. Wild!

  7. #7
    Thanks for the link Keith!

  8. #8
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    Kerry, thanks for pointing me on the websites, I understand how it's works.
    Never saw such a demonstration, to be honest nearly possible here in the Netherlands, not so many wellknowned woodturners here, as in compare with the USA. Most of the woodturners here are anonymous.
    Using hardwood would be my chooce, for the sliding construction I would use Shambam, is a linear bearing material, don't have to lubricate this stuff, so it can run dry. Used this material as linear bearing material in rotating tables in my profession many times. Maybe I come in the future to that point to develop such a unit by myself, would love it to brake my brains on that subject.
    Do you have serious plans in buying or building this?
    With what you came up it seems to me to complicated.

  9. #9
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    Quote Originally Posted by Ad de Crom View Post
    Using hardwood would be my chooce, for the sliding construction I would use Shambam, is a linear bearing material, don't have to lubricate this stuff, so it can run dry.
    Hmmm ... Shambam? Is that wood known by any other name? It sounds like good stuff ... something like the way Roy Underhill (of "The Woodwright's Shop") describes dogwood. If I remember right, he says they once used it for machine parts, and that it just got smoother and better with wear.


    Quote Originally Posted by Ad de Crom View Post
    Do you have serious plans in buying or building this?
    Did you have to ask the "hard question"? If there's one thing I know about myself, it's that I like to learn things more than I like to do them. But once in a while I surprise myself ... so who knows?


    Quote Originally Posted by Ad de Crom View Post
    With what you came up it seems to me to complicated.
    Maybe if you had 16 pages of David Springett explaining how to do it... (Just kidding!)

  10. #10
    Kerry, please forgive me but... I can see what it do but for the life of me I can't fathom How it do...

    Does the piece sling around in an oval motion? What makes it turn in an even concentric circle? I'm stupified here. My Son-I Law is a machinist and I might be able to talk him into some manufacturing if I understood what is actually going on.

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