Removing and replacing a turning on a jam chuck?

Discussion in 'Newbie' started by Jesse Tutterrow, Oct 28, 2017.

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  1. Jesse Tutterrow

    Jesse Tutterrow

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    I am wanting to build miniature bird houses for Christmas. The videos I am watching use a wooden dowel as a jam chuck. They will remove and replace the turing on the jam chuck. I was taught that if you remove a turning from a chuck and latter replace it it will not be perfectly aligned and therefore will be out of true. Is this true for dowels used as jam chucks.
     
  2. Owen Lowe

    Owen Lowe

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    It all depends on the amount of fiddling you are willing to go through to get a turning running true again. Removing and replacing on a dowel is very doable if the dowel is trued to the spindle axis and the turning is true to the dowel. It may still require some futzing if you don’t mark the turning/dowel relationship before removing.
     
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  3. hockenbery

    hockenbery AAW Advisor Staff Member

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    Depends on the centers used.
    If you are sliding the birdhouse body over a pin that is running true and have a snug fit
    You should be able to remount the bodies.

    If you take the pin off the lathe it may or may not center back properly.

    There is always some error but if you can’t see it, feel it, or measure it - it isn’t a problem.

    I turned pins for my mini birdhouses on wooden Morse tapers.
    They always centered nicely when put back in the lathe.

    Many ways of mounting wood allow recentering.
    I use cup centers for spindles. They recenter perfectly when remounting a piece turned on this centers. They also recenter if I flip the piece end to end.

    Two cones recenter exceptionally well.

    A 4 jaw chuck or a spur drive rarely recenter. With fiddling you can often get a usable recentering.
     
    Last edited: Oct 28, 2017
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  4. Clifton C

    Clifton C

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    I guess it's the old, "Better is the enemy of good". Yes, if you remove a piece and then try to remount it, it may go back, close to perfect, or it may need some fiddling to get it as close to acceptable as possible. How accurate is acceptable or how off is too much, is the question. Not sure what your method is, or what style bird house ornament you are making but I've changed my method of operation so that the body is finished in one mounting on the dowel. Finished turning, lacquer is sprayed on after the ornament is assembled, however, you could easily use a friction polish while still on the dowel. Here is a fun little ornament. Body in one mounting.
     

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  5. john lucas

    john lucas

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    If you make your jam chuck almost as long as the birdhouse and very very slightly tapered toward the rear it will go on virtually perfect every time. You gotta make the jam chuck accurately.
     
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  6. William Rogers

    William Rogers

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    You can use jam chucks successfully as described in the previous post. I'm not sure of your process, but here is how I make mine. For those without finials; I usually make the base complete and sanded. Then part to about 1/8 thickness and saw the remainder to prevent fibers from pulling out. The only thing left to do at then is sand where parted off. Even if not perfectly true, it's not something you cannot detect. I use to use a jam chuck, but I have a small Penn State chuck with small jaws and now use that. If I am going to add a finial I usually drill 1/4" hole for the finial through before parting off. However I have also added the finial hole after parting using the Penn State chuck. That is usually what I do for the top with a finial, though rarely have one on the top. Below are two I have done one with a base finial and one without.
    IMG_0882.JPG IMG_0880.JPG
     
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  7. Derek Lane

    Derek Lane

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    I make the little bird houses and always turn the outside after having done the inside but I always turn to completion so that way you don't need to remove or replace at any stage. Te top is a case of making a tenon to fit the bottom then use that to hole the top and turn that to completion once both parts are done glue together. I have not included the drilling the holes
     

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