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Thread: Non-flat kauri

  1. #1
    Join Date
    May 2018
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    Default Non-flat kauri

    I am helping a friend out with some repairs to an old kauri box. One of the issues is the lid which has turned up a bit down one side. It is, or certainly appears to be, a single slab of kauri and it measures 1250 x 680 x 27. Whilst there is no expectation of getting it totally flat are there any suggestions on how to improve the situation? Here are a few pictures.
    Thanks
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  3. #2
    Join Date
    Jun 2015
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    Wolvi
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    Using a circular saw and a fence I'd make longitudinal cuts along the full length of the underside of the board at a spacing of about 20mmish. I'd probably go to 20mm deep. That may or may not be enough, the point I'm making is that you're going to have to break the back of the board such that a reasonable amount of pressure will flatten the board.

    Once you've achieved that you'll then have to add some stiffeners transversely across the underside of the board, there's innumerable ways you can do that, and looking at you're workshop I'd say you're more than capable.

    Personally I'd fill the cuts with a flexible & sandable filler.

    My 2c.

  4. #3
    Join Date
    May 2007
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    Vic
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    You can get this sort of thing to swing back the other way with moisture . If you lay the cupped side down on a floor with the underneath wet, you will see it comes back to straight . Controlling it is tricky . It can go to far in a short time. Making it stay that way is tricky as well . If itís a piece thatís been fitted and has been taken out for the repair then the re fixing back in can help hold it .
    On a box top you sometimes have mouldings around three sides that help with that, and hinges , which wonít do much . If there is nothing to help like that then itís just a matter of either getting it back straight and seeing if it swings back when dry. Or going a little further with it, let it dry and then seal the top . Control with doing this is a 50/50 thing . It works though .
    Laying the cupped side in a wet lawn with the top in the sun is another way if you want the turbo charged version .

    With the sealing bit . I would use a PVA water based glue size for this . Mix some PVA in a cup with warm water 20% glue , the plain white stuff . Once the sealed side is dry you can go over the whole thing with whatever sealer you like , oil or spirit based .
    Iíve usually had to give a top like this a few runs to get it where I want it .

    Once I did an interesting experiment while doing this with a top . I had it clamped on one side to a solid work table with the cupped top facing up . I mounted a dial indicator to the table on the oposite side to the clamps reading off the cupped top , when I applied the water I could watch the dial moving as the top took on the moisture . It was a pretty amazing thing to see this happen! Constant movement on the dial as soon as the water was put down .

    Rob

  5. #4
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    May 2018
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    Melbourne
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    Thanks auscab, much appreciated. I had been starting to wonder about steaming, if I could get a big enough container. The lid did originally have mouldings but there is not much left of them and they need to be re-made.

  6. #5
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    May 2007
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    No probs .

    Steaming would be a good option for some of these bent and twisted problems . It would be great to have the set up to be able to handle flat boards . Specially for twisted boards . Ive had a few of them to try and fix before . nothing really fixes them . But a steam set up probably would .


    If your interested
    Ive been watching Dave Engel from Engels coach shopin the US on Youtube .
    I was hooked as soon as I saw his very good steam set up .
    Its compact and very capable of amazing bending .
    The bending set up with the winch and the tips he gives are GOLD. lots to see and learn watching this bloke in his great workshop . The metal work is just as good as the steaming .

    https://www.youtube.com/watch?v=mHAbShWQ7JI

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