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Thread: Warps in bent sides

  1. #1
    Registered User David Houchens's Avatar
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    Default Warps in bent sides

    No specific mandolin content, but a building concern. I've had this happen on an earlier set of guitar sides. I heated and clamped it back in shape kinda and sanded some also.
    I was wondering if I'm getting the side too wet or something else. My forms are not solid. Two sides connected with 1/2" dowels. Solid forms would be nice but awful heavy. This side goes from riff cut to about dead flat where the warp is but the last set I had do this wasn't flatsawn. Any suggestions welcome. Click image for larger version. 

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  2. #2
    Registered User David Houchens's Avatar
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    Default Re: Warps in bent sides

    Also if this is just a flatsawn problem how to get around it. Thanks

  3. #3
    Registered User tonydxn's Avatar
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    Default Re: Warps in bent sides

    I think this is caused by varying run-out within the board. Gluing small struts to the side may help to hold it flat (some builders do this anyway). Scraping may even it out a bit. I find it doesn't show too badly in the finished instrument anyway.
    Mandolins: Bandolim by Antonio Pereira Cabral
    German flatback by unknown maker converted from a descant Waldzither

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  5. #4
    Registered User David Houchens's Avatar
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    Default Re: Warps in bent sides

    I made two solid cauls to fit and clamped with heat blanket. Letting it cool and set over night

  6. #5
    Registered User Tavy's Avatar
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    Default Re: Warps in bent sides

    Been there done that - yours doesn't look too bad to be honest, some struts glued to the sides would indeed help a lot (and improve long term stability too).

  7. #6
    Registered User tonydxn's Avatar
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    Default Re: Warps in bent sides

    Quote Originally Posted by David Houchens View Post
    I made two solid cauls to fit and clamped with heat blanket. Letting it cool and set over night
    Phew! That sounds like a lot of work. Did it do the trick?
    Mandolins: Bandolim by Antonio Pereira Cabral
    German flatback by unknown maker converted from a descant Waldzither

  8. #7
    Registered User David Houchens's Avatar
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    Default Re: Warps in bent sides

    How would I glue the struts to the warped surface? It wasn't very giving.
    I haven't taken the clamps off yet. Fingers crossed.
    Last edited by David Houchens; Nov-15-2019 at 6:26am.

  9. #8
    Registered User tonydxn's Avatar
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    Default Re: Warps in bent sides

    Quote Originally Posted by David Houchens View Post
    How would I glue the struts to the warped surface? It wasn't very giving.
    I haven't taken the clamps off yet. Fingers crossed.
    Put a sturdy piece of wood against the strut on the inside, another on the outside, clamp it up tight. This is assuming the guitar is partly assembled and not in the mould.
    Mandolins: Bandolim by Antonio Pereira Cabral
    German flatback by unknown maker converted from a descant Waldzither

  10. #9

    Default Re: Warps in bent sides

    I'm a big fan of solid bending forms, but they use up almost a full sheet of mdf.

    My first thought is did you cook them a second time? Ribbony mahogany does the same thing you showed- bends good on the easy places and then gets squirrely on the ribbon areas, but I can usually get it all even by moving them around just a little and then cooking for a second time at a slightly lower heat but for a longer time and then letting them cool in the bender. If not, it will be a nice evening for a bonfire in Virginia....I'll be doing the same down here!
    Spruce dork

  11. #10
    Registered User David Houchens's Avatar
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    Default Re: Warps in bent sides

    Tony, the ripples were too spread out for one strut to straighten it all but I appreciate the suggestion. The solid cauls I made did take most of it out.
    James I did heat a second time. I may invest in the time to make solid forms .
    I've heard John Hamlett (I Think) speak of dry bending mandolin sides. Has anyone tried that with guitar sides? I may sand out an ugly set to try it.

  12. #11

    Default Re: Warps in bent sides

    The ugly set will sound as good as that fancy LLoarax wood....
    Spruce dork

  13. #12
    Registered User David Houchens's Avatar
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    Default Re: Warps in bent sides

    But if I break it, it's less painful. Haha

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