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Thread: A5 top thickness

  1. #1
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    Default A5 top thickness

    I would like to try tuning the top of A5 number 2 using something similar to the article James wrote for the GAL # 129. I have already cut the top and back to close to final size so the overlap will not be possible, but I hope to come up with an arrangement using clamps on the perimeter.
    I am using the thickness numbers from HoGo's F5 plans, so my question is how much extra thickness over those numbers should I start with?
    It is a red spruce top.
    This will be a new adventure, so any advice will be appreciated.
    Bob Schmidt

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    Default Re: A5 top thickness

    OK, having read a couple of other threads on this topic, I get that no one wants to open this can of worms. I suppose I am trying to circumvent to some extent what only comes from experience, but I would hate to see a top that I put a lot of hours in colapse.
    So maybe a less controversial question would be do builders reshape the arch height and recurve under string tension, or is it more about shaping braces and sound holes.
    Bob Schmidt

  3. #3
    Fingertips of leather Bill McCall's Avatar
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    Default Re: A5 top thickness

    Removing the overburden is burdensome. I would think leaving no more that 1/16 would be sufficient

    I wouldn’t know about reshaping under tension as a common practice, although maybe that’s a secret someone uses.
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  5. #4

    Default Re: A5 top thickness

    I think we've all reshaped a top after an initial string-up in the white. Or even after finishing the instrument completely.

    I left my first mandolin top entirely too thick, no real recurve. It didn't seem possible that the top could actually hold string tension, seemed like magic. It was around .180" all around the perimeter. I eventually reshaped it with a proper recurve, it sounded a lot better.

    Of course, I could have aimed for the high side of normal numbers to begin with, and saved myself a lot of awkward scraping and sanding.

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    Registered User j. condino's Avatar
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    Default Re: A5 top thickness

    You could call up the guy who actually wrote that article and interact like real people rather than waiting for a response from the internet....

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    Default Re: A5 top thickness

    Quote Originally Posted by j. condino View Post
    You could call up the guy who actually wrote that article and interact like real people rather than waiting for a response from the internet....
    That's just crazy talk!
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  11. #7
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    Default Re: A5 top thickness

    James, I would not have presumed to be able to do that but I would certainly like to; that is a generous offer.
    To update progress, I have the top carved pretty close to Adrians plans. I did balance out a couple of the thickness numbers where there was some asymetry around the center line. I am guessing that was for the F5 top shape but I am building an A5.
    My drill press stop slipped last night and bored too deep into the back. At least it happened before I started carving, so since I have to start over with the back it is an oportunity to oversize the edges to allow experimenting.
    Bob Schmidt

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    Default Re: A5 top thickness

    I've built four mandolins, and the top and back on each one is thinner than the one before it. I now have a concept of how flexible the top and back have to be, which seems too thin like Andrew said. It's one of several games of chicken that builders have to play as Marty has said. I don't think anyone can tell you much more without the pieces in their hands. I would save the back by plugging the rogue pilot hole with a dowel of the same wood.

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  14. #9
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    Default Re: A5 top thickness

    I am glad to hear that you have some feel for it after 4 tops. I do understand that experience is the best judge of this. This one is thinner then the first and I will probably be holding my breath while I string it up, but it is very close to the thickness specs on Adrian's F5 plans.
    I have set that back aside. I may cut it down to use it as a flat back at some point.
    Bob Schmidt

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