Paul H. Jacobson, Luthier

Custom Hand-crafted Guitars

Luthiers Q&A

  • QuestionWhat are the preferred materials used as fillers when replacing the tuning machines?Joe Pitman

    AnswerI presume you're referring to filling the old screw holes, Joe.  I drill the old holes larger with a #44 or #45 bit, then fill this hole with a piece of round toothpick.  Clip the point off the toothpick, insert it with TiteBond, clip off the excess toothpick and razor off the remainder so it is level with the surface of the headstock tuner plate face. You can then drill new holes to fit the new tuners; overlapping the hole into the toothpick fill works just fine if the hole locations for the new tuners require this.

  • Question When gluing the fingerboard to the neck I have a problem of having gaps you can see from the side. When I use wood filler it never seems to look right. Is there anything I can do to make this look smoother. The fingerboards I use are pre-slotted and usually rosewood. If you have any advice I would greatly appreciate it.—Jason, Detroit, MI

    Answer
    Three things will have a bearing on the glue joint gaps problem, Jason
    (1) The fit of the fingerboard to the gluing surface of the neck must be true. It's important that the neck gluing surface be very flat from side to side of the neck and that it be straight from end to end. Same thing is true of the fingerboard gluing surface. This is so that the gluing surfaces will be as close to wood-to-wood as possible.
    (2) You need to use lots and lots of clamps when gluing the fingerboard. I use over 30 clamps...there're just about as many clamps as it's possible to squeeze into the available space. It's especially important that the fingerboard edges be clamped, as there is a tendency for the neck and, especially, the fingerboard to go convex because of wood expansion from the water in the glue. (Do not use epoxy to glue a fingerboard as a way of defeating this; epoxy creates a moisture barrier between fingerboard and neck which will cause neck backbow when humidity rises.) I use strip cauls for clamping in order not to damage the fingerboard surface. Do not dampen the gluing surfaces before applying glue; this will help minimize expansion of the gluing surface.
    (3) Use lots and lots of glue when gluing a fingerboard to a neck; you will want to see great globs of squeezed out glue...cleaning that up is the least of your problems. This helps make sure there is something between the fingerboard and neck and not just air.
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