Hi everyone!
I have a banjo mandolin, which I inherited through various family members, and which originally belonged to my great-grandfather. He and my nan (his daughter) both played, but since my dad inherited it it has sat ide (and strung) in a cupboard.
I'm very interested in repairing this instrument and it's case as well as possible. I'm not concerned with monetary value, and suspect it has very little anyway. If I can make this relatively playable I would like to, and I understand it will never be like new.
It has a number of issues, all of which I believe are pretty standard for these kinds of instruments. First of all, the neck and bowl are both bowed from years of string tension (it was strung with heavy gauge strings, and has spent 30 years strung in a cupboard!).
The tuners are not original, as you can see from the photo. Above the tuner on the left you can see the holes for the original tuners.
You can also see that the tuners have no bushings, and actually have been crammed into the original holes, bending them slightly out from square. The tension on the posts has brought them all forward into the space where a bushing should be.
The nut is very heavily worn and needs replacing, and the frets likewise are heavily worn and need replacing.
I've spent some time now reading through the forum posts, and my brother is a violin luthier, so I feel confident that I can perform the work required. I'd like to do as much as I can by myself, but my brother is on hand to help. Still, I do have a few questions which I hope other forum members may be able to help with.
To begin with I would like to straighten the neck and reinforce the bowl somehow to prevent further warping. A carbon fibre rod through the neck seems a sensible idea, but I'm unsure what size rod would be suitable and how far through the neck it needs to go? The neck thickness directly under the nut is only 1 inch and the neck from bowl to nut is 8.5 inches.
My next, related question, is the best method for straightening the neck if a CF rod is being added? I thought perhaps heating and clamping rather than planing, to retain as much original material as possible.
For the bowl I had thought to insert an improvised coordinator rod like you would find in a banjo bowl. The bowl is 8 inches across, and I haven't found a pre-made coordinator rod that would suit. I've also realised that the whole banjo head frame, which sits inside the bowl, extends down into the bowl almost an inch. This would mean the rod, which must neccessarily sit below this, would be sitting below the mid point of the bowls walls. As I'm not all that up on the physics of these instruments, I wonder whether this will matter?
My brother suggested asd an alternative a 'floating' cross brace - i.e. two dowels which cross each other diagonally under the banjo head, both braces touching joining with the bowls walls at around it's mid height.
My last question is to do with the tuners. The StewMac golden age tuners fit the original spacings for this instrument, though the holes will need to be widened just slightly to fit the bushings. The string holes in the posts however are a little higher than the tuners that are already on it. I'm assuming the post holes must have some relation to the nut, but I don't entirely understand how this works. Will a higher string at the post matter?
Sorry for all the questions. I have more, but as these relate to the repair of the case I will post them seperatly.
Any help will be greatly appreciated.
All the best,
John
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