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Thread: Banjo mandolin and case repairs

  1. #1
    Registered User Happy gnome's Avatar
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    Default Banjo mandolin and case repairs

    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!).

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    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.

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    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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  2. #2
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    Default Re: Banjo mandolin and case repairs

    I noticed that no one has answered your question(s) for a couple of days.... I think the reason is that you are undertaking some major adjustments and modifications way beyond the value of the instrument and perhaps way beyond first time amateur repair person's capabilities. All of those things you mentioned are doable of course, but as I look through your list i see simple problems being approached with overly complex solutions. For instance you may not need to straighten the neck by untwisting it... It may be possible to deal with a slight twist by modifying the fretboard or sanding the neck instead of trying to untwist it. but if you can untwist it you may no longer need a truss rod. And by the way, replacement necks are not particularly expensive.

    Your project sounds like a thousand dollar repair on a $25 instrument. And though I think it would be a great learning experience to do all you mentioned I think you are biting off way more than you can chew on your first repair attempt and are most likely headed for disapointment. Even if you succeed you will have turned a $25 instrument into a $75 instrument which may or may not play well. The materials on a inexpensive instrument to begin with are likely not top quality by any means.

    Sorry to seem cynical but as a amateur repair person myself I think you are way over your head for a first repair/restoration.
    Bart McNeil

  3. #3
    Registered User Happy gnome's Avatar
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    Default Re: Banjo mandolin and case repairs

    Thanks for the reply bmac,

    I appreciate your comments. I realise the instrument is essentially valueless in terms of resale, and noted the fact in my OP. Having said that, until my dad inherited it it was owned by some very dear family members and was a heavily played instrument. To make this playable would be worth more to me than the monetary outlay.

    In terms of my inexperience (which I certainly don't dispute!) I must point out again that my brother is a violin luthier, with all that entails (8 years experience making and repairing stringed instruments and a workshop full of tools).

    What I would really like is some advice about how to proceed with the repairs for this particular instrument, especially the support of the neck and bowl. Your advice regarding the planing of the neck is good - my concern is that the neck will continue to bow under tension (because, as you say, it is made from inexpensive materials to start with). If planing is all that's required, then that is all I will attempt. If a CF rod will be a 'better' option (i.e. more structurally sound in the long term) then, with my brothers help, that is what I will do.

  4. #4
    Registered User Bill Snyder's Avatar
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    Default Re: Banjo mandolin and case repairs

    Let me start off this post by acknowledging that I am not anything more than a hobbyist builder and I have never done any kind of work to a banjo or banjo mandolin.
    Bart mentioned a twisted neck but I only see mention of a bowed neck in your opening post. If the neck is just slightly bowed I agree with Bart that judicious planing might be in order. As for adding some CF to help stiffen it that would most likely be worth doing or you risk having it bow again. Of course if you just use light or ultralight strings on it from now on that may keep if from bowing again as well. How much bow does it have as it is? If it is slight some luthiers claim to be able to correct it with compression fretting. That is using fretwire with a bigger tang size. The larger tang going into the existing fret slot causes the neck to flatten out or even bow back some.
    OF course this all gets back to Bart's concern about being in over your head. Your brother's knowledge about violins will be valuable and if you go with planing the fretboard he most likely can handle that or help you. If you decide to insert carbon fiber or compression fret his general skill will come in handy but I doubt he has done either on a violin.
    I am not a banjo player so I cannot address the issues with the pot other than to say that I think you are probably correct in wanting to add a coordinator rod.
    Now if Paul H. Or John H. will chime in you might get some answers from some real experts.
    Bill Snyder

  5. #5
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    Default Re: Banjo mandolin and case repairs

    A local shoe repair shop is often a good option for case repair.

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    Default Re: Banjo mandolin and case repairs

    I would take the fingerboard off and try to glue it as flat as possible, planing if you have to to flatten. With the light strings you will be putting on this i don't feel you need to reinforce the neck. Remember it's a banjo after all and the strings you put on should be for a banjo and a 32 is about the heaviest string i would use for sound so it will help with the tension. If you use a skin head you will not have to support the rim as a lot of these are not round and the skin will not care. Unless it has changed the action of the neck then any reinforcement will be fine. You need only concern about supporting the neck and neck to tail would be all i would worry about. Good luck.
    THE WORLD IS A BETTER PLACE JUST FOR YOUR SMILE!

  7. #7
    Mandolin tragic Graham McDonald's Avatar
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    Default Re: Banjo mandolin and case repairs

    Those cheap English banjo mandolins are very hard to make playable. The unplayability of them is usually a combination of the neck bending, a shift in the angle of the neck relative to the body and warping of the wooden body itself. The freeboards are usually very thin and will almost certainly disintergrate if you try to remove it. Heat-lamps and pressure might get it straight, but the neck is usually only the least of your problems. The necks on those instruments are pretty short and don't usually bend very much. It is more often the deformation of the wooden ring and where the neck joins the body and this is much harder to fix. If you can avoid it, do not disassemble the metal structure holding the skin head. Getting a skin back on those can be a thankless task with many rude words spoken. My usual suggestion, over years of having these kinds of instruments brought to me, is that they can be strung up and make a decorative wall hanging or mantle piece ornament, but it is most unlikely that they will ever be an even marginally functional musical instrument.

    Yours might be one that is restorable and it will certainly be an interesting process of discovery along the way. Good luck!

    cheers

    graham

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    Default Re: Banjo mandolin and case repairs

    Quote Originally Posted by Graham McDonald View Post
    Those cheap English banjo mandolins are very hard to make playable.
    I bought one like this, spent weeks doing a thorough job on fixing the rim and the neck and correcting the neck set, proper setup etc and.......

    It sounded truly horrible!!

    Tried some different strings fiddled with head tension etc and......

    It still sounded truly horrible!!!

    several months later found the head had split, spent the cash on a new vellum, exhausted my supply of expletives fitting it and......

    It still sounded truly horrible!!!!

    So I went and bought a 1920's Majestic tenor banjo and.....

    It sounds incredible (in a good way)

    I would not invest too much time or money into one of these, if it has family interest tidy it up as a wall hanger.

    Neil
    Last edited by NAS; Apr-19-2012 at 7:27am. Reason: Typo!

  9. #9
    Registered User Happy gnome's Avatar
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    Default Re: Banjo mandolin and case repairs

    Thanks everyone, thsi has been helpful.

    Graham, how thin is thin for a fretbord? The fretboard on this is 5mm.

    Neil, I had to chuckle at your tale, as it is pretty much the repsonse I have heard from everyone who has heard one of these being played (including my family). I should note, my family on my dad's mother's side (who owned the banjo-mando) were chinese, so I suspect the high pitched twanginess suited their musical tastes!

    I'll let you all know how I get on. If it plays (well or not) then that's a bonus. If not, I'll have learnt something, will have tried my best and will have something shiny to look at!

  10. #10
    Orso grasso FatBear's Avatar
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    Default Re: Banjo mandolin and case repairs

    I just stumbled on to this and wondered how you came out.

  11. #11
    Registered User Happy gnome's Avatar
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    Default Re: Banjo mandolin and case repairs

    Hey FatBear,

    Good timing; I was only thinking last weekend I should post a progress report.

    I think the instrument came out pretty well - it looks pretty good. Unfortunately I've moved house about six times in the past year , so I haven't had a chance to actually do the set-up or play it yet. This seems like a good excuse to do just that. Give me a week or so and I'll get it out of storage and post some pics.

    John

  12. #12
    Registered User Happy gnome's Avatar
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    Default Re: Banjo mandolin and case repairs

    Finally finished the case last night and thought I'd post some pics of the final result for those interested.


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    Time consuming project, but fun.

    No major surgery in the end, just planed the fretboard (as flat as I could without removing the stamped serial number), filled dings and chips in the ebony head veneer, refretted, cleaned, polished and lubricated all the metal parts and installed a new goat skin head.

    The action is still high (2.5mm at 12th fret on G), but with GHS Custom Ultralight strings (8-24) it's certainly playable.


    p.s. both the nut and bridge are 'stop-gaps' until materials arrive (i.e. ignore how dodgy they are)

  13. #13
    Orso grasso FatBear's Avatar
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    Default Re: Banjo mandolin and case repairs

    Well that came out real nice. It looks like you kept the original tuners. You are lucky the knobs are good. How did you deal with the different hole spacing?

    I had to replace the vintage Waverley tuners on my M.banjo because they were so tight that the shrunken knobs started to break off when I tuned. Mine was built sometime in or before 1925 when hole spacings were apparently more random. Neither the "old" nor the new standard spacings in Golden Age tuners would fit. I finally bought the new standard tuners and a reamer and drifted the holes slightly, then when I reamed the top slightly for the bushings I made sure they were correctly centered for the tuners. Now I have really nice, smooth tuners, but clearly not original.

  14. #14
    Registered User Happy gnome's Avatar
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    Default Re: Banjo mandolin and case repairs

    Thanks FatBear,

    I figured I'd keep the tuners if I could, as they still had all working parts - it was just the spacing was a little out. After giving the tuners a really thorough clean and some lubrication (to make sure they actually worked well) it was just a matter of some careful reaming to open the holes enough to allow the tuners free movement.

    I'm glad I took the time to do some reading and to clean them up. I was so sure they were trashed, but now they work like new!

  15. #15
    Orso grasso FatBear's Avatar
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    Default Re: Banjo mandolin and case repairs

    Well done. You are lucky the tuners just needed clean and lube.

    I tried to rehab my tuners, but without success. I did buy new knobs to put on. Most of the gear sets had tight spots, some really tight. The knob that broke off was on the tightest set. I chucked it into my drill (after removing the tuner from the instrument!) and daubed on some lapping compound and lapped away for quite a while. Eventually the tight spot started to loosen up just the tiniest bit, but by then the rest of the gear was also getting too loose. That's when I decided to replace them.

    If anyone wants some 1925- Waverly mandolin tuners with weird spacing, let me know.

  16. #16

    Default Re: Banjo mandolin and case repairs

    Hi Happy Gnome
    Did you work out what make your Banjo Mandolin was?
    I am guessing it is actually a Manbys. It has all the characteristics of one, except where the number is on yours, mines on the actual head under Manbys name.

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