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Thread: Odd headstock repair

  1. #1

    Default Odd headstock repair

    Hi,

    Here's the latest project/dilemma. This is an Ebay purchase that was reasonably priced, but had a serious issue, a broken headstock.

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    It has an odd fiddle style headstock with unusual tuners on a bowl back mandolin body with a lovely, though damaged, mother of pearl and abalone fingerboard. I was not able to clearly see all of the break area in the pictures online, but happily, it's a clean break with just a bit of wood tear out on each side of the neck where the first set of Tuning machine screws pulled out when the head was broken off.

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    My concern is that while this is a clean break, it's a very small surface are to deal with the stress of the neck and I'm wondering about the best glue. Usually I use hot hide glue, and that's my thought at the moment, but with the area to glue being so small and that being the critical pressure pint in the neck, I wonder if I should consider a higher gram weight glue to make for a stronger glue joint.

    I've read conflicting reports online about the virtues of high gram weight, but many are furniture makers, not instrument repairmen (and women). I have seen a number of folks mention 192 as the gram weight of choice. I'd be interested in hearing thoughts from the forum on this.

    Frank Ford once said these old pearl inlaid mandolins are "black holes" and I have to agree, he's right (I'm still tinkering with the one I wrote about then), but I think this one actually stands a good chance of being restorable if I get the headstock re-gluing right. Thanks!

  2. #2
    Registered User sunburst's Avatar
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    Default Re: Odd headstock repair

    Considering how gram strength is determined, it apparently has very little if anything to do with joint strength.
    I'd glue it with my usual hot hide glue, which is 192 gram strength high clarity, because I think it is up to the challenge. If I was at all worried about the glue joint I might consider Knox gelatin. Gotta work fast using it, but it might make a stronger joint.
    At any rate, I suspect fit and clamping method will be the main challenge, and if that is done well any high quality glue will be fine (until it takes another hit).

  3. #3

    Default Re: Odd headstock repair

    Thanks John. That's sort of what I was getting a sense of. I've got Behlen's hide glue from Stu Mac, but I didn't see a gram strength on it. I'll mix up a fresh batch for this one. The fit looks to be very good.

    I've been using the moldable plastic to create a clamping caw for this type of repair and this one should be pretty straight forward, famous last words!

  4. #4
    Adrian Minarovic
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    Default Re: Odd headstock repair

    The "higher strength glue" does mean that at some given concentration the glue gel is stiffer when a probe is set against it. It has nothing to do with glue joint strength.
    I haven't seen ANY real research about this so we can only rely on hearsay or personal experience.
    The higher strength glue has longer molecular chains. It requires much more water to get to working consistency (1 part glue to 4-4.5 parts of water for 450 gram glue versus 1.5-2 parts of water for 190 gram glue) and it gels much faster giving shorter working time. The amount of water makes the higher strength glue more prone to get sucked into pores (requires sizing especially on maple) or squeezed out of joint resulting in starved joints.
    For repairs I prefer ~190 gram strength not too thin (without sizing as sizing the break would likely change the fit), warmer environment and good clamping (everything prepared and dry tested before gluing).
    Well done 190 gram HHG joint will be as strong as surrounding wood. I've been using that ever since I started and always test offcuts of plates for joint strength (hit them with hammer).
    Adrian

  5. #5
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    Default Re: Odd headstock repair

    Quote Originally Posted by Ginridge View Post
    I've got Behlen's hide glue from Stu Mac, but I didn't see a gram strength on it. I'll mix up a fresh batch for this one.
    The only info I could find on Behlen's hide glue indicated a gram strength of 164 g. Sorry, I don't remember the source.

    You can mix a low gram strength glue with a higher one. I learned about it when I accidently ordered a 315 glue, which is something you don't want to use by itself. I've mixed one part by weight to 3 or 4 parts of the Behlen glue.

    I have been working with a gram strength of about 200 to 220. I find that the thickness of hide glue is important. Too thin, weak joint. Too thick, doesn't penetrate well enough for a good bond. I suspect that any strength between 190 and 220 will work for most repairs. For some reason, many violin people seem to be leaning towards higher gram strengths.

    If you are concerned about the long term strength of this repair, you could add a thin overlay or "back strap" which spans the break by a fair distance. For good examples of what this can look like if done skillfully, look at some pictures of old Fairbanks/Vega banjos.
    Last edited by rcc56; Sep-03-2020 at 10:13am.

  6. #6
    Registered User j. condino's Avatar
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    Default Re: Odd headstock repair

    Remember that all of the traditional granular hide glue in the US is cow based and made by one company- Milligan & Higgins. It is then sold in bulk quantities to other folks who relabel it with their own marketing twist and mythical qualities and fancy containers.

    Behlens = the same as LMII = the same as International violin = the same as Metropolitain Music...et cetera.

    John Preston from Old World Tonewoods has what I believe is the best price in the nation: $8 for a 1/2 pound. He is also a fantastic guy to do business with and sells some of the finest instrument grade woods in the country:

    https://www.oldworldtonewood.com/pro...ory/hide-glue/

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  8. #7
    Registered User sunburst's Avatar
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    Default Re: Odd headstock repair

    I've used a couple of cans of Behlen's hide glue. One was from a hobby wood worker that I bought a bunch of tools from, I don't remember where the other came from, but both were unopened, so I figured I might as well use them. Both were very good glue, but one must have come from a better batch than the other because it was very clear and seemed to appear just a little better than the other batch. I would give Behlen's a good recommendation as long as it is consistently equal to what I had.
    I've since bought a sack of hide glue from Milligan & Higgins, so now I have a lifetime supply and I know what to expect each time I mix a new batch.

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  10. #8

    Default Re: Odd headstock repair

    Any idea on the maker and date? That tuner doesn’t look like a one-off. Design looks terribly weak in that area, but looks like a quality build overall, without seeing the bowl side. Really worth a rescue!

  11. #9

    Default Re: Odd headstock repair

    The maker is J N O Brandt, Chicago. Patent date of 1899 on the Mandolin and 1898 on the tailpiece. Every indication I can see suggests that this is a well crafted instrument though I haven't studied into closely yet. It got a top split in transit, but it was closed and I was able to superglue it closed nearly perfectly.

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    The tuners are clearly production of some kind (see the pat. date). I have never seen a Bowl back mandolin with a fiddle head before. I appreciate the elegance the design, but it clearly has a weak spot where it snapped. RE including a support of some kind. The area beneath the tuners is slightly hollowed out and would possibly be a place where I could discretely add in some support with an inlay or overlay.

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    I don't see much other than the headstock break in the way of issues. All the braces seem to be tight, no warps on the top, won't know for sure about the neck until I string it up, but looking good so far. All the original parts are there, though the nut may have some damage in the lowest set of string slots. I may try to repair it and keep the original nut for restoration sake, we'll see. If the glue job on the neck takes, this might just be worthy of a full on restoration effort.

    I've got several other MOP fingerboard mandolins, a Washurn and a Bruno. There are subtle differences in the construction that make me conclude that this is not a production run from Regal or Washburn. Also, the pearl fingerboard is less intricate (thankfully!) with full panels of shell for each position. Both the Washburn and the Regal have Abalone inlaid into Mother of Pearl and are much more intricate.

    I'll let you know how it goes.

  12. #10

    Default Re: Odd headstock repair

    A few more details, the bowl side has a single split section that should be an easy fix.

    Attachment 188330

    What looks like a missing section in this pic actually turned out to be a black section of the Brazilian Rosewood.

    RE glue, I do have a bag of this stuff that I could mix with the Behlen glue. Attachment 188331 Depending on how fast I do this, I may try to get the good stuff, though.

  13. #11

    Default Re: Odd headstock repair

    For some reason, these pics didn't come through. Here they are again.

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    Attachment 188345

  14. #12

    Default Re: Odd headstock repair

    From a Jonathan Peck forum post 10 years ago, here’s the fiddlehead “Gibson’s main competitor”Click image for larger version. 

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  15. #13

    Default Re: Odd headstock repair

    I broke down and bought a bag of Milligan & Higgins. Might as well try to do it right.

    I glued it up this morning. This proved to be a bit more difficult than I imagined, and I didn't expect it to be easy! It was a very clean break, but the joint had some wear and had been glued previously with a yellow wood glue which had to be removed. That was no problem, but the issue, as expected, turned out to be clamping. I had to try 3 attempts with the friendly plastic before I managed to create a caul that I could effectively clamp off of.

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    Ultimately I got it together in what appears to be a solid joint. Once it fully hardens, I'll look into inlaying a wood support of some sort in the scooped out section beneath the tuners.

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    I'll clean it up tomorrow and see what it looks like.

  16. #14
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    Default Re: Odd headstock repair

    We'll cross our fingers.
    It would be a good idea to wait 72 hours minimum before you stress the joint.

  17. #15

    Default Re: Odd headstock repair

    OK, I cleaned off the excess glue and the joint does indeed look solid, though as suggested, it will be a while before I put it to the test!

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    There definitely was wear at the break edges from the previous repair and failure of the old glue job which I'll eventually drop fill once I'm confident the joint is stable.

    The next phase will be to look at how I can add a re-enforcement to the "inside" of the headstock. It's currently scooped out to accept the tuning machines, but if I were to enlarge that scoop and glue in a splint of some sort, that should help support the headstock. I don't see how I could work a router in this unusual of a situation. Creating the clamping caul was difficult enough to do with the stepped top.

    Would anyone have any ideas on the best material to use??? I assume a hardwood of some kind, Your collected thoughts would be appreciated!

  18. #16
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    Default Re: Odd headstock repair

    Hmmm. Impossible for me to say without the instrument in hand, but one thing you can consider [if there's room] would be to work the surface of the "scoop" down 1/16" or more, get it nice and flat and regular, and lay a piece of maple or [perhaps] walnut over the whole surface, thick enough to bring the surface back up to its original height. Choice a good stiff piece of wood for the overlay, but avoid oily woods such as rosewood. I might also avoid ebony.

    I wouldn't try this until your fracture repair is well cured, and you have gently tried to flex it to insure that your repair will hold. Touchy business. I hope you got all the old glue out of there before you re-glued, and you got your clamps tightened before the glue cooled off too much. If not, your repair might not hold, and you'll have to try to re-do it. And every time a glue joint has to be re-done, it gets more difficult to get a reliable bond.

    Others might suggest inlaying a spline. I prefer the idea of an overlay if you feel you have enough material to work with.

    Whatever you decide on, good luck. On repairs of this nature we just have to cross our fingers and do the best we can, especially when a previous repair attempt has failed.

  19. #17

    Default Re: Odd headstock repair

    Thanks very much! Just the advice I needed to hear. I have access to maple and walnut, and was pondering rosewood or ebony but will avoid them now.

    RE old glue, yes, I did take time and carefully remove it. It took several tries, but I wet the are and the glue showed up as pale yellow. In order to get it out of the grain, I eventually went from a stiff bristle brush to a fine brass brush in order to get it all out. I didn't see the glue until I noticed it didn't line up as well as it should have. I do think I got all, but that will be the first thing I check before moving forward. I used hot hide glue and
    did heat the area and clamp quickly (once I finally managed to get a caul that worked!).

    I don't think there's any way to precisely cut a spline given the complex nature of the area, but I do think that I can easily increase the scoop out. The actual tuning machines that sitting the spot are flat bottomed so there will definitely be some space there already. it's just a question of increasing that as much as I can safely.

    I'll let you know how it goes!

  20. #18
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    Default Re: Odd headstock repair

    My theory on this is that most of the strength of this repair is going to come from the new reinforcement and its new glue joint. I don't think there will be much strength derived from the old repaired break, no matter how well you executed the repair. However you decide to proceed, the objective is to execute a repair that will be able to withstand 200 lbs. of constant string tension, "eight days a week."

    If the instrument had a more "standard" head rather than a violin head, I might recommend making a "sandwich," with new wood covering the break on both sides. But so far as I can tell, that would not be a viable option here.


    Don't rush on making a final decision here. One of the other seasoned repair guys might be able to come up with a better idea.

    Again, good luck. The best solution will be the one that provides the maximum strength without making a new neck or butchering the instrument.

  21. #19

    Default Re: Odd headstock repair

    While I would be hesitant to do this if the instrument has any historical value.
    How about drilling across the break and inserting a couple of dowels or carbon fibre rods. If you then plug the holes carefully and refinish it could be almost invisible to anyone else (you’ll always see it as with any perceived imperfections).

  22. #20

    Default Re: Odd headstock repair

    Thanks! RC66, I think you are essentially correct. I need to create a solid support for the neck. The glue joint is simply too small of a surface area to be effective in the long run. With the back of the break being a fiddle head, it wouldn't be possible to sandwich the break, but I'll need to make any re-enforcement big enough, and deep enough to create a significant glue joint since all the pressure will be pulling forward and I can't support the joint from the back. It appears that the tuning machines sit at the very edge of the scooped out area and I'll be able to glue in a support of whatever depth I can manage as long as I level it with the edges.

    Sonic, I'm not necessarily averse to the idea of "drilling across the break and inserting a couple of dowels or carbon fibre rods", there is simply not much depth of material to work with... perhaps no more than 1" at the very best and probably less. I'll continue to ponder this and look at other responses to get the forum's thoughts here.

  23. #21
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    Default Re: Odd headstock repair

    Although I sometimes used to successfully use dowels, several folks whose judgement I trust have told me that dowels can [at least sometimes] weaken a peghead repair rather than strengthening it. Since then, I have looked for other ways to create a strong repair.

    I won't say that I will never use them again, but with the old wood and the short thin glueing surface on this break, my instincts on this one are to avoid dowels.

  24. #22
    Registered User sunburst's Avatar
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    Default Re: Odd headstock repair

    Drilling holes through the glue joint and inserting dowels is not a good idea. When you drill the holes you remove part of your carefully cleaned, aligned and clamped glue joint. When you insert dowels you can't get particularly good glue joints between the holes and the dowels because; -The surfaces of the dowels are not cleanly cut. They are cut with a dowel maker, so the gluing surface is not the best. -The drilled holes likewise have surfaces that are not cleanly cut. They are cut by a drill bit, and even in the best case scenario (a razor sharp auger bit or forstner bit) it is not the best glue surface. -The glue joint between the dowel and the hole cannot be clamped. In order to get glue into the joint there must be clearance between the dowel and the hole so there will be a thick glue layer in the joint.
    So, when we drill and dowel we sacrifice part of our well fit glue joint for an inferior glue joint. We end up relying on the strength of the dowels themselves, and that may well not make up for the strength lost from drilling away part of the glue joint.
    Square, tapered or rectangular splines, on the other hand, can be well fit and can add some strength but only if they are well fit and well glued... or if they are epoxied. All in all, I think adding as much surface reinforcement as you can get away with will be best. Make sure you use strong, straight grained wood, a well prepared glue joint and good clamping method.

  25. #23

    Default Re: Odd headstock repair

    I always start simple and see if that works. I would wait a week, then string it up as it sits and see if it holds. It may be fine.

    Otherwise, you have a nightmare instrument as far as a backstrap installation is concerned, due to the carving it is pretty much impossible. A front strap reinforcement under the tuners won't do nearly as much good because the string force is in that direction.

    Dowels would not be an option on this particular instrument, due to the lack of space.

    The key is to wait a week or longer before attempting to string it up. Although, people like to say overnight, the joint is actually still damp for several days.

    Good luck. She's a beauty!

  26. #24

    Default Re: Odd headstock repair

    I was wondering why rods or dowels were not suggested at first; now I have an idea. You may be ok as is because those 200 pounds are not all pulling the joint apart. Without a measured drawing can’t tell where or how much the strain is. One idea is to relieve the glue joint of any forces perpendicular to the joint’s plane assuming that inplane forces are not going to shear that much glue. That’s the ‘sandwich and rivet’ which seems cosmetically a bad idea. The other idea is to create a beam running from deep in the neck to deep in the head that has sufficient stiffness to take the entire load in the principal direction. Again, a drawing might show what might be possible. The wood also might be weak elsewhere, and there’s no way to tell. Give it a go as it is and see, shouldn’t be too dangerous. Point it away from you.

  27. #25
    Mando-Accumulator Jim Garber's Avatar
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    Default Re: Odd headstock repair

    The problem with both Brandt instruments and the earlier scrolled Lyon & Healy mandolins centered around the design of the headstock which used inlaid tuners. I bought an early L&H A model with a snapped headstock and had a couple of expert luthiers work on it. It was playable for awhile then just stopped working. One of these days I will invest in some remedy. I am convinced that it was the design fault. I also own a much later Washburn labelled scroll A which has a much heavier neck join and at that point L&H figure it out. That one is an exquisite instrument.
    Jim

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