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Thread: Got the neck off, now how do I put it back?

  1. #1

    Default Got the neck off, now how do I put it back?

    Newbie here, I've messed around with fiddles and just learning to play mandolin. My first mandolin quickly began pulling at the neck so I set it aside and got a nice used Epiphone and had it set up at the shop to learn on. That freed me to try to repair this mass-produced one. It's called Degas but I've seen many more just like it under a variety of names. I was drawn to the back and sides being maple and not painted over, although I suspect it's laminate.

    I watched the videos, read everything I could find, made some mistakes. I got the fingerboard off with my good iron for sewing and the spatulas I use for my job as a cake decorator. And a hammer lol.
    The adjustable-heat soldering iron I use on my motorcycles comes apart to make a skinny rod that conducts the heat, so a tiny drill bit got me into the space under the dovetail where lots of steam finally got the GLOBS of glue loose enough to get it apart. There was more glue than wood making contact in this. I think I've got the glue out now.

    Beyond the obvious invitation for advice from y'all based on the photos, I'm looking for how to set it back up so the neck is 1) straight side-to-side and 2) puts the fingerboard at the right angle. I'm assuming I will need to use shims to fill the void that allowed the neck to pull in the first place. Without a jig, I'm wondering how to clamp it up at the right angle.

    And the glue--what came out was white and rubbery. Will the fish glue I use on my violins be strong enough?

    So...glue type and neck angle. Help please?
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  2. #2
    Registered User sunburst's Avatar
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    Default Re: Got the neck off, now how do I put it back?

    That's a lot of questions in one post! I'll see if I can cover most of it...
    Roll, pitch and yaw. Those terms from aviation are the three things we must monitor when setting a neck, but first we have to know the three angles. We also have to maintain center, so add center line to roll pitch and yaw.

    Pitch is determined by the height of the top arch and the desired bridge height. It can be checked by laying a straight edge on the neck fingerboard surface and gauging the clearance above the top. Without a fingerboard on the neck, that must be taken into account and the space between the straight edge and the top at the bridge position calculated.

    Yaw is the angle of the neck relative to the body center line. To maintain that while fitting a neck I usually tape a short straight edge at the tail end of the mandolin, directly on the center line, extending upward above the top. I lay a straight edge on the center line of the neck and see that it intersects the short straight edge when the neck in st in place. That angle must be maintained throughout the process.

    Roll is whether the fingerboard will be level with the rim of the mandolin. Easiest thing to do (for me) is maintain alignment of the neck center line with the center of the top while also maintaining the center line of the heel with the center line of the back.

    I suspect you'll have to rebuild the dovetail. It was probably fit loosely and globbed full of glue to take up the space. Simply adding shims might achieve a good fit, but they might end up being thick shims more like filler pieces.

    If (and only if) you can remove all of the old glue, your fish glue will do the job. That's part of what I meant when I said you might have to rebuild the dovetail. Shaving away some wood from the sides of the tenon with a chisel and then gluing on "shims"; shaving away wood from the sides of the mortise, and then refitting the dovetail would give you clean glue surfaces, and fish glue would work.

    As for clamping, if the dovetail is well fit it is self clamping and self aligning, and you should only have to clamp it (possibly) to fully seat the tenon in the mortise. Once it is fully seated there is no particular need for clamps as the glue cures.

  3. #3

    Default Re: Got the neck off, now how do I put it back?

    Looks like you’ve hunted down a few fiddles! Since I own a Degas, I’m happy and surprised to know these have dovetails, even sloppy ones. John’s advice is absolutely a clear and concise recipe. Good straightedges, with especially clean edges and easy and strong enough to clamp are helpful: I have some accurate square aluminum tubing that’s handy and good enough to see fret alignment, and clamp the fretboard on installation.
    But still, if you don’t get the neck precisely right, you have the further adjustments of neck and fretboard planing available, especially useful if the tenon does slip a smidge after the repair.
    My Degas, which I converted to mandola because it’s kinda big, has a different problem: the front part of the soundboard sank either because the structure behind the neck is flimsy, or from other pressures. I added an external brace laterally, and it’s stabilized for several years. Not a proper thing to do, and visible, but so what.

  4. #4

    Default Re: Got the neck off, now how do I put it back?

    OK cool, y'all make good sense. I have a few good steel straight edges (grew up in a welding shop). I reckon if I can cut down a violin bridge, I can make the dovetail bigger and then trim the body to fit the neck. That and the mandolin bridge should help compensate if I the fingerboard ends up tilted a little?

    Richard is your Degas laminate? I know I ham-fisted it a little bit trying to get the neck out, I'm surprised I didn't break the top. Heck I'm surprised I was strong enough, There was enough glue globbed up in there that it looked like two sticks of chewing gum.

    I need to post a photo, but the centerline of the body does not line up with the tail piece. Is this normal?
    Sorry for the obvious questions, just learning here, and not getting frustrated because I do have something to play and practice while I mess with this project.

    Thanks!!

  5. #5
    Registered User sunburst's Avatar
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    Default Re: Got the neck off, now how do I put it back?

    Quote Originally Posted by coffee_brake View Post
    ...the centerline of the body does not line up with the tail piece. Is this normal?
    It probably means they didn't get their yaw correct when setting the neck so they placed the tailpiece to compensate. That happens more often than one might think, so in that sense it is 'normal' but not exactly 'correct'.

    Now's your chance to correct that, or else you can set the neck to the tailpiece position rather than the center line.

  6. #6

    Default Re: Got the neck off, now how do I put it back?

    Quote Originally Posted by sunburst View Post
    It probably means they didn't get their yaw correct when setting the neck so they placed the tailpiece to compensate. That happens more often than one might think, so in that sense it is 'normal' but not exactly 'correct'.

    Now's your chance to correct that, or else you can set the neck to the tailpiece position rather than the center line.
    Check out where the tail piece is screwed on, and I've put my finger pretty near the center of the top. Is it wrong or does it just look wrong? Click image for larger version. 

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  7. #7
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    Default Re: Got the neck off, now how do I put it back?

    As John said, they didn't get the neck correct and compensated with the tailpiece. Yours' isn't the first.
    THE WORLD IS A BETTER PLACE JUST FOR YOUR SMILE!

  8. #8

    Default Re: Got the neck off, now how do I put it back?

    Quote Originally Posted by pops1 View Post
    As John said, they didn't get the neck correct and compensated with the tailpiece. Yours' isn't the first.
    Thanks y'all, I think I understand. I'm not sure I have the skills to fix that, but no reason I can't try. I kept some thin pieces of maple from fiddle parts, will that be good to try to make the neck joint thicker?
    And the same fish glue? I've never seen this done, I'll hit Google to look for a video before bedtime.

  9. #9

    Default Re: Got the neck off, now how do I put it back?

    My Degas doesn’t appear to be laminated, unless the thick finish counts, but it’s hard to tell. Just looked at the f hole edges and it appears solid, and there’s hardly any figure in the wood to see on both sides. The tailpiece is right on the seam line, and the bridge centered on the top. Strings align well with the fretboard too.
    I would only bother moving the tailpiece if there’s a fretboard alignment issue when you rearrange the neck. I think friction at the bridge bottom can overcome minor asymmetry behind it. And unlike on a violin, a mandolin bridge has a lot of latitude in location.
    An excellent educational project, and likely to be successful. You might even like the muted sound as compared with a ‘better’ instrument.

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  11. #10
    Adrian Minarovic
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    Default Re: Got the neck off, now how do I put it back?

    I wouldn't count on the centerjoint to be really centered on one of these. Often the only usable centerline is compromise between body shape and f hole positions. Measure from both sides and you'll find what looks best.
    For rebuilding of joint I would clean all glue with minimal wood loss make sure the body dovetail is clean and sides perfectly flat, in this case probably the neck mating surface was meant to be flat as well. I would add shims of appropriate thickness to angled sides of neck dovetail. You can use ordinary hardwood veneer or even popsicle sticks if the gap was really thick. from there it is fitting of the surfaces. if the mating surfaces of neck and body are flat (or fitting well) most of the work would be in removal of material from the shims only bare minimum would be removed from the other surface to assure the neck follows centerline. If the neck angle is not correct (usually too low) you'd need to add shim to the mating surfaces or remove more wood from the heel.
    I wouldn't fear of glue not holding, if there is good wood to wood contact any wood glue would work.
    Adrian

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  13. #11
    Registered User j. condino's Avatar
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    Default Re: Got the neck off, now how do I put it back?

    Give them some credit.

    Ask anyone who has ever worked in a factory- the guy who made that mandolin probably built 25 of them before lunch, all while getting verbally abused and threatened by management...(wait...that story sounds somehow familiar...)!

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  15. #12
    Registered User sunburst's Avatar
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    Default Re: Got the neck off, now how do I put it back?

    Quote Originally Posted by HoGo View Post
    ... You can use ordinary hardwood veneer or even popsicle sticks if the gap was really thick...
    If you want to be able to shave away wood from the shims easily, hardwood veneers are seldom the best choice, and I wouldn't advise popsicle sticks.
    For shimming dovetails I use mahogany scraps (from guitar sides or backs), and only after first checking for grain run out and applying the shims so that the chisel is cutting into the grain for clean easy cutting when re-fitting the joint. Of course, we don't all have mahogany scraps at our disposal, but it can be very frustrating to encounter contrary grain run out and/or very hard wood in a shim that needs to be carved to fit. I have used walnut veneers with reasonable success, but avoid maple, birch or any other very hard wood with questionable grain direction.
    If popsicle sticks can be confirmed to have decent grain direction, if they are made from wood that is not difficult to carve and if they are wide enough to cover the dovetail surface, then they will probably work well. Still, not my first choice.

  16. #13
    Adrian Minarovic
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    Default Re: Got the neck off, now how do I put it back?

    Quote Originally Posted by sunburst View Post
    If you want to be able to shave away wood from the shims easily, hardwood veneers are seldom the best choice, and I wouldn't advise popsicle sticks.
    For shimming dovetails I use mahogany scraps (from guitar sides or backs), and only after first checking for grain run out and applying the shims so that the chisel is cutting into the grain for clean easy cutting when re-fitting the joint. Of course, we don't all have mahogany scraps at our disposal, but it can be very frustrating to encounter contrary grain run out and/or very hard wood in a shim that needs to be carved to fit. I have used walnut veneers with reasonable success, but avoid maple, birch or any other very hard wood with questionable grain direction.
    If popsicle sticks can be confirmed to have decent grain direction, if they are made from wood that is not difficult to carve and if they are wide enough to cover the dovetail surface, then they will probably work well. Still, not my first choice.
    You are correct.
    I suppose OP doesn't have set of perfectly sharp chisels and will mostly use more common tools like files or sandpaper on sticks etc... My popsicle sticks are almost 1" wide 1/16" thick and made of sliced white poplar veneer so they cut easily with chisel, they are my source of good quality poplar veneer shims. Mahogany (honduran) is hard to get here and sapele has interlocked grain.
    In most cases I shimmed dovetail all that was needed was standard 0.5-0.8mm veneer (I mostly have birch, maple and beech veneers for this) and few well aimed strokes of sharp file.
    Adrian

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    Registered User sunburst's Avatar
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    Default Re: Got the neck off, now how do I put it back?

    Quote Originally Posted by HoGo View Post
    ...My popsicle sticks are almost 1" wide 1/16" thick and made of sliced white poplar veneer so they cut easily with chisel...
    I see. "Our" popsicles sticks (in US) are 3/8" wide, 1/16" thick and made from mystery wood with unpredictable grain direction. A search revealed that most are birch.

  18. #15
    Registered User Sue Rieter's Avatar
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    Default Re: Got the neck off, now how do I put it back?

    Tongue depressors?
    "To be obsessed with the destination is to remove the focus from where you are." Philip Toshio Sudo, Zen Guitar

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  20. #16

    Default Re: Got the neck off, now how do I put it back?

    How about a piece of a broken rosewood fingerboard from a guitar? I'm not sure where it came from but it's in my wood pieces stash.

    I have lots of spruce from violin tops and ebony from violin fingerboards. Also have a curly walnut cracked shotgun stock LOL but y'all said no funky grain. not experienced with using a chisel effectively but I have a set of very small ones.

    That rosewood (or whatever it is, maybe some species of mahogany, it was an undeniably terrible guitar) is the best straight grain I have.


    Thanks for replies. Will a sanding block and sandpaper get the old glue out of the neck and get the flat finished with clean wood I need?
    I'm afraid I'm going to have to use those chisel blades for the first time to get the glue out of the body. I got the biggest globs out with a dremmel on low speed but won't that burnish the new wood and prevent an effective glue fitment? Also the dremmel tips are all round, and won't yield a flat finish.

    Going slow, learning...thanks!

  21. #17

    Default Re: Got the neck off, now how do I put it back?

    You’re correct about trying to not burnish glue surfaces, but the virtue of a dovetail is that the strength is fitment, not glue, and an incompressible hard surface should be fine. However…. the subject of glue, especially concerning so-called oily woods like some rosewood, is as contentious as pick architecture, and probably not too meaningful. For small flat surfaces, a Dremel with a large diameter diamond wheel is very handy - that is, a thin disk coated on the large surface with diamond. Also, there are cup-type wire brushes that are useful for getting muck off surfaces that would otherwise clog stones or sandpaper. These are about 1//2” diameter, and come with brass or steel wires. Do not buy the ultra cheap ones if you value your eyesight. They should leave a clean and ‘toothy’ surface. Another handy resource is the humble two-sided nail file board.
    Unless you want to engage in graduate arcane technology, learn as little as possible about chisels and use fresh utility knives, scalpels, etc when possible. I happen to like arcane stuff, and I also don’t mind sharpening as meditation. Maintenance and use of small planes; same deal.

  22. #18
    Registered User oldhawkeye's Avatar
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    Default Re: Got the neck off, now how do I put it back?

    I'm unsure how helpful this will be but Ted Woodford, a luthier in Canada, has what I consider very informative videos showing how he does the work on guitars.
    There are quite a few on neck resets and the basics can be applied to mandolins. Here is a link:
    https://www.youtube.com/user/twoodfrd/videos
    Good luck on your quest.
    Dave
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  24. #19

    Default Re: Got the neck off, now how do I put it back?

    Those are great videos!
    I'm more overwhelmed than ever. These folks are measuring thousandths and I don't even know what the neck angle is supposed to be. I don't know how I'm going to stabilize the joint in three dimensions, much less get that neck at the right angle with all the wood snug enough to hold.

    Is just fitting it and honing down the rub marks not enough? LOL

  25. #20

    Default Re: Got the neck off, now how do I put it back?

    Measurement ‘in thouandths’, precise jigs; forget about it. Wasn’t needed back when, and isn’t now. You define the alignments according to the instrument itself: the one you are repairing. Just like a violin. There is no single neck angle. All you have to do is put the thing together so that the strings let the bridge be a usable height, which on this particular item is, say, in the middle of its adjustment range - likely about one standard US finger thickness. The fretboard, and neck top surface is at a smaller angle than the strings. How much? Just enough so that the action is - usable. The only measurement is using a straght edge and maybe a coin or two for action height.

    The Degas top may have sunk, or vary from sample to sample: the neck angle (and the aeronautical pitch, yaw and rolll) are eyeball-level accuracy, and can vary. All you need to do is get the strings more or less centered left-right and not much twist between the bridge top and the fretoard plane. The angle the strings make behind the bridge is pretty well fixed, and mostly has to be more than zero, so nothing to be done there.

    Where the thousandths come in, you don’t need to really measure. The fit of a violin peg is much less than one-thousandth of an inch, and the taper angle a tiny fraction of a degree but you don’t caliper or micrometer the thing. Get all the frets filed or sanded so that no light shows past that straight edge, none of them sticking up or low, and you’re done. And as I mentioned before: even if the glue up is a little wonky, you still can correct things before you paste the fretboard back down. Unless the internal stuff on the Degas is actually loose or broken, it’s guaranteed success.

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  27. #21
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    Default Re: Got the neck off, now how do I put it back?

    It would be nice if you could recenter the neck to the body, but since this is your first reset I would just get in back in tight. The tailpiece is already off center and you can place it where you need it. Of course it would be nice to be somewhere near center, but as Richard says don't sweat the small stuff.
    THE WORLD IS A BETTER PLACE JUST FOR YOUR SMILE!

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  29. #22

    Default Re: Got the neck off, now how do I put it back?

    There is tear-out in the neck (I didn't do it!) from just an awful cut at the factory. I know there's going to not be a smooth wood-to-wood fit when chunks are missing out of the dovetail. I'm reading and youtube-ing my way around, looking for answers, but anybody got any tips? I can see some videos with shims on a neck reset, guitar usually, but I'm not sure if my grain direction will matter.
    All I could find in my stash that would be even remotely suitable was a piece of oak from some old furniture. It's gonna be a long time on the tabletop belt sander thing to get it thin enough. I've got my eyes open for any junk furniture with veneer, too, that I can snag.

  30. #23

    Default Re: Got the neck off, now how do I put it back?

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  31. #24
    Registered User sunburst's Avatar
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    Default Re: Got the neck off, now how do I put it back?

    Back to what I said about rebuilding the dovetail.
    The tenon is damaged, and likely the mortise too. Shims can be added, but it would be better with good glue surfaces. Cutting away the damaged wood from the sides of the tenon and gluing new wood in place, then re-fitting the dovetail joint would improve things considerably. Probably shaving some wood from the mortise would too. Now, of course, we back to needing some decent quality wood for shims, and oak would be waaaay down on the list for me. Surely there is someone near you who would have wood scraps the look through(?).

    One other thing. I can't really tell from the pictures, but it looks like you might be dealing with a straight (rather than tapered) dovetail. This might put you beyond your desired level of immersion here, but if it is a straight dovetail, I would convert it to a taper. That requires shims that are pretty thick (and some expertise with chisels).

  32. #25

    Default Re: Got the neck off, now how do I put it back?

    Oh, you mean cut even more wood away. I gotcha. And yes, it appears to be a straight dovetail.

    On the way to work there was an old water-damaged interior door out for trash day. The laminate was coming off it, so I snagged a good length of it. It's one of those 60s or 70s doors and it curled up into a circle without splitting too much more. Would that be ok? I'm assuming it's pine, most of the houses around me all had the same doors.

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