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Thread: Necks

  1. #1
    Registered User John Bertotti's Avatar
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    Default Necks

    Do any of you make your neck with using a scarf joint to attach the headstock?
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  2. #2
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    Default Re: Necks

    No---consider that each string has tension that varies but is roughly 22 pounds per string times 8 or about, give or take, 180 pounds of pull. That pull is essentially two anchored ends against the middle, quite a lot of force. Scarfed joints may be used in Ukes but I would not recommend them for a mando.

  3. #3
    Adrian Minarovic
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    Default Re: Necks

    Mandolin necks are smaller and generally made of woods that are not endangered so one piece necks are pretty much standard. Also truss rod pockets are typically on the headstock side so glue joint may affect strength of that area as well.
    Adrian

  4. #4

    Default Re: Necks

    Scarfed necks are far stronger than one piece necks, one piece necks are far more aesthetically pleasing than scarfed necks, as mentioned above, mandolin necks being smaller can utilise wood better, so less wastage.

    Steve

  5. #5
    Adrian Minarovic
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    Default Re: Necks

    Quote Originally Posted by mirwa View Post
    Scarfed necks are far stronger than one piece necks,
    Steve
    WHY? You want to say that two glued pieces of wood are stronger than one solid piece? ANd one of them being angled endgrain?
    IMO, each glue joint is potential weak spot - for any reason (heat, humidity, abuse, whatever...) the glue may become weak but solid wood is one piece, no potential weak points (unless poorly designed to start with).
    Adrian

  6. #6

    Default Re: Necks

    Quote Originally Posted by HoGo View Post
    WHY? You want to say that two glued pieces of wood are stronger than one solid piece? ANd one of them being angled endgrain?
    IMO, each glue joint is potential weak spot - for any reason (heat, humidity, abuse, whatever...) the glue may become weak but solid wood is one piece, no potential weak points (unless poorly designed to start with).
    Yes scarfed is way stronger.

    A one piece neck has got long grain running the length of the neck, but once it transitions into the headstock it has a long grain length of around 14mm or less, as the grain lines do not run with the headstock but across it at an angle, very weak in comparison to a scarfed headstock which has long grain running the length of the neck and then the length of the headstock.

    The scarf join is not an end grain join but also not a true long grain join, the grain fibres are cut at an angle and then attached to long grain, still a very strong gluing surface, it is also reinforced with the fingerboard over the top of the join. Long story short, far superior strength wise in normal operating conditions and use.

    Steve

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  8. #7
    Registered User John Bertotti's Avatar
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    Default Re: Necks

    Quote Originally Posted by mirwa View Post
    Yes scarfed is way stronger.

    A one piece neck has got long grain running the length of the neck, but once it transitions into the headstock it has a long grain length of around 14mm or less, as the grain lines do not run with the headstock but across it at an angle, very weak in comparison to a scarfed headstock which has long grain running the length of the neck and then the length of the headstock.

    The scarf join is not an end grain join but also not a true long grain join, the grain fibres are cut at an angle and then attached to long grain, still a very strong gluing surface, it is also reinforced with the fingerboard over the top of the join. Long story short, far superior strength wise in normal operating conditions and use.

    Steve
    Yes these were my thoughts as well. The long grain of the headstock would be glued to the end grain of the neck. In years of sod working and cabinet making classes we were always taught a good glue joint was stronger than the wood itself. One test was hand jointing boards then letting th instructor break them. If they broke on the glue joint it was a bad join if it broke anywhere else it was a good join. One big but though is none of them were scarf joints like a head stock because in that case the long grain is joined to an angled end grain. Might be worth a few experiments. A few boards glued up like this and then intentionally busted to see what happens. I suspect that if the headstock is figured it would be more inclined to break in the figure somewhere. On the other hand I have seen old glue joints just open which I attributed to old glue failing before the wood.i kind of think it is a case of pick your poison, if the instrument is well maintained, proper care and humidity the joint could age well. Perhaps the best of both world would be a one piece like most see to use then a front and back cap of long grain applied? A bit wore work and time intensive.
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  9. #8

    Default Re: Necks

    No research imo is required, hundreds of thousands of instruments exist if not millions with scarfed head stocks that have not failed, I have seen a couple of failures in my repair life on the glue line, but contributed that to excessive heat exposure and or lack of initial glue.

    Steve

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  11. #9
    Registered User John Bertotti's Avatar
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    Default Re: Necks

    Quote Originally Posted by mirwa View Post
    No research imo is required, hundreds of thousands of instruments exist if not millions with scarfed head stocks that have not failed, I have seen a couple of failures in my repair life on the glue line, but contributed that to excessive heat exposure and or lack of initial glue.

    Steve
    I know it was common practice in Guitars, my Martina 000-18 GE might be that way for all I know. But an experiment would be for my own curiosity becasue i just don't have the experience with instruments a lot of you guys have. I am one of the needs to see it kind of guys. I never discount what I am told by experienced people, that would just be ignorant to do becasue there is always somethign to lern, but I like to see for myself as well. At times it has shown me that although the information was good my process to get there was bad.
    Last edited by John Bertotti; Jun-11-2019 at 10:11am.
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  13. #10

    Default Re: Necks

    Quote Originally Posted by mirwa View Post
    Yes scarfed is way stronger.......

    Steve
    I’d need to see numbers. The proof is in the testing.
    Play it like you mean it.

  14. #11
    Registered User John Bertotti's Avatar
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    Default Re: Necks

    Funny thing is I just looked at the leaves of a 150 or older oak table that was stored in my grandmother's very humid basement for almost as long. I have glue joints opening up along a lot of the joins. Illinois and an old coal-heated house in the winter so the humidity was all over the place. Teens in the winter way-way higher in the summer. I don't expect any glue joint to hold up to that. Now if there is an adhesive that can hold up to that I would certainly like to know. Most normal woodworking projects I use good old white woodworking glue or Titebond, honestly, I don't know what the difference is between them they just work. For the limited instruments I have built it was hot hide glue and sadly found out after the fact the can be labeled incorrectly and I had mixed way to much hide glue into the water, kind of brittle over time. I actually still have those granules but haven't used it since. I wonder if they would still work if mixed properly, the can must be 15 years old now.
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  15. #12

    Default Re: Necks

    I must have repaired twenty or thirty broken headstocks by now and not once have I ever encountered a broken scarf joint. On occasion, I have repaired instruments that I have previously repaired with another break to the headstock at a later date and not once has the previous repair failed at the glued joint. That said, a joint is only as good as its execution and there is a limit to the safe angle that you can employ in a scarf joint where the woodgrain orientation differs.

    Solid one piece necks or with a scarf joint, I tend to build with a minimal headstock angle with only enough angle to achieve a sufficient break angle of the string at the nut. It makes for a stronger headstock and lends to tuning stability associated with nut slot complications.

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    Default Re: Necks

    If the granules are in a sealed container, they should be good.
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  19. #14
    Registered User John Bertotti's Avatar
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    Default Re: Necks

    Quote Originally Posted by Wrnchbndr View Post
    I must have repaired twenty or thirty broken headstocks by now and not once have I ever encountered a broken scarf joint. On occasion, I have repaired instruments that I have previously repaired with another break to the headstock at a later date and not once has the previous repair failed at the glued joint. That said, a joint is only as good as its execution and there is a limit to the safe angle that you can employ in a scarf joint where the woodgrain orientation differs.

    Solid one piece necks or with a scarf joint, I tend to build with a minimal headstock angle with only enough angle to achieve a sufficient break angle of the string at the nut. It makes for a stronger headstock and lends to tuning stability associated with nut slot complications.
    Is there a rule of thumb as to when the angle is to much on a neck?
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  20. #15
    Adrian Minarovic
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    Default Re: Necks

    I still don't see any reason why scarfed neck should be stronger.
    Normal scarf like in classical guitar is right in the place or more typically slightly below where the headstocks commonly break so to that spot it adds nothing. There is still all the "short" grain that can fail with hit AND the glue joint to that. I had to repair more than few broken scarf headstocks and mostly they break along the joint with splinters of wood here and there - you have to clean the surfaces from old glue and make it fit again for succesful repair. With simple solid wood if it breaks you just glue it back together no additional work needed and it is easier to get nearly invisible repair of solid neck than on broken scarf.
    The body of headstock itself is actually stronger on scarfed head as the grain runs along and not at an angle but I have never seen headstock broken in half in that place that I could call material failure as well (considering most mandolin headstocks are sanwiched between headstock overlay and backing veneer that make it a lot stronger).
    Then there is the scarf that goes the direction of headstock. That solves the short grain but still the mostly stressed part of the joint is exposed and over time may lead to failure (humidity or heat involved) and in this case the damage is often bad as the end of fingerboard can break way at first fret... I've seen few classical mandolins with this - not simple job.
    While scarfed jonts are accepted in guitar world and certainly do work the solid necks don't break because of exposure to heat or humidity cycles. They do break when the instrument falls or is hit hard, but just as easily the scarfed necks break.
    Adrian

  21. #16
    Registered User tonydxn's Avatar
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    Default Re: Necks

    German mandolins, even quite cheap ones, often had heads joined to the neck with a V-joint. That gives the strength of grain running parallel to both the neck and the head (as explained by Mirwa), but is stronger than a scarf joint. These V-joints were tapered so they had mechanical strength and did not rely for their strength only on glue. Failure of these V-joints is very rare.
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  22. #17

    Default Re: Necks

    Quote Originally Posted by HoGo View Post
    I still don't see any reason why scarfed neck should be stronger.
    Totally okay, my job is not to convince you.

    Steve

  23. #18
    Registered User John Bertotti's Avatar
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    Default Re: Necks

    Well, I see it like this. Either works and any glue joint will fail with improper care and non-long grain will break easier than long grain orientation so the question is, is having long grain worth the effort of a scarf joint or another way to put it is no having long grain on a headstock, which it has if it is capped, better then having a scarf joint.

    In my mind, you can't protect against stupid if someone doesn't want to take care of an instrument if it isn't the scarf joint it will be a different area that takes damage and we can't always protect against accidents and or slips so long grain or not the headstock could be broken.

    In the end, it seems it is a case of pick your poison.

    I have never done a V neck join but have read about them and to me, it seems the most difficult to pull off. I could be wrong.
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  24. #19

    Default Re: Necks

    V joint is a tricky one to get right, i totally agree its a strong joint, approximatley 45minutes IMO for any luthier to cut and make.

    Scarf joint incredibly simplistic and takes less than 5 minutes to make for any luthier.

    One piece neck, maybe an extra 15 minutes for rough shaping the headstock area.

    So time is really not a huge factor unless you are commercially making them.

    The grain orientation on the headstock is IMO not an issue at all, the shorter long grain on a one piece is more than sufficient.

    Steve

  25. #20
    Registered User fscotte's Avatar
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    Default Re: Necks

    The kind of wood species matters.

    A glue joint will not be stronger than Brazilian Cherry, as an example...

    But a glue joint on Sitka spruce will always be stronger.

    It's quite easy to test. Cut a piece of wood in half, glue the cut line, let sit for an hour, place on edge of table, strike with hammer.

    I do this test to see if my glue is still good before using it.

  26. #21
    Registered User sunburst's Avatar
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    Default Re: Necks

    Quote Originally Posted by fscotte View Post
    ...a glue joint on Sitka spruce will always be stronger...
    Even at 170 degrees? That can happen inside a car in summertime.

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    Default Re: Necks

    Can someone explain to me what a "v joint" neck to headstock joint is? I can't picture it.
    belbein

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  28. #23
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    Default Re: Necks

    Quote Originally Posted by belbein View Post
    Can someone explain to me what a "v joint" neck to headstock joint is? I can't picture it.
    Nice little slide show on this guitar makers site.
    http://www.grevenguitars.com/tablet/...beak-demo.html
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  30. #24
    Registered User sunburst's Avatar
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    Default Re: Necks

    [QUOTE=John Bertotti;1719948]Nice little slide show on this guitar makers site.

    That's actually the "modified bridle joint" that martin used in the past. Martin also used a simpler V-joint in even earlier years. It looks like this:
    Click image for larger version. 

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  32. #25
    Registered User John Bertotti's Avatar
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    Default Re: Necks

    [QUOTE=sunburst;1719951]
    Quote Originally Posted by John Bertotti View Post
    Nice little slide show on this guitar makers site.

    That's actually the "modified bridle joint" that martin used in the past. Martin also used a simpler V-joint in even earlier years. It looks like this:
    Click image for larger version. 

Name:	V-joint.jpg 
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ID:	177631
    I wondered about that. I have seen both but didn’t know which came
    First. I have not tried making one but am oddly drawn to them. Why? I can not say.
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