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Thread: less heavy tuners

  1. #26

    Default Re: less heavy tuners

    As in #15, two needed for that ounce. A little while ago, the same topic got me to measure tail pin counterweights for better balance. (Post 12). Your results could be different. However, lopping off those silly Victorian headstock and body scrolls can help with the issue.

  2. #27

    Default Re: less heavy tuners

    Nice, GMTA

  3. #28
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    Default Re: less heavy tuners

    After years of really neck heavy monsters, open back banjos, 5 string warwick, and 8 string multiscale guitars, I'd say: a wide suede strap, piece of sticky yoga mat slotted to fit as a shoulder pad or small weight taped on the strap (this is the easiest, from scuba diving store). For warwicks and 8 strings, moving the rear strap button.

    But i'm still gonna replace the chromed tuners on my Flat, they don't look right.
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  4. #29

    Default Re: less heavy tuners

    I bought a Kratzer A style that came with what looks like someone's "economy" tuners (cream plastic buttons). I bought a Grover set to replace these, as kind of a knee-jerk reaction. The spacing did not match, so the originals are still on the mandolin, and they work as well as any (Schaller and Grover) that I've had on my other instruments, and are quite a bit lighter, although I can't tell you now the exact weight.
    Last edited by Mike Sayre; Nov-06-2022 at 3:03pm.

  5. #30
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    Default Re: less heavy tuners

    Quote Originally Posted by Richard500 View Post
    As in #15, two needed for that ounce. A little while ago, the same topic got me to measure tail pin counterweights for better balance. (Post 12). Your results could be different. However, lopping off those silly Victorian headstock and body scrolls can help with the issue.
    An F mandolin that I made recently has no truss rod, but has a CF composite "inverted T" buried in the neck. The mass of the neck, including the F5-style headstock, was a little over 160 grams. The fretboard and frets add another ~60 grams, though part of that is over the body. A conventional adjustable truss rod would add another net 30 grams or so to the neck mass. Otoh, the tuners alone weigh 166 grams, and that is not counting the grommets and screws.

    I always weigh parts as I build. Years ago, I originally thought that the ornate ornamentation of the F5 headstock was adding more mass to the neck than simpler headstock shapes, but measurements showed me I was wrong about that. The body scroll is another story. It adds significant mass to the ribset, and to both plates. However, that mass is right about at the balance point of the instrument, so it does not have a huge impact on the balance of the instrument.

    One way to lower the mass of the heck+headstock assembly is to use a slotted headstock. I found that the necks I made with those were about 30 grams lighter than the conventional post-through ones. So, do away with the conventional adjustable truss rod and use CF composite reinforcement, and make a slotted headstock, and you can drop as much as 60 grams from the mass of your neck+headstock assembly. That still leaves the ~140-160 grams of tuners up there, which is the perennial problem for mandolin family instruments. Seems to me that selective use of a lightweight alloy (like 6061 Al maybe?) would help. A tuner baseplate made of 6061 Al would be about 1/3 the mass of a brass or steel one.

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  7. #31

    Default Re: less heavy tuners

    Dave, I see from the photos of your latest build that we read at least one of the same magazines, so I definitely agree with measurement as necessary, compared with arm, or pick waving. But I was being just a little facetious about chopping the scrolls!

    Sure, tuners don’t need to be steel and brass, and the headstock itself could be very much different since the tuners offer no resistance to the bending torque from the strings at the neck. I think that market-induced design stagnation, making reproduction of a 19th century instrument a necessity for achieving price means that builders have to limit innovation in materials and design, except for a very small potential market. The freedom that exists in, for example, electrics simply isn’t allowable.
    So performers and listeners in certain genres will continue to expect standing musicians, F- mandolins and a certain acoustic signature, probably for many years to come.
    (6061 in several tempers is probably what most product engineers use for general purposes. Because the plate acts as a bearing for the post, we need a bit of stiffness or an insert there, and at the worm supports…none of it a big deal).

  8. #32
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    Default Re: less heavy tuners

    Make it a big red helium balloon and change out the tailpiece cover to look like a sewer grate and make the top white and paint the f-holes red (and the inside) and you can have a Pennywise mandolin!

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  10. #33
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    Default Re: less heavy tuners

    Had to look up Pennywise.

  11. #34
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    Default Re: less heavy tuners

    So, I had some more to say about tuner mass, but also about neck stiffness. The attached photos are of a mandolin I built in 2010 for laboratory use. I call it Fronkenshteen (Thanks, Mel Brooks!). I built two interchangeable necks for it. The one on the mandolin is a hollow CF composite, with some CF composite stiffening in the middle of the neck shaft. The headstock part is also hollow, albeit with some wood blocks in the tuner areas. The other neck is conventional, with an adjustable truss rod. In the CF composite neck, I did away with the tuner grommets, replacing them with some very minimal bushings made by cutting ca 0.060" deep sections from a 0.25" i.d. brass tube and inlaying Tham in the headplate. From the 2nd photo, you can see that I also ground away material from the tuner baseplates as aggressively as I dared. That effort was somewhat disappointing, as I was only able to bring the total tuner mass down to around 130 grams. Tuners on both mandolins are Schallers. So how do the properties of the two necks compare? The CF neck is a LOT lighter, and from deflection measurements, about 50% stiffer.

    I also made two ribsets. The one on the mandolin has a layer of CF cloth around the inside, which raised the mass by about 15 grams compared to the other ribset, which weighs about 95 grams. The ribs with the CF lining is considerable stiffer, however. I started with the CF-lined ribset, never got around to using the other one.

    I did interferometry experiments with both necks installed, and also with no neck at all for comparison. I shouldn't say too much about the results without publishing them, but some things did stand out. One is that with the CF neck installed, the upper (0,0) body mode frequency was raised by about 30 Hz compared to the same mode with the conventional neck installed. The resonance peak of the mode was also considerably broader with the CF neck installed, indicative of stronger coupling. I don't know whether the coupling to air modes is stronger or not. I also don't know how much of the frequency difference is due to the lower mass and how much is due to the increased stiffness. I'll need to do some simulations to try to sort that out. Originally couldn't afford the software for that, but now there is a freeware [rograsm called Octave that should do the job. Sound?? My impressions, purely subjective, were that the mandolin was considerably louder and brighter with the CF neck than it was with with the conventional neck, but were a bit more refined with the conventional neck. I subsequently scraped the inside of the back plate some, bringing out a bit more bass response and warming up the sound of the Fronkenshteen monster.
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  13. #35

    Default Re: less heavy tuners

    Excellent set of experiments. One takeaway might be that a very light and stiff neck changes the body fundamental but isn’t a bad thing. Especially like the idea of inlaid ferrules; lots of design options, but also requires very clean seats - covers no raggedy edges. Skeletizing the tuner plates likely wouldn’t appeal to the tuner-as-jewelry crowd, but is an analog of what the collector mechanical watch makers do on some models, certainly not for weight reduction!
    How about adapting the sometimes guitar layout where the nut end is just an anchor, and the tuners are at the tail?

  14. #36

    Default Re: less heavy tuners

    A true test to see if lighter tuners would make any difference would be to remove the existing tuners and see if it still nosedives.....when worn with the strap. If it does, you are in trouble -- but have saved the cost of new tuners. The answer might surprise you.

    Also, fitting lighter tuners would be meaningless unless you know exactly how much lighter they need to be. (to balance)
    Last edited by Jeff Mando; Nov-12-2022 at 5:59pm.

  15. #37
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    Default Re: less heavy tuners

    In the case of mandolins, also guitars, the "body fundamental" is what is called the (0,0) mode, also sometimes referred to as the "trampoline mode", that being somewhat descriptive of its motion - zero amplitude at the edge of the plates, no nodes other than that. And it is actually a doublet or triplet. I've actually seen it split into four (a 'quadruplet'?) on guitars, that also having to do with splitting from a whole body + neck bending motion. This is more than I wanted to bother people with, but since it was brought up, I'll fill in another detail. In mandolins, the lower (0,0) mode (occurring around 250-280 Hz) was not significantly affected by the change in necks; no change in frequency, no change in half-width. The UPPER (0,0) mode peaked at around 370 or 380 Hz (Iirc) with the conventional neck. With the lighter & stiffer CF composite neck, the upper (0,0) mode peaked at over 400 Hz, and the half-width was significantly wider, due to coupling with the 2nd whole-body+neck bending motion.

    Regarding the balance, some ballpark figures: A top plate mass is typically around 90-130 grams (depending on A or F). A back plate is in the range of anywhere from 130 grams to over 170 grams (again affected by A or F, plus the individual piece of wood). Ribsets are in the range of 90 grams (A) to about 130 grams (F). A neck with a conventional truss rod weighs about 200 grams, +/- a few tens of grams. Add those up, and the balance point of a mandolin usually occurs somewhere around the heel button. Now add ca 150-170 grams to the far end of the neck for tuners, and you can see that the tuners have a significant impact on the balance point of the instrument. Mandolins are typically head-heavy, due to the relatively heavy tuning machines on a relatively small instrument.

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  17. #38
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    Default Re: less heavy tuners

    I played Dave's innovative mandolin shown above at the Guild of American Luthier's Convention that year.

    I found it brilliant and inspirational on many levels.

    The removable back design was part of what I modified into my voicing test rig with interchangeable plates attaching outside of the body cavity perimeter.
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  18. #39
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    Default Re: less heavy tuners

    In post #37, I forgot to add the mass of the fretboard and frets to the head end of the mandolin. Depending on the thickness of your fretboard, that will add ca 60-65 grams.

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