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Thread: Tuning pin spacing

  1. #1

    Tuning pin spacing

    Hi all. I'm designing an instrument modeled after a clavichord or early square piano. I'm currently trying to decide on the spacing between tuning pins and am wondering if any of you could provide some insight on minimum / ideal spacing. That is, I don't want to place pins too close to each other so that the strength of the wood is compromised, but I want to keep the distance as small as possible because this dimension directly correlates with the overall width of the instrument.

    I plan on using modern zither pins which require 3/16" holes, and the spacing I'm considering is 1/2" from center-to-center of adjacent holes. Should this suffice to not compromise the wood? Can I go smaller, maybe 7/16"? There is about 23 lbs of tension on each string.

    Thanks!
    Last edited by Sasha Kern; 01-25-2024 at 2:58 PM.

  2. #2
    A lot is going to depend on the wood species and how straight or not the grain is.
    Depending on the number of strings, staggering them may be the way to go.

  3. #3
    Quote Originally Posted by Edward Weber View Post
    A lot is going to depend on the wood species and how straight or not the grain is.
    Depending on the number of strings, staggering them may be the way to go.
    I want to use either oak, beech, or maple, and the options I'm considering for the construction are:

    1) a single thick piece which is quarter-sawn on the surface with tight grain running perpendicular to the strings
    2) several laminated layers with alternating grain
    3) a thinner piece which is laminated onto pine to reduce weight

    There are 68 strings total, which I planned on dividing into two rows of 34 strings each. So, if I were to stagger the pins in this setup, you mean I would end up with something akin to four rows?

  4. #4
    Not quite 4 rows but two alternating rows or zig-zag
    In my mind, I was thinking of what you might find on an autoharp

  5. #5
    I will look into autoharps. Thanks!

  6. #6
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    It depends in part on how big the pins are and the string tension-- piano strings with a piano size pin will want to be farther apart. Pins will hold better in a laminated block-- look at piano pin block construction. Hard maple is good.

  7. #7
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    I bought 2 Katalox boards today. I bet that wood will hold a pin. A few thick laminations of rock maple are what the better piano makers brag about their pin blocks being made from.

    Here is tension data for guitars etc.

    String Tensions

    and another that is way over my head.

    (no title)
    Last edited by Maurice Mcmurry; 01-26-2024 at 9:48 PM.

  8. #8
    Quote Originally Posted by roger wiegand View Post
    It depends in part on how big the pins are and the string tension-- piano strings with a piano size pin will want to be farther apart. Pins will hold better in a laminated block-- look at piano pin block construction. Hard maple is good.
    Factoring in pin size and string tension, a piano has about 4x more stress on each pin than what I'm planning. The distance between closest tuning pins (center-to-center) in my piano is 1/2". Earlier today I tentatively decided on a distance between closest tuning pins of about .7" inch. This seems to be a quite sufficient minimum distance, and I could likely lower it, but I should also take into account the fact that I'm a complete amateur and thus my pinblock will not be as robust as that of a professional piano. I doubt it would be 4x less robust, but I might as well be extra safe. Do you think this makes sense?

  9. #9
    Quote Originally Posted by Maurice Mcmurry View Post
    I bought 2 Katalox boards today. I bet that wood will hold a pin. A few thick laminations of rock maple are what the better piano makers brag about their pin blocks being made from.

    Here is tension data for guitars etc.

    String Tensions

    and another that is way over my head.

    (no title)
    Any estimate as to what those piano makers mean when they say 'thick' lamination? Like 3-4 strips of 1/2" thickness or so?

    I had already read the pdf you linked. It's definitely a doozy.

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  11. #11
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    When I built hammered dulcimers I used what Schaff calls "zither and harpsichord pins" 0.198" X 1-5/8". I used the nickel plated ones because they showed. They were about a half inch apart. I used grand pinblock blanks I bought from Schaff, veneered as appropriate for the instrument. They were of the thick ply type, with the grain rotated by ~45 degrees between plies. Still have a few pieces around the shop. Last I checked those pins were still holding tight after 40 years. Overall my construction was way too robust, those instruments rang like a bell and sounded pretty terrible. I later learned about the importance, in that case, of keeping things light, just on the verge of collapsing under the string tension, to get the right tone.

  12. #12
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    Sasha,

    I've been building harpsichords for 39 years so perhaps I can offer my 2 cents on the subject. I think your worries about the strength of your proposed pinblock are unwarranted. The biggest problem with pinblocks in very low tension instruments is not holding power. Rather, it is pins that are too tight that are the problem. Zither pins, which are the pins I've used for decades, do not necessarily require a 3/16" hole. It depends on what wood your pinblock is made out of. I can guarantee you that using a multi-ply piano type pinblock would make a zither pin in a 3/16" hole way too tight for comfortable tuning. I use a solid slab (1 1/2" thick) of red oak for my pinblock material and a 3/16" hole works well in that material. I know of one builder (now deceased) who routinely used regular plywood for his pinblocks - and they held up fairly well. While I wouldn't dare to use plywood it does seem to work in a low tension instrument. In the harpsichord community, it is generally thought that if a tuning pin can't be turned by hand, it's tight enough. I may not go that far, but a pin doesn't have to be tight in the pinblock to resist the moderate amount of string tension. A pin that is too tight will jerk or jump when turned rather than move smoothly. This makes fine tuning difficult and, in some cases, impossible.

    Similarly, spacing between tuning pins is rarely, if ever, a problem. The spacing is more or less dependent of the octave width of the keyboard. If the keyboard has a width of 6.5" from a note to the same note an octave higher, then generally speaking, the spacing of the tuning pins will be somewhere close to 6.5" divided by 13 or about 1/2". If the spacing is much wider than that, the instrument's case will not be wide enough to contain all of the pins. Also, the larger the spacing, the more severe the angle between the nut pins and the tuning pins will be. This angle, while necessary for bearing, is usually between 5 and 10 degrees. More than that places additional stress on the string and less than that will not produce a workable amount of side bearing. I do believe that staggering the pins is a good idea, not only for the health of the pinblock, but for ease of pin identification for the tuner. The picture below shows the pinblock area of my current project.

    sttagger.jpg

    This instrument will have two sets of strings, and 8' rank and a 4' rank, so there are two rows of staggered tuning pin holes. The first hole on the left is a C tuning pin. The holes on the bottom row of each rank are for the natural key tuning pins. The holes on the top row of the stagger are for the sharp key tuning pins. In other words, the stagger is arranged to mimic the look of the keyboard with 7 naturals on the bottom staggered row and 5 sharps on the top row.

    I feel I am starting to get too dorky in my response, so I'll stop here. I doubt that going into much detail would be of interest to most folks on the Creek. If I can help you in any way, don't hesitate to contact me privately.

    Ernie
    "A lot of people are afraid of heights. Not me, I'm afraid of widths."
    -Steven Wright.

  13. #13
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    I enjoy the details! Happy birthday to Mr. Mozart.
    Best Regards, Maurice

  14. #14
    Quote Originally Posted by Ernie Miller View Post
    I feel I am starting to get too dorky in my response, so I'll stop here. I doubt that going into much detail would be of interest to most folks on the Creek. If I can help you in any way, don't hesitate to contact me privately.

    Ernie
    Hi Ernie. Unfortunately I'm unable to send private messages due to a lack of user privileges.

    Thanks for clarifying the risk of tuning pins being too tight, I had not considered it. Before reading about laminated pinblocks, I had concluded that a single piece 1.5" - 1.75" pinblock of a dense wood such as oak would be sufficient, so it's good to hear that this has worked for you. I'm curious if the overall tensions in our respective instruments are similar. Mine is looking to be about 1500 lbs total (68 strings x 22 lbs per string). Is that in the same ballpark as yours?

    Regarding spacing, the strings will be horizontal like a virginal, so the spacing is not decided by key width and therefore I have some flexibility with this measurement. I was considering having adjacent pitches be 1/2" apart with 3/8" stagger, meaning the actual center-to-center distance is 5/8". It seems you're saying I could lower these dimensions. Do you think I could get away with 3/8" apart with 2/8" stagger yielding a center-to-center distance of about .45"?

    Unfortunately I was unable to view your image (again, user privileges).

  15. #15
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    Sasha

    Yes, I'm sure you'll be fine with a .45" spacing. I'm not sure of the Creek rules, but if you Google Miller Harpsichord you can get to my website where my contact info is listed.
    "A lot of people are afraid of heights. Not me, I'm afraid of widths."
    -Steven Wright.

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