Musical Instrument Tuner Using Elastic String





Introduction: Musical Instrument Tuner Using Elastic String

About: A retired electronics engineer -motorola. delveing into new craft ideas and contest entries.

INTRO- In this instructable i will show you how to make an instrument tuner device.

It is constructed using simple, easy to get, parts .

It is useful when tuning a string instrument or when making one and needs to be tuned.

It is strictly mechanical -no battery needed.

I built it in one afternoon.

I am entering it in the Klutz Competition.

I make an sell plans for miniature string instruments such as Lyres and Modified Zithers. See my Web page for details on

[[Video(akinst 2-4-22-9, {width:425, height:350})]]

Step 1:

Using the tuner see video.

Step 2: Step 1 How It Operates

The pictured view shows the general view of a plastic box and 3 elastic strings tied at one end to the bottom and at the other end to a tuning mechanism .A similar sized box is attached to the bottom and used as a resonator amplifier if more sound volume is needed.
The plastic box should be semi-rigid. A plastic pencil box is just right to work with .Use a square of stiff, white card-board for the notes printing surface.You will need to mark the notes as you press down to sound the note,I used my Casio to sound the notes. The first string is tuned to C below middle C. Second string tuned to middle C. Third string is tuned to C above Middle C. Use the thumb nail of left hand and press string to card-board,Hit the note ona casio or harmonica,etc.D mark, E mark, etc.Pluck string with your right hand. Repete with all strings. Tuner is now complete.

Step 3: Materials-Tools

Tools can be a plier. saw, awl or pick,Hemostat {locking type}
I used gas pliers to close the open looped cup hook [tuner screw]. This is need to easily tie a knot at this end.Home Depot sells 5/8 hooks nickel plate steel with a collar.cost about 5 cents.
A Dremel can be used to drill 1/16 drill bit pilot holes for the three screws.Screw the hooks all the way down to the little collars on thescrew. For tuning you might need assistance in screwing the tuner clockwise farther when tightening the strings.

String- canbe a rubber band cut into a string. I found it will work but I note the rubber deteriorates over time. I found an elastic string, made by Pepperell Crafts called 1mm bead/jewelry cord,is more stable and they last at least 5 years. Buy a spool at most Craft stores for under $2.00

Anchors- The string is passed through the 1/16 in hole and anchored on the under side with a crimp bead [found in any craft store] cost about 5 cents ea.

Step 4: Step 3 Assembly and Tune It

My pencil box was 4 x 8 x 1 in. deep. The strings were 4.5 inches long inside but started with 7 in. long to easily tie a knot and stretch to tune to the C note.
I tied a knot at the closed cup hook rotated the string about3 times clock-wise around the collar and routed it down to the 1/16 hole and clamped it with my hemostat plier close to the hole.Then I strung a crimp bead of 1.3mm ID and crushed the bead with pliers close to the hole.This works better than tying a large knot that wont squeeze through the hole.
I pulled the string and plucked it to get it to sound slightly lower note than the C note I played on my Casio.Then I applied the crimp. Then I final tuned it to C with the tuner screw about 3 rotations or less.

Tune - Each string was separately tuned C lowest Octave, Middle C then High C..Use your thumbnail Start with note D then E, etc Pencil mark each note location where your thumb is holding the string down on the card board plate.The marked 7 notes per string should be located similarly across from each other.
After initial tuning let the finished tuner sit for 2 hours to stabilize then final tune only the 3 strings.
I made this one 3 years ago and had to re-tune it only once a month due to humidity, etc.
Standards rubber bands only were stable for a week.They also broke.
Anyone who knows music can even play a song on this device Have fun. Mistic



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    14 Discussions

    you should put more information on your website, it held my intrest for less than 10 seconds. have different pages, maybe information on the people who design and build the instruments, materials used, and past projects.

    this tuner project is not as exciting as a airplanezooming down the class room but it has a lot of science behind it including basic music theory and theory of vibrating strings.

    2 replies

    I'd have to agree with erio on this one. A tuner should be able to provide a reliable reference pitch or listen for a pitch coming from an instrument to show if it's sharp or flat. This tuner would surely need to be re-tuned often, thus not always providing a reliable reference pitch. Of course you could re-tune it your self if you're good at discerning pitch just by hearing, but that's not totally reliable or accurate either.

    Yeah, it's not a practical way to make a tuner, but it's a GREAT demonstration of some of the physics and math of musical acoustics. I teach music privately, and talk to school groups and such a lot. This will definitely go into my repertoire of tricks, more of which I'll be sharing now that I've signed up for this amazing site.

    1 reply

    thanks for input lg- i have used the plastic elastic string for making musical instruments such as a zither and lyre. Works really good too. ref. web site .

    I think more constructive criticism would be that which would help him/her improve this Instructable. First the instructable, Second your comment. Mistic - I think you could prove this type of device's viability by making a HUGE one. That way the perceived resolution of the tuning would be much greater than the finite "cents" that digital tuners have. Nexnaught - It tends to seem easier to buy things. Easiness seems to be a subjective and relative term. Buying a car seems easier than designing and building one. This part of the comment is useless. Also electrical tuners are vastly different. You may be used to digital tuners. These, as discussed ultra-briefly before, are finite in their measuring capabilities. If you are going for chamber music or just have a picky ear, fractions of cents can be heard. This is where electronic analog tuners come in. They consist of a spinning disc revolving at a constant rate, and a strobe light illuminating said disc with a strobe frequency relative to that of the pitch being measured. When the measured pitch is in tune, the strobe illuminates the spinning disc such that a pattern appears to come to a standstill. Much like how spinning wheels on television seem to come to a halt when spinning at integer multiples of the frame rate of the televised image. So in short, the easiness is subjective and such criticism is useless. However some more information on electrical tuners brings up how analog tuners can be more "effective" in some situations and this brings to light how mistic built a possibly more "effective" tuner than a standard digital tuner.

    thanks 789- very good comments. I did get better resolution using longer strings. I made one using one string. it tunes over two octaves. My string tuner applicability is a lot faster than my electronic tuner for my string instruments My URL describes these make it your self instruments.

    on second thought you are right-I have one. easy to use too.I get more fun out of the string tuner using it as a mini uke.!! On third thought I believe I will call it a mini- uke.

    The project is nice, but... Won't the tuner detune itself over time? So it has to be tuned again, right? A tuner that has to be tuned as often as a actual instrument is not *really* a tuner. The principle of a tuner is to have some material that don't detune over time (typically a metal tuning fork, which only depends on temperature, or electronic devices which can be very accurate). Or... I didn't understand (that's possible, too). Anyway, it could transform into a pocket ukulele, what can be nice.

    1 reply

    I had a similar thought as you mentioned on detuning over time. I have found that it is stable if the elastic is a high polymer and wont detune one cent over a 3 month period. thus it was practical to use when I was making my mini-Lyres and zithers. using these strings. They were also stable over a 5 month play period. I have a URL site that i use to sell plans of these instruments.Quite a hobby.

    Ref- drift stability---- I have noted that an 1/4 to 1/8 pitch change is almost indistinguishable by most people who tune their instruments. But as to tuning it up I use a pitch whistle, recorder or my harmonica C note. Tuning the 3 strings takes 5 seconds.