A Simple Copper Pipe Tubaphone

This project originated in a science competition the kids competed in a couple of years ago; they needed to produce an instrument with three specific notes. They designed the original mounts for the pipes, which are used as the straight pipe holders in the example design. The next version the kids built had a full octave of 8 notes. The version described in this instructable was used for sound effects in a stage play.

If you are of more advanced years, have traveled by train, or have been on a cruise ship, you may have heard dinner or announcement chimes. More likely, you heard it in a movie or cartoon. You might have heard the station identifier for your local NBC affiliate. 

The three-note melody is an example of early sonic branding. It is used to identify radio, TV, and companies. It was also used to announce events, such as lunch, dinner, the start of the school day, or a class. Some traditional cruise lines still use this today. 

Our example is a simple three-tone model, but the construction techniques can produce any size instrument.

Let's define a couple of terms;

Metallophone - an instrument where a bar (of wood or metal) or a pipe is struck over a resonator box to produce a note. The bars are arranged in a single row.

Glockenspiel - an instrument that generates sound by striking an aluminum or steel bar. It may or may not have some type of resonator. The bars may be arranged in single or multiple rows and mounted horizontally or vertically.

Tubaphone - an instrument arranged similarly to a glockenspiel but uses metal tubes or pipes instead of plates.

This instructable is about building a specialized tubaphone using 3D-printed mounts and a wooden frame. Although not absolutely technically correct, we will refer to the project using the broader "glockenspiel" reference. It also contains information helpful in building wind chimes.

In this instructable, we will build a three-note glockenspiel that approximates the NBC chime.

G₃ E₄ C₄

g3 = 196Hz

e4 = 329.63Hz

c4 = 261.63

Notes to frequency chart

The files

You must print these two files for each pipe to construct the glockenspiel.

Base Piece one-inch lumber: Printabels or Thingiverse

or

Base Piece for 3/4 inch lumber: Printabels or Thingiverse

One of these designs may help if you use a slanted headpiece on your glockenspiel.

Variable offset V1: Printables or Thingiverse

Variable offset V2: Printables or Thingiverse

Variable offset V3: Printables or Thingiverse

In addition, you may wish to print these parts. They are shown in the pictures.

The 3D-printed mallets can be found here:

Simple Mallet for Glockenspiel by AtomicusPrime 

The pipe carrier on the inside of the frame is found here:

Broom Holder by robeitor 

Construction material for the frame

Wood -

Extruded aluminum

Other supplies

Rubberbands

Felt pads

Several instructables we found useful: Article 1, Article 2, and Article 3 as background for construction.

Here are a couple of articles that explain the history of the chime.

https://methodshop.com/origin-of-the-nbc-chimes/

https://en.wikipedia.org/wiki/NBC_chimes

https://www.nbcchimes.info/index.php

https://www.madeinchicagomuseum.com/single-post/j-c-deagan-co/

https://boxedlight.com/degan-chimes/deagan21.htm

https://leehite.org/Chimes.htm#tubes_pipes_rods

https://dynamicmusicroom.com/xylophone-vs-metallophone/

The original version of this project produced only five notes. It was built on a square frame. The problem was that two tubes ( copper pipes) were short, and three were long. The tubes were not supported at nodal points, making the notes sound flat. This instructable gave us a better understanding of the need to support the tubes at nodal points and how to calculate the length of the tubes for each note. This also required us to change the frame design to the triangular design. The next version had 13 notes built on a triangular frame that supported the nodal points correctly.

So, as you might guess, the math comes first.

1. Decide how many notes you want the glockenspiel to produce and what they are. Find the frequency in Hz for each note. ( you might want to create a spreadsheet.)
2. The tube length was then calculated or looked up on a table for each note. (Round up the lengths a little bit. You will be cutting the tubes down when you tune them.)
3. The longest and shortest values will give you the approximate dimensions of your frame.
4. Add up the estimated lengths of the tubes.
5. Calculate the amount of lumber you will need.
6. Head to the local home improvement store and your scrap bin to gather your supplies.
7. If you are going to find A ( see below), do it now and update the tube cut list.

This example is only three notes. The length of the pipes allows us to use a simple rectangular frame. Although we could use a rectangular frame, it required three cross-support pieces. This will be discussed in section seven.

We constructed a tuning bench for pipes. It is based on a 91cm piece of 8020 Series 10 1020 aluminum extrusion and several adjustable supports that could be adjusted to the nodal points on a pipe. It was the longest piece in the scrap bin at the time. We designed feet for the beam and put felt pads for furniture in each corner to protect the counter and reduce transmitted vibration. The ends of the beam are great for storing a mallet used to test the pipe and a hex key used to reposition the supports.

We describe the construction and use in a separate instructable.

Beam: 8020 Series 10 1020 or compatible

Supports: Printables Thingiverse

Mounting feet: Printables Thingiverse

A is a constant for the pipe based on the material's size, density, and speed of sound travel. (This is a gross simplification.) It is used to calculate the length of the tube for each note. (See the referenced articles for more information. )

We need to derive a value for A for each piece of pipe stock, which will change for each piece of pipe stock.

1. Cut a test piece of the pipe you are going to use. I used a 200mm section. Mark the tube with the length and date using a Sharpie.
2. Support it in the tuning stand, positioning the support rubberbands at the two node points 1/4 and 3/4 from the end of the tube. You should mark these points with a sharpie, too. (The actual node is at 22.7% of the tube length.)
3. Using an audio tuning application on your phone or an audio spectrum analyzer, find the frequency the tube resonates when taping it with a mallet. ( The applications on your phone usually read out the note and frequency. An instrument tuner usually only reads out the note. )
4. Repeat the test several times so you are sure of the frequency.
5. Enter the values for the length and frequency to calculate a value for A.
6. I usually write the value for A on the test section of the pipe we use to derive it.
7. Use this value to calculate the corrected pipe lengths for the note you wish to produce.

frequency of note = f in Hz

Length of pipe = L in mm

A = constant for tube

L = Sqr ( A / f )

For more reading

http://users.df.uba.ar/sgil/physics_paper_doc/papers_phys/lapp.pdf

http://leehite.org/chime_dimensions/Family%20Copper%20Type%20M%20Red.pdf

https://theprojectlady.com/diy-tutorial-for-making-a-copper-pipe-wind-chime/

You should now have a list of notes and their tube lengths that you want to be included in the instrument. These tube lengths should have been calculated using the method described in Step 4 for the best results.

You will cut one pipe for each note.

There are several different ways to cut the tubes; it is left to the user to decide what method is most comfortable for them. Our preferred method is to use a pipe cutter, but a bandsaw or a hacksaw works just as well. We always cut the pipes a little longer by a mm or two to provide material for the final tune.

You should also mark the Null points on each end of the tubes with a Sharpie or other marker.

Tuning is an art.

Place the rough-cut piece of pipe on the tuning bench.

1. Support it in the tuning stand, positioning the support rubberbands at the two node points 1/4 and 3/4 from the end of the tube. You should mark these points with a sharpie, too. (The actual node is at 22.7% of the tube length.)
2. Using an audio tuning application on your phone or an audio spectrum analyzer, find the frequency the tube resonates when taping it with a mallet. ( The applications on your phone usually read out the note and frequency. An instrument tuner usually only reads out the note. )
3. Repeat the test several times so you are sure of the frequency.
4. Compare the measured frequency with the target frequency.
5. If the frequency is close enough, call it done. If you need to move closer to the target frequency, remove a small amount of material from the end of the pipe. This can be done by cutting 1 or 2 mm off with a pipe cutter or a file if you are close to the target.
6. Jump back to step 2 if you removed material.
7. Write the value for the frequency on the finished pipe.
8. Mark the nodal points on the pipe.

Why do a fusion diagram?

It quickly becomes apparent that building the frame first is a path to an instrument that does not sound all that great. One of the reasons for this is that the pipes are not supported at the nodal points. It isn't easy to deal with this during construction. We adopted the approach of sketching out a frame on a piece of construction paper, and this works ok. We then realized we could do it in Fusion 360 and explore different options. The diagrams above show the evolution of the design of the chime.

The process we follow.

1. Make a part for each tube. Calculate a value for 22.7% of the tube's length. Using the calculated value, add an attachment point this distance from each end of the tube.
2. Create a model piece of the straight bracket with an attachment point in the center.
3. Make a straight line of the straight bracket, one bracket for each tube.
4. Attach a tube to each bracket.
5. Make a model of the angled brackets With an attachment point in the center of the two pylons.
6. Attach an angled bracket to the free ends of the tubes.
7. You can now use the holes in the brackets to lay out the frame. The pipes will dictate the shape and supports needed for the frame as well as exploring optional designs by reordering things.
8. Use the diagram to produce the cut list for the frame.

We printed the parts in PLA. You need two brackets to support each pipe.

There are many ways to assemble the frame; you should pick one you are comfortable with. We have used screws, glue, wood screws, deck screws and pocket screws. All worked and provided an excellent, clean result.

The method we followed was roughly the same for all assembly methods.

1. Using your plans, create a cult list for the wood. ( You spent the time with Fusion, didn't you? )
2. Cut your wood to the lengths specified in the cut list.
3. Assemble the frame using your preferred method, ensuring the frame is as level and square as possible. We always use wood glue in addition to screws.
4. Let the frame dry / settle overnight.
5. Starting with the straight run (usually at the bottom of the frame), install the straight pipe mount according to the spacing on your plans. Using the decking screws, attach the bracket to the frame.
6. Using the nodal marks on the pipes, install the upper pipe bracket. Correct the angle to make the bracket parallel to the pipe if you are using the adjustable pipe mount. Using the decking screws, attach the bracket to the frame.
7. Install felt pads on the bottom of the frame.

Rubberbands are a finicky little part of the project. The user must experiment to find a rubberband configuration that produces their desired sound. Rubberbands (when you can find them) come in different widths and lengths. They can be wrapped around the post in different configurations or doubled up.

The more "springy" the tube is supported, the longer the tone is emitted. The firmer the tube is supported, the quicker the sound will dampen out.

We recommend not storing the rubber bands attached to the mounting post. When they start to dry out, they stick to the material used to print the supports.

Install the pipes on the frame. The nodal point should align with the rubber bands on the mounts. Arrange the pipes in a manner that makes sense for your use case, such as a scale for playing music or the sequence of notes in a chime.

Several add-ons to the project make it easier to transport and use. They will entirely depend on your application. Pipe holders, mallet holders, carrying handles, and surface-protecting feet can nicely finish the project.

We have links to a few models shown in the pictures above in the supplies section of this document.