Xylophone
Fred Sykes
June 2016
The Idea
My daughter, Beth, sent me a link several years ago to an advertisement for Utomo cell phones.
Utomo contracted with an agency that made a wood xylophone that played Jesu Joy of Man’s
Desiring by Bach. If you google the words ‘Japanese xylophone forest’, you can see a Utube
video – it is quite amazing.
Initial Testing
The first thing I wanted to do was see if I could get sound from wood. I took two pieces of 1x6
and screwed them at ~30 degree angle to a piece of plywood. I then draped some felt over the
wood and put various pieces of wood across the 1x6’s and hit them with various things. I was
able to get sound using a golf ball. If you look up the science of a xylophone, you will find that a
‘note’ has ‘nodes’ that are about 2/9 from each end. These would be the ideal place to contact
my 1x6’s. I experimented by moving the pieces around. There was some difference as the notes
were moved – but not that much – particularly if the note was free standing. I made a major
effort to find the ball that the Japanese used. I was unsuccessful. I tried the following: cue ball,
lacrosse ball, pet ball, glass ball, metal ball, bouncy ball, wood ball, and probably a few others.
The golf ball worked the best. I thought about using the golf balls with out dimples – but they
were too expensive for me. If anyone reading this knows what type of ball they used, please let
me know.
Detailed Testing
The next thing I did was get some 3/4inch [ 1by] red oak, poplar and clear pine to experiment
with various types of fairly inexpensive woods. I made wood notes with the width 2 inches and
the length ~12-15 inches. I also tried some 5/4 pine, because I read that thicker was better.
I found out that the Japanese used a 12 degree angle for their xylophone. I made an experimental
mockup that was pitched at 12 degrees. I discovered pretty quickly that I could not make a
xylophone as good as the Japanese. It looked to me like they mounted ball collectors directly on
a 1by or a 5/4 piece of wood. My experiments showed me that I needed some space between the
note and the board underneath [ I call this a sound box]. So I decided to take 1x6 and screw it to
the sides of a 2x6. My collectors would be mounted on top of the 1x6. This gave a constant
spacing for the ‘node’ points, but as I said before, my testing showed that if the note was
basically free to move, the sound was okay. So I had a mockup that I could test with.
I tried the various woods and thicknesses. The pine was good enough for my purposes. I also
found that if I simply used pine and avoided knots that I could get pretty good sound from the
notes. I tried various balls I had collected. Let me say about the ball. I think the proper ball
needs to be fairly hard on the outer surface and be able to bounce.
I used a tuner to see if I could get the notes. The first thing I did was make a scale from low C to
middle C. This covered the range of notes I would need for the song I intended. There is
considerable variation in length of the note even from the same piece of wood. Approximate
lengths are 18 to 10 inches.
My testing with the ball collector consisted of basically duplicating the Japanese design of a
double V. I tried various angles on the collectors but settled on 12 degrees. The starter for the
xylophone is 11 degrees. Shallower simply sped the ball up too much. I also realized that if I
wanted to slow or speed a particular note up, I could put shims under the collector and change
the angle.
The last thing I needed to figure out how to do was how to hold the note on the collector. I tried
a nail through a large hole, with the note on felt. This did not work that well. I eventually
decided to use Velcro. Velcro has the advantage that you can have motion built into the joint.
Motion that allows the note to vibrate sort of freely. This mostly gets around the node problem.
Also, I could not see anything from the video that the Japanese did to account for note nodes.
They seemed to use one size collector fits all.
Production of Pieces
I used 1X [3/4 inch] #2 pine board and ripped it to 2 inch wide boards. I started cutting to get the
longest pieces I needed first. This meant that if I ended up with left overs, I might be able to use
them for shorter pieces [ higher notes]. As I said before, note length varies considerably, but this
is approximately what works: low C = 17 ¾ inch; D 16 ¾ inch E 15 ¾ inch; G 13 ¼ inch; A 12
¾ inch; and middle C 10 ¾ inch. So I cut the pieces long so that I could tune by cutting off.
The Japanese tuned their notes with a chromatic tuner and a disc sander to remove material. I
painted my notes first and then tuned them by using a chop saw to remove material. I sometimes
only took off the pressure of the piece against the saw blade [~1/64 inch or less].
After tuning the notes, I painted them with spray paint. This allowed me to keep the different
notes separate. A problem it created was that it made all the notes go flat. Flat is better than
sharp. With ‘flat’ you tune by taking off material. With sharp you can reduce the thickness.
Since all my notes were flat, I decided to live with it. I put two coats of white exterior paint and
then two coats of exterior spray paint. I cut the pieces after the white paint.
I built the fram in three identical sections. 2x6x12ft with two 1x6x12foot side rails to create the
sound box.
I built the ball collectors by cutting the piece to give two different tapers. When put together
they were basically two V’s. The interior V was deeper so that if the ball got in there, it would
likely stay there and thus get consistently transferred to the next note. The outer parts of the
collector helped ensure that the ball would always be directed toward the center. I decided to
attach side rails. In my mockups and experiments I found that the ball sometimes rolled off.
This seemed the easiest way to prevent ball drops. I used 12 degrees for the angle pieces holding
the collector up. The angle pieces allowed for a surface to attach the Velcro and the piece to the
rails of the sound box.
I made extra of everything. I put the collectors on the sound board sections and allowed about ¼
inch total between the end of each collector and the width of the note. I had a mockup also
pitched at 12 degrees so that I could try as I assembled.
Assembly
I had three extra 2x6x12 foots to use underneath the sound box sections. My idea was a T frame.
The cross bar was the sound box section and the leg of the T was these 2x6x12 foot sections. I
also had scab sections of 2x6 to screw the joints together. I made cleats that could be strapped to
two trees. I also needed a center section brace. The end went to a few inches above the ground.
I made a pipe that allowed anyone to get a ball to the starter section.
Operation
The notes changed pitch after it rained. The tune is still recognizable. The speed of the ball on
the collectors varies. Some of this is due to debris from the trees. All in all it works great.
Jesus Loves Me
I chose Jesus Loves Me because it was simple 6 different notes with no flats, fairly short – 49
notes, and because the song goes along with our Vacation Bible School.
Questions
If you have specific questions that I have not answered in this note, please call the church at 315386-8608, I will be happy to answer your questions.