CONSTRUCTION PROCESS - DAY 3

BUILDING THE RAILS: 

     1.  Cut the plastic tubing into 12mm pieces using a stanley knife (the tubing will be used to 
            cover each nail) (Figure 14).
     2.  Thread plastic tube onto each nail (Figure 15, 16).

NOTE: Blanking caps finally arrived in the post from Fitch Rubber (South Australia). However, they were the incorrect size (Figure 17) and had to be reshaped in order to fit through the key holes.

  

  3.  Reshape rubber caps using a disk sander (Figure 18).

  4.  Cut them to the correct length (15mm) using stanley knife (Figure 19, 20).

    5.  Place rubber blanking caps over each nail (Figure 21, 22).

    6.  Place steel bars in position, using 10mm foam as a height spacer for the back rails 

         (Figure 23).

CONSTRUCTION PROCESS - DAY 2

BUILDING THE RAILS: 

  1. Cut suspension tube roughly the length of each rail (Figure 8).
  2. Clamp suspension to the rail (Figure 9).

  3.  Mark centre points on suspension for the nails (Figure 10).

  4.  Pierce suspension with a sharp nail (Figure 11). 

  5.  Thread suspension tubing over each nail (Figure 12, 13). 

NOTE: Waiting for blanking caps to arrive in the mail. Without the rubber caps the bars cannot be fitted and the frame cannot be aligned.

CONSTRUCTION PROCESS - DAY 1

BUILDING THE RAILS:  

     1.  Rule a line across the centre of the rails; this will be a guideline for the suspension/nails   
          (Figure 2).  
     2.  Next you need to work out the required spacing between the nails.
     3.  Mark a point on the left for a pin to hold the suspension.  
     4.  Measure 45mm to the right of the pin and mark a point for the first nail.  
     5.  Measure 38mm and mark a point for each consecutive nail (13 times) (Figure 3). 
     6.  Repeat this process for the second rail.  
     7.  For the 3^rd and 4^th rails measure 105mm to the right of the pin and mark a point for the 
          first nail.  Measure 38mm between consecutive #/♭ keys and 76mm for the breaks.

 8.  Using a 2.6mm drill bit, drill pilot holes as a guide for each nail (Figure 4).

 9.  Hammer a nail into each point (approx. 10mm into the timber) (Figure 5).

 10.   Mark each nail at 15mm (Figure 6).

 11.   Cut of excess nail with a dremmel (Figure 7).

GETTING ORGANISED - PROJECT GLOCK

MATERIALS:      

• 3000mm x 420mm x 30mm Timber slab (maple)
• 2440mm x 1220mm x 8mm Plywood sheet
• 3000mm x 32mm x 3mm High Carbon Steel
• 3000mm x 6mm surgical rubber tubing (suspension)
• 1.5mm pins (QTY: 8)
•  50 x 2.80mm bullet head nails (QTY: 42)
• 10G x 30mm stainless steel countersunk screws (QTY: 8)
• 100G x 12mm x 1.60mm tacks
• 2000mm x 3mm plastic tubing (1/8”)
• Rubber blanking caps (3/16”) (QTY: 42)
• 1800mm x 4mm dowel
• Wooden beads approx. 15mm (QTY:2) 

The 3m maple slab was taken to Tolga woodworks and machined by a professional (Figure 1).

TIMBER DIMENSIONS:
 
4 x 600mm x 40mm x 13mm
2 x 800mm x 100mm x 20mm
1 x 450mm x 100mm x 20mm
1 x 350mm x 100mm x 20mm
1 x 450mm x 115mm x 13mm
1 x 350mm x 115mm x 13mm
 
The high carbon steel bars were also machined and drilled professionally to achieve the best results.
 
STEEL BAR DIMENSIONS:

B :  185mm x 32mm x 3mm
C :  177mm x 32mm x 3mm
C#/D♭ : 173mm x 32mm x 3mm
D :  166mm x 32mm x 3mm
D#/E♭ : 163mm x 32mm x 3mm
E : 158mm x 32mm x 3mm
F :  153mm x 32mm x 3mm
F#/G♭ :  149mm x 32mm x 3mm
G : 146mm x 32mm x 3mm
G#/A♭ : 141mm x 32mm x 3mm
A : 138mm x 32mm x 3mm
A#/B♭ : 133mm x 32mm x 3mm
B : 130mm x 32mm x 3mm
C : 126mm x 32mm x 3mm
C#/D♭ : 122mm x 32mm x 3mm
D : 118mm x 32mm x 3mm
D#/E♭ : 116mm x 32mm x 3mm
E : 112mm x 32mm x 3mm
F : 108mm x 32mm x 3mm
F#/G♭: 106mm x 32mm x 3mm
G : 102mm x 32mm x 3mm

GLOCKENSPIEL BLUEPRINT

Here is a blueprint of my glockenspiel, dimensions included:

DESIGN COMPONENTS - MATERIAL SELECTION

1. The Steel 
There are glockenspiel designs which use round metal rods or hollow metal tubing instead of flat bars (such forms follow the same vibrational patterns as flat bars), however, I prefer the standard flat-bar design. For this project I will be using high-carbon steel bars to produce a pure, bright tone. High-carbon steels are difficult to machine, form and weld. Therefore, I will be getting the bars cut and drilled by a professional.

2. The Suspension/ Mounting System

1)      The system should be rattle-free

2)      The system should allow supports at or near the nodes

3)      The point of contact between bars and mounts should be loose and/or padded rather  
   than tight and rigid.

4)      The arrangement should prevent the bars from dancing around too much and touching 
   one another or getting out of position. 

Here the bar is held to a padded frame by a screw running through at the nodes. It should run through an oversized hole, and the shaft must be padded with soft surgical tubing or something similar.  

3.  The Frame/Case

The glockenspiel bar rails and extra-deep case will be made from solid maple. Maple is well known for imparting bright tone to an instrument and was chosen for its high quality resonance. The bar rails are completely suspended and do not touch the floor of the case. All the contact points, including the bottom exterior of the case are insulated with rubber, eliminating any case noise and leaving the space under the bars to act as one big reflecting and resonating chamber.

References: 
Baird, Chris. “Tonewood Qualities.”

http://www.archesmusic.com/tonewood.html

2009; accessed 17 July 2012

Hopkin, Bart, and John Scoville. Musical Instrument Design Practical Information for Instrument Making. Chicago: See Sharp Press, 1996.

DESIGN COMPONENTS

1. The Steel 

The essence of the glockenspiel or orchestra bell tone is largely determined by the quality of the steel and dimensions of the bars. The great glocks made in the first half of the 20th century were made from absolutely the hardest steel available. Today, the major manufacturers start with a much softer steel that is easier to cut, tune and polish. However, a softer metal can never produce the crystalline tonal brilliance of the old formula steel.

2. The Suspension

Many glockenspiels made today still have the bars attached to the frame with screws. Hardly anything could dampen the vibration of the bars better! Other makers have the steel bar lay across a felt pad or string, similarly stifling the tone. The ideal support system allows each glockenspiel bar to ring freely, almost as if it were suspended on air.

 

3.  The Frame/Case 

Glockenspiel cases are an integral part of the acoustics of the instrument, greatly amplifying the volume, reinforcing the fundamentals and adding to the ring time. The construction of the frame/case has the most significant impact on the resonance and durability of the instrument.

References:
Campbell, Murray, and Clive A. Greated. The Musicians' Guide to Acoustics. New York: Schirmer Books, 1988.
Hopkin, Bart, and John Scoville. Musical Instrument Design Practical Information for Instrument Making. Chicago: See Sharp Press, 1996.

FINAL DECISION

Building a marimba or a vibraphone is an expensive pursuit; not to mention a time-consuming one. The glockenspiel is the simplest of the tuned percussion instruments, consisting of a set of rectangular cross-section metal bars supported horizontally on a frame. It is much smaller in size than the xylophone, marimba and vibraphone and does not require resonators (the case acts as the resonating chamber).

The glockenspiel, or orchestral bells, comprises a series of steel bars of graduated length (2.5-3.2 cm wide and 6-9 mm thick), arranged in two rows chromatically. Its range is customarily from G5 (f = 784 Hz) to C8 (f = 4186 Hz), although it is scored two octaves lower than it sounds. To obtain the maximum resonance the bars are supported on felt or similar insulation, or suspended at the nodal points. It is usual for the ‘back row’ to be raised.

The glockenspiel is played with a variety of mallets: ebonite, wood, plastic, and brass for a loud, bright sound and mallets with soft rubber heads for soft passages.  When struck with a hard mallet, a glockenspiel bar produces a crisp metallic sound, which quickly gives way to a clear ring at the designated pitch. Because the overtones have very high frequencies and die out rather quickly, they are of relatively less importance in determining the timbre of the glockenspiel than are the overtones of the marimba or xylophone, for example. For this reason, little effort is made to bring the inharmonic overtones of a glockenspiel into a harmonic relationship through overtone tuning. 

References:

Fletcher, Neville H., and Thomas D. Rossing. The Physics of Musical Instruments. New York: Springer, 1998.

Olson, Harry Ferdinand. Music, Physics and Engineering. New York: Dover, 1967.

Rossing, Thomas D. Science of Percussion Instruments. Singapore: World Scientific, 2000.

TUNED IDIOPHONES (Mallet Percussion)

Tuned idiophones (struck instruments) such as marimbas, vibraphones, xylophones, glockenspiels chimes and bells have undergone centuries of development, resulting in complex profiles, the purpose of which is usually to optimise the sound of the strike. When building a tuned percussion instrument, there are certain aspects to be considered which will affect the design.

1. TUNING 

The difficulty lies in tuning the instrument.  The designer seeks to produce an instrument that responds with sounds that are pleasing to the ear, and for the most part this means that normal modes of vibration are appropriately tuned. The many modes of vibration in bar affect the sound it produces and give it its distinctive quality; however a strong fundamental is essential for a good tone.  In the case of a xylophone or marimba bar, it is the undercut that is used to tune the appropriate vibrational modes (Figure 1). Removing material from any point on a bar affects all the modal frequencies to some extent. The exact dimensions of the undercut are an empirical design.

 

2. RESONATOR (Marimba & Vibraphone)

The purpose of the resonator is to amplify the fundamental frequency produced by the bar and also to increase the loudness, which is done at the expense of shortening the decay time of the sound. This becomes increasingly important as the frequency extends lower and the radiation power of the bar becomes weaker. 

References:

Vienna Symphonic Library. “A comparison between four mallet instruments.”

http://www.vsl.co.at/en/70/3196/3204/3208/5768.vsl

2002; accessed 30 June 2012

Flynt, W.E. “The Construction and Tuning of Vibrating Bars.” Mechanical Music Digest V1 (Jan 2009), 51-53.

Legge, K.A and J. Petrolito. “Designing Idiophones with Tuned Overtones.” Acoustics Australia V35 (Aug 2007), 2-47.