MET 349 Stringed Instrument Design
and Manufacture
Instructor:
Mark French
138 Knoy Hall
desk:
765-494-7521
mobile:
765-714-9382
Text:
Technology of
the Guitar
Springer
ISBN
Syllabus
This class meets for lecture once each week and for
lab twice each week. Initially, labs
will be divided between CAD work and fabrication in the guitar lab.
The central task for the semester is designing and
building solid body electric guitars.
You will work in teams of 5-7 people and each team will do its own
instrument. Each team must complete one
instrument for each team member.
You will be allowed to buy commercially available
necks if you choose. In the past, making
necks took more time than was reasonably available. Each design must have an electronic component
in addition to the usual pickups, volume and tone controls. Some teams choose to add a headphone
amp. Others have tried to make a
separate amplifier, though this has been a challenge.
The teams will have a parts and materials budget of
$200 per instrument. There are four
allowable suppliers: Mighty Mite, All Parts,
Stewart MacDonald and Guitar Fetish (no, I dont know who names these
companies). This is funded through purchase
cards you will get from Boiler Copy. The
purchase cards cost $300 each and the difference between the purchase card cost
and your budget is used for consumable materials, bits, blades and replacement parts.
No parts orders will be placed until all teams have
2D layouts completed and approved. There
will be one parts order from each supplier.
Successful manufacturers plan their operations carefully; if additional orders
are required because of poor planning, a tax of 15% will be assessed on each
additional order. Additional orders
required for reasons beyond the control of the build teams will not be taxed.
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Week |
Date |
Lecture Topic |
Reading |
Homework |
Homework Due Date |
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1 |
Intro, notes and scales |
Ch 1 Ch 2.1 |
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Intro to CAD lab |
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Intro to Guitar Lab Safety |
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2 |
Scales and Chords |
Ch 2.2 |
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Instrument Preliminary Design |
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CNC Laser Operation |
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3 |
Fret Layout |
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HW
#1: 1 - Find the notes that make up: ·
C
major scale ·
D
major scale ·
A
minor scale 2 Find the notes that make up: ·
C
major chord ·
D
major chord ·
A
minor chord ·
F
major chord ·
G
major chord ·
E
minor chord 3
Completed Bill of Materials ·
One
list per build group ·
Include
part numbers, estimated prices, quantities and suppliers ·
Names
of all group members |
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Aesthetic
Elements of Instrument Design |
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3D Printer
Operation |
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4 |
String Tension |
Ch 2.3 2.6 |
HW
#2: Calculate the fret layout for the
following scale lengths: 1.
25.5
inch guitar 2.
24.75
inch guitar 3.
34
inch bass 4.
600mm
classical guitar 13.7 inch mandolin |
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No
Lab Career Fair |
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Basic CNC Router Operation |
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5 |
Sound, quantifying sound |
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HW
#3: The frequency for A4 is
440 Hz 1 - Find the notes for a major scale
starting at A2 and the corresponding frequencies. 2 - Repeat for a major scale
starting at C2 3 Make a table of the locations
(measured from the nut) of the frets for an instrument with a 22 inch scale
length. 4 If a sound has an RMS pressure
of 0.50 Pa, what is the sound pressure level in dB? 5 If a sound has an SPL of 110 db
(really loud), what is the RMS pressure? 6 If a steel string with a
diameter of 0.012 inch is tuned to 330 Hz, what is the tension? Assume E=29*10^6 psi and a weight density
of 0.3 lb/in^3. Scale length is 25.5 in. |
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2D CAD Layout |
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CNC Router Operation |
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6 |
Electronics Resistance and impedance Input and Output Impedance |
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Homework
#4 1 For a voltage divider where R1
is the output resistance of a pickup and R2 is the input
resistance of an amplifier. If Vin=12V,
find Vout for these values: a)
R1=1MΩ,
R2=100kΩ b)
R1=1MΩ,
R2=1MΩ c)
R1=100kΩ,
R2=1MΩ d)
R1=15kΩ,
R2=500kΩ |
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2D CAD Layout |
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Body Prototypes |
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7 |
Op-Amps |
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Homework
#5 2 For a non-inverting pre-amp made
using a TL061 op amp, What are the values of the feedback resistor for gain
A=2, A=10, A=20? Assume Rg=100 kΩ |
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3D Models |
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Body Prototypes |
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8 |
Impedance Matching |
Homework
#6 Given a circuit diagram for a
pre-amp 1 A pre-amp is to be made using a
TL061 op-amp and powered by a 9v battery.
If you have a pile of 50kΩ resistors, how do you set the input
bias voltage to 4.5V? 2 If the pre-amp gain needs to be
6 (i.e. A=6) and the ground resistance, Rg,
is 1000Ω, what is the required value of Rf ? 3 The input impedance is
If the input impedance needs to be 100kΩ
and the input bias voltage needs to be 4.5V, what are the resistance values
of RA and RB ? |
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3D Models |
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Initial Assembly of Prototype
Instruments |
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9 |
Intonation Note: The frequencies for the open
strings on a guitar at standard tuning are: E - 84.2 Hz A - 110 D - 146.8 G - 196 B - 246.9 E - 329.6 |
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3D Models |
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Verifying Dimensions and Alignment
of Prototypes |
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10 |
Basics of
Amplifier Design |
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Production Bodies |
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Production Bodies |
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11 |
String Mechanics |
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Production Bodies |
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Production Bodies |
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12 |
Inharmonicity |
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Wiring Harnesses |
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Wiring Harnesses |
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13 |
Dynamic Testing |
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Final Assembly |
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Final Assembly |
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14 |
Measuring Build Variation |
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Tuning and Intonation |
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Tuning and Intonation |
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15 |
Review for Exam |
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Homework
#6 Use the real string equation for all
4 problems 1 Calculate the frequency error for
a 25.5 inch nylon G string (E=10^6 psi) with a diameter of 0.040 in, stopped
at the 12th fret. String
Tension is 11.7 lb. Calculate the
error due to inharmonicity. Assume that nylon is 1250 kg/m3. 2 Calculate frequency error for a
steel G string (E=29*10^6 psi). String
diameter is 0.023 in. String Tension
is 27.2 lb. Assume steel is 7850 kg/m3. 3 Calculate the saddle offset
needed for the nylon string using frequency at the 12th fret 4 Calculate the saddle offset
needed for the steel string. Note: Use the metric system for all
calculations. If you need help
converting units, so to onlineconversion.com |
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Dynamic Testing of Completed
Instruments |
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Dynamic Testing of Completed
Instruments |
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16 |
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Exam |
Open Book, Open Notes |
Practice Questions: 1 How far from the nut would the
12th fret be on a guitar with a 24 in scale length? 2 If a string is 700mm, is made
from steel and has a diameter of 0.4mm, what tension is required for it to be
at a frequency of 150 Hz? 3 What are the notes in an F major
scale? 4 What are the notes in an A#
chord? 5 The bias resistors, RA
and RB, in a pre-amp need to create a bias voltage of 4.5V and the
circuit is powered by a 9V battery. The sum of the two resistances must be 440kΩ. Find RA and RB |
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Last Day of Class |
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Instrument Grading |
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Grading
Exam: 20%
Homework: 15%
Design: 20% completeness, accuracy, creative solutions to
design problems, aesthetics
Construction: 20%
accuracy, organization, meeting build schedule, build process, jigs and
fixtures
Final
Product: 15% accuracy, playability,
finish, balance, sound, aesthetics
Peer Grade 10%
We added this after a class discussion in which we decided that peer
ratings would capture important information that might be missed by the other
grades