MET 490G – Musical Instrument Manufacture and Test

MET 490G – Musical Instrument Manufacture and Test

Mark French

138 Knoy Hall

desk: 765-494-7521

Syllabus

Week	Lecture Topic	Homework	Homework Due Date	Lab Activity - Tuesday	Lab Activity - Thursday

1 (Jan 7)	Intro, notes and scales			Intro, Lab cleanup
2 (Jan 14)	Fret Layout
3 (Jan 21)	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	Homework #1 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 – 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 12^th fret. String Tension is 11.7 lb. Calculate the error due to stretching and the inharmonicity. 4 – 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 the distance between the bottom of the string and the fretboard is 0.20 inches.	Jan 30 – End of the Day Please put your homework in the drop box in Knoy hall. There will be a box marked MET490G. I will empty out the box at 4:30.	CNC Laser Checkout Start Cutting Tops/Backs Layout Dust Collection	Cut sample with CNC Laser
4
5
6
7
8				Parts Complete
9
10
11				Assembly Complete
12
13
14				Testing Complete
15
16

Note: I encourage anyone who hasn't finished their instrument to take some time during finals week (if possible - don't neglect your other classes) and finish. I'll be around most of the time finals week and will be happy to let you into the lab as long as there will be two people present in the lab - RMF

Instructions for doing the final report:

In lieu of a final, each student must submit a short report based on the semester's activities. The report should include:

List of tasks worked on during the semester along with a sentence or two of description. Please use bullet points (like the ones used here) with one bullet point for each task.
A data sheet for your instrument only. The data sheet should follow the format of this sample data sheet (PDF or PowerPoint). In the notes section, include the notes 'Body tested without finish and before neck or bridge installed' and 'Body supported by soft foam blocks at the perimeter' along with whatever other comments you wish to include. All the data sets recorded to date appear in this Test Data Zip File. Note - either change the footer to replace Kendall Brubaker's name with yours or remove the footer. Also, be sure to use a log scale for the vertical axis when making the plot of the Frequency Response Function (FRF).
User instructions for any CNC programs you wrote that should be passed on to the next class
Notes on what changes need to be made in the construction drawings. Please print out a copy of the relevant pages on 11 x 17 paper and use a red or blue pen to note required changes. Please make your comments clear and legible.
Correlated 2-DOF discrete model of your guitar body using the Mathcad file provided: xmcd file PDF file. I understand that the ENAD machines have an older version of Mathcad; here's the oldest version I can save with my software.

Please submit a paper copy of the elements listed above no later than the end of the day Friday, May 4. In addition to the paper copies please forward electronic files containing:

Your report
Your data set from the tap test
Mathcad file of correlated discrete model with filename in the form: Lastname - Spring 2007.xmcd (i.e.: French - Spring 2007.xmcd)
Your data sheet in PowerPoint format with filename in form: Lastname Data Sheet - Spring 2007.xmcd (i.e.: French Data Sheet - Spring 2007.xmcd)
Pictures of any fixtures you worked on
Any CNC router programs for which you wrote instructions
Any picture files you think would be helpful

The sooner I get all the reports, the sooner I can post grades on WebCT.

In this course, we will manufacture and test classical guitars as a means of learning production methods, tolerance stackup, musical acoustics and experimental mechanics. The instruments will be made according to the description found on the web site for the Mechanical Engineering Technology Acoustics Lab (METAL). The instrument is designated M1 and is one of four or five standard instrument designs that will eventually be developed. The construction drawings for the instrument are on the METAL web site (click here)

The instruments will have a 25.5 in scale length. Fret locations can be calculated using either an Excel file or a mathcad file.

Links: Click here for some links to other sites with helpful information and pictures. When you are trying to design a fixture or manufacturing operation, it helps to see how other people have done it.

The supplies each student will need are:

From Hardware Store or Home Improvement Store:

· ¼” Birch face plywood for bracing (2’ x 2’ piece is plenty) – make sure core is free of defects

· Titebond glue – medium sized bottle is enough for 1 or 2 guitars

· Sandpaper 120, 240, 320 grit – At least two sheets of each

· Oil Finish (Tru-Oil sealer and Tru-Oil Finish)

From Luthier Supplier (Stew-Mac or LMI)

· Fret wire – medium

o Stew-Mac #0148

o LMI # FWSS74

o A guitar takes about 5 feet of wire

· Tuners (Economy grade is OK, better tuners are preferred, but cost more)

o Economy Tuners: Stew-Mac #0940-G, LMI # GGC)

o Pretty Good Tuners: Stew-Mac #0646 , LMI # GGC2

· Kerfing – You will need about 12 linear feet

o Stew-Mac: #4513

o LMI: # WKFB

From Wood Supplier (I’m working with Pacific Rim Tonewoods on a discount deal)

· Bridge blank

· Neck blank

· Side blanks

· Top (Sitka Spruce or Cedar are good choices, 2^nd grade is OK)

· Back (Mahogany is a good choice)

· Fretboard

Good suppliers:

Stewart-MacDonald (www.stewmac.com) - educational discount

Luthier’s Mercantile (www.lmii.com) – educational discount

Gilmer Wood (www.gilmerwood.com)

Northwest Lumber (Northwest Indianapolis on Lafayette Rd.)