Official Luthiers Forum!

I received the following invitation this morning:


Hello Everyone,
You are invited to attend the following graduate seminar:
Date: Friday - January 15, 2010
Time: 13:00 to 14:00
Room: CBY- C011

"Towards Improving the Manufactured Consistency of Wooden Musical Instruments through Frequency Matching"

Patrick Dumond
M. A. Sc Graduate Student
Department of Mechanical Engineering
University of Ottawa

Prof. Yehia Haddad, P. Eng.
Dept. of Mechanical Engineering

University of Ottawa

yhaddad@uottawa.ca


The abstract the came with this notice is equally intriguing:

TOWARDS IMPROVING THE MANUFACTURED
CONSISTENCY OF WOODEN MUSICAL INSTRUMENTS
THROUGH FREQUENCY MATCHING
Patrick Dumond
A thesis submitted to the Faculty of Graduate and Postdoctoral Studies
in partial fulfilment of the requirement for the degree of
MASTER OF APPLIED SCIENCE
In Mechanical Engineering
Ottawa-Carleton Institute for Mechanical and Aerospace Engineering
University of Ottawa
Ottawa, Canada
January 2010
©2010 Patrick Dumond

Abstract
Although many improvements in the manufacturing of musical instruments have been
made recently, one aspect that has often been overlooked is that of the acoustic
consistency of the final manufactured product. The aim of this thesis is to create a method
in which a soundboard can be frequency matched to a brace in order to meet a set
standard after assembly.
A simple analytical model is created in order to study the effect of the plate’s stiffness
and brace thickness on the combined system. The assumed shape method is used in the
analysis.
Results show that by adjusting the thickness of the brace in order to compensate for
the stiffness of the plate, one of the natural frequencies can be adjusted to meet a certain
value. However, matching multiple natural frequencies cannot be done with a rectangular
brace. Therefore modifications to the shape of the brace are suggested.
***

I'll look up this guy's work, perhaps attend the seminar and keep you all posted.

Pat

_________________
There are three kinds of people:

Those that make things happen,
those that watch things happen,
and those that wondered what happened.

Thanks Pat,

Would love to hear more on this.

_________________
Michael Lloyd

“I was born to ignorance, yes, and lesser poverties ...
I was born to privilege that I did not see ... I didn’t know it, but my way was paved” – John Gorka

now why couldn't a university of Toronto student come up with this! sounds very interesting but wish it wasn't an 8 hour drive

Less than 3 hours for me... Maybe it could be a good excuse to go see my family around there

_________________
Francis Richer, Montréal
Les Guitares F&M Guitars

sounds interesting enough .. isnt it the same idea as Chaldni tuning ???

factory setting ???.... they dont have the time to frequency match the braces to every single top ... they make identical braces by the hundred(s) every day just to meet the production requirements .. the worker simply grabs a set and starts gluing ... so now he/she has to get the top into the tuning rig, and see what it says, then make/alter a set of braces to the required dimension .... i dont see it happening at any larger factory ... but thats just the pessimist in my coming out

_________________
Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

"Is there any practical application for your results?" is a common question to a candidate defending his thesis. Especially in an engineering faculty, the answer: "Not really, but it is very interesting nonetheless..." would probably not garner a lot of enthusiasm.
So all the stuff about applications on the factory floor may not be too practical in real life, as Tony points out.

Cheers
John

As promised, I went to Ottawa U. yesterday and saw the presentation made by an enthusiastic Masters student (Patrick Dumond). He described an analytical approach (assumed shape method) to estimating the change in frequency of a wood plate with a single brace given a change in the Young's of the brace. His three most important conclusions were:

1) It is possible to adjust the frequencies of a plate-brace system to a given standard given the variation in Young's modulus.
2) Rectangular braces are not sufficient in matching more than one frequency.
3) Scalloped braces are able to modify two natural frequencies.

His ultimate objective with this work was to see if it could be possible to better match brace sizes to their plates after having measured the plates stiffness. He was clear that there was much more to be done such as taking into account more wood properties, using more than one brace and backing up the analytical work with experimental work.

Although I don't know if his work will have a practical application any time soon, I liked what he was doing and wish him well for the rest of his studies. He had a braced top there from a Stew-Mac kit but said he hasn't had time to progress on it since starting his Masters. I hope he finishes that project too.

Cheers,
Pat

_________________
There are three kinds of people:

Those that make things happen,
those that watch things happen,
and those that wondered what happened.

Thanks for the report, Pat.
Interesting.

Hello all,

I am the presenter of this seminar. If you have any questions, shoot.

Pat

PS. Pat, Nice job at sumarizing my presentation

Welcome to the forum Pat. I hope you find this a useful place to hang out.

Pat

_________________
There are three kinds of people:

Those that make things happen,
those that watch things happen,
and those that wondered what happened.

Pat, is there somewhere online that I can read about your research, I'm very curious. thanks.

I will be posting my thesis online very shortly. I will let you know.

Pat