Fiona’s Bow

Fiona’s Bow

Design Team

Harvest MontemayorFahad Al-SubaieiSamuel ZerbibMatt Joganic

The Clients

NAU instructor 13-year old violinist

Karin Hallberg Fiona Carroll

Problem Definition•Current attachment is heavy – 28 grams•Does not fit her hand as it has grown•Her hand slips out when playing fast•Hand position is uncomfortable for long periods of time•Inhibits sound quality by touching bow hairs

Requirements

• Do NOT change the violin bow

• Light-weight Typical bow: 52 grams = 3 ounces

• Custom fit for pinky and thumb

• Non-slip grip

• Allow for tone quality

Violin Research

• Violin techniques and playing • Concert recitals and

performances

• Bow physics and vibrations

Fiona’s hand conditionBetter understanding of range of motion and muscle strength

•Full range of motion in her wrists

•Missing 3 central metacarpals and the 5th proximal phalanx

•Missing tendons that allow knuckle bending

• Motion of movement in thumbis only in one plane

Physical Model of Hand1Valuable reference tool

• One solution to a problem we had early on with Fiona’s shyness

• Used for measurements of the size of Fiona’s fingers and distance between fingers

• Easier for us to build and test the prototypes before we give them to Fiona

Previous attachment attempts

• Helped to see what was already tried

Materials research

Donation from Carl’s PlasticsFrom Minneapolis

WoodFoamMachineable WaxABSPVCLDPEHDPERubberNylonTeflonAluminumCarbon FiberDelrin

Prototype 1

1) Light-weight attachment

• Low-weight design would improve balance

• Attachment would not be in contact with bow hairs

Prototype 22) Light-weight attachment fit-form material

• Polyurethane inserts for finger holes

• Improved comfort and grip-ability

Prototype 33) Ball-Joint between attachment and

bow

• Creates tripod action giving improved leverage

• Allowing wider range of movement

tPrototypes

200 hours work time

Prototype feedback• Each prototype considered in detail by Fiona

• Feedback questionnaires completed, prototypes rated

‘What did you think?’

• We had to provide Fiona a design with which she felt most comfortable

‘Should be simple, light-weight, comfortable,’ Adrian Anantawan,

SolidWorks model

• Helped to refine design

• Reduce extra weight

Final Design

• Universal fit• Any bow• Any location

• Thumb hole is off the bow hairs

• Two piece design

Analysis

Next Engine 3-D scanner 2 pass curve generation based off of point cloud scan data

AnalysisAudi-Graph Program• Display of different

harmonic frequencies for each note

• Measures “timbre” -A measure of sound quality

• Allow us to compare amplitude and envelope

Budget

Purchases Costs

Prototyping materials $143.25

Final design plastic $40.00

Total cost $183.25Budget allowance $500.00

Remaining balance $316.75

Requirement Results

No changes to bow • Two piece design screws on• Removable• Universal fit (any bow)

Conclusions

Requirement Results

Light-weight • 8 grams • 75% reduced weight

Conclusions

Requirements Results

Custom fit • Contoured holes and edges• Angled holes

Non-slip • Contours help• Wax impregnated texture

Conclusions

Requirements Results

Tone quality • Lengthened bow hairs• Corrected hair tension

Conclusions

Final Thoughts• Initially hoped to calculate a ‘perfect’

solution

• Quickly realized that our design depended on Fiona’s interaction and opinion

• We were not dealing with machines, people will directly interact with our design

• Our goal was to make Fiona as comfortable as possible, the more she likes the attachment , the more she will want to play and advance

Questions ?