From DDL Wiki

Revision as of 22:56, 19 September 2008

Executive Summary

Executive Summary will go here. Assigned to Jeremy.

Stakeholders and Needs

Stakeholders and Needs will go here. Assigned to Mike.

Use of the Current Design

Use of Current Design will go here. Assigned to Mike.

How the Current Design Functions

Assigned to Mike.

List of Parts with Functions and Illustrations

Assigned to Aaron.

Part Number	Name	Qty.	Weight	Function	Material	Maunfacturing Process	Image
				Guitar Parts
G1	Back Panel/Pickguard Screws	12	.4 g	Fastener for Back Panel	Steel	Die Cast or Rolled
G2	Back Panel	1	30 g	Panel for Protecting Rear Bridge mount and tension springs	Plastic	Stamped or Molded
G3	Strings	6	2.33g	Strings are plucked to produce sound	Nickel/Steel	Wound
G4	Springs	3	10.33g	Used to keep strings under tension, connected to bridge	Steel	Wound
G5	Whammy Bar	1	10.33g	A lever which is pressed down to produce tremolo effect by tilting bridge	Steel/Plastic	Cast
G6	Bridge Mounting Screws	6	10g	Fasteners for bridge	Steel	Cast or Rolled
G7	Bridge (assembly)	1	N/A	Used to keep strings connected to guitar body and under tension	N/A	N/A
G8	Spring Claw	1	12g	Used to mount springs onto guitar body	Steel	Cast or Stamped
G9	Spring Claw Screws	2	2.5g	Used to fasten spring claw to guitar body	Steel	Cast or Rolled	[[Image:|100px]]
G10	Saddle Plate	6	8.5g	Mounting point for strings in bridge	Brass	Cast or Stamped	[[Image:|100px]]
G11	Saddle Spring	6	.166g	Maintains string tension in bridge while still allowing strings to move	Steel	Cast or Stamped	[[Image:|100px]]
G12	Saddle Screw	6	.833g	Fastens Saddles to bridge plate	Steel	Cast or Rolled	[[Image:|100px]]
G13	Neck	1	736g	Part of guitar body, Frets and tuning equipment attached to neck	Wood	Carved or Machined	[[Image:|100px]]
G14	Neck Mounting Plate	1	57g	Used to mount neck to body	Steel/Plastic	Stamped	[[Image:|100px]]
G15	Bridge Block	1	69g	Used to keep tension in strings, pass strings through bridge into body of guitar	Steel	Cast	[[Image:|100px]]
G16	Bridge Block Mounting Screws	3	.666g	Used to fasten bridge block to bridge assembly	Steel	Cast or Rolled	[[Image:|100px]]
G17	Guitar Body	1	N/A	Main body of guitar, contains bridge, strings, electronics	Wood	Carved or machined	[[Image:|100px]]
				Floyd Rose Parts
FR1	Whammy Bar	1	49	A lever which is pressed down to produce tremolo effect	Steel	Cast
FR2	Springs	3	10.66g	Used to keep strings under tension, connected to bridge	Steel	Wound	[[Image:|100px]]
FR3	Pivot Mounts	1	8g	Used for mounting pivot saddles	Steel	Cast	[[Image:|100px]]
FR4	Pivot Screws	1	5g	Used for mounting pivots to bridge	Steel	Cast or rolled	[[Image:|100px]]
FR5	Tuner Screws	6	2.66g	Used for minor tuning of the guitar	Steel	Cast or rolled	[[Image:|100px]]
FR6	Bridge Bottom Screws	2	.05g	Used for fastening sustain block to bridge plate	Steel	Cast	[[Image:|100px]]
FR7	String Clamps	6	1g	Used to keep strings attached to bridge	Steel	Cast	[[Image:|100px]]
FR8	Clamp Screws	6	1.66g	Used to put force on string clamps	Steel	Cast or rolled	[[Image:|100px]]
FR9	Saddle	6	20g	Used to provide motion for tremolo effect	Steel	Cast	[[Image:|100px]]
FR10	Sustain Block	1	32g	Used to keep tension in strings, pass strings through bridge into body of guitar	Steel	Cast	[[Image:|100px]]
FR11	Tuner Spring	1	6g	Used to keep pivots in place and provide motion for tremolo	Steel	Stamped	[[Image:|100px]]
FR12	Bridge Plate	1	125g	Used to mount all pivots and other hardware to body of guitar	Steel	Cast	[[Image:|100px]]

DFMA

Assigned to Jonathan.

FMEA

Assigned to Jonathan.

DFE

Assigned to Jonathan.

Mechanical Analysis

Assigned to Jeremy.

Summary of Quantitative Analysis

In our quantitative analysis, we chose to analyze the forces acting upon the bridge. As an offshoot of this, we were also able to analyze the effect of using the bridge on the pitch of the strings. We determined that although each of the components of the guitar bridge act in an easily predictable linear fashion, the complex combination of all the factors combine together into a very non-linear system. The main independent variable of our device is the angle that the bridge is depressed by the guitarist. We called this variable theta.

For our analysis, we used a simplified, but relatively accurate model of the guitar bridge. The Floyd Rose bridge is functionally very similar to our bridge model. The original Fender bridge has a number of design flaws which introduce large unpredictable changes to the forces on the strings, which we could not model easily. Consider our model a “best case scenario” for a pivoting bridge. Any tuning problems with our model would be exacerbated, not alleviated in a real world implementation.

Assumptions

1. The strings are fixed at both the bridge and the nut. Without this assumption, the unpredictable shifting of the strings at the tuners and ball-ends introduces additional tuning problems. The Floyd Rose bridge employ’s clamps at the bridge and nut which fix the strings.

2. Strings behave as steel linear springs. Strings are made of nickel steel alloys. Since the exact recipe for the steel is a closely guarded industry secret, we assumed the properties of the strings match that of standard stainless steel. The density of stainless steel is 7800 kg/m3 and the elastic modulus is 200 GPa.

3. The guitar neck and body do not deform. In a real guitar, the body and neck are made of wood, and deform under the tension of the strings. This deformation is very small, and we chose to ignore it for simplicity.

4. We assumed that the strings used are of the common “8-42” variety. The string diameters are 8, 11, 15, 22, 30, and 42 thousandths of an inch. The thickest three strings are thinner steel cores wrapped with wire, which provide increased linear mass without making the strings too stiff to vibrate.

Figure 1: INSERT GUITAR MODEL IMAGE HERE

Determining the String Tension

Each string on the guitar is made out of a very thin wire of nickel steel. The wire is either made of solid steel, or a solid steel core wrapped in another coil of steel wire. This wrapping allows the string to have a relatively high mass, while remaining flexible, as a solid string of the same thickness would be very hard to pluck. The wires can be viewed as springs, since under standard guitar tuning, the strings stretch an appreciable amount. Although each string can be viewed as an ideal spring, the combination of the tension forces of all six strings on the bridge is a non-linear function when compared to the angle of the tremolo.

One cause of this non-linearity is the fact that for any string, its tension vs. bridge angle function is a piecewise function. The tension in the string decreases linearly as the bridge angle increases, but when the tension reaches zero, the string does not compress like an ideal spring would. Instead, the tension remains zero. When you add together all six string functions, the resulting total plots as a curve, not a straight line.

Figure 2: Trem Angle vs. String Tension

Team Member Roles

Assigned to Jeremy.

References

ALL GROUP MEMBERS: Please put whatever references you use here in bibliographical format.