MECH 690-01 SENIOR MECHANICAL DESIGN PROJECT PROFS. ROBERTS & ROURKE SUMMER 2010 GROUP 2
Summary Problem Definition / Need Objective Data Acquisition / Design Parameters Design Concepts Kinematic Solutions Prototype Fabrication Testing Future Plans Conclusion
Problem Definition There are no guitar display fixtures on the market that can keep a guitar off of the floor and out of harms way, without the requirement of permanent drilling into the wall.
Existing Designs Floor stands leave the guitar in harms way and take up floor space. Wall mounted fixtures consist of permanent mounting holes, damaging walls and causing unnecessary costly repairs in apartments or dormitories.
Objective Design a portable, door-mounted guitar display for a max 15 lb guitar that protects the electric guitar by elevating it above floor level and restricting any movement caused by opening and closing of a door. Keep manual operation to a minimum Able to adapt to a variety of popular electric guitar / bass model shapes Minimize bulkiness of fixture, allowing for clean display of guitar. Utilize Lightweight / Cost effective materials
Who Will Benefit? Any musicians who lease rent apartments or live inside a college dormitory. Musicians who need to keep their guitar elevated for protection against pets or small children. Any musician who desires easy access to their instrument, while still being able to display it out in the open and keep it safe.
Data Collection Measurements were taken from various guitar models found on the wall at Daddy s Junky Music on Mass Ave.
Design Parameters - Over 20 of the most popular guitar and bass guitars were measured. - Provided base measurements - Determined a range for prototype operation for the leading guitar models. Model Length (in) Current Guitar Measurements Thickness (in) Neck Width (in) Body Width (in) Telecaster 32 1 3/4 1 5/8 13 Stratocaster 32 1 3/4 1 5/8 13 Firebird 35 1/4 1 1/2 1 11/16 12.5 Les Paul 32 15/16 2 1/4 1 11/16 13 SG 33 5/16 1 3/4 1 3/4 13 Ibanez GRX 31 1/12 1 15/16 1 3/4 12.5 Ibanez ART300 33 2 1/4 1 3/4 16 Epiphone Dot 35 1/4 2 1/4 1 11/16 16 Emperor Swinger 34 3/4 3 1/8 1 3/4 14 Jazz Bass 37 1/2 2 1/8 1 1/2 13 P Bass 37 2 1/8 1 3/4 13 Thunderbird 39 2 1/4 1 3/4 12.5 Yamaha RBX 150 37 2 1 5/16 13.5 EPB epiphone 34 5/8 2 1/4 1 1/2 13 Max Dimensions 39 3.125 1.75 16 Min Dimensions 31.0833 1.5 1.3125 12.5
Design Matrix
Early Concept Designs - D Chain and Sprocket Design Planetary Gears to bring pieces together Linear motion allows for adjustability. As guitar is placed on hanger, bottom is raised to secure the base. System Equilibrium
Final Design - B Linear motion is contained within the spine Rotating Arms Protect from damage Utilization of pulleys
Pulley Relations
Rotational to Linear
Spring Conditions
Spring Conditions
Prototype Fabrication 6061 aluminum 2 x 2 OD 5/8 thick wall with a internal surface finish was used as the backbone for the project. Considerations - Internal moving components - Guide Block(s) tolerances - Friction Advantages - Lightweight - Easily machined - Readily available - Durable
Prototype Fabrication Pulleys - Outer most pulleys were turned out of 6061 aluminum at a diameter of 3 width of 0.5 - Center most pulley was turned out of 6061 aluminum at a diameter of 1 width of 1 - Offset pulley risers by 0.5 for use of separate belts; allowing maximum belt surface area = no slipping - Center pulley rotates ¾ turn while the outer pulleys move ¼ turn - 3:1 Ratio
Prototype Fabrication Internal Components - Each and every part was modeled using Solidworks, and dimensioned drawings followed. - Were milled on a Proto-Trak vertical milling machine with very tight tolerances for alignment and mating issues. - Made out of 6061 Aluminum stock - Counter bores and relief cuts made it possible for maximum functionality out of major components.
Prototype Fabrication SHEETMETAL WORK - Made out of 1020 14-Guage sheet metal. - Metal was annealed with Oxy- Acetylene torches to relieve stress, which allowed for easy and clean bends without stress related hair fractures.
Material 6061 Aluminum - 6061 is a precipitation hardening aluminum alloy, containing magnesium and silicon as its major alloying elements. - The mechanical properties of 6061 depend greatly on the temper, or heat treatment, of the material. - Typical properties of aluminum alloy 6061 include: Medium to high strength Good toughness Good surface finish Excellent corrosion resistance to atmospheric conditions Can be anodized Good weldability and brazability Good workability Widely available Component Amount (wt.%) Aluminium Balance Magnesium 0.8-1.2 Silicon 0.4 0.8 Iron Max. 0.7 Copper 0.15-0.40 Zinc Max. 0.25 Titanium Max. 0.15 Manganese Max. 0.15 Chromium 0.04-0.35 Others 0.05
AISI 1020 Stress analysis on the Guitar hanger. When a 15 lb load is applied there is a Max Stress= 25,796 psi
Displacement in the Y-Direction Displacement from 15 lb load= 0.023 in
Door Hanger Analysis 25 lb force applied Max Stress = 6152 Material: AISI 1020 0.1 thickness
Arm Analysis-Applying a 15 lb Force (Caused by minor impact) Max Stress is 14,635 psi Material: 6061-T6- Alloy
Max Displacement in the Z-Direction = 0.45 in
Analysis Overview Applied Lod (lb) Max Stress (psi) Yield Stress (psi) Max Displacement (in) Part Material FoS Guitar Hangar AISI 1020 15 25796.7 50991.1 0.023 1.976652 Door Mount AISI 1020 25 6152.9 50991.1 X 8.287328 Arm 6061-T6 15 14635 39885.4 0.45 2.725343 Max Force on Arm to yield = 40 lb
Final Budget 2"x2"x36" Aluminum Tube 34.81 1 5/8" Square x 3" Guide Blocks 11.48 3" Pulley Stock 9.57 Spur Gear 16.31 Spur Gear Rack 1.55 Sheet metal mount 30.7 Standard Hangar 12.99 Connecting Rod 1.49 2x Pulley Belts 18.88 Spring 1.62 Aluminum Arms 14.87 Misc. Hardare 10 Total 164.27
Project s Future Mass Production Capability Interchangeable / Extendable Arms to accommodate large body acoustic instruments Addition of door straps to restrict fixture movement
Alternative Materials IF MASS PRODUCED - Pulleys Made out of Plastic - Arms Low-cost composite such as fiberglass or fiberglass reinforced plastic (FRP) - Spine Plastic injection mold, with gear rack incorporated (various colors) - Centering Guide Blocks High density plastic with helicoil inserts - Gear Nylon (wear resistant)
Conclusion Holds a 15 lb guitar Restricts DOF limiting movement Safely elevates guitar Portable + Automated locking Adapts to many guitar models Prototype weighs 10lb 4 oz Relatively low cost for a prototype
Work Plan
So Now what? More in depth FEA testing of assemblies Testing of different materials Spring insertion into prototype Finish SolidWorks Animation Motion Analysis Poster board Formal Write-up
Questions or Comments Thank You