April 1st, 2016
St. Francis Xavier University
3034 Physical Science Centre
Antigonish, Nova Scotia
BOH 1X0
Subject: Letter of Transmittal
Dear Dr. Emeka Oguejiofor and Paul Doiron,
The members of group 9 are pleased to present our report The E-Z Plate for academic credit in the course Design and Communications II. This report addresses the concerns regarding the loading and unloading of weight-lifting plates on to a barbell that is resting on the ground and the implementation of a new design.
As active citizens who benefit from the services provided at recreational facilities we feel there is need for improvement in the design of standard weightlifting plates. Weightlifting plates have been designed to easily slide on to the collars of barbells that are elevated on a rack. This design is insufficient when loading and unloading a barbell that is on the floor because the perimeter of the plate is subject to friction from the ground as the weightlifter attempts to slide the plate onto the barbell. Therefore our goal regarding the design and implementation of The E-Z Plate is to improve an athlete’s workout by removing the deficiencies associated with the loading and unloading of weightlifting plates on to a barbell that is resting on the ground. Following several meetings with the Senior Machinist and Design Technician of STFX, Steven Macdonald, the design of our plate was re-evaluated and improved to enhance the efficiency of our final product.
The formulation of this report was a valuable and rewarding experience as it brought with it many challenges that enhanced our engineering skills in strength of materials, problem-solving, and graphics and design. As aspiring engineers we hope that we have presented a detailed description and sufficient model of our design so as to fully aid the understanding of the problem and our solution.
If you have any furthers questions or concerns regarding our design, please contact one of the group members.
Best Regards,
Michael Scarth Tristan Martel Simon Pellerin Caitlyn Peddigrew
Table of Contents
LETTER OF TRANSMITTAL2
LIST OF ILLUSTRATIONS4
EXECUTIVE SUMMARY5
ABSTRACT6
1.0 INTRODUCTION6
1.1 tERMINOLOGY6
1.1.0 GENERAL WEIGHT LIFTING TERMINOLOGY7
1.1.1 OUR DESIGN TERMINOLOGY7
1.2 pROJECT dESCRIPTION7
2.0 The Project phases8
2.1 initiation phase8
2.2 planning phase8
2.3 execution phase12
2.3.0 CARDBOARD PROTOTYPE12
2.3.1 MACHINING A PROTOTYPE13
2.3.2 DESIGNING THE FINAL PROTOTYPE15
2.4 CLOSING phase19
3.0 PRODUCTION AND COST19
4.0 RECCOMENDATIONS 21
5.0 CONCLUSION21
rEFERENCES23
aPPENDIX A24
APPENDIX B25
List of Illustrations
coNCEPT A9
CONCEPT B9
coNCEPT C9
CONCEPT D9
mODIFIED coNCEPT C10
CARDBOARD PROTOTYPE12
MACHINED PROTOTYPE13
PROTOTYPE CONTRAST15
LOADING SCENARIOS17
DEFLECTION EQUATION18
SHEAR STRESS EQUATION18
CENTROID EQUATION19
APPENDIX A24
A.1 BARBELL DIAGRAM24
A.2 COMPONENT LABELS25
A.3 PLATE DETAIL26
A.4 SLIDER DETAIL27
APPENDIX B28
B.1 BARBELL DIAGRAM28
B.2 MASS AND CENTROID CALCULATIONS29
Executive Summary
Professional athletes and frequent gym users are constantly putting themselves at an unnecessary risk for injury due to the inefficiency associated with the design of standard weight lifting plates. Group 9 has set forth a goal to re-engineer the standard weight lifting plate so as to provide enhanced efficiency when loading and unloading a barbell that is resting on the ground. This report provides insight into the design and implementation of The E-Z Plate as developed by the members of Group 9 for our term project in Design and Communications II.
Standard weight lifting plates are designed so that they can easily slide onto the collar of a barbell that is elevated on a rack. The problem associated with this design is that the perimeter of the plate is subject to friction from the surface when the user is attempting to slide a plate onto a barbell that is resting on the ground. This can put the user at risk for injury because they are required to partially lift the barbell off the ground with one hand while simultaneously sliding the weight on to the collar with the other. This can lead to back problems and is overall an inefficient process for users. As various exercises that require the loading and unloading of barbells on the ground become increasingly popular, the current design of the standard weight lifting plate has become a prominent problem.
We determined a new way to design the standard weight lifting plate so as to eliminate the deficiencies associated with the loading and unloading of plates onto the collar of a barbell that is resting on the ground. Our design uses a sliding locking mechanism that changes how the plate can be loaded or unloaded from the barbell. After consultation with Paul Doiron of the AH Roy & Associates team, our group was able to narrow our design down to one concept of the five possibilities we had considered. After further consultation with Steven Macdonald, Senior Machinist and Design Technician at STFX, the implementation of the proposed locking mechanism on a 10-lb plate was achieved. The physical 10-lb model only accounts for the performance of the locking mechanism. Proper calculations and re-designing of the standard 25 kilogram weight were performed on a virtual model to display the proposed re-modeling that would need to be done if our design were to be carried out for production.
ABSTRACT
The standard weight lifting plate is designed to easily slide onto the collar of a barbell that is elevated on a rack. This design is inadequate for exercises that require loading to occur on the ground as the perimeter of the plate is subject to friction from the surface and therefore puts a strain on users. This report describes a redesign of the weight lifting plate to make the process of loading barbells on the ground more efficient. The design consists of an enlarged whole and a sliding locking mechanism. The sliding locking mechanism is built to support the loading of 25-kilogram plates and is simple to use. We recommend the design to be implemented into new gyms and targeted towards highly trained athletes.
1.0 INTRODUCTION
The aim of The E-Z Plate project is to improve the design of a standard weight lifting plate by removing the deficiencies associated with the loading and unloading of plates onto the collar of a barbell that is resting on the ground. This report presents designs of the various concepts our group considered, a description of the design and analysis of the operational efficiency of each, and the necessary calculations. The E-Z Plate is aimed at the upper end of the market and is suitable for experienced athletes and weight lifting trainees.
1.1 TERMINOLOGY
This report includes terminology that describes various aspects of weight lifting and the equipment used. To avoid confusion the following sections use visuals and descriptions to assist in understanding these terms.
1.1.0 GENERAL WEIGHT LIFTING TERMINOLOGY
The barbell refers to the bar that is used in various weight lifting exercises. The barbell collars are the ends of the bar in which the plates are loaded onto (see appendix A.1). The plates come in standard sizes depending on their weight and can vary in mass distribution and material.
1.1.1 OUR DESIGN TERMINOLOGY
The sliding/locking mechanism is the term used to address the machined component that slides within the curved cutout in the plate and then locks once in place. The sliders refers to the two curved steel pieces that make up the sliding mechanism. The slider rods are the individual steel rods that connect the two curved pieces together. The handle refers to the protrusion on one of the sliders and the indentation on the opposing side is the groove in which the plates will fit together in when stacked (see appendix A.2).
1.2 PROJECT DESCRIPTION
The standard weight lifting plate has been designed to easily slide on to the collar of a barbell that is elevated on a rack. The problem associated with this design is that the perimeter of the plate is subject to friction from the ground as the user attempts to slide the plate onto the collar of the barbell. To avoid this problem, users are required to lift the partially loaded barbell off the ground with one hand while simultaneously trying to slide additional plates (up to twenty five kilograms each) onto the collar with the other. This is difficult to perform and produces a risk for injury. Currently, barbell jacks have been used to elevate the bar a few inches of the ground. Jacks have helped reduce the problem, however they are expensive, bulky and many public gyms do not have them.
There are many exercises that require the barbell to be loaded on the ground, some of which include the deadlift, snatch, and the clean and jerk. These exercises have become increasingly popular for both the average gym enthusiast and professional athlete and therefore the inefficient loading process has become a more prominent problem. The E-Z Plate is designed to eliminate this problem by improving the efficiency of the plate while still maintaining the standard weight of the current existing plates.
Five concepts were discussed and analyzed to assist in the development and implementation of our final product.
2.0 THE PROJECT PHASES
The goals Group 9 set forth at the beginning of the design project were constantly addressed throughout the various stages of the project. These goals included creating a product that was efficient, durable and low in cost. In doing so we were able to successfully invent a new design of the standard weight lifting plate that reduces the problem associated with the loading and unloading of plates on to the collars of barbells resting on the ground. The phases of the project are broken down into their component tasks and displayed on the Gantt Chart (see Appendix B.1). The following sections outline the steps taken to create our final product.
2.1 INTIATION PHASE
During the initiation phase of the project, our group met to discuss and brainstorm possible ideas and problems that are encountered in our everyday life. The problems were analyzed and possible solutions were considered. Group 9 narrowed down the range of ideas based on feasibility, complexity and general interest in the subject matter. Once the conclusion was made on the design project, we met with Dr. Emeka Oguejiofor to discuss our ideas and get the design approved.
2.2 PLANNING PHASE
During the planning phase the main focus was on determining the best design approach to re-engineer the standard plate so that it could easily slide onto the collar of a barbell on the ground. The original design, dubbed Concept A, which was presented during the individual proposals, consisted of a pin mechanism and an elongated hole in which a plate could be dropped onto the collar of a barbell and be locked in (see Concept ‘A’ on the next page). Concept B resulted from a small adjustment in the design of Concept A (see Concept ‘B’ on the next page). By eliminating the extension of the inner hole to the outer perimeter of the plate, Concept B would reduce the impacts the design has on the mass balance and center of mass. Concept C eliminated the horizontal pin mechanism and replaced it with a curved locking mechanism as we felt the horizontal pin mechanism was impractical and less efficient (see Concept ‘C’ below). In addition, the curvature increased the surface area the barbell has in contact with the sliders, dispersing the force acting on the sliders. The main challenge with Concept A, B and C was that the designs were non-symmetrical and therefore posed a problem because standard weight lifting plates are designed so as to have a center of mass at the middle of the collar hole because when on a barbell they need to have the ability to rotate freely around the bar. Concept D originated as a solution to this problem, as it consisted of a spinning locking mechanism and ensured full symmetry (see Concept ‘D’ below).
*Note: Dimensioned in millimeters
Having Concept A, B, C and D as a foundation for the design project a meeting was scheduled with Paul Doiron of the A.H. Roy & Associates team. Mr. Doiron assisted in helping determine which concept would be most feasible. He also suggested a list of criteria Group 9 would need to assess in order to successfully design a more efficient weight lifting plate. These included overcoming safety problems and keeping costs of the design and assembly low in order to be competitive. Following the meeting with Mr. Doiron, Group 9 met to analyze the designs and discuss other alternatives. Concept D was discarded as a possible solution due to the complexity of the system and the difficulty associated with ensuring the strength and safety of the plate when locked into its static position. Concept C was concluded to be the most sufficient design, however many adjustments were made along the course of the execution phase and are discuss later in greater detail. Originally the locking mechanism was intended to only move along a quarter circle. It was decided that by extending the cut out to a half circle, the overall design would be more symmetrical and would assist with maintaining the mass balance about its center (see Modified Concept ‘C’ below). It should be noted that the following modified concept includes the letters “E-Z” and the “25 kg” however these are aesthetic and will only be painted on following the production of the plate.
After making the necessary conclusions regarding Concept C, a meeting was scheduled with the Senior Machinist and Design Technician at STFX, Steven Macdonald. Steven provided the group with practical feedback with regards to material selections, feasibility of construction for the locking mechanism and the possibility of constructing a model or prototype for testing and presentation. The following recommendations were made during the meeting: