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TRANSCRIPT
Home Gym with Inversion Table
A Baccalaureate thesis submitted to the School of Dynamic Systems
College of Engineering and Applied Science University of Cincinnati
in partial fulfillment of the
requirements for the degree of
Bachelor of Science
in Mechanical Engineering Technology
by
Aaron Crum
April 2013
Thesis Advisor: Professor Amir Salehpour
ii
TABLE OF CONTENTS
TABLE OF CONTENTS .......................................................................................................... II
LIST OF FIGURES ................................................................................................................ III
LIST OF TABLES .................................................................................................................. III
INTRODUCTION .................................................................................................................... 1
EXISTING PRODUCTS .......................................................................................................... 2
HOME GYM FITNESS EQUIPMENT ....................................................................................................................... 2 INVERSION TABLES ............................................................................................................................................. 4 SUMMARY .......................................................................................................................................................... 5
CUSTOMER FEEDBACK, FEATURES, AND OBJECTIVES ............................................. 6
INTERVIEWS ........................................................................................................................................................ 6 SURVEY ANALYSIS ............................................................................................................................................. 7 FEATURES AND OBJECTIVES ............................................................................................................................... 8 PROTOTYPE OBJECTIVES - QFD ............................................................................................................... 10
SCHEDULE AND BUDGET ................................................................................................. 11
SCHEDULE ........................................................................................................................................................ 11 BUDGET ............................................................................................................................................................ 12
3D SOLID MODELS OF THE TOTAL GYM ...................................................................... 14
DRAWINGS ........................................................................................................................................................ 14 LOADING CONDITIONS AND SAFETY FACTOR .................................................................................... 16 COMPONENT SELECTION .......................................................................................................................... 20
BILL OF MATERIALS .......................................................................................................... 21
EXPLODED VIEW ................................................................................................................ 22
FABRICATION ...................................................................................................................... 23
TESTING AND CONCLUSION ........................................................................................... 32
REFERENCES ....................................................................................................................... 33
APPENDIX A - RESEARCH ................................................................................................ A1
APPENDIX B – SURVEY .................................................................................................... A2
APPENDIX C – QUALITY FUNCTION DEPLOYMENT ANALYSIS ............................ A3
APPENDIX D – PRODUCT OBJECT IVES ....................................................................... A4
APPENDIX E – SCHEDULE ............................................................................................... A5
APPENDIX F – BUDGET .................................................................................................... A6
APPENDIX G – SHOP DRAWINGS ................................................................................... A7
iii
LIST OF FIGURES Figure 1 - Bowflex Home Gym ................................................................................................ 2
Figure 2 - Total Home Gym...................................................................................................... 3
Figure 3 - Teeter Fitspine Inversion Table ............................................................................... 4
Figure 4 - IronMan LXT850 Inversion Table ........................................................................... 5
Figure 5 – 3D Model of Machine in Workout Position .......................................................... 14
Figure 6 - 3D Model of Machine in Inversion Table Position ................................................ 15
Figure 7 – Foot Plate Stress .................................................................................................... 16
Figure 8 – Full System Deflection .......................................................................................... 17
Figure 9 – Bending Stress in Rails .......................................................................................... 18
Figure 10 – Shear Stress of Rotational Pins............................................................................ 19
Figure 11 – Exploded View of Full Gym ............................................................................... 22
Figure 12 – Waterjetting Aluminum Rotational Plates ........................................................... 23
Figure 13 – Band Saw Cutting ................................................................................................ 24
Figure 14 – Upholstering The Backrest .................................................................................. 25
Figure 15 – Wheels Added onto Backrest .............................................................................. 26
Figure 16 – Welding Steel Brackets ....................................................................................... 26
Figure 17 – Creating T-brackets ............................................................................................. 27
Figure 18 – Foot Slider Assembly .......................................................................................... 28
Figure 19 – Footrest Assembly ............................................................................................... 28
Figure 20 – Frame Coming Together...................................................................................... 29
Figure 21 – Rotational Plate Assembly .................................................................................. 29
Figure 22 – Machine Fully Assembled ................................................................................... 30
LIST OF TABLES Table 1 - Survey of Important Features 7
Table 2 – QFD Analysis for Engineering Characteristics 10
Table 3 – Schedule 11
Table 4 – Budget 12
Table 5 - Final Budget 13
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INTRODUCTION
Home gyms have been around for decades, with promises that just a few minutes a day
can help turn the average couch potato into the next Sylvester Stalone. They come in all
shapes and sizes from the simple Bullworker spring to complex home gyms systems such as
the Bowflex.
Before a workout begins, and after a workout ends, the best thing for your muscles is a
good stretching. Stretching is important for people of all ages and skill levels. The benefits
include increasing the range of motion, reduced muscle tension, and increased circulation to
various parts of the body. Also, stretching after working out is beneficial workout recovery
and decreases muscle soreness.
One of the most useful stretching devices on the market today are inversion tables. These
are machines that turn the user’s body upside-down, with their ankles supported by the table.
The purpose of using this machine is to allow the user to stretch out after working out, and
provide a method to decompress the spine.
On the market today, there are hundreds of types of home gyms, as well as inversion
tables for sale. The focus of this project is to design a machine that can both incorporate a
home gym, and an inversion table into one unit.
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EXISTING PRODUCTS
HOME GYM FITNESS EQUIPMENT
There are many different types of home gyms, but they all perform a very similar task. They
can be broken down into two categories. One contains some type of resistance band, or
spring that gives resistance to a particular motion. The other utilizes gravity as resistance,
whether it is a set of weights, or the user’s own body weight.
When it comes to resistance bands, the most well-known home gym is the Bowflex, as
shown in Figure 1 (1). The Bowflex requires the user to overcome the bending force of the
resistance bands. The different bands on the back of the machine are rated at different weight
capacities. The problems with these kind of machines are their price, as well as lack of ability
to stretch using the machine. Initial investment cost is a very key factor in purchasing a home
gym, and many of these gyms can cost thousands of dollars, turning many people away.
Figure 1 - Bowflex Home Gym
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Gravity-based workout units are the predominant ones found in fitness centers. They
typically consist of a stack of weights, a steel cable, and a few pulleys. The simplicity causes
the machines to be durable and allows the user to track their progress by seeing exactly how
much weight they are lifting. The downsides to these machines are their high cost, and size.
Other examples of gravity-based workout units include free weights such as dumbbells, and
products that involve the user lifting a percentage of their own body weight. These machines
take up less space and are relatively inexpensive. The main complaint for these home gyms
are that they lack versatility and the time it takes to adjust between workouts. An example of
one of these systems is the Total Home Gym XLS as shown in Figure 2 (2).
Figure 2 - Total Home Gym
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INVERSION TABLES
While many people haven’t used an inversion table, most people are familiar with them
through TV ads, and seeing similar devices in various gyms. Almost all of them work by
strapping the user’s ankles to the lower part of the table and then flipping the user upside
down to relax and let their muscles and spine stretch out.
The most popular model on the market is the Teeter Fitspine, as shown in Figure 3 (3) is
the most popular model on the market today. It is a very basic no-frills device that allows the
user to strap their feet and ankles in and flip upside-down. As with most exercise equipment,
the price always tends to be an issue. This model is over $400, while others by the same
company can cost upwards of $900. For a device that only serves one purpose, many people
think the cost outweighs the benefits. Also for this particular model, there is no locking
mechanism to keep someone in place. This could be an issue causing the user to rock back
and forth in the machine.
Figure 3 - Teeter Fitspine Inversion Table
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The IronMan LXT850 as shown in Figure 4 (4) overcomes most of the bad qualities of the
Teeter device. It has a lower cost at a sub-$300 price point, and has a locking mechanism that
can hold it into 10 different positions.
Figure 4 - IronMan LXT850 Inversion Table
SUMMARY
There is a gap in the market where working out, and stretching is combined into one single
unit. The goal of this project is to fill this gap with a machine that can be used to have a full-
body workout, and then quickly turn into an inversion table to stretch out with.
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CUSTOMER FEEDBACK, FEATURES, AND OBJECTIVES
INTERVIEWS
Interviews were conducted with people that have a close relationship with the world of
fitness and home gyms. The interviews were conducted to find out what kind of qualities are
liked and disliked with home gyms and/or inversion tables.
In an interview with Katy Brian, she explains how she liked and disliked her Total Home
Gym (5). She explained how she has used the machine for over 5 years and has enjoyed it
very much. Also, that it was a much cheaper and more convenient solution to working out
than a gym membership.
Jayme Johnson is the Coordinator of Facilities for the University of Cincinnati
Recreation Center (6). As a Rec Center Coordinator, he is familiar with the hundreds of
pieces of gym equipment, and has finished his Master’s Degree in the field of Exercise
Science. He typically does not enjoy home gyms, and prefers to go to fitness centers for a
few reasons. First, there is typically a larger variety of exercises that can be performed due to
many different machines. Secondly, changing from one type of workout to another is as
simple as switching machines. Finally, he believes home gyms are prone to breaking, and are
not of the same quality as equipment found in fitness centers.
In an interview with Christos Sampanis, he gave similar points as the previous
interviewees (7). He says that the costs of home gyms are too much and he would prefer to
pay a lower monthly fee rather than huge upfront costs. He also prefers fitness centers due to
the wide variety in machines. On the other hand, he also enjoys a few aspects of home gyms.
These include the privacy of working out at home, as well as not having to drive somewhere
to workout.
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SURVEY ANALYSIS
Fourteen surveys were handed out to people within the UC Rec Center to provide
feedback from people who regularly workout. The survey listed a range of product features
with which they were to give a 1-5 rating based on their importance (1 being least important
– 5 being most important). The first section of the survey was to get information on what
aspects of the machine are most important to them. The second was to find out what their
opinions were on home gyms they have previously used (detailed survey results can be found
in Appendix B).
The results of the survey, along with the designer improvement plan can be seen in
Table 1. The average customer importance column shows the survey results. The following
columns show the expected improvement upon each of these qualities. The price has the
second highest improvement ratio as this is the highest importance factor when considering
the purchase of a home gym. This information shown is crucial in coming up with specific
engineering requirements and finding ways to achieve high customer satisfaction.
Table 1 - Survey of Important Features
Questions
Avg
Customer
Importance
Designer's
Multiplier
Current
Satisfaction
Planned
Satisfaction
Improvement
Ratio
Modified
Importance
Relative
Weight
%
Price 4.14 1.10 2.73 3.50 1.28 5.84 13.00
Capacity for varied user height/weight 3.71 1.00 3.23 3.50 1.08 4.02 9.00
Ease of operation 4.36 1.10 3.46 4.00 1.16 5.54 13.00
Ease of assembly 3.43 1.00 2.70 3.00 1.07 3.68 8.00
Quiet operation 2.92 1.00 3.69 4.00 1.08 3.17 7.00
Comfort 3.43 1.10 3.38 3.50 1.04 3.91 9.00
Stability 4.57 1.10 4.00 4.00 1.00 5.03 11.00
Small footprint 2.93 1.00 3.17 4.00 1.26 3.68 8.00
Safety 4.07 1.00 3.77 4.50 1.19 4.89 11.00
Ease of maintenance 3.64 1.00 3.15 3.50 1.11 4.04 9.00
Importance of Features of a Home Gym
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FEATURES AND OBJECTIVES
The product objectives are the same as the list of customer features. In this section, these
features have been listed in order of importance, along with their relative weight percentages.
Also, under each one there are a number of objectives for how the prototype of this machine
can fulfill the customer’s needs.
1. Cost (13%)
a. Prototype under $500
2. Ease of operation (13%)
a. Adjustment between exercises requires ≤ 3 steps
b. Adjusts from workout station to inversion table in ≤ 3 steps
c. Mechanisms to help with inversion
d. Inversion table can be locked in all angles from horizontal to vertical with one
hand
e. Allows user ability to work out all muscle groups without reconfiguration
3. Stability (11%)
a. Symmetrical design
b. Consistent loading conditions and design for CG at or below comparable
machines
c. Frame to be welded instead of fastened
4. Safety (11%)
a. All corners covered with rubber bumpers
b. Ankle supports to lock to prevent falling
c. No pinch points
d. Safety bars on side of machine
5. Capacity for varied user height/weight (9%)
a. Adjustable positioning for heights between 5’0” – 6’6”
b. Includes ankle supports for range of human ankles
c. Material and design will be sized and selected based on a 3.0 safety factor
6. Ease of maintenance (9%)
a. All steels are stainless or coated to prevent rust
b. All bearings are sealed requiring no lubrication
7. Comfort (9%)
a. Back rest is typical weight bench padding
b. Ankle supports are adjustable and padded comparable to Teeter brand
c. Handle grips will be ergonomic
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8. Ease of assembly (8%)
a. Uses standard hardware
b. Uses standard tools for assembly and teardown
c. Unit has ≤ 10 parts that need assembling
9. Small footprint (8%)
a. Product to take up no more than 6’x4’ floor space
b. Foldable frame to take up no more than 3’x4’ floor space
10. Quiet operation (7%)
a. Contains roller bearings for smooth movements
b. Uses rubber feet to prevent floor noise and vibration
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PROTOTYPE OBJECTIVES - QFD
The analysis in Table 2 shows how the engineering characteristics given at the top of the
chart are going to be solutions to the customer requirements in the left-hand side of the chart.
These have been weighted and compared to achieve a relative weight percentage that will
dictate which of these engineering characteristics are the most important to the final design.
Table 2 – QFD Analysis for Engineering Characteristics
The left side of this table shows the customer features. The top and center of the table
shows how engineering characteristics relate to these features. To the right of the body, we
have importance weights to each feature determined by taking the average responses from
the surveys. Also, there is a designer’s multiplier and a final relative weight percentage.
Finally, we have a relative importance percentage at the very bottom row that shows which
characteristics are most important to implement in the design.
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Price 3 9 9 1 1 1 3 1 1 4.14 1.10 2.73 3.50 1.28 5.84 0.13 13%
Ease of Operation 1 9 1 4.36 1.10 3.46 4.00 1.16 5.54 0.13 13%
Stability 3 1 9 4.57 1.10 4.00 4.00 1.00 5.03 0.11 11%
Safety 9 9 3 3 4.10 1.00 3.77 4.50 1.19 4.89 0.11 11%
Comfort 9 1 9 3.43 1.10 3.38 3.50 1.04 3.91 0.09 9%
Ease of Maintenance 9 1 9 3 3.64 1.00 3.15 3.50 1.11 4.04 0.09 9%
Capacity for varied height/weight 9 3.71 1.00 3.23 3.50 1.08 4.02 0.09 9%
Small footprint 9 2.92 1.00 3.17 4.00 1.26 3.68 0.08 8%
Ease of assembly 9 9 1 3 3.43 1.00 2.80 3.00 1.07 3.68 0.08 8%
Quiet operation 9 9 2.92 1.00 3.69 4.00 1.08 3.17 0.07 7%
Abs. importance 3.16 2.38 2.05 1.79 1.72 1.69 1.52 1.28 1.27 1.03 17.9 37.0 0.84 0.84
Rel. importance 0.18 0.13 0.11 0.10 0.10 0.09 0.09 0.07 0.07 0.06 1.0
Rel. importance % 18% 13% 11% 10% 10% 9% 9% 7% 7% 6% 100%
Aaron CrumHome Gym with Inversion Table
9 = Strong3 = Moderate
1 = Weak
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SCHEDULE AND BUDGET
SCHEDULE
The project time-table can be seen in Table 3. The concept development marks the beginning
of the design phase of this project beginning in October. The design phase continues up till
the end of December. Upon the start of spring semester, the fabrication phase will begin. This
will run up till through March, with another month of tweaking and customer testing.
Table 3 – Schedule
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BUDGET An initial budget of expenses is included in
Table 4. This does not take into account machining and tooling costs. Prices based on
internet quotes as of October 18, 2012.
Table 4 – Budget
Frame
40’ Tube steel ($2/ft.) $80
10’ Channel steel ($2.1/ft.) $21
Rolling Backrest
Bearings $13
Wheels $19
Sheet of plywood $11
Shoulder bolts ($2.5/ea.) $10
Vinyl sheeting ($11/yd^2) $22
Foam padding $25
Inversion Table Pivot Joint and Handles
Bar steel ($2.90/ft.) $3
Tube steel ($2/ft.) $8
Resistance System
Handles $13
Resistance band set $20
Pulleys ($11/ea.) $22
Steel cable ($1/ft.) $10
Subtotal $277
20% Miscellaneous expenses $55
Total $333
Budget
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Table 5 - Final Budget
Final Budget
Frame
2" Square tubing $130
2.5" Square tubing $75
2"x2" Angle Steel $30
Aluminum Sheet $25
Steel Rod $5
Rolling Backrest
Trucks/Wheel Assembly $40
Wood $25
Vinyl Sheeting $20
Foam Padding $8
Resistance System
Handles $20
Pulleys $30
Steel Cable $12
Cable Clamps $4
Carabiners $15
Foam Padding $20
Hardware
Nuts, Bolts, Washers, Clips $15
Casters and Feet $30
Total $504
The cost ran over the planned budget. There were parts that were unanticipated, and
the cost of the metals changed based off the vendor used. These parts were purchased based
on what could be readily found, thus altering the original design slightly and increasing
overall costs.
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3D SOLID MODELS OF THE TOTAL GYM
DRAWINGS
A full 3D model was created to see ensure all pieces will fit together properly. The
rendering below in Figure 5 shows the machine as it is setup for working out. This position
allows the user to work out against their own body weight by laying on the backrest and
pulling themselves upwards (pulley cables and handles not shown).
Figure 5 – 3D Model of Machine in Workout Position
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The rendering below in Figure 5 shows the machine as it is setup for use as an inversion
table. This position allows the user to be suspended upside down by their ankles. Due to a
locking mechanism, they can stay in this position until they are ready to rotate back to
standing position.
Figure 6 - 3D Model of Machine in Inversion Table Position
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LOADING CONDITIONS AND SAFETY FACTOR
Most of the stress that this machine will see comes from the weight of the user in
different positions. Points of high-stress have been analyzed to ensure there will not be
failure. Since this machine will be holding a human above the ground, it is critical to ensure
this machine will not fail and cause serious injury to the user. A maximum weight limit has
been set at 300lbs, with a safety factor of two when calculating stresses. The following FEA
calculations have shown that with 600lbs of force loading on critical points, there should be
no mechanical issues.
When stepping onto the machine to prepare for inversion, it is likely that the user will
step on one side of the foot plate bar with their entire weight. Figure 7 shows the stress
incurred in this subassembly if the user steps on the far edge. The force given for this
calculation is 600lbs, which equates to ~36kpsi of stress on the joint edge. Because of a
90kpsi yield strength, this gives a total safety factor greater than 4.
Figure 7 – Foot Plate Stress
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The same force has been applied in Figure 8 to check for deflection other parts of the
system. This shows that most of the deflection will occur within the foot plate area. While the
deflection is as important as the stress on the parts, it is important to include it because too
much deflection will cause the user to think the machine is cheaply made.
Figure 8 – Full System Deflection
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Another stress to be considered was the bending force occurred on the rails due to the
user laying on the backrest. This is shown below in Figure 9. In this calculation, it has been
assumed the four wheels will be in contact with the longest portion of channel aluminum for
a worst case scenario and a 2.5 safety factor. This yields just under 5000 psi bending stress.
This is significantly under the bending yield stress.
Figure 9 – Bending Stress in Rails
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Finally, hand calculations have been done to show that a ½” steel bolt should be
sufficient to support the shear stresses in the rotational joints. As shown in Figure 10, the pin
will have a shear stress under 2300psi with 450 lbs of load. This is significantly under the
18000psi shear stress yield mark for 304 stainless steel.
Figure 10 – Shear Stress of Rotational Pins
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COMPONENT SELECTION
For the majority of this project, standard parts have been chosen to cut costs and ease
procurement. Only a few parts, including casters, spring pins, and backrest rolling assembly
are parts that need to be purchased and cannot be created from stock materials in the machine
shop. All joints are designed to be fastened with standard bolt sizes that are readily available
at any hardware store.
The rails were originally chosen to be aluminum, but after a trial, this showed to be too
malleable. Steel was then chosen. It turned out very well in terms of rigidity, and the ability
to weld brackets onto it.
Almost the entire rest of the assembly is composed of 2” square tube steel. It will have
more than enough strength to support any kind of stresses this machine will incur. Secondly,
it is readily available at many steel warehouse locations. Finally, this steel is easily
machined, and weldable.
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BILL OF MATERIALS
Bill of Materials Quantity Unit Description Material Vendor
426 in. 2" Square Tube Steel Metals Depot
180 in. 2" Channel Steel Metals Depot
1 pc. 20" x 20" x 1/4" Plate Steel Metals Depot
10 in. 1/2" Dia. Rod Steel Metals Depot
32 in. 2.5" Square Tube Steel Metals Depot
180 in. 3/16” Steel Wire Steel Home Depot
24 in. 3" Dia Tube Foam Amazon.com
1 pc. 48" x 20" x 3/4" Plywood Home Depot
1 pc. 100" x 20" Sheeting Vinyl Walmart
2 pc. Casters - McMaster Carr
6 pc. Adjustable Height Feet - McMaster Carr
4 pc. Pulleys - Grainger
1 pc. Spring Pin - J.W.Winco Inc.
1 pc. Longboard Wheel Assy - Amazon.com
1 pc. Nylon Strap Handles - Amazon.com
10 pc. 1/2" Dia Pins With Handles - National Gym Supply Inc.
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EXPLODED VIEW
The following drawing shows the parts and assemblies in an exploded view. Also
included is a list of part and assembly names that correspond with the bill of materials.
Figure 11 – Exploded View of Full Gym
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FABRICATION
After acquiring metals, and placing orders online through vendors such as McMaster
Carr, and Grainger, the construction phase was started. The first pieces, the rotational plates
were done at work with the use of a waterjet machine. The precision and tolerances needed to
be CNC cut.
Figure 12 – Waterjetting Aluminum Rotational Plates
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The band-saw was used to cut the tube steel down to size, as well as to put 45 degree angles
on pieces.
Figure 13 – Band Saw Cutting
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Here, after cutting the wood to size, the vinyl sheeting is being wrapped and stapled into
the wood. Also, polyfil was stuffed inside to create a comfortable seat.
Figure 14 – Upholstering The Backrest
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Finally, longboard trucks and wheels were attached to the backrest to have a finished
product. The truck assemblies came with the wheels and bearings, so this process was fairly
easy.
Figure 15 – Wheels Added onto Backrest
In the shop, pieces were getting welded together to later form the other assemblies.
Figure 16 – Welding Steel Brackets
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These two T-joints were created for supporting the vertical posts. They were welded out
of 2.5” square tube steel with a webbing thickness that allowed 2.0” steel to slide through
easily.
Figure 17 – Creating T-brackets
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This piece is part of the footrest assembly that will allow for change in leg thickness of
the user. The pin will hold this slider in place. The following picture shows it on the footrest
assembly.
Figure 18 – Foot Slider Assembly
Figure 19 – Footrest Assembly
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The following photo shows how all the bandsaw cuts are coming together to put the
frame intact.
Figure 20 – Frame Coming Together
The rotational place assembly was then bolted on, causing two different parts to be able
to rotate independantly of one-another.
Figure 21 – Rotational Plate Assembly
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After cutting the foam for the footrest assembly, and adding cables, pulleys, and other
hardware, the workout part of the machine is finished.
Figure 22 – Machine Fully Assembled
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The final photo here shows the machine in an inverted position, although not fully 90
degrees vertical. This was just to show that the backrest was held in place, and that there was
no issues with the machine in terms of usability.
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TESTING AND CONCLUSION
The machine was tested under real-world conditions. Different people tried out the
machine to check for any issues with the system. While the machine could be used as
projected, there were parts that were difficult to use.
The first issue was the rotational plates. While good on paper, these plates were very
difficult to use in the real world. The issue here was that the pin that holds the two plates
together absorbs all torque within the system. Because of this, the pin has a large amount of
friction between the pin and the plates causing it to be very difficult to pull out when a user
was on the machine. In fact, during testing of the inversion table, it was nearly impossible for
the user to extract the pin while inverted. This was the most limiting factor in using the
machine, and would call for a complete redesign of the rotational locking mechanism.
Secondly, there was a metal-on-metal sliding joint that caused issues when raising and
lowering the rails. The assembly consisted of a 2.5” section of tube sliding over a 2” section
of tube. This was not a large problem, but it did get stuck on numerous occasions, even after
grinding down any sharp edges. This would definitely be a hassle for the end user of the
machine.
Thirdly, since the machine was built with a modular design, everything was pinned or
bolted together. This was good for assembling and disassembling the unit, but bad because it
caused some slop where the bolt-holes weren’t perfectly aligned. Also, pinning everything
into place was difficult for the user. In retrospect, it would have been a much better design to
have a different locking mechanism than pins holding everything in place. Also, drilling very
well-aligned holes for the pins to fit perfectly was very difficult on large pieces.
In terms of manufacturability, the machine could be mass-produced very easily,
requiring very few pieces of machinery. The prototype build was extremely over-built with
the gauge of steel used, and further increasing the budget. If refined, this home gym could
easily be produced at a priced point at or below $300. The modular design would allow the
parts to be packaged into smaller boxes, and assembled at home. Finally, the entire machine
could be assembled using just two common wrench sizes.
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REFERENCES 1. Nautilus Inc. Bowflex Xtreme 2 SE Home Gym. [Online] [Cited: September 2, 2012.]
http://www.bowflexhomegyms.com/bowflex_home_gyms_us/products/xtreme2se/prdcdovr~
100070/Bowflex+Xtreme+2+SE+Home+Gym.jsp.
2. IronMan. IronMan LXT850 Locking Inversion Table. Overstock.com. [Online] [Cited:
September 2, 2012.] http://www.overstock.com/Sports-Toys/Ironman-LXT850-Locking-
Inversion-System/3987541/product.html.
3. Total Gym. Total Gym XLS. [Online] [Cited: September 2, 2012.]
http://www.totalgymdirect.com/total-gym-xls.php.
4. Teeter Hangups. FitSpine Trainer Inversion Table. [Online] [Cited: September 2, 2012.]
http://www.teeter-inversion.com/Store/P-FS1002/Fitspine+Trainer+Inversiontable.
5. Brian, Katy. Interview with Total Home Gym owner. September 9, 2012.
6. Johnson, Jayme. Interview with Coordinator of Facility Operation at the UC Campus Rec
Center. September 10, 2012.
7. Sampanis, Christos. Interview with Home Gym User. September 9, 2012.
Appendix A1
APPENDIX A - RESEARCH
Interview with Total Home Gym owner: Katy Bryan 307 Deer Chase Drive
Duncan South Carolina 29334 09/09/12
She has owned the Total Home Gym for 5+ years, and uses it a few times per
week. The ease of changing out accessories is a big plus, as well as the range
of different workouts than can be done with one machine. She says the incline
that the bench has does help for stretching, but the idea of an inversion table
included would be very helpful. She has not heard of the idea to have a home
gym and inversion table in one unit. Katy prefers using a home gym over
going to a fitness center due to convenience, gym fees, and dealing with
irritating people.
Interview with Jayme Johnson: Coordinator of Facility Operations at the
University of Cincinnati Campus Recreation Center. 2820 Bearcat Way PO
Box 210017 Cincinnati, OH 45221 09/10/12
Background: Bachelors in Exercise Physiology, Masters in Exercise Science
Jayme has used a variety of home exercise equipment, but prefers to go to
fitness centers. His biggest complaint with a home gym is the time it takes to
set up when going from one work-out to the next. For instance, he says “The
time spent on changing resistances between workouts takes just as much time
as the workout itself”. Secondly, he believes the quality of build on many
home gyms is subpar, and they are prone to breaking. On the other hand, he
praises home gyms on the variety of exercises that can be performed with one
piece of equipment. He has used an inversion table for physical therapy, and
thinks the idea of incorporating it into a workout machine is a wise idea.
Besides the similarities of this and the Total Home Gym, he has not seen a
similar product currently on the market.
Interview with home gym user: Christos Sampanis 240 Greenup St.
Covington, KY 41011 09/09/12
Christos has used many types of home gym equipment, including dumbbells,
barbells, the Iron Gym, treadmills, and multiple types of benches. He says the
downside of home gyms are cost, the total space it takes up, and lack of
different exercises like are found in a fitness center. He enjoys having home
gym equipment because it is more private, there is a lack of driving, and
because he does not have to deal with the continued cost of fitness centers.
He has not heard of a single piece of equipment that allows for both working
out, and an inversion table but he would definitely be interested in trying out a
machine like this.
Appendix A2
Bowflex Xtreme 2 SE Home Gym
The Bowflex Xtreme 2 SE is a Bowflex’s top selling home gym.
It uses a series of “Power Rods” that act as different resistance
levels to give the user approximately 70 different exercises from
head to toe. The maximum resistance available for this home gym
is 210lbs, but is expandable to 410lbs.
The Bowflex works very
well as a home gym, but
does not provide the
option of having an
inversion table to stretch
with after working out.
Also, this home gym is
very expensive at $1600
for this model. For more
versatility in your
workouts, the higher end
models cost upwards of
$3000.
http://www.bowflexhom
egyms.com/bowflex_ho
me_gyms_us/products/x
treme2se/prdcdovr~100
070/Bowflex+Xtreme+2
+SE+Home+Gym.jsp
09/02/2012
Appendix A3
Total Gym XLS
The Total Gym XLS is the top model from the Total Gym line.
The resistance is based off the user’s weight. The incline of the
bench can provide resistances from 6% to 50% of the user’s
body weight. The company claims that the XLS model can
provide 80 different exercises.
The Total Gym workout
system has been around
for many years with
very little change. As
with the Bowflex, this
does not include an
option to turn it into an
inversion table. This
higher model is very
costly at about $1000.
Also, the range of
resistance is very limited
to the weight of the user.
http://www.totalgymdire
ct.com/total-gym-
xls.php
09/02/2012
Appendix A4
Teeter FitSpine Inversion Table
The Teeter FitSpine Inversion Table is the #1 rated inversion
table on the market today. This model includes adjustable ankle
support for any size foot. It also has a strap to control the
maximum angle of rotation.
Features:
Pre-set rotation control
Smooth and Quiet rotation
Easy Assembly
Foldable for storage
Customizable accessories
Weight limit of 300lbs
Height capacity of 4’8” – 6’6”
The Teeter FitSpine, as
with many other
inversion tables does not
have a locking
mechanism to lock into
a specific angle. This
model is $429, but
others range from $289 -
$999. The only
exercises than can be
performed on this
product are abdominal.
http://www.teeter-
inversion.com/Store/P-
FS1002/Fitspine+Traine
r+Inversiontable
09/02/12
Appendix A5
IronMan LXT850 Locking Inversion Table
The IronMan LXT850 Locking inversion table comes equiped
with a racheting mechanism to lock it at 10 different angles.
Features include:
Comfortable ankle holder to prevent pinch point pressure
Foam backrest with lumbar support
Supports up to 300lbs
Side holder for cell phones, glasses, wallets, etc.
Extended handles to return body to upright position.
This model only allows
locking in ten positions.
The price point for this
model is $250, but other
models range up to
$330. As with other
inversion tables, the
machine cannot be used
for exercising anything
other than abdominal
muscles.
http://www.overstock.co
m/Sports-
Toys/Ironman-LXT850-
Locking-Inversion-
System/3987541/produc
t.html
09/02/2012
Appendix B1
APPENDIX B – SURVEY
Home Gym and Inversion Table
CUSTOMER SURVEY
There is a gap in the market for home gyms that also give the user the ability to stretch
after working out. This purpose of this survey is to gather data about the current satisfaction
with home gyms and inversion tables.
How important is each feature to you for the design of a home gym?
Please circle the appropriate answer. 1 = low importance 5 = high importance Avg. Price 1 (0) 2 (0) 3 (4) 4 (4) 5 (6) N/A (0) 4.14
Capacity for varied user height/weight 1 (0) 2 (2) 3 (3) 4 (6) 5 (3) N/A (0) 3.71
Ease of operation 1 (0) 2 (1) 3 (1) 4 (4) 5 (8) N/A (0) 4.36
Ease of assembly 1 (0) 2 (4) 3 (3) 4 (4) 5 (3) N/A (0) 3.43
Quiet operation 1 (2) 2 (3) 3 (4) 4 (2) 5 (2) N/A (0) 2.92
Comfort 1 (1) 2 (2) 3 (3) 4 (6) 5 (2) N/A (0) 3.43
Stability 1 (0) 2 (0) 3 (1) 4 (4) 5 (9) N/A (0) 4.57
Small footprint 1 (3) 2 (2) 3 (4) 4 (3) 5 (2) N/A (0) 2.93
Safety 1 (0) 2 (1) 3 (3) 4 (4) 5 (6) N/A (0) 4.07
Ease of maintenance 1 (1) 2 (0) 3 (4) 4 (7) 5 (2) N/A (0) 3.64
How satisfied are you with the current home gyms or inversion tables currently on the market?
Please circle the appropriate answer. 1 = very unsatisfied 5 = very satisfied
Avg. Price 1 (0) 2 (5) 3 (5) 4 (4) 5 (1) N/A (3) 2.73
Capacity for varied user height/weight 1 (1) 2 (1) 3 (7) 4 (2) 5 (2) N/A (1) 3.23
Ease of operation 1 (1) 2 (1) 3 (3) 4 (7) 5 (0) N/A (1) 3.46
Ease of assembly 1 (1) 2 (4) 3 (2) 4 (2) 5 (0) N/A (4) 2.80
Quiet operation 1 (0) 2 (1) 3 (5) 4 (4) 5 (3) N/A (1) 3.69
Comfort 1 (1) 2 (0) 3 (6) 4 (5) 5 (1) N/A (1) 3.38
Stability 1 (0) 2 (0) 3 (3) 4 (7) 5 (3) N/A (1) 4.00
Small footprint 1 (0) 2 (3) 3 (4) 4 (5) 5 (0) N/A (2) 3.17
Safety 1 (1) 2 (0) 3 (3) 4 (6) 5 (3) N/A (1) 3.77
Ease of maintenance 1 (0) 2 (4) 3 (3) 4 (6) 5 (0) N/A (1) 3.15
Appendix C1
APPENDIX C – QUALITY FUNCTION DEPLOYMENT ANALYSIS
Handle
s
Ankle
support
s
Rolle
r B
earings
Sta
ndard
hard
ware
Fold
able
fra
me
Coate
d o
r sta
inle
ss s
teel
Rubber
corn
ers
and f
eet
Sym
metr
ical D
esig
n
Back r
est
Sta
ndard
tools
used f
or
assem
bly
Custo
mer
import
ance
Desig
ner's M
ultip
lier
Curr
ent
Satisfa
ction
Pla
nned S
atisfa
ction
Impro
vem
ent
ratio
Modifie
d I
mport
ance
Rela
tive w
eig
ht
Rela
tive w
eig
ht
%
Price 1 3 1 9 3 9 1 1 1 4.14 1.10 2.73 3.50 1.28 5.84 0.13 13%
Capacity for varied height/weight 9 3.71 1.00 3.23 3.50 1.08 4.02 0.09 9%
Ease of Operation 9 1 1 4.36 1.10 3.46 4.00 1.16 5.54 0.13 13%
Ease of assembly 1 9 3 9 3.43 1.00 2.80 3.00 1.07 3.68 0.08 8%
Quiet operation 9 9 2.92 1.00 3.69 4.00 1.08 3.17 0.07 7%
Comfort 9 1 9 3.43 1.10 3.38 3.50 1.04 3.91 0.09 9%
Stability 1 3 9 4.57 1.10 4.00 4.00 1.00 5.03 0.11 11%
Small footprint 9 2.92 1.00 3.17 4.00 1.26 3.68 0.08 8%
Safety 3 9 9 3 4.10 1.00 3.77 4.50 1.19 4.89 0.11 11%
Ease of Maintenance 3 1 9 9 3.64 1.00 3.15 3.50 1.11 4.04 0.09 9%
Abs. importance 1.69 3.16 1.28 2.05 1.52 2.38 1.79 1.03 1.27 1.72 17.9 43.8 1.00 1.00
Rel. importance 0.09 0.18 0.07 0.11 0.09 0.13 0.10 0.06 0.07 0.10 1.0
Aaron Crum Home Gym with Inversion Table
9 = Strong
3 = Moderate 1 = Weak
Appendix D1
APPENDIX D – PRODUCT OBJECT IVES Based on the research, the product objectives are the list of features that are taken into
consideration. The following is a list of product objectives and how they will be obtained or
measured to ensure that the goal of the project was met.
11. Cost (13%)
a. Prototype under $500
12. Ease of operation (13%)
a. Adjustment between exercises requires ≤ 3 steps
b. Adjusts from workout station to inversion table in ≤ 3 steps
c. Mechanisms to help with inversion
d. Inversion table can be locked in all angles from horizontal to vertical with one
hand
e. Allows user ability to work out all muscle groups without reconfiguration
13. Stability (11%)
a. Symmetrical design
b. Consistent loading conditions and design for CG at or below comparable
machines
c. Frame to be welded instead of fastened
14. Safety (11%)
a. All corners covered with rubber bumpers
b. Ankle supports to lock to prevent falling
c. No pinch points
d. Safety bars on side of machine
15. Capacity for varied user height/weight (9%)
a. Adjustable positioning for heights between 5’0” – 6’6”
b. Includes ankle supports for range of human ankles
c. Material and design will be sized and selected based on a 3.0 safety factor
16. Ease of maintenance (9%)
a. All steels are stainless or coated to prevent rust
b. All bearings are sealed requiring no lubrication
17. Comfort (9%)
a. Back rest is typical weight bench padding
b. Ankle supports are adjustable and padded comparable to Teeter brand
c. Handle grips will be ergonomic
Appendix D2
18. Ease of assembly (8%)
a. Uses standard hardware
b. Uses standard tools for assembly and teardown
c. Unit has ≤ 10 parts that need assembling
19. Small footprint (8%)
a. Product to take up no more than 6’x4’ floor space
b. Foldable frame to take up no more than 3’x4’ floor space
20. Quiet operation (7%)
a. Contains roller bearings for smooth movements
b. Uses rubber feet to prevent floor noise and vibration
Appendix E1
APPENDIX E – SCHEDULE
TASKS Oct
14
-20
Oct
21
-27
Oct
28
- N
ov
3
No
v 4
- 1
0
No
v 1
1 -
17
No
v 1
8 -
24
No
v 2
5 -
Dec
1
Dec
2 -
8
Dec
9 -
15
Dec
16
- 2
2
Dec
23
- 2
9
Dec
30
- J
an 5
Jan
6 -
12
Jan
13
- 1
9
Jan
20
- 2
6
Jan
27
- F
eb 2
Feb
3 -
9
Feb
10
- 1
6
Feb
17
- 2
3
Feb
24
- M
ar 2
Mar
3 -
9
Mar
10
- 1
6
Mar
17
- 2
3
Mar
24
- 3
0
Mar
31
- A
pr
6
Ap
r 7
- 1
3
Ap
r 1
4 -
20
Ap
r 2
1 -
27
Proof of Design to advisor 18
First Report 29
Full Senior Design Report 13
Concept sketches to advisor 1
3D Model - (Frame sub-assembly) 8
3D Model - (Rolling backrest sub-assembly) 15
3D Model - Full system assembled 6
System Analysis Calculations 6
Order Components 13
Bill of Materials 13
Oral Report to Faculty 17
Frabricate frame assembly 7
Fabriate rolling backrest assembly 28
Full Assembly and Testing 14
Modification and Tweaking 28
Customer Testing 4
Oral Report to Faculty 11
Project Final Report 18
Aaron Crum Home Gym with Inversion Table
Appendix G1
APPENDIX F – BUDGET
Frame
40’ Tube steel ($2/ft.) $80
10’ Channel steel ($2.1/ft.) $21
Rolling Backrest
Bearings $13
Wheels $19
Sheet of plywood $11
Shoulder bolts ($2.5/ea.) $10
Vinyl sheeting ($11/yd^2) $22
Foam padding $25
Inversion Table Pivot Joint and Handles
Bar steel ($2.90/ft.) $3
Tube steel ($2/ft.) $8
Resistance System
Handles $13
Resistance band set $20
Pulleys ($11/ea.) $22
Steel cable ($1/ft.) $10
Subtotal $277
20% Miscellaneous expenses $55
Total $333