Home gym with inversion table - UC DRC Home

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

Home Gym with Inversion Table Aaron Crum

1

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.


2

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


3

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


4

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


5

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.


6

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.


7

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


8

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


9

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


10

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


11

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


12

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


13

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.


14

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


15

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


16

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


17

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


18

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


19

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


20

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.


21

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.


22

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


23

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


24

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


25

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


26

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


27

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


28

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


29

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


30

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


31

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.


32

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.


33

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

http://www.bowflexhomegyms.com/bowflex_home_gyms_us/products/xtreme2se/prdcdovr~100070/Bowflex+Xtreme+2+SE+Home+Gym.jsp






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

http://www.totalgymdirect.com/total-gym-xls.php



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

http://www.teeter-inversion.com/Store/P-FS1002/Fitspine+Trainer+Inversiontable




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

http://www.overstock.com/Sports-Toys/Ironman-LXT850-Locking-Inversion-System/3987541/product.html






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

Appendix G1

APPENDIX G – SHOP DRAWINGS

Appendix G1

Appendix G1

Appendix G1

Appendix G1

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