Pack Pitch



The Curveballinator

Overview|Concept Overview|Proof of Concept|Design Overview|Fabrication|Results|Acknowledgements|Trailer



Pack Pitch understands there is a need for a cost effective, portable pitching machine that can simulate different styles of pitches to help train young baseball players. Our team conducted research through surveys, and results show that parents would like to help their children with hitting varying types of pitches, while still at a young age. Pack pitch has designed the Curveballinator to be able to simulate pitches such as fastballs, curveballs, and sliders. One of the biggest needs Pack Pitch has to satisfy for the product is to have a small operational footprint in order to be used comfortably in areas such as a backyard or indoor gym. The Curveballinator will also be designed to achieve a fast assembly and disassembly time in order to remain highly portable!


Concept Overview

Pack Pitch’s design for the Curveballinator is a simple, yet effective design that can simulate pitch types for younger children such as curveballs, sliders, and fastballs. This design incorporates a square frame with elastic bands attached to each corner of the frame. There will be a total of five bands that will be attached to the back of the ball. As mentioned before, four of the bands will be attached to the corners of the frame, but the fifth band will be connected to a pulley system in the back which will be able to reel the ball back. This pulley system will create tension in the bands, and when the ball is released this tension will cause the ball to shoot toward the pitcher. In order to simulate a curve ball or slider, different levels of tension can be set in each band, which will give direction to the ball during flight. To give a better understanding of what this design will look like, here is a model created in SolidWorks.

 15_12_SolidWorks 15_12_SolidWorks2


Proof of Concept

Pack Pitch fabricated the SolidWorks model for the proof of concept and all of the material for the construction process was bought at Home Depot. The model was built out of 2”x4” pieces of wood that were cut down to the correct dimensions. Three-inch wood screws were used to hold the pieces of wood together. Bungee chords were connected to the frame and the ball with the use of eyehooks. Pack Pitch’s goal was to manually pull the ball back and release to see if the ball would travel in a straight line fast enough for a batter to hit the ball. Our next step was to tighten the bottom bungee chords using zip ties, which would create more tension on the bottom of the ball, causing it to curve downward during flight ultimately simulating a curve ball. Our tests proved that this design works as intended. Our proof of concept showed us that a fastball, curveball, and slider could be simulated with the Curveballinator!

The following picture shows the proof of concept during testing. Currently the reeling system will need the most improvement


Our proof of concept built out of wood.



Design Overview

The Curveballinator is a lightweight, low cost, portable pitching machine. This design is intended to be used by children between 10 and 14 years of age. The Curveballinator will be able to throw four pitches, a curveball, fastball, change-up, and slider at three different speeds. One ball will be attached to four bands and will be repeatedly launched through a frame using motors on the corners of the frame to adjust tension in the bands for movement and speed.


A simulated assembly of the Curveballinator which has four elastic bands attached to a ball that has an autonomous reeling and band adjustment system.


The frame will also fold up to allow for easy carry at a weight of less than 40 lbs. and a storage volume of less than 6 ft3. The operational footprint only takes up 50 ft2 and only uses one ball to reduce reload time. The device uses a reeling system in order to allow for an autonomous quick reload. The autonomy of the system will be completely controlled by an Arduino Uno processor. A Bluetooth device was added to the Arduino for the capability of a remote being able to control the number of pitches thrown in one session and what types of pitches will be thrown. The sensitive parts of the Curveballinator are protected by metal plates that do not interfere with any aspect of the device.


The current design of our prototype.

Here is a video of early testing for the prototype



The frame of the curveballinator is fabricated from 80/20 aluminum that was cut to specified dimensions. All of the members of the frame were fastened together with the use of blots and t-nuts. The front and back arms of the frame are fully collapsible as intended for easy storage and set up times. The majority of machining was done at the University of Nevada, Reno machine shop in the Palmer Engineering building.

Front of the frame

First, it was determined through calculations that the bottom two bands were unnecessary to achieve the types of pitches desired so we decided to eliminate those bands. Next we constructed steel brackets that would support the spooling motors as well as the spools that were located in the front of the frame. After this was done, a set of steel brackets were constructed to protect both the spools and motors from being struck by the ball and potentially damaged. Here is an image of the spools and motors encased in the steel brackets. The following images show the spool within the protective casing and the rotary encoder attached to the left side of the spool.

Optimized-15_12_Spool  15_12_EncasedSpool  Optimized-15_12_Espool



The brackets ended up adding a significant amount of weight to the top of the aluminum arms which resulted in the arm tending to bend backward when the ball was pulled back to is starting position. In order to prevent this from happening, we moved the spools and motors to the bottom of the arms and ran the bands through eye hooks at the top of the frame. By doing this, all of the weight from the brackets was now shifted to the bottom which lessened the amount of force that was generated at the top of the aluminum arms when the ball was pulled back.

In order for our motors to work properly, we had to attach rotary encoders onto the spools in order to measure how many revolutions it would take to create the proper tension in the bands to achieve fast balls, curve balls and sliders. So a metal rod was fabricated, attached to the motor, inserted through the spool and the rotary encoder was attached at the other end.


Frontal view showing the spools at the bottom of the frame.


The bands were run through the ball and onto each of the spooling mechanisms. They are secured in place by clamping 5 mm hog rings onto each of the bands. The bands run through a small metal tube within the ball to ensure that they do not start tearing through the outer edges of the ball. Mason twine is also run through the back of the ball through a thin metal tube and attached to our reeling mechanism at the back of the frame.


Ball attached to bands and pulled back to its starting position.


During testing we found that the ball would wrap around the front arms multiple times so to prevent this from happening, we created nets that extended outward from the sides and top of the frame by 1 foot. The netting was hand woven to ensure that our ball couldn’t break through the holes and that the material was strong enough to withstand the force of the ball after its been hit by the batter. The netting is also attached to steel bars that can be slid on or off the frame and locked into place when in use.


This shows the netting around the frame to prevent the ball from wrapping around the poles.


 Back of the frame

A fishing reel was used as our reeling mechanism due to its ability to quick release a line that is attached to it. Steel brackets were fabricated to mount the fishing reel to the frame. Another small bracket was created to attach the motor to the fishing reel to wind the ball back to its starting position for release. In order to get the quick release switch to flip, a steel arm was mounted to a low RPM motor that could push the switch up to release the line from a locked position.  Once all of these components were mounted and working properly, a large steel plate was machined to attach to the frame and cover all of these components so that the ball could not damage them during use.


This picture shows the fishing reel attached to both DC motors.


The reeling mechanism behind protective casing.


Arduino and Wiring

All of the motors and rotary encoders are connected to an arduino that is mounted in the back of the frame behind the protective covering for the reeling system. A motor shield was connected to the arduino so that the speed of each motor could be individually controlled. All of the wires used are 18 gauge and were soldered to the motors. The wires were then run through the 80/20 aluminum to ensure that no one could potentially trip over or sever them in any way. Programs were created for the arduino to replicate the types of desired pitches and an IR receiver is placed at the front of the frame, encased in one of the spools enclosures, so that the batter can use a remote control and choose what type of pitch they want.


Arduino with motor shield equipped.



Overall Design

This is an overall view of the finished design. All brackets were painted black.




After fabrication of our prototype was complete, we had to perform multiple tests. This includes checking that:

• All wires are connected and that each motor could turn individually.

• The Arduino is programmed properly with multiple pitch types.

• The IR receiver could pick up the signal from the remote when the user selects the pitch type.

• Reeling system can release upon press of “play” button on the remote.

• Ball can easily be reset.

During testing, we found out that the ball and bands were actually getting more tangled in the protective side netting than preventing tangling as intended so we decided to remove the netting. Also, after the ball was released, the line attached to the back of the ball was becoming too tangled for the fishing reel to reel back to the starting position. The first attempt at fixing this issue was to add fishing swivels to the line to help it untangle as it was reeled back however, the swivels could not handle the force of the ball and would break under too much tension. Next we tried to use mason twine for the reeling line but it was also tangling too much to be reeled back by the fishing reel. Ultimately we had to get rid of the fishing reel and replace it with a small steel arm attached to a 5 RPM DC motor. The line on the back of the ball was then cut shorter and a loop was added to the end of it. By doing this, we were able to pull the ball back to its starting position and hook the line over the small steel arm that would initially start in a downward facing position. When the “play” button was pressed, the small arm would move in an upward direction and the line would unhook itself from the arm, releasing the ball toward the batter. All of the other features were working as intended and were tested multiple times to ensure that our prototype was performing consistently and reliably.


This is a picture behind the protective back plate with the string from the back of the ball attached to the release arm.

Here is a video of the arm releasing the string attached to the back of the ball.

Innovation Day

During testing the night before innovation day, one of the rotary encoders on the spools broke. Unfortunately our entire arduino program was based on the encoders reading the rotations and angle of the spools in order to set each individual pitch type, this resulted in our entire code having to be reworked and based off timing of the spools rotating rather than being able to read the rotations. While setting up, before innovation day started, a laptop was used to update and check that the all of the codes were working properly. After doing so, we were having trouble with the IR receiver picking up the signal from the remote control. After reviewing the code and not having success at finding the issue, we called our electrical specialist (Luke Fraser) and he informed us that we needed to make sure that the arduino was  receiving the correct values from the remote control. It turns out that the laptop being used had an updated library for arduino and that our code was unknowingly updated and our IR receiver was reading different values for the remote than what was previously used. After fine tuning new values for the buttons on the remote controller, everything was working properly again and the Curveballinator was able to be used by guests attending innovation day! We provided baseball bats and a helmet for safety.

These pictures show our user setting up for the pitch and then making contact with the ball after its released!

15_12_Set-up  15_12_Hit-ball



Pack Pitch would first like to thank the University of Nevada, Reno for providing the funds to be able to bring this project to completion. Doctor Emil Geiger for his efforts in teaching and organizing the class. Tony Berendsen for sharing his machining knowledge with the group. Doctor Eric Wang for advice and allowing the group to work in his lab. Andy Smith for design and programming advice. Jacob Wik for providing SolidWorks help. Mossberg Industries, for donating the spools used in our final prototype. Luke Fraser, for helping us debug our arduino code. Finally, our mentor Dr. Matteo Aureli, for giving us advice throughout the entirety of the senior design class.



Meet the Team

James McChesney

James McChesney

James is studying mechanical engineering with a minor in mathematics at the University of Nevada, Reno and will graduate in May 2015. He currently works at the Hamilton Company as a research and development engineering intern where he has been for the past year and a half. Through this experience James has learned a great deal about designing parts, products, and tools as well as developing skills involving project management, teamwork, and document control. He also possesses automotive knowledge and enjoys working on cars and trucks in his free time.


James Majdanac

James is a senior mechanical engineering student at the University of Nevada, Reno. He enjoys working on computer aided models with the use of SolidWorks. He has worked at Costco Wholesale for four years, which has given him an understanding in time management and teamwork.  He also enjoys playing video games, watching movies, hiking, snowboarding and other outdoor activities!

Gregg Rosenberg


Gregg is a senior mechanical engineering student at the University of Nevada, Reno. He is currently a logistics and industrial engineering intern for Randa Accessories. He has received his competent communicator award for Toastmasters International. He also has leadership experience by being the treasurer and risk manager of the Alpha Epsilon Pi fraternity at the University of Nevada, Reno. He is proficient in many computer programs including Microsoft Office Suite, Autodesk Inventor, Autodesk Revit, AutoCAD, Solidworks, LabView, and Matlab. He has many years of experience in baseball from playing in Little League for 12 years and then umpiring for 4 years. Gregg is a hard worker with a lot of aspiration and drive to accomplish what he needs with the highest quality in mind.


Christopher Mack


Christopher Mack is an undergraduate Mechanical Engineer at the University of Nevada Reno. He is currently in his senior year and plans to graduate in the Fall of 2015 with a minor in electrical engineering and mathematics. Since 2011 he has been employed by the Desert Research Institute where he has developed his interests in areas of Renewable Energy and Controls. Working at DRI has given Christopher unprecedented experience in research topics ranging from solar energy to water resource management, all utilizing his skills in automation and data acquisition. As a student, Christopher has achieved academic success in the STEM related courses where he boasts a 3.8 GPA. Christopher has been a resident of Nevada since December 2000. He currently lives in Sparks where he is happily married. Christopher is also the proud parent of a daughter who is in kindergarten. In his free time, Christopher enjoys spending time with his family, volunteering in his daughter’s class, and just being a Father. If you wish to contact Christopher he is happy to talk to you. He can be reached by phone: (775) 303-8807 or by email:


George Kehagias


George is a senior in the Mechanical Engineering department at the University of Nevada, Reno. He has worked in a research laboratory for Dr. Eric Wang for three years. This experience has helped him learn how to manage projects well and what is expected of research projects similar to the capstone project. He has also been a teaching assistant for ENGR 100 for three semesters and has learned how functional teams behave through observation of the ENGR 100 students.

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