Marching Band Triangles

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Team photo.2.jpg

Sponsors Mechanical Engineering Department

Lionel Hampton School of Music

Team Name Pressure Angles
Faculty Advisers Dr. Steven Beyerlein

Dr. Matthew Swenson

Dr. Robert Rinker

Dr. Edwin Odom

Graduate Student Adviser Selso Gallegos
Client Spencer Martin
Duration Summer 2019
  • Faris Alamri
  • Abdullah Bahattab
  • Brock Baughman
  • Bryce Dinger

The University of Idaho Marching Band will have a new addition to their halftime performances from this point forward, musical triangles. The Mechanical Engineering Capstone group, Pressure Angles has designed and manufactured musical triangles for each band member which feature flashing lights coming from our thoughtfully designed handle that will light up upon being struck. This project incorporates the design, manufacturing, and fabrication of: jigs, musical triangles, chimes, handles with internal circuitry and LEDs, and a sling allowing each band member to keep this rhythmic surprise hidden until they are ready light up the stadium.

Problem Definition[edit]


The Marching Band has been featured with many capstone projects like the Bandbeesten for many years. But this year, 2019 the Marching Band director Spencer Martin had the idea of bringing the musical triangle back to life. Musical triangles aren't new to the marching band, but their high cost made it difficult to justify implementing them with each member of the band.

The triangles were decided to be made out of constructional rebar to cut cost without sacrificing sound. Mr. Martin wanted the triangles to have some flair so he envisioned a triangle that would have lights that would flash upon hitting the triangle with the chime. To house the electronics and protect them Pressure Angles decided to design a handle for the triangles that would incorporate an ergonomic fit, all of the necessary electronics. Working with Dr. Robert Rinker, Associate Professor and Associate Chair of the Computer Science Department we were able to receive guidance with prototyping the electrical components that go into creating this light emitting response.

With the help and guidance of Dr. Matthew Swenson, Dr. Edwin Odom, Dr. Steven Beyerlein, and Graduate Student Selso Gallegos we were able to develop the handle design to meet all criteria Spencer had in mind while remaining sleek and robust. With the help of the advisers above and machine shop manager Bill Magnie our team was able to developer a jig to create consistently sized triangles to make sure each sounded the same.


The Band Department, led by Spencer Martin, asked the Mechanical Engineering Department to create musical triangles for each band member. The triangles themselves are made out of rebar, and will be held with our custom handles specially designed to house a battery, LEDs, and a sensor that can pick up vibration from contact with the chime to signal the lights to turn on. It is important that each band member can remove and stow the triangle and its components swiftly during performances.


By the end of the project Pressure Angles will have designed, manufactured, and fabricated 150 triangle packages. Each package consists of a triangle, handle with functioning electronics, chime, and a holster for everything to fit in.

Design Considerations[edit]

Goals Requirements for Handle
  • Test jury, Spencer Martin, must approve final handle design fit and ergonomics to ensure it is comfortable and fit any size of hand
  • Spencer must also approve the overall look of handle as some Triangle packages will be given as gifts at performances
  • Handles must have logos for the College of Engineering and Lionel Hampton School of Music
  • Durability
  • Electronics must be housed internally and must have redundancy to keep in place
  • Triangle to handle connector must also be redundant and have at least two means of connection
  • LEDs must be protected from wear and tear of band equipment
  • Electronics
  • Piezo sensor must be removable from triangle
  • System must have battery switch operated by user before and after use
  • LEDs must be visible from stands when in use
  • Batteries must be rechargeable
  • Goals Requirements for Triangles
  • Rebar will be cut to the same length for each triangle
  • Using a jig in manufacturing, angles of triangle must be consistently 120°
  • Hard edges will be ground down as needed
  • Orientation
  • handle orientation must be 90° off of the orientation from the triangle
  • Smooth side of rebar must be vertical to optimize play
  • Goals Requirements for Stowable Triangle Pouch
  • Pouch must match well with Marching Band outfits
  • Must be sleek and not be an eye sore for audience
  • Function
  • Pouch must be easy to access triangles
  • Must not hinder performers in any way
  • Must hold entire triangle package
  • Must be robust and allow for simple maintenance
  • Project Learning[edit]

    Lights circuit and battery housing[edit]

    The requirements for the circuit housing are the lights must be visible to the audience, the circuit board and battery must be secure and protected from damage while still giving access to switch on circuit board, and provide enough space to house all electronics.

    Design one perpendicular design

    Perpendicular Design[edit]

    With this design the light could me mounted directly to the surface board making manufacturing easier and easier to install into the handle. The problems with this design are the storage when not in use and the manufacturability. The storage would have to be fragile because a twisting the part would cause it to break. this would be fixed by using thicker wood but this would rain the cost and lower the manufacturability even more. Using the laser cutter does make them easier to manufacture but this design uses a lot of material making it more expensive.

    compact housing design

    Compact Design[edit]

    Design 2 offers a design that is easier to store and make the handle easier to manufacture. The second design has the lights mounted around the otter rim in the form of light strips instead of surface mounted lights. This requires wires to be attached to the circuit board which makes manufacturing the circuitry more difficulty and time consuming. the problem of this is the design has gotten wider then wanted in order to house the components.

    Handel Grip[edit]

    Balancing Handel Grip

    Balancing Design[edit]

    Initial grip design for both options positioned the triangle in the incorrect angle so both designs we modified so the triangle would be perpendicular to the handle in order to face the audience. Design one is a simple designed for both right and left handed people to be able to silence the triangle as needed with being balanced on the thumb and index finger. This design can fit any finger size but can be easily dropped if not careful.

    pinch Handel Grip

    Pinch Design[edit]

    The second Design is similar to design one but instead offers more of a grip to hold onto. This design is more comfortable but does restrict people with bigger fingers. This grip offers more control when holding triangle but can interfere while playing. what worked with this design is it is very easy to hold onto which will help the band not drop it. What does not work is it takes more material and could make it hard to deaden the triangle.

    Sensor Connection[edit]

    The sensor needs to be attached to the triangle in a way that will not disrupt hot it is played. It is preferred to be able to be removable but it is not a requirement the current plan is to use a magnet to have a removable connection.

    Triangle Dimensions[edit]

    jig used to bend musical triangles

    The dimensions of the triangle are key to the sound the first diminutions used for the triangle were 7.35” sides this ended up being too large and hard to reproduce. So in order to make them repeatable the sides were down sized to 7.16”. This did not affect sound quality and made them easier to make. an important piece of this is to be able to manufacture the same triangle 150 times. To do this constant improvements are being made to the jig in order for it to be Consistent. we started with a simple just just to bend the rebar around this worked to make a contant length but the rebar would slide around. to fix this thumb screws were added to hold it in place. then stoppers where put into place to get the correct angle.

    Final Design[edit]


    Lights testing[edit]

    Team Members[edit]

    Photos Bio Discipline
    Faris head shot.jpg
    Faris Alamri: I am currently senior student in Mechanical Engineering at the University of Idaho, from Jeddah, Saudi Arabia, graduating in August 2019. My goal is to start my career in the Oil and Gas Industry. ME
    Abdullah Bahattab: I am graduating in Mechanical Engineering at the University of Idaho in August 2019. I am from Jeddah, Saudi Arabia, and I hope to return and start my career in Systems Design. ME
    Brock headshot.jpg
    Brock Baughman:I am currently a senior Mechanical Engineering student at the University of Idaho. I grew up in Coeur d'Alene, ID. After graduation I hope to start my career in research and development or design. ME
    Bryce head shot.jpg
    Bryce Dinger: I am graduating this August with a bachelors in Mechanical Engineering and Renewable Materials. I grew up near Seattle and when I am done with school I plan on moving back to the area to work in product design. ME & RM

    Additional Documentation[edit]

    Project Schedule


    Meeting Minutes



    Client Interview