Same but different: say hello to the 3D printed trombone

It looks and sounds like a standard trombone - but is actually lightweight and made of carbon fiber rather than brass metal. To craft the musical instrument using this raw material, additive manufacturing is the right application for success: the process provides great options to manufacture the relevant molds used to build the instrument.

When Anna-Lena Rotter studied for her bachelor's degree in mechanical engineering, she searched for a bachelor thesis project and landed on trombone molds from the 3D printer. What started out as somewhat of a crazy idea turned into a very successful project. In this K-MAG interview, she talks about the challenges of the project and ventures a glimpse at how this type of manufacturing process might affect the field of music in the future.

Ms. Rotter, how did you come up with the idea of ​​creating the molds for a trombone using a 3D printer?

Anna-Lena Rotter: The idea of ​using a 3D printer to make the molds for a trombone happened by chance. At first, I merely had this crazy idea of making a trombone out of carbon fiber and explored possible processes and technologies to get there. I had an epiphany after reading how model makers use 3D printers in the hobby sector. Armed with basic knowledge of additive manufacturing thanks to my academic studies and the testimonials of the model makers, I decided to use a 3D printer to create the molds. To implement the trombone made of fiber-reinforced plastics, I believe additive manufacturing, and especially the fused layer manufacturing (FLM) process, provides great benefits: apart from favorable economic factors such as the acquisition, material, and production costs, the FLM process offers almost unlimited possibilities, allowing you to create intricate contours and multifunctional mold halves.

How did you get from your initial idea to the final form?

Rotter: It took a long process of development prior to the creation of the finished mold halves. The idea of making the parts of the trombone using additively manufactured molds proved more difficult than I expected. Stretched out, a trombone is made of an average tubing length of about 1.40 meters (55 inches). The dimensions make it impossible to produce the device with only one mold or two mold halves. That meant I had to split the trombone into several smaller segments to facilitate production from an additive manufacturing and carbon fiber technology perspective. After considering the requirements pertaining to the trombone and the individual mold halves, I used the SolidEdge Student Edition software to complete the structural design. At home, I made the first prototypes of the mold halves with an Ender 3 V2 3D printer and used them to create a carbon fiber component. After optimizing the mold halves and another carbon fiber component, I adopted the concept for the final mold halves and used them to produce the carbon fiber trombone.

How happy are you with the results in terms of the molds and the finished trombone?

Rotter: I have been and still am very surprised by the positive results. The idea of ​​using additive manufacturing to create the molds was priceless. The accuracies of the molds were within a small tolerance range. The resulting carbon fiber parts hardly needed any rework. Despite the bulky contours of the mold halves and the awkward build orientations, there was practically no disturbance during the manufacturing process of the finished molds. The molds were of high quality, which meant the surfaces only needed minimal rework.

All told, I am very pleased with the results, meaning the additively manufactured mold halves and the carbon fiber trombone, and thrilled about the success of the project.

What's next for you? Was this a one-time experiment or do you plan to continue making musical instruments via this method?

Rotter: This was definitely not a one-time experiment. There is still so much room for improvement and optimization when it comes to creating production-ready molds for carbon fiber instruments. Aside from the FLM process, there are other types of additive manufacturing processes and different methods for creating carbon fiber parts on the market we should further explore and establish. For me, additive manufacturing will be an important tool, especially as it pertains to ​​​prototypes and the first small series production of musical instruments made of fiber-reinforced plastics. In the long run, molds made of aluminum or other materials are also an option to produce large series parts.

What is your prediction for the future of 3D printing?

Rotter: Additive manufacturing will continue to be an integral part when it comes to creating carbon fiber instruments. From an economic, manufacturing and time perspective, the process offers many benefits as it pertains to prototype, small series and first model production, ensuring it will play an important role in the future development process.