IN THE SHOP: 3D Printing Replacement Trapwork Elbows for Vintage Pianos

If you’ve ever worked on vintage pianos—such as 40- to 50-year-old models from Kawai or Yamaha—you’ve likely encountered a frustrating problem: broken plastic trapwork elbows.

Because these original plastic components degrade over time, technicians and piano owners often find themselves searching for replacements, only to discover that the original parts are completely obsolete and unavailable.

In our latest shop update, we tackle this exact problem by custom-designing and 3D printing high-durability replacement elbows. Here is a look behind the scenes at how we bring these obsolete parts back to life.

The Problem: Aging Plastic & Unobtainable Parts

Recently, several fellow piano technicians brought in broken trapwork elbows from different pianos. While the breaks occurred in different places on each piece, the key dimensions and mounting hole alignments were identical.

When original manufacturers no longer produce replacement parts for vintage instruments, piano owners are often left stuck. Thankfully, modern 3D modeling and printing technologies give us a way to fabricate exact, high-strength replacements right in our shop.

Step-by-Step: Modeling in Fusion 360

Re-creating a precision piano part starts with accurate measurements using digital calipers, followed by modeling in CAD (Computer-Aided Design) software like Fusion 360:

Mapping the Critical Hole Locations:

Precision is everything. The mounting holes were measured at 0.175" (175 thousandths).

Constraining these holes to equal dimensions and fixing the exact distance between them ensures the new part installs seamlessly into the trapwork mechanism.

Building the Outer Structure:

Outer cylindrical boundaries around the holes were set to 0.390" with connecting wall thicknesses defined at 0.155".

Tangent constraints were added to keep the geometric transitions smooth and strong.

Extruding 3D Geometry:

Using symmetric extrusions from the center sketch plane, the outer rim thickness was set to 0.372".

The center boss section, which extends slightly wider, was extruded to 0.571", with connecting web sections defined at 0.142".

Finishing Touches:

Applying a 0.050" fillet along sharp edges smooths out stress points and gives the final model a clean, professional finish.

3D Printing & Final Result

Once the 3D model was complete, we sent it off to the printer to produce a full batch of replacement elbows.

Why 3D Printed Replacements Beat the Originals:

• Superior Durability: Modern 3D printing polymers are significantly tougher and far less prone to brittle fractures than the 40- to 50-year-old plastics used in the originals.
• Cost-Effective Availability: Instead of searching for rare legacy parts or custom-machining expensive alternatives, 3D printing allows for fast, batch-manufactured components.

Need Replacement Elbows for Your Piano?

Whether you're a fellow piano technician working on a client's instrument or a piano owner trying to restore a classic upright or grand, don't let broken plastic trapwork stall your restoration.

Feel free to reach out to Brigham Larson Pianos if you need a batch of these replacement elbows for your project!