3D Printed Valve "Felts"
Perfect valve alignment and extended life over felt/cork
I recently began experimenting with 3D printing valve cap and valve stem felts after having difficulty finding the right size for an older trumpet I was working on for a client. After much experimentation with different 3D printing filaments, I've settled on a softer plastic material that produces great results.
In case you don't know, these felts server two purposes. The first, and most important purpose, is that they are used to ensure the valve ports line up correctly with the tubes in each valve -- even a few millimeters too high or low will cause airflow issues which will affect the instrument's sound and play-ability. The second purpose is that they help dampen the sound of the valves by acting like shock absorbers on the up and down-stroke of the piston in the valve casing.
The pistons/valves have felt in 2 places. The felt on the top of the valve cap (below the finger button) is called the top cap felt, and it is used to control how far down you can press the valve. The felt on the valve stem is only seen when you unscrew the top cap, and it is, unsurprisingly, called the valve stem felt. It's used to control how high the piston goes when it is not pressed down. Using the correct size felts is very important to ensure proper valve alignment. Each trumpet manufacturer (and often each model) uses slightly different size felts on their instruments. This makes life complicated for a repair technician because finding the exact felt is sometimes difficult, and you have to keep all possible sizes in stock, even though some of them are very rarely used, and hope something will work correctly.
Over time the felts will naturally compress and affect valve alignment. Also, the valve stem felts on the inside often get filthy with valve oils and all the other pleasant stuff (spit) inside the valve casing. This why I always replace the felts whenever I clean a trumpet, and one of the many reasons I recommend you have a deep cleaning performed yearly.
But what if we can remove the need to replace them very frequently? And eliminate the problem of finding the exact right size? This is where the 3D printed versions save the day. They can be custom printed for each horn after measuring the required size. These 3D version won't compress and wear out like the felt does. And the softer, more flexible printing material makes the valves quiet (very similar to the felt) and provides a snappier response. And they can be printed in a variety of colors to customize your horn's look!
If this is a service that you are interested in, please reach out and let's chat.
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