Sylphyo Bell Port Plug

thingiverse

A small plug for the "Bell Port" at the foot end of the **Sylphyo electronic wind instrument**. The Sylphyo is designed and produced by **Aodyo Instruments** in France. The plug can be directly inserted into the small Bell Port at the foot end of the instrument and reduces the breath pressure and airflow requirements by about half. This plug is intended to be inserted into the bell port with the three tabs holding it in place. The flared foot end with four sharp nubs is designed to make it easy to remove with your fingers. The design also includes a number of bevels in the internal airway channel to reduce the wind noise produced when breathing through the Sylphyo with this plug inserted. Sanding the internal airway channel with a cylindrical needle file can further reduce the wind noise (somewhat). This part was originally posted on 19-Feb-2021. **Version 2** was posted on 7-Mar-2021 and includes numerous improvements in fit and reliability. It also accommodates different Inside Diameter (ID) values. Three ID sizes are provided - 4.0mm, 3.6mm, and 3.2mm - resulting in progressively less airflow requirements when playing the Sylphyo. **Please see the Post-Printing section regarding sanding requirements *before* inserting this part into your Sylphyo!** In the photos, I have printed the black at 4.0mm, the brown at 3.6mm, and the red at 3.2mm. Airflow ===== The 4.0mm ID version reduces the amount of air needed to produce any given pressure by about half (I've tested this with an intra-oral breath pressure meter). Pressure in the Sylphyo usually translates to volume, so you can play as loud with half the air. If you want to use more air, that's a challenge, because the inside diameter would need to be larger, and that would weaken the tabs at the top. If you want to use even less air, the 3.6mm and 3.2mm versions are provided. If you use OpenSCAD, the model could be adjusted further refine the diameter of the internal air channel for your needs. Caution, because small changes in diameter produce big changes in airflow! Print Settings ========== The dimensions of your printed plugs is critical. PLA has an inherent shrinkage factor, and that varies depending the type of PLA you use and all the other many things that go into 3D printing. You may need to adjust your slicer to (every so slightly) enlarge or shrink the part. Z-axis dimensions are not critical, but XY-axis dimensions are ultra-critical. My best prints - and I am primarily looking at the sturdiness of the tabs at the top of the part - are with print temps at the top of the PLA range - 212C in my case - about 10-15 hotter than I normally print PLA, with reduced fan setting (I use 40%), and I print these slower - about 75% of the overall speed I normally print PLA. I use a 0.1mm layer height with 100% infill and print concentric circles with random start points. The prints at the hotter temps tend to produce more random nubs and ridges - protrusion sticking out of the tabs at the top of the printed plug. However, this probably increases inter-layer adhesion. Post-Processing ============= First test the newly printed part (after it has cooled!) with your fingers. Press on the top of each tab with your fingernail - firmly but not excessively. Discard the part if it cracks. Now - if you insert the plug at this point, it will likely crack **and possibly damage your Sylphyo!** This is because of the small protrusions on the outside of the tabs. (In reality, I have cracked a number of these printed plugs when inserted into my Sylphyo, and I have done no visible damage to my instrument ... however ... caution is still warranted). This part **must** be sanded to: (a) remove the protrusions on the outside of the tube and the tabs. If you insert a newly printed part into the bell port, it will likely crack because of these protrusions. (b) to knock down the ridges on the inside air channel. This smooths out the airflow and reduces wind noise a bit, without affecting back pressure very much. I use needle files - a flat one and a cylindrical one (slightly conical, actually). I roll the part in my fingers while filing the inside with the cylindrical file. Be sure to get the angled flare at the bottom end. You can feel the initial resistance to the file from the ridges. Notice how, after a dozen light strokes you can feel that resistance fade ... you've knocked down the ridges. I then roll the part while it is on the cylindrical file and I file down the outside of the tabs and tube the using the flat file. Check for visible protrusions on the tabs with a magnifying glass. Sand more, if needed - not to change the dimensions, but to smooth things out. Carefully insert your plug into the Bell Port of the Sylphyo. **Do not force it** (although I have used a fair amount of force initially, and never had a problem with the Sylphyo). My guideline now is that I should be able to insert the plug with my pinky fairly comfortably. The plug should sit all the way in the bell port. The "step down" collar should be snug against the bell port. It should not wiggle (much) side to side (you can test this very gently). My experience is that, even with fairly light insertion pressures, the plug has *never* "flown out" of my Sylphyo, regardless of how much breath pressure I use. If you hear a "TIC" - even a light one - at any time when you insert the plug, one of the tabs has likely broken. Test it (fingernail pushing on the tabs) and discard. Update March 19, 2021 ======= I uploaded STL files for three additional plugs that are even more restrictive. See Also ======= See https://www.prusaprinters.org/prints/52163-sylphyo-plug for an alternate design, which partially inspired this design. See https://community.aodyo.com/topic/544/blocking-the-bell-port for a related discussion.