This is the second iteration of a compact and easy-to-print whistle that can also be batch printed due to being printed on its side. This takes less time to print and less filament than my first iteration, but you might like that style more.

The reason for this second design is faster production and a more shrill tone. The need for whistles around Chicago was outpacing my ability to print V1s.

This is pretty loud at around 100db, and shrill due to each chamber being slightly different volumes, creating warbles that are attention-grabbing. Chamber frequencies are around 2850hz and 2800hz. It is still compatible with keychains.

These take about 3.6g-3.9g of filament, and they take around 5-7 minutes to print, depending on your printer.

There is also a Whistle Holder Jig to hold 10 whistles at a time for post-processing

My observed printing times

• Voron 2.4: 6 minutes
• Annex K3: 4 minutes
• Bambu X1-C: 15 minutes, but I've printed it at 166% speed and they came out fine -- The first iteration is faster to print on an X1-C

Printing I've been able to print this successfully with a 0.25mm layer height with some filaments (LDO ABS, Fusion FIlaments ABS 1.5), but I would recommend starting with 0.2mm. With “Whistle V2 v23 - Overpressure Release” I've been able to print with adaptive layer heights up to 0.3mm.

I've only ever printed this out of ABS or ASA, but assume PLA would be fine.

Biggest Tip for a Successful Print - A Fully-Solid Chamber Separating Wall

This took me a while to finally figure out, but has massively reduced my random failures. I ended up figuring it out by popping off the left side of a whistle who's right-hand chamber (the chamber with the over-pressure release hole) was non-functional or barely functional. I then put some super glue on the separating wall, let it dry, and tested again. Out of 10 whistles I tried this on, all 10 went from barely functioning to fully functioning.

Issue

If the separating wall between 2 chambers isn't fully solid, even by just a bit, air will move between the 2 chambers. This majorly messes with the whistle.

Symptoms

• Left-hand chamber consistently works, but the right-hand chamber sometimes works
• Right-hand chamber is quick to cut out
• Right-hand chamber only works when blocking the left-hand chamber output

Fix

• "Bridge Flow Ratio" (under "Quality") -- Increase to 1.01 - 1.02 --This over-extrudes the bridge intentionally -- I have not seen any negative affect on bumping it up to 1.02, so that's what I use
• "Extra bridge layers" -- Enable -- This adds another bridge layer rotated 90deg

Other Tips

• Print them on their side. Do not print them how slicer's orient them with “auto orient”
• You need to have pressure advance and flow tuned in.
• If printing in a material that shrinks (ABS, ASA, etc) you need to make sure your “Shrinkage (XY)” setting under your filament is set correctly. This messed me up when trying out a new filament brand and not noticing it as set to 100%. -- I've found 99.6%-99.8% to be good for multiple different ASA/ABS brands.

Print Settings

• layer height: 0.2mm
• walls: 3
• Infll: 30%
• Bridges -- Make sure the bridge orientation looks correct, you may need to adjust “external bridge infill direction” in OrcaSlicer

Happy printing and stay safe!