[DIY] Fan Muffler & Poop Chute Baffle for Bambu P1/X1 - 3D Print

Got tired of the noise from the P1S's chamber fan. It exits the air at the back of the printer and ramps up to 70% speed when printing PLA. But for the little airflow this fan provides it is obnoxiously loud.

Replacing it with a properly engineered Noctua-like fan would have been sensible, but printing a muffler sounded more fun 😂  And while at it, why not also design a baffle to cut down the secondary noise sources from the poop chute and the electronics' vent opening ?

The parts above mount on the back panel thanks to magnets and can be easily installed or removed as needed. They cut down the noise by over 20dB across a large spectrum. Did not expect that, it makes an unbelievable difference !

STEP and F3D CAD files are on Github

Note that Bambu Lab specifically advices against such mods ! Because of back pressure on the fan, and as the filament can sometimes fail to form into a ball during a purge and instead create a long string that can get stuck.

The 1st concern is bogus, as long as the muffler does not impede flow. The 2nd is valid and requires monitoring purges in case of an unusual purge ball shape. Which I experienced a couple of times, when switching filament between PLA and ABS. But the chute was not at fault: the weird elongated ball was just dragged by the nozzle onto the bed.

In any case, probably not a good idea for multicolor prints that send handfuls of purge balls down the chute instead of purging everything into a purge tower. In that case, just temporarily remove the chute muffler.

For those brave enough to consider such illicit mods, happy printing !

Poop Chute Baffle & Bucket

The baffle also covers the vent opening that cools down the electronics cavity. Air in that area only moves via convection, so it was essential to leave an open vertical channel there.

The various ribs and inclined surfaces are supposed to diffuse and scatter the sound waves, but were just made up and probably don't do much for the frequency range of interest. But I had a lot of fun designing them ! 😅

A lip helps with positioning. Just butt it up against the top of the chute's opening and it'll self-center and provide the vertical clearance for the bucket underneath.

The parts were printed with PLA, 0.28mm layer height, 2 walls / top / bottom, 15% grid infill. Took ~300 grams of filament.

Four 12x3mm magnets are glued in and hold the thing against the printer.

So, how does it fare noise-wise ? Negligible benefits when printing PLA, where most of the noise comes from the chamber fan. However, when that fan is off, like with ASA or ABS that require a high chamber temp, most of the noise then comes from motion and toolhead sounds leaking out the back via the chute. They get perceptibly muffled with the baffle in place.

Note that this part is not compatible with the presence of a spool on the spool holder, as spools partially cover the chute and the adjacent vent openings. Although, since the baffle is simply held in place with magnets, it can easily be removed when needed.

Also, it is designed to not interfere with the AMS buffer. However, it is not compatible with the bigger AMS hub when using more than 1 AMS.

 

Fan Muffler

Took 9 hours to print this one. Had too much fun stuffing it with diffusers, walls and ribs 😂

A 3/16" wide 1/8" thick (~5x3mm) high density open cell foam weatherstrip was installed along the base of each wall to get a tight seal as the P1S's back panel is quite wavy, with ~2mm dips in some spots. Could clearly hear noise escaping from those. But it requires doubling up each 12x3mm magnet to compensate for the add'l thickness.

The thin foam strips were cut out of this larger 1" piece high density neoprene tape. Make sure to use either high density or closed cell foam. Many weatherstrips are made with thin and light foam that stops air leaks but does nothing for sound.

The result was jaw dopping. When running the Chamber fan at 100% the acoustic gain is about -25dB above ~1KHz ! The fan's whine is still there (305Hz peak is only ~5dB less) but still, the perceived difference is staggering. Spectroid plot:

(3' / 1m away from back of printer)
(Mic not calibrated)

Belt Pulleys Covers

Unfortunately, the fan exhaust muffler actually worked too well 😅

Once installed next to the chute baffle, 2 new sources of noise stood out: the openings for the belt tension pulleys !

So, covers were also designed. They too hold in place with magnets, and seal tight thanks to some thin weatherstrip.

 

The acoustic gain from the whole package is insane. Sapristi, this printer might actually stay in the living room, after all ! 😂