The100
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Why do we need Sideblowers?
🕑 Added 2025-02-19 18:59:59 +0000 UTCOver the last four or five weeks, I’ve been asked twice whether the side blowers are truly necessary for the T250, or if removing them would be a good way to save some money. The answer isn’t as straightforward as it might seem, but it’s definitely worth discussing—so I decided to cover it here on Patreon.
To explore this topic, I’ve set up the following test scenario:
It’s basically a 3 cm-wide cylinder with a single wall and no infill, which results in a consistent minimum layer time of 0.6 seconds. I used Klipper’s TUNING_TOWER macro to progressively reduce part cooling layer by layer, allowing me to observe how decreasing levels of cooling affect the print quality:
Here is the result for CPAP cooling only:
The print results show that at CPAP speeds of 100% to 50%, surfaces come out perfectly. However, once the speed drops below 50%, print quality degrades abruptly, resulting in wobbly outer perimeters.
Let’s have a look at how a print looks with Side blower cooling only (CPAP disabled):
Even at maximum fan speed, the outer perimeter still looked terrible. Does that mean the side blowers weren’t doing anything at all? Well, it’s not that simple!
Here’s a comparison of four different towers printed at varying side blower speeds:
As you can see in the comparison, even setting the side blowers to 30% power can reduce CPAP cooling from about 55% to around 35–40%, which also lowers overall noise levels. The sweet spot seems to be around 70% side blower power, at which point you only need 25–30% CPAP cooling for a flawless print.
With that in mind lets have a look at the noisefloor for the different configurations:
At 30% power, the CPAP is roughly a quarter as loud as the Dual 5015 setup on my T100, and the noise level isn’t particularly bothersome. However, at 70%, it starts to hiss and howl—enough to make you want to leave the room. At 100%, it becomes so loud you’d probably want to evacuate from the next room over as well.
The side blowers behave differently. At 30%, they’re extremely irritating because their inertia is so high that there’s barely enough power to keep them spinning, creating an uneven, almost psychedelic noise. This disappears at around 70%, producing a steady hum that isn’t unpleasant to the human ear. At 100%, it’s almost unbearable to stay in the same room.
Let’s combine the best of both worlds. In this configuration, I ran the CPAP at 40% power and the side blowers at 70%, creating a sound profile that’s still easy on the ears. While it’s louder than a typical bed slinger, it also delivers significantly more power:
At around 55 dB, it’s approximately 4 dB quieter than my T100—cutting its perceived loudness by more than half—and it also produces a more ear-friendly sound. In contrast, the 5015 blowers generate a higher-pitched noise, making them much harder to tune out.
So, circling back to the initial question: Are side blowers necessary? In my view, absolutely. They’re the primary reason I even considered using a CPAP for cooling at all. Without them, you’d have to run the CPAP at a narrow sweet spot that quickly becomes aggravating—so you’d likely end up buying them later anyway. Why not start off on the right foot?
Matt
P.S.: For anyone who thinks 55 dB is still too loud, remember that you can always slow down your printing speed to reduce cooling requirements. My profiles are optimized for smaller prints, but if you load your print bed with multiple objects and stretch the minimum layer time to around 15 seconds, you can easily dial in part cooling to levels under 45 dB.
Comments
Matt the Printing Nerd
I’d recommend going with a RatRig, a HevOrt, or possibly a Voron. While my printer is indeed more optimized than most DIY options, you lose those benefits once you alter the fundamental design principles it relies on. Technically, you could install a pellet extruder on the T250/T100, but because it weighs twice as much as the gantry, integrating it properly would be quite difficult. Add in the doubled Z-height (and therefore a higher center of gravity), and it becomes a real nightmare to build. Ultimately, you’d end up with a subpar printer or be forced to rebuild the entire frame based on your own design..
christophe BAYON
ok, for my project I don't necessarily intend to aim for the maximum possible acceleration. I would like a 3d printer with the greenboy3d print head, which is a pellet extruder. The problem is that this extruder weighs 700g, which I really like in the t250 project, apart from the fact that the speed is really cool. it is designed and optimized to handle, and to have the best value for money, ease of maintenance and if it is as easy to build as the 100, it would be really perfect to make a printer that matches my project. the parts that I intend to print will be high and rather narrow, I prefer your machines to the vorons and when I see the enormous work of optimizations that you do, I only have one desire, it is to work with your machine
Matt the Printing Nerd
I designed the frame for 250k acceleration. To get as much performance as possible you have to maintain the diagonal between the feet and the gantry. From the experience we have gained in the community with the T100 tank, I would rather go the route of maintaining the ratio of the diagonals and thus linearly increasing the pressure space. What would be conceivable would be a 280x280mm print bed of which around 265mm2 would be usable and a height of 275-290mm. I would estimate that you could then achieve a maximum acceleration of 80k-120k with the frame. But since no one has built and tested this frame yet, this is nothing more than an educated guess
christophe BAYON
looking forward to being able to mount the t250, it would be possible to mount only the height, I would like a construction height of 35 cm in z. Will this have a big impact on performance? I don't plan to print at hyper high speed
Matt the Printing Nerd
Without a CPAP, sideblowers have a bigger impact. They mainly shorten the time each layer needs to cool rather than boosting cooling power. Normally, a mini Stealthburner needs around 12–18 seconds per layer, but a single sideblower can bring that down to about 6–10 seconds. However, using just one blower gets rid of warm air without creating the helpful vortex that pulls air upward inside the printer instead of blowing it straight forward.
Alex B
I've also wondered the relationship between these two different part cooling tools! I didn't know that the side, sheet cooling had a relatively small effect on its own! I had considered adding one to my v0.2 as an easy fix to improve part cooling, but now I see it can't be the primary part of the solution.
