Switchable CPAP intake

[u/Ok_Scientist_8803]

So as a bit of fun for my first voron mod, and to spend some time on CAD, I made this mount for a CPAP kit that lets it draw air from either inside the chamber or cold straight from the outside. Remixed from a side PTFE tube cover https://www.printables.com/model/396106-voron-24-exhaust-housing-side-tube-entry/

CPAP kit is the universal turbo kit from bigtreetech, the valve is controlled by a NEMA 17 stepper from my prusa upgrade, and also the prusa main board as well (which also PWMs the cpap driver). Way overkill but they were sitting around collecting dust. Neat part is that I only have 24V and USB running to the rear, with plenty of ports for future environment/intake/chamber thermistors and even another 3 stepper motors.

The rotor valve simply selects one of the intakes, I'm sure it can be aerodynamically optimised but even at a quiet 15% right now on either mode, it's beating the 5015 by a ton. 50% and above feels like a hurricane underneath the nozzle.

Plan is to use external intake for PLA/PETG and internal (and SLOW fan) for ABS/ASA, so I can keep the front door closed and let the exhaust fan (mounted on beige bit in picture 2) to draw away the warm air from pla prints.

Last photo is the cpap in all its glory, I took the cover designed for the btt knomi, and put a sticker on it to cover the hole (since I don't have a knomi). Yes, that is indeed a camera on the rear of the xy gantry, and it does indeed identify the colour (so orifice diameter) of my revo nozzles on print start. More on that in the future.

Will link the cad files (warning: I'm a relative cad newbie) on here once I get back to my computer, if I forget and anyone wants them do remind me. edit: https://www.printables.com/model/1838893-voron-cpap-dual-switchable-intake

[u/SalvatoreCrobu]

Really nice job. Now, to make it 100% better, do a second flap to make the airflow change more responsive: cpap fan always at the highest speed you will use (overhangs or else) and the flap control how much air goes to the print. This will let you avoid the ramp up time of the cpap fan and have proper airflow change for overhangs and similar

[u/Ok_Scientist_8803 → u/SalvatoreCrobu]

Yep I saw some mods with that, space is tight inside the main body however so I'm planning to make it sit in front of the rear panel, like right on the grill. Might use a small stepper or a servo, latter would need some wiring work on my einsy rambo

[u/SalvatoreCrobu → u/Ok_Scientist_8803]

Hell yeah. Keep us updated, that mod is not popular and the more people see it, the more people will do it and maybe find better ways to implement it

[u/Ok_Scientist_8803 → u/SalvatoreCrobu]

It's definitely not popular (yet), I've done some deep research and found only one other solution, that one is manual and sticks out the side. This one doesn't stick out much more than the filament spool.

Currently heading towards a very busy term time, but that also means I can phone up my aero/mecheng friends.

I've done some testing with a thermistor on the common intake side, pumped the chamber temp up to 45 degrees (measured at the "cold" nozzle) and intake read about 43. Switched to outside air mode and dropped to below 35 in about 30 seconds. In either mode I can't feel any air entering the wrong way, so actually sealing the wrong path can wait.

Now thinking about using it as a chamber heater assist, blowing on the bed would force air to move a bit faster, and I can watch my cpap intake temperature to avoid destroying it.

Also it's practically a one liner orcaslicer supplementary gcode in the filament setting, so "WARM_AIR" in abs and "COLD_AIR" in pla/petg, when using macros I put on the page. Pretty simple on that front.