Does anyone know where the exhaust fan on the back gets the air in if mode is set to heating? Thought from the openings at the bottom but those are closed in heating mode. The only opening is the poop shoot but covering it with a piece of paper has no influence on the amount of air pushed out. There must be another opening somewhere.
There are holes next to the poop hole, where the master control board is
I’ve already spotted these openings but I don’t feel any airflow through that openings when the exhaust fan is running at full speed.
I will ask Bambu support and report any outcome. They should know how their devices work.
You may prompt them to change it in the next firmware update to where you can’t operate the exhaust fan in heating mode. I would just stay quiet on this one lol.
My understanding is that it really doesn’t. There are 2 holes near the rear x,y motors that allow air to enter the chamber, but there is no “fresh” air during heating, nor chamber air leaving the chamber while heating.
The entire point of the system, my understanding anyways, is that the heater is simply recirculating air that’s already in the chamber and does so by creating a negative pressure (vacuum) inside. If you open the door while it’s heating you can actually feel the pull on the door.
The reason for my question was that I had the impression some fumes still leaving the chamber when printing ASA. Thought about generating slight negative pressure by running the exhaust fan at 10% in heating mode. The air would then leave the chamber through the exhaust fan which has a carbon filter.
Meanwhile I’ve realized that the poop shoot is fully open and likely the main reason for the fumes leaving the chamber. Printed a bucket that fully seals the poop shoot and that significantly reduces the smell without the need to run the exhaust fan.
It probably wasn‘t intended by Bambu to run the exhaust fan while heating and there is no real open intake slot.
The review that Stefan did on CNCKitchen showed some fumes were still able to escape out of the rear vents.
in heating mode you can turn on rear vent at 10% or 20% or whatever. This will create negative preasure.
So if I’m running at 100% on cooling mode there’s def negative pressure right? I just get confused because I feel some
we have 3 fans total, only one vents outside, the rest cool the part from left and right
Pete, I too smell fumes while printing. I want insure negative pressure in the cabinet. I have tried running the exhaust fan at various % 's 10% -100% all while printing ABS.
PROS: The cabinet temperatures remained stable.
Cons: Very little air flow detected even at 100% - really feel heat more than air flow out of the built in fan exhaust. .
My thoughts for a solution to maintain Neg. pressure. As the cabinet is “somewhat tight” with openings as already stated, I need low volume while printing. I plan on using a 3d printed fan shroud connected to…get this a 1" hose and an auxiliary fan to the outside I can speed control to keep a negative pressure while keeping the monitored temperatures stable. WHY 1" vent hose and fan? I need to conceal the hose and 2" plus fans/hoses will not make the wife happy and keeping the idea I don’t need high volume to maintain a negative pressure cabinet I think it will work.. During the cooling faze after printing maybe not so much. The cooling phase after printing does show a noticeable CFM increase, I’m concerned even an increased auxiliary fan speed thru a 1" hose isn’t going to provide enough flow.. 1-11/4" maybe.. THOUGHTS?
Update: the preceding was the first time printing ABS. As stated - little to no venting air coming out of the rear fan - probably due to the higher temp needed by ABS??.
Just started PETG for the first time and rear fan is obviously moving air out the back - shows 80% fan. The 1" vent hose idea doesn’t sound so practical with that amount of CFM. 2" maybe..