Intake vent. Is a 40cm^2 intake area enough for PLA, PETG, and PCTG?
For mainly OCD reasons I am considering replacing the top acrylic panel of my CoreOne. The vent I made has 13 74.8x4mm slats which amounts to about 40cm^2 of area when open. Obviously, this is less than the current intake vent. I do have a 4" hose which connects from the rear fans through an in-line fan and outside.
Is this enough intake for these materials?
Thanks for your help!
RE: Intake vent. Is a 40cm^2 intake area enough for PLA, PETG, and PCTG?
The standard vent inlet is already limiting the airflow, I'd say. When you open the door during a print, you can see the chamber temperature drop by several degrees. So I would not feel too comfortable with reducing the inlet profile further.
We have mixed reports about the sensitivity of the Core One to chamber temperatures. I have seen users report that even with the significantly limited airflow allowed by the advanced filtration unit, their PLA and PETG prints work fine. And I have seem other reports that the "cold" end of the heatbreak gets too warm, causing the Nextruder to jam if the output resistance is too high. (Small nozzle diameter, or nozzle close above the prior layer.)
What's wrong with the original geometry of the vent slits?
RE: Intake vent. Is a 40cm^2 intake area enough for PLA, PETG, and PCTG?
Forgot to mention: I don't think you can simply compare the area of the slits to estimate the expected airflow. The flow velocity will show a gradient -- zero at the edges of a slit, faster towards the center. Hence, one wide slit is more effective than multiple narrow slits with the same open area.
RE:
I second, what Jürgen says. I had 20°C room temperature a few weeks ago and could print smaller objects with PLA with the vent closed. Chamber stayed below 27°C and the heatbreak around 37°C. (you can enable the heatbreak temp monitoring in the control panel - > settings - > User Interface - > Footer)
But yesterday I had 26.5°C room temperature and with a smaller nozzle or fast print speeds, I would've had to open the door. The chamber fans were at 38%, already being quite noisy. With just the vent opened, the chamber went up to 32°C and the heatbreak to 43°C.
Opened the door to see the impact and it dropped to 27°C chamber and 36°C heatbreak.
I was printing a simple object, slowly and with a non-HF 0.6 mm nozzle, making clogging almost impossible.
My 0.25 mm nozzle probably would've clogged up due to the filament becoming too soft for getting pushed through the small nozzle.
So if you're doing your own design: make the slits bigger! Both in area per slit and overall area.
An idea if it's also about dust: I've bought some "0.1 mm 65/35% polyester/nylon fabric" and cut it to fit the original "slide cover". Very low air resistance but keeps most of the dust out.
RE: Intake vent. Is a 40cm^2 intake area enough for PLA, PETG, and PCTG?
If dust intake is a concern: One user had the bright idea to add automatic closing of the vent post-print to my Nextruder-driven, automatic chamber vent. Just an extra small code snippet in the end-of-print G-Code, and the printer automatically closes the vent right after it has finished a print. (And opens it before the print if PLA or PETG are to be printed.)
RE: Intake vent. Is a 40cm^2 intake area enough for PLA, PETG, and PCTG?
Thank you everyone. The slats are v-shaped which should prevent any drafts, but will lessen the airflow further. I understand Jurgen's comment about the cross-sectional area. My OCD issue isn't so much with dust as much is that I accidentally deeply scratched the top panel and went down this rabbit hole. I also didn't like that the weight of my filament dryer caused the panel to flex, which led me to buy an aluminum block (which has imperfect edges that I don't have the tools to properly fix so I want to hide...). Anyway, all is not lost and I can certainly redesign things! I will experiment against the original panel and the info you have provided. Thanks again!
RE: Intake vent. Is a 40cm^2 intake area enough for PLA, PETG, and PCTG?
Here is my new model.
There are now 17 7x7.5mm slats with no v-bend like before. I believe this should provide a significant improvement over my previous model. Thoughts?
RE: Intake vent. Is a 40cm^2 intake area enough for PLA, PETG, and PCTG?
It looks to me like the individual slits are still narrower than in the original vent, so there may be some additional resistance to the flow.
In the central area, there will always be slits on the orange part, and presumably on the bottom black part as well. I assume you are relying on a displacement by half the slit pattern width there, to open and close the vents? If so, why don't you do that over the whole width of the vent, and move it left and right by only half a pattern width to open/close? (Much like the original vent, but in your nicer design.) That way you could have slits across the whole width of the printer, giving you extra air intake.
RE: Intake vent. Is a 40cm^2 intake area enough for PLA, PETG, and PCTG?
I only have the Core One printer, so this is put together in a way that makes it printable on the Core One itself. The orange grille slide has a maximal width of roughly the diagonal of the print bed. There are slats in the black part are most of the entire width of the panel. Yes, when it is fully to the right, it sits at half the width. To cover the remaining slats, it then pulls a little black secondary grille slide that sits in a thin channel underneath. I guess I could just print it in two side-by-side pieces and glue them tight, but I thought this was cooler! Still, I need function over the coolness factor! The slats are 7mm wide (the Prusa ones are 7.8), they look narrow because they are angled at near 60°. The width of the slide is 4mm so for 60° that is a width of 4sqrt(3). Perhaps this is more aesthetic than anything else, but no air can flow directly downward. I used to have a v-bend in it to prevent drafts, but I abandon that design. The airflow does pass through a longer channel however, so it will encounter more friction - this is the biggest difference, I believe, between my design and the original Prusa one. Another issue is that the aluminum block is already cut to size, so I have limited overall depth for the grille area. My other option is to have a solid panel for the grill area that tilts open like in Bambulab's.
RE: Intake vent. Is a 40cm^2 intake area enough for PLA, PETG, and PCTG?
Followup. Actually the slates have a width of 7, yes, but if you measure the angled width, they are still quite narrow. I don't really need them angled like I do... I will adjust this and get back to you!
RE: Intake vent. Is a 40cm^2 intake area enough for PLA, PETG, and PCTG?
I don't know if I need all the edge magnets, but I put them in because they are easier to take out of the model then to put them in. They are only 5x2, so they aren't very strong. Don't worry, I will give the vents nice fillets and chamfers, but for now, this is the newest prototype. There are 12 vents that are 10.2x7.2.
RE: Intake vent. Is a 40cm^2 intake area enough for PLA, PETG, and PCTG?
This is where I have ended up. I apologize for all of the updates. There are 12 7.2x10.2 slats. I have also updated the secondary slider to use a physical (rather than magnetic) mechanism. Overall, I think it is going to work out well! Again, thank you to everyone for your input!
RE: Intake vent. Is a 40cm^2 intake area enough for PLA, PETG, and PCTG?
Looks good! No chamfers needed imo, apart from some micro-champfer to not have sharp edges that could scratch on each other, when sliding it open/closed.
RE: Intake vent. Is a 40cm^2 intake area enough for PLA, PETG, and PCTG?
Right. Thank you again for all of your helpful feedback!