Ok, why did i put this off so long? (external exhaust)

When everyone said it was quieter, i though, “I’m sure it’s quieter.”


holy crap. i mean, holy crap. i can barely hear it. damn.


Which one did you go with?

My Glowforge is not working and being sent back, but when I get the Glowforge back, I plan on adding an external exhaust also.

I am looking at the VIVOSUN 4 Inch 195 CFM Inline Duct Ventilation Fan:


the cheap on.

i may upgrade at some point. probably to the cloudline, because it is getting a lot of reviews and i only have $28 sunk in the vivosun. .

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If the VIVOSUN is doing a good job I will probably start with that one also. I could definitely see upgrading in the future too.

I do not recommend the 4" vivosun for use by itself.

I have one and used it for over two years in my setup, but not by itself. When my built-in exhaust fan failed, I quickly noticed an increase in debris accumulation inside the machine.

I then purchased a 6" 390CFM fan and it actually keeps the machine cleaner than the built-in fan with the 4" vivosun did.


So you just used a converter, from 4 to 6 inch vent, and used a bigger fan?

That is double output too. (390 vs. 195 cfm)

I was astounded also. Such a difference.
That original exhaust fan did 13,000 RPM, that’s what my 4" angle grinder does - High pitched whine.
For a self-contained system that was required, no room for a massive slower spinning fan. A lot of people have purchased the cheap Chinese alternative laser, only to discover vast improvements by adding to it. That’s all we are doing, improving the design beyond (or in spite of) what manufacturing standards require.
The noise reduction is amazing because the larger impellers or fans, the boosters don’t need to spin at that high an RPM = Piece. :sunglasses:


Yes. I made a simple adapter and shared the design here, but buggered if I can find it now.


When everyone was saying it was quieter you were still saying “WHAT?! I CAN"T HEAR YOU”

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I have the 4" vivosun and i would recommend something with a higher cfm. I find it lacking on prints with heavy cutting.

yeah, just did a longer acrylic cut and i can see that it’s a little less functional for that. i’ll keep using it for now to be an additional fan and let it keep evacuating odors after the cut stops. but i’m looking at the 6" fans. i have to make sure i have room in my setup to fit whichever one i buy. it’s a snug fit behind there. especially since i like my hard elbow. but maybe i’ll have to give that up.

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I have the Vivosun 6" and it’s insanely quiet compared to the 4". It makes me want to get an 8" and adapt it from 4" inlet to a nice breathable 8" outlet. I mounted the speed control near the GF button. It makes for a nice compliment when engraving slate a fan speed 1. PRICELESS!!

I can actually listen to music while using the machine now!


I have tte 195 cfm vivosun and most of the time I use both but if there will not be a lot of smoke I use just the Vivosun

yeah for simple cuts i use just the external, when its like 30mins of cutting plywood i turn on the fan in the glowforge and just deal with the noise. thinking of swapping out the fan tho for the 6" one above

I’ve been thinking of doing this too. Problem is, I have a 4” vent in my wall. I keep hearing that the 4” fan isn’t sufficient, but I don’t think putting a reducer from the 6 inch fan to the 4 inch vent makes any sense either. I can’t see any obvious way to increase the hole size, & I don’t really want to cut another hole in the wall. Any suggestions?


This sounds amazing , but I am confused do I just add to the back of the machine that that i have already going out the window or do I need something extra for it ? Do i turn off the glowforge fan to use it. Where is that ?

Thank you .

When i was talking to the Engravers Network guy that I’m getting the 150-watt ULS from about cutting capabilities, he said on things like thick acrylic it’s all about the exhaust.

Lots of things go into it, but pressure is a big one. It might be a 400 CFM fan, but that’s probably at 0.00” static pressure. The further the run is, the more turns and angle of turns, the type of tubing etc all add resistance thus decreasing pressure and decreasing airflow, usually drastically. The closer you can get the fan to the exhaust port, the less fan you’ll need overall. Putting it at the end of the run will hide exhaust leaks by keeping it under negative pressure but you’ll need more fan.

A 4” duct is capable of flowing nearly 400 CFM before it maxes out. Using reducers to go into the fan isn’t an issue. Pretty sure Boyle’s law comes into play here also at some point.


i have a pretty short run, thankfully. and two 90 degree turns.

My 6" fan is 25’ away from the machine, back in the hallway near the window it vents from.

Alexa kindly turns it on and off for me… :slight_smile:


Mine is pretty short too (only about 4 feet). So maybe the 4 inch fan will work.