About the vent hose for Glowforge. I’m still waiting for my order. I plan to put Glowforge in my office at
my house basement. There is about 12 to 15 feet distances between Glowforge to basement window for 4 inch pvc pipe or vent hose (either one). I know that it is not enough to push the smoke out of the vent outdoors.
Do you think 8 inch vent fan (see pix) will work or will the vacuum be too strong for Glowforge?
I think the CFM on that will be too strong, my Son had that unit on his CNC plasma down draft table.
A 4" booster fan mounted at the exit would be ideal.
yeah, not a lot of point in adding an 8-inch fan to the 4-inch venting, anyway.
If it can do variable speed and you can get an 8 to 4 inch adapters, it will help.
Cleaning will be needed as part of your maintenance schedule. Keep tabs on how quickly it gets build up and schedule around that.
Counter to everyone saying dont do a 8 inch… You should do a 8inchs and then just get a speed control for it the 8in can have a Mich higher flow or can have the same flow at a much less of a sound level.
My 8inch 800 cfm fan at 400cfm is dead silent. The 4 inch in the gf at a estimated 200-300cfm(no one actually knows) is audible through two rooms and doors and with head phones on
that’s a great point - i don’t worry about noise so i didn’t think about it (even though i know better from putting together my computers).
Ya its not just you that’s something people always over look or forget thats the same cfm out of a 20mm vs a 40 vs a 120 the 20 and 40 will make your ears bleed the 120 will annoy and the 240 you won’t even hear. Also the pitch of the larger fans is much nicer even if at the same sound level the pitch of the larger fans will be lower and less bleeding ears
I’m curious, what is the problem with having too much fume extraction (i.e. vacuum)?
Lighter weight materials could be sucked into areas that could effect the GF 
functionality.
I don’t know if internal hardware (fans and other components) would be effected. I think @dan has commented that the GF is designed for around a 200 CFM airflow.
You can also collapse flexi vent tubing with too much negative pressure.
The two fine examples make sense. Is there anything that would affect the actual operation of the GF Laser?
There is an unanswered question that’s been floating around: Is the fan in the GF isolated so that “windmilling” doesn’t create current that could potentially damage the electronics. I don’t know enough to know if that’s even a valid concern. I’m just throwing that out there.
If you put a vacuum on the first fan you can over rev it and generate power causing back feed to the pcb
That is going to work well for you.
Try to keep the 8 inch fan to outputting about 200 to 250 CFM with the 4 inch PVC.
That will keep in step with the GF exhaust (until you can test material that might come loose during the lasering).
Here is what I found:
From:
Great find!!!
And also a shame because its so darn loud for only 200cfm
Something to consider with putting a higher-draw fan at the end of that length of hose is the hose pressure rating to prevent collapse. You wrote down that you’re using PVC, which is fine…
But if you have a high draw fan at the end, and a weak walled dryer hose, the suction could collapse the hose in on itself like trying to suck a thick milkshake through a cheap straw.
I have a similar set up for my in my basement office. Appox 12 ft along the joist. I put an inline assist fan plugged into a switched outlet and it works great.
