Sorry but I gotta call BS on all this 'air loss' talk. Yes there's going to be some loss, but it's totally insignificant when it comes to sucking smoke from a laser cabinet. I have an 80 foot run of 4" duct from a big HF blower in a plastic shed outside, across the entire basement ceiling in this place...
this is the end, at my ebay1 fiber, it's 3"
from the blast gate to the laser-
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the blast gate steers some of the suction
to the BIL's C2000 to suck engraving chips-
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From there onward... the reason the vent is just danglingis because at night I have to disconnect from the blast gate
to my LS100 laser to keep a neighbor happy. Look above/left of the paper towels, you'll find another T,
this goes to one of my XT machines, and that black shopvac hose has a hole in it to accomodate the 1-1/2"
PVC pipe you see running parallel to the light fixture, that PVC pipe T's off all over the place to supply suction for
three more engaving machines--
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look close you can see PVC pipe running everywhere-
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--and finally to the other end of the house. Note the shop vac hose...
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The blower and all that hose got put in during 2006, and I've never replaced any of it, just added to it.
And with all that hose and leaky halfassed tees and connections, that blower is still able to suck the
smoke out an LS100, the fiber, and engraving chips from 5 machines, all at the same time.
Yeah, it might suck better with 4" pvc, but other than it's prettier, is it worth it?
And- as fantastically messy as this place appears, if you look close you see that 90% of it is exhaust vent,
computer cables and compressed air lines, peppered with a few zip ties and rubber bands. When it's time to turn this place
back into a house, all that crap can be removed in a few hours with nothing more than tin snips
--and, you've seen the garage, plenty more cheap dryer vent doing it's job just fine...