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I have the CV1800 with the larger impeller as well. You understand it correctly, but in a home shop sometimes what's perfect isn't possible. One thing to remember, the CV 1800 will pull so much air that it's more likely to be restricted by whatever you have for a pick up at the CNC than it will be by the elbows. I most certainly wouldn't run it another 8' and then 180 back to the CNC.
I started with absolutely nothing. Now, thanks to years of hard work, careful planning, and perseverance, I find I still have most of it left.
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That's a fine tuning detail. You're hitting that gnat with a 12 lb sledge hammer. Use it as you originally wanted to, and don't worry about the details, as fredhargis suggested.
IMO, of course.
Tom
“This place smells like that odd combination of flop sweat, hopelessness, aaaand feet"
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I thought the desire with the straight run was to improve separation efficiency on the cyclone rather than maximizing air flow.
Matt
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It is, but that's only the section leading into the cyclone. Oneida wanted 5' (maybe it was 7', don't remember) but the smooth air flow (a laminar flow I think it's called). does indeed maximize separation. But a smooth flow along the whole line of ducting also improves flow. I'm pretty sure that it's an amount you could only measure in a lab (the fine tuning thing Tom mentioned)....but it's a truth. That's why many of us use 2-45º els with a short piece of pipe in between them instead of the sharp 90s that PVC usually has. On mine the best I could do on the inlet was a piece of straight about 15" long. One thing you need to consider is the CV has an upward angle to the inlet (about 10º according my HF angle thingy) so you have to consider ceiling height to get the straight infeed. I can tell you the separation is still very good on mine even with the short infeed tube I used.
I started with absolutely nothing. Now, thanks to years of hard work, careful planning, and perseverance, I find I still have most of it left.