This is actually a reply to a question I got on my YouTube video Dust Collection for Newbies: Introduction to Dust Collection, but I thought I’d post it here in case I needed to refer to it again.
The question was “I’m curious though on how far can a pipe go and still pull dust to the vacuum? I’m guessing with a lot of drops, even with gates closed whatever is last in line may not have much suction?”
Here’s my reply, which is basically thinking out loud:
Yes, you’re right - the more drops you have, the bigger the impact on airflow. And they affect all the drops, not just the last one, although it’s conceivable the last drop would be affected the most.
Length can be a factor, but in my mind, a 20 foot long pipe with one dust gate should work the same as a 5 foot long pipe with one dust gate, as long as they’re both straight. I don’t have any evidence to back this up, but to me, it would seem logical. But sometimes airflow bypasses conventional logic, so take that with a grain of salt.
Remember, the fewer turns the better. Experience is the only way to know for sure. If you’ve already got a shop vac, then it isn’t prohibitively expensive to experiment, since PVC is relatively cheap.
But if you need a lot of drops, here’s some things to consider:
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Pay attention to all the airflow tips. Things like using Ys instead of Ts. Two 45-degree turns are better than one 90-degree turn. And like I said above, straight is better than lots of turns.
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Probably the best choice, if you have a lot of drops, is to get a dedicated dust collector and use 4” pipes. I’ll comment on that more, below, because I have some ideas for a shop-vac system you could consider first (or not).
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You could attach a Y to the shop vac’s dust port, and have two runs of pipe. I’ve seen videos of this, but I don’t know for sure if it’s an improvement, although it would make sense.
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I don’t know if I can describe this, but I’ll give it a shot. I saw a video once, which I can’t find now of course, where someone had two runs of pipes coming from one dust collector. He had the ends of the two pipes side-by-side, attached to two holes in a piece of plywood which he could slide, kind of like a dust gate, and it would slide one or the other pipes over the dust collector’s port.
Dedicated Dust Collector with 4” pipes
Personally, if I needed a lot of drops, I’d probably get a dedicated dust collector - possibly this one from Harbor Freight (make sure you use a coupon) - and go the 4” pipe route. From what I understand, the dedicated dust collectors handle airflow differently (they rely more on the volume of air moved than the velocity), and can handle more drops. I think. :)
If you do go the dedicated dust collector route, then by all means pay attention to all the airflow tips. With what you’ve learned from my video, you shouldn’t have any trouble understanding other videos about the bigger systems. It’s one of the reasons I made this video, because those other videos always seem to leave out the “simple” parts. :)
Good luck, and leave another comment telling us what you learned! Take pictures and/or videos!
To leave a comment…
…go to my YouTube video and leave a comment there. Thanks!