Dust Collection

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Forum topic by Notw posted 11-24-2014 05:57 PM 1069 views 0 times favorited 6 replies Add to Favorites Watch
View Notw's profile


649 posts in 1778 days

11-24-2014 05:57 PM

Currently my dust collection consist of a 3HP shop vac and a dust deputy separator on a small cart that I made. I have been dragging this around my shop and connecting it to each machine as I use if via a 2.5” hose. As this can get annoying when going from machine to machine I sometimes forget to move the hose if I’m going to make a quick cut or 20 on another machine.

I would like to run some hard 2.5” ducting to some places throughout my shop (1-car garage) but am curious how much suction I would lose if I did this. Ideally I would like to run the ducting along the ceiling but with 13’ ceiling I don’t think this is an option. Right now upgrading to a larger dust collector is not in the budget.

So my 2 questions are:

Should I continue to drag the shop vac and hose around or will I have enough suction to do hard ducting?

Is there an online calculator (one that a layman can use) that can be used to calculate how much CFM loss there would be?

Thank you.

6 replies so far

View Bill White's profile

Bill White

4948 posts in 3986 days

#1 posted 11-24-2014 06:13 PM

First off, the 3 hp. rating is pie in the sky. That rating is based on stats just before the vac motor will explode.
A standard vac won’t support ducting as you have described.
Looks as if you’re gonna have to continue draggin’ and changin’ hose from tool to tool.
Just my thoughts.


View Fred Hargis's profile

Fred Hargis

4999 posts in 2518 days

#2 posted 11-24-2014 06:42 PM

While I believe your 2 1/2” ducting is a waste of money, I don’t really think you’ll loose much. I knwo our last house had a central vac with ducting running the length of the house (about 60’) and it seemed to me the suction was as strong there as it was at the port next to the unit. But trying to do DC duties with a vac is a compromise at best. I’d just keep doing what you are and plan on a real DC in the future when you can.

-- Our village hasn't lost it's idiot, he was elected to congress.

View ADHDan's profile


800 posts in 2134 days

#3 posted 11-24-2014 06:46 PM

+1 to the above posts. It really isn’t worth investing in a central dust collection system driven by a shop-vac; it just doesn’t move the volume of air required for that type of a setup. Keep dragging the hose around for now, and if you want to switch to an actual DC system I’d suggest getting the Harbor Freight dust collector when it’s on sale, using a coupon.

For a cheap set of central-system components, I think Harbor Freight also sells a kit with hoses, blast gates, etc. It’s a little janky (the hoses are kind of a pain to fit on the connections), but when I picked one up it was like $40 pre-coupon and decent enough for the price. Eventually I switched to Rockler fittings with quick-connect adapters, but certainly I could have made do with the HF components.

-- Dan in Minneapolis, woodworking since 11/11.

View Rob's profile


704 posts in 3096 days

#4 posted 11-24-2014 06:58 PM

Are you sure it’s not 3 amps, rather than 3 HP? Standard residential household circuits in the US (120V, 15A) can’t deliver 3 HP (2237 watts). I’m not sure about other countries.

There are several static pressure calculators available online, like this one:

For now, move the shop vac from tool to tool or buy multiple shop vacs (there are at least a few decent Black Friday deals). The problem with 2-1/2” duct or hose is not only the pressure loss, but you’re also more likely to get clogs. That said, I used a shop-vac for a while on my table saw and planer and didn’t have a problem.

Also wear a P100 respirator anytime you’re in your shop. If you can smell the sawdust, you’re inhaling harmful particles.

When you do upgrade, keep in mind that an inexpensive dust collector will do a better job at dust collection than a shop vac on your stationary tools, but you’ll get worse filtration (air quality) than the shop-vac unless you upgrade to a sub-micron canister filter. For Black Friday the HF DC is on sale for $159, and you may be able to stack a 20% or 25% off coupon on top of that to get the price down well below most craigslist listings (at least in my area). But on the other hand, the HF DC still effectively has only half the power you need for a decent central dust collection system.

-- Ask an expert or be the expert -

View bkseitz's profile


295 posts in 1335 days

#5 posted 11-24-2014 07:03 PM

I’ve an old Ridgid 1HP portable. Works for one tool if you’re close. Trying to decide wither to god the HF and Super Dust Deputy route or spend the big bucks on a Clear Vue Cylcone ~ 3x the price. Considering I’ve asthma my wife is suggesting I don’t go cheap and seriously consider the Clear Vue. I checked out Stumpy Nubs’s site and videos; awesome system and I think he’s got a point…think of DC as another tool. This one to keep you from getting seriously injured over the years.

-- bkseitz, Washington "if everything is going well, you've obviously overlooked something"

View Holbs's profile


1878 posts in 2054 days

#6 posted 11-24-2014 11:47 PM

for a couple months of temporary purposes, sink some $$$ into a pvc pipe or 2. 10’ stick and that’s about it with 1 or 2 wye’s, no 90’s but instead all 45’s. This will be a bandaid to the real problem. All the $$$ you sink into the bandaid will be lost when you upgrade. Keep eye on craigslist or local auctions for larger dust collectors (1, 2, 3HP) and be prepared to REALLY work on ducting then :) With a shopvac, you are really only able to do “chip collection”, not “dust collection”. But, if low on funds, gotta do with what you gots.

-- The Carpenter Bee is derived from the Ancient Greek word wood-cutter

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