hose/thing for shop vac that will take wood dust right out window?

March 7, 2015 6:38 PM

Don't mean to start another long thread on wood dust collection... but I don't know if my Ridgid 4 Gal vac is quite what I need. My question is, is there anything in the amateur (i.e. non-business) shop vacuum category that is built to run its hose right out of a window? I guess it would include a plate that would look like a short air cond. unit, but would just be for getting the finer dust out of the room...

Why?
I want to do occasional indoor woodcutting with a miter saw that I've built a 3 foot high, 6 foot long compartment around (with 2 x 8 planks). Its just not perfectly sealed.

posted by disnchntd to Sports, Hobbies, & Recreation (8 answers total)

Well, it would be easy enough to make something. What you want is to get a dust collector as the "motor" rather than a shop vac. Dust collectors move more air at a lower pressure, so they do the job of collecting dust better. They're also a lot quieter.

Here's what I'd do: First, I'd see if the dust collector by itself does a good enough job - they leak a little dust when you start using them but dusts builds up on the inside of the bags and improves filtration soon enough. So you might be fine with a decent dust collector that you use inside and clean out occaisonally. They usually use cloth bags for top and bottom but I usually use a plastic bag on the bottom for easy removal.

If that doesn't suit then I would basically cannibalize the thing. If I had a good safe space for it outside the window, I'd put the motor outside, leading to a plate in the window with hose attachments on both sides, leading to your saw. You could dispense with the bags entirely and just spew the dust outside if you felt like it. Depending on where you live you might be able to just make a small lean-to over it to keep water off it.

Harbor Freight mostly makes crap but they have a few cheap dust collectors that are OK. I have this one and I keep it in my attic. I have 4" PVC pipe throughout the shop that feeds to my machines and then up into the attic. I have a keychain remote that I can start/stop it with from the shop.
posted by RustyBrooks at 7:07 PM on March 7, 2015

Actually, the one I linked to, you could keep the motor inside, since it has hose mounts on the inlet and the outlet.
posted by RustyBrooks at 7:11 PM on March 7, 2015

Rusty is on the right track with this. Besides the fact that the volume of air moved by a shop vac is too small to be of much use in an application like this, shop vac impellers are not designed to have particles of material passing through them; the dust has to be filtered out before it gets to the impeller, which precludes shooting said dust past the impeller and on to some further destination such as a window opening.
posted by jon1270 at 9:03 PM on March 7, 2015

Harbor Freight sells a cheap dust collection blower, sans the collection bag or anything else, that is what you want. It's regular price is $130 but a few weeks ago they had it for $99 and they routinely have 20% off coupons.

It comes with a stupid fabric bag to hang on the output which is worse than useless because it doesn't catch fine dust (so it basically is the "filtered cigarettes" of dust collection, taking out the big chunks and leaving you with the fine dust that gets really down into your lungs) but if you buy some extra hose you can just run the output out a window. This is a much better setup than trying to filter the interior air, IMO.

Keep in mind you will need a source for 'make up air' anytime you are ventilating inside to outside, or you'll just create a static partial vacuum in the room.

There are a bunch of hacks around online for the various models of HF dust collector (the small '13 gal' one and the larger ones that RustyBrooks links to) for improving the switches, making the impellers less noisy or more powerful, etc. Like most of the imported stuff HF sells, the blowers can stand to be improved substantially. They do work, though.
posted by Kadin2048 at 9:45 PM on March 7, 2015

Kadin2048: Keep in mind you will need a source for 'make up air' anytime you are ventilating inside to outside, or you'll just create a static partial vacuum in the room.

Curious as to why this is a problem... It's not like it's going to make a door hard to open (easier, actually, if noticeable at all).
posted by IAmBroom at 5:58 PM on March 8, 2015

Because it becomes a source to suck in crap elsewhere (which could be satisfied from an undesirable source, like the unheated outside/exhaust-filled garage, whatever), as well as reducing the ability of the pump to actually move the air outside.
posted by phearlez at 7:58 PM on March 8, 2015

Without getting too deep into the topic, basically if you run a powerful exhaust system without a source of make-up air—which can be as simple as opening a window—a couple of things either may or will happen: (1) the exhaust system won't work as well in terms of moving air volume, because it'll be trying to work against a pressure differential sort of like pumping water uphill, eliminating the whole point of having the exhaust system in the first place; (2) it might suck air into the house through places you don't want air sucked, e.g. through cracks in the exterior envelope and into living spaces, creating drafts; (3) it can cause issues with stoves / furnaces / water heaters / etc. especially concerning exhaust gas ventilation through flues, and in an extreme case causing carbon monoxide risks.
posted by Kadin2048 at 9:28 PM on March 8, 2015

Curious as to why this is a problem... It's not like it's going to make a door hard to open (easier, actually, if noticeable at all).

We have a powerful extractor fan for our kitchen unit. If I'm getting a fire going in the fireplace, and we put the extractor fan on at the same time, it sucks the smoke back down the chimney, into the living room. The installation guide for the (cassette-style) fire does mention the need for decompression venting if you're not taking the combustion air from a source outside the room. The shop vac could easily do the same thing if the tube leading outside has no air gaps around it.
posted by guy72277 at 8:33 AM on March 9, 2015