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Cheap options for lining a shop vac silencing box

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Forum topic by leftcoaster posted 01-22-2016 05:39 PM 1143 views 2 times favorited 21 replies Add to Favorites Watch
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leftcoaster

82 posts in 344 days


01-22-2016 05:39 PM

Topic tags/keywords: noise silencing shop vac liner soundproofing

I’m interested in building one of these: http://www.startwoodworking.com/post/how-silence-your-shop-vac

but the acoustic pads illustrated are quite expensive thanks to shipping. The soundproofing benefits come from mass and, unsurprisingly, the shipping companies want to be paid for delivering heavy items.

Has anyone built one of these on the cheap and gotten comparable results?


21 replies so far

View AZWoody's profile

AZWoody

700 posts in 691 days


#1 posted 01-22-2016 05:44 PM

I would think that drywall attached with liquid nails, not nails or screws would work. Doubling it up would be better.

View JAAune's profile

JAAune

1646 posts in 1784 days


#2 posted 01-22-2016 06:22 PM

A combination of dense materials plus isolation and dampening will reduce sound. There’s a company in Italy that builds confessional boxes with lead sheeting between an inner and outer wall. The two walls are separated as much as possible from direct physical connection and rubber dampeners are used where applicable.

Here’s a good overview on the theory behind soundproofing: 4 Elements of Soundproofing

-- See my work at http://remmertstudios.com and http://altaredesign.com

View leftcoaster's profile

leftcoaster

82 posts in 344 days


#3 posted 01-22-2016 06:32 PM

Since I have to allow exhaust I’m concerned that drywall alone would permit too much reflection of sound waves. Foam on top of it?

I’m obviously inexpert and am unclear how much the rules for soundproofing a full wall or ceiling can extend to a partially open box (the exhaust problem).

View AZWoody's profile

AZWoody

700 posts in 691 days


#4 posted 01-22-2016 06:41 PM


Since I have to allow exhaust I m concerned that drywall alone would permit too much reflection of sound waves. Foam on top of it?

I m obviously inexpert and am unclear how much the rules for soundproofing a full wall or ceiling can extend to a partially open box (the exhaust problem).

- leftcoaster

As long as it’s closed, the sound waves won’t bounce out. The reason to use liquid nails is so that the sound vibrations don’t pass from the drywall through to the plywood shell on the outside, which would then pass the sound to the outside.

Music studios use drywall on offset studs so that the sound doesn’t pass from one side to the other. Also, there are some denser forms of drywall that are made for soundproofing but double up on regular drywall works as well.

Now, for such a small enclosure, to me this is all theory. I just know how it works on a large scale.

I’m not sure how to really account for the exhaust. I know there are small enclosures studios have for computers, etc to keep the sound from leaking into the control room but i never really paid attention to them.

View BonPacific's profile

BonPacific

20 posts in 323 days


#5 posted 01-22-2016 06:56 PM

I built a box for my (Oil-less) air compressor using a 3/4” particleboard cabinet I had lying around, and lining it with Acoustic Wedge foam. It’s not silent by any means, but probably cut the noise by more than half. I can now have a conversation while the compressor is running.

The foam is cheap to ship, since it is compressed first, and if you look around on Ebay you can find boxes of visual-blemish pieces for a nice discount.

You could also call a local carpet company and see if you can buy some offcuts of the heavy-duty underlay they use, it’s pretty similar to the stuff in the post you linked to.

P.S. This is my first post, been lurking for a while now. Great site.

View FirehouseWoodworking's profile

FirehouseWoodworking

689 posts in 2741 days


#6 posted 01-23-2016 12:55 AM

Another “cheap” idea for you to consider is the grey, paper mache’ (sp?) egg cartons bottoms. Save hem up and glue them to the sides. They act just like acoustical linings and work fairly well. I can’t give you “scientific” numbers for their acoustical value, but I can tell you from experience that they cut down the noise level considerably! And they’re inexpensive!

Just a suggestion for your consideration. Good luck!

Cheers!

-- Dave; Lansing, Kansas

View TravisH's profile

TravisH

452 posts in 1403 days


#7 posted 01-23-2016 01:39 AM

Use the second option they reference in your link….ceiling tiles.

View leftcoaster's profile

leftcoaster

82 posts in 344 days


#8 posted 01-23-2016 02:05 AM

Yeah, I was looking around for those online at HD and didn’t see any that made acoustic claims. I’m going to go over there and take a closer look.

View builtinbkyn's profile

builtinbkyn

651 posts in 408 days


#9 posted 01-23-2016 02:08 AM

Carpet padding, if it hasn’t been mentioned.

-- Bill, Yo!......in Brooklyn :)

View leftcoaster's profile

leftcoaster

82 posts in 344 days


#10 posted 01-23-2016 02:37 AM

From what I’ve read carpet padding seems to solve foot impact noise rather than noise through the air.

There’s a guy on YouTube who got good results with the acoustical foam though an acoustical engineer questions its contribution in the comments.

View bigblockyeti's profile

bigblockyeti

3668 posts in 1188 days


#11 posted 01-23-2016 02:38 AM

How much room are you going to leave around your vacuum? If it’s more than just an inch or so, you might be able to use the contained insulation used at the perimeter of basement walls on the inside. I’m almost certain it’s fiberglass, but since it’s inside plastic you wouldn’t have all the negatives of just placing loose batts of fiberglass on the interior and you would still benefit from it’s acoustic properties.

View clin's profile

clin

514 posts in 464 days


#12 posted 01-23-2016 04:07 AM

In this case, since you need exhaust, What I would do is have the exhaust port of the box as long as possible and lined with sound absorbing material. Make the exhaust fold back and forth like a maze.

Dow makes an insulation that is very popular with acoustic designers. I think it is Dow 703 rigid fiberglass insulation. It’s 2” thick in 2’x4’ pieces. It’s sort of like regular fiberglass insulation, but stiff like it has starch in it.

You may be able to find it locally at an insulation supplier if you are in a large city.

The idea is to get the sounds that are trying to bounce back and forth across the exhaust port to be absorbed. The longer the exhaust path, the more it gets absorbed. Of course, as other have mentioned, isolate the inside from the outside of the box.

Something else that might help quiet a shop vac itself would be to attach mass to the body of the vac. There are sheets of heavy rubber like material, designed for attaching to car panels to quiet a car. This would probably reduce the noise coming right off the shop vac. Though this would alter the vac and probably is not that cheap. But just thought I’d mention it as a possibility.

-- Clin

View leftcoaster's profile

leftcoaster

82 posts in 344 days


#13 posted 01-23-2016 04:25 AM

Yes the long circuitous channel is a feature of many of the designs I have seen.

View DaveHuber's profile

DaveHuber

43 posts in 2585 days


#14 posted 01-23-2016 11:10 AM

Consider lining your box or channel,with acoustic tile from a drop ceiling.
Cheap.
Deadens noise very effectively

Dave

-- Dave, Oak Park, IL

View JoeinGa's profile

JoeinGa

7489 posts in 1475 days


#15 posted 01-23-2016 12:34 PM

I believe you are overthinking this. Build the box 3 or 4 inches bigger then the vac. Use Locktite construction adhesive to attach drywall. Then use the same adhesive to layer on carpet padding, PLUS a layer of the heaviest carpet you can fine. Maybe even those heavy rubber mats you put in front of a workbench.

Or perhaps check with a sewing store and see about buying some 3” memory foam.

-- Perform A Random Act Of Kindness Today ... Pay It Forward

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