How to Use a Muffler to Reduce Noise and Make Your Shop-Vac Quieter

I fell down a rabbit hole recently while browsing YouTube about people making their shop vacs quieter by building a muffler around them. They use an insulated box to reduce shop-vac noise, foam rubber or styrofoam. I know I can do better because I happen to have some acoustic mineral wool lying around. Mineral wool absorbs sound in concert halls, music studios, gymnasiums and more. The results of it? My Shop-Vac muffler box reduced the noise from 87dB to 61dB at a distance of 24 inches. If you're not familiar with the decibel scale, every 10 dB drop cuts your perceived volume in half. Cut another 10 dB, then cut it in half again (1/4 of the original).

When I show you how to reduce the noise of a Shop-Vac, the volume level will go from a loud vacuum to less than a microwave.

Who is this program for?

This Shop-Vac muffler item is for people who use their vacuum cleaner as a dust collector. It should sit in one place in your store and cannot be moved. It always attaches to your miter or table saw. Due to the final size of the box, this item is not suitable for people who use the shop-vac as a portable vacuum or dust collector. If you want to take your vacuum to the car or basement, this is not the project for you. We show you how to reduce Shop-Vac noise on tools you don't mind leaving in place.

However, if you have a small shop, at shop-vac prices you can easily buy a second tool to attach to your saw, add an automatic switch, and the investment in a shop is well worth it – the vacuum is much quieter .

But what about overheating?

It does no good to make your shop vac quieter to reduce noise if you kill it. When I see someone working on this project, my first thought is to overheat the vacuum. Everyone who has done this claims they have had no overheating issues. I let mine run for 15 minutes and it got warm as usual but not overheated. I don't want to have it run for an hour because shop vacs are not supposed to run continuously. If you work so fast that your dust collection system needs to run continuously, you need a real dust collector.

A quieter vacuum cleaner! I am sold. How do i build it?

For materials, you will need the following:

• 1 sheet of MDF or 3/4" plywood (or 2 if you have a giant vacuum)
• 2 tops, 8' long
• Four 2-inch thick Roxul Rockboard 60 mineral wool boards
• wood glue
• Screws, biscuits, pocket holes, or your preferred method of box assembly
• 2 1/2" hole saw (yours may vary)

First, we need to keep your shop-vac as small as possible. Delete any unnecessary parts. This includes wheels, handles, accessory tool holders, and more. All of this unscrewed on me. At the top there is a protrusion designed as a noose. I removed it in about 3 seconds using a reciprocating saw with a metal cutting blade.

Once your vacuum is as small as it gets, it's time to measure your shop vac. Take the width and add 4 inches on each side for a total of 8 inches greater than the width and depth of the vacuum. If your shop vac has very complicated or difficult-to-connect hoses, leave an extra inch or two in front of the hose connections.

You need 4 inches on each side because of the 2 inches of mineral wool inside the box, plus 2 inches of space around the shop vac for ventilation and airflow.

Lay out your clips

I placed the cutouts on a sheet of plywood, shown below, for my shop-vac. This is a genuine 16 gallon Shop-Vac brand vacuum circa 2015. My box has no bottom to save material and height. My vacuum just sits on the floor with boxes around it. I did this for height considerations as I was trying to mount it below the miter saw stand. Feel free to add a bottom if desired, and even casters so you can move it around.

Assemble the box

Next, assemble the box using biscuit joints, screws, pocket hole jigs, or whatever you prefer. Just make sure to use glue all the way around the seams to make it as airtight as possible.

cut hole

Afterwards, cut holes for vents, hoses, and power cords. Air enters the hose and needs to exit the box through the vent. The vent can go anywhere, but I chose to put mine where I could feel the air coming out of it, just to make sure it didn't overheat during initial testing. In other words, I didn't put my vents where I couldn't reach them or where I might accidentally cover them.

I put the hose and wire side by side so I don't need to drill a big hole for the power cord. I can run the cord through the hose hole first, then install the hose. To find the hole for the hose, remove the hose from the vacuum, put the vacuum in its box, and place a pencil into the hole in the vacuum hose. Now trace the circular outline of the hose inside the box. My shop-vac hose requires a 2 1/2" hole saw to drill the holes. I then drilled a 3/8" hole in one side and chiseled away the scrap between the two holes so I could attach the power wires.

insert mineral wool

Cutting mineral wool with a utility knife or a small sharp knife is an easy task (although it won't be sharp when you're done). I cut it tight enough that the friction held it in place. I then used a hole saw to cut straight through the vent and hose holes, punching holes in the mineral wool.

Just a tiny V-notch is enough to make room for the power cord in the mineral wool. Mineral wool is the key to making this shop vacuum muffler quieter than other boxes.

add top cover

We're almost done with how to reduce noise in a Shop-Vac. Now for the final assembly! Connect the power cord, then thread the hose and connect it to the shop-vac. Turn on the vacuum, unplug it from the power source, and the top cover can be attached. Always centered.

The next step is to take the scale strips and cut them to create a seal all the way around the top once you've centered it. I screw in vertically starting from one side. Work your way around the top from below. When I'm done I have a top that opens and closes and it's more or less airtight.

Plug in the vacuum and give it a try. A muffler (or quiet box) should make your shop vac a lot quieter. It may not be quiet – but it should be much quieter.

Additional features make it even better

That's how to reduce the noise of your Shop-Vac with a homemade muffler, but wait, there's more. You can add two add-ons to this project to make it even better. The first is the cyclone filter which makes the shop-vac more efficient as all the heavy particles fall into the bucket outside the box. It saves you from almost ever having to change filters or open boxes. The most famous is Deputy Dust. For now, though, I'm using a less expensive Woodstock Mini 2-stage skimmer. It sits on a 5 gallon bucket into which the sawdust is poured.

The second add-on is the EToolCity auto switch, which turns the vacuum on every time you start the power tool, and then turns it off about 15 seconds after the tool stops running. This is a huge help because you never have to think about turning your shop vac on and off. In my case, I hooked it up to my miter saw, so it only runs for a few seconds at a time, then shuts off. The automatic switch alone makes my studio a lot quieter. It's well worth the price.

Conclusion: The Quieter Shop-Vac

Is this project worth your time? Hope it helps you learn how to reduce Shop-Vac noise. If you're trying to minimize noise in your shop, then yes. If you're always using a duster when you're working with your tools, then yes, I think it's worth your time to make your shop-vac quieter.