How to quiet a shop vac

Thursday, December 18, 2014

How to quiet a shop vac


In this episode of House of Hacks, Harley shows how he changed a normal shop vac into a central vac system for the shop.

Associate Links

Measuring the efficiency of a centralized shop vac system

Alternate DIY blast gate videos

Background video about the design evolution of the switch

For a written transcript, go to How to quiet a shop vac

Music and sound effects under Creative Commons License By Attribution 3.0.
Intro/Exit: "Hot Swing" by Kevin MacLeod at


[Vacuum getting stuck between equipment]

[Vacuum tipping over]

[Loud vacuum]

In this episode of the House of Hacks I'm going to show how I made my shop vac easier to use.


Hi makers, builders and do-it-yourselfers. Harley here.

In general I'm pretty bad at house cleaning. I tend to put off vacuuming and straightening up until it's unbearable. Around the workshop, this is exacerbated by the inconvenience of the shop vac. It has a tendency to tip over on its own cord. It's big and awkward in a cramped space. And it's uncomfortably loud.

I wanted a change based on some requirements: 1) minimal daily setup: it should basically always be ready to use and not take much to clean-up at the end of the day; 2) be convenient when using: I don't want to drag it all over the shop from one tool to another; 3) quiet: I want it to be really, really quiet; 4) inexpensive: I didn't want to spend a lot of money.

So to solve all these issues, I made it into a central vac system. At some point I'd like to get a real dust collection system, but right now that's outside both my money and space budgets.

Today I'll show: the box I built for the vacuum, the way I plumbed it in to the shop and how I turn it on and off. In a future episode I plan to show before and after measurements of both noise and vacuum efficiency and finally some future improvements I'd like to do.

Since noise was a big issue for me, I built this box to hold the vacuum and muffle its whine. In the junk pile from previous projects, I had some rigid insulation foam, softer foam rubber and some scrap 2x2. I figured this would work well as the main components.

I measured the shop vac dimensions, added a couple inches to each side for air circulation and the thickness of the foam.

This gave me the target outside dimensions. I went to the local home store and got two sheets of the cheapest 3/8" sheathing I could find. This is usually used under roofs and siding so it has a lot of visual imperfections, but it's good enough for this use and really cheap. When I got home I sliced up the sheathing and built the box by simply screwing it to the scrap 2x2. It's not pretty or square, but it does serve the purpose.

When I got the sheathing, I also picked up a piano hinge and some casters.

The casters I mounted on the bottom to make it easy to move around and of course I used the hinge for the door to give me easy access to the shop vac inside.

I mounted three spare electrical boxes in one corner on the inside. Two of the boxes go through holes to the back and the other points into the box. I'll get to the details of all that in a minute.

Next I cut up the foam and used spray adhesive to glue it to each of the sides.

Finally, I cut a hole in the side for the hose to run through and a hole in the top for the exhaust vent.

The electrical part has two components. A line voltage side and a low voltage side.

On the line voltage side, one of the boxes pointing to the outside has a male plug on it. This allows me to plug an extension cord into the box. This type of plug is convenient to use on projects like this but I couldn't find one at the normal places I typically get electrical parts. I ended up having to order this online. If you're looking for something like this, search for "flanged inlet receptacle". There's also an Amazon associate link in the description.

The box inside just has a normal duplex plug wired to the plug in the other box. The boxes are connected by a standard conduit connector. Combined, the two boxes provide a clean way to run power through the wall of the wooden box.

I plugged two things into the duplex outlet: a surplus low-voltage wall-wart power supply and this PowerSwitch Tail. The power supply provides low-voltage for the switch. The PowerSwitch Tail is basically a short extension cord with a relay built into it. When a low voltage is applied to these two connectors, it turns on the plug. This allows low voltage devices, like micro-controllers or other digital electronics to easily control line powered devices, like shop vacs.

I put another electrical box pointing to the outside for a remote switch. This is the low-voltage side. I installed a barrel style power connector in the electrical box pointing into the larger enclosure for the wall wart output to plug into.

On the outside of this box I installed a standard RJ-45 connector plate, like we used to use for those old-fashioned telephones. The connectors have four wires. The barrel power connector is attached to two of the connectors on the RJ-45 jack.

The other two lines of the RJ-45 run through the electrical box and go to the relay control connectors on the PowerSwitch Tail.

I then built a little switch box. It has an RJ-45 connector on the side and two switches: red and green. Inside it has a simple flip-flop circuit. Press the green button and the circuit turns on. Press the red button and the circuit turns off. A standard 4-conductor telephone cord connects the remote box on the side to the big box with the vacuum in it. I have a pretty long cord here that allows me to turn this on and off from anywhere in the shop. If you want more details of how this works, please leave a comment letting me know and I'll make another video about it. And if you're interested in the design evolution of this switch, there's a video on my second channel going into those details.

For plumbing, I used 2" black ABS drain pipe. This is pretty close to the diameter of the flexible hose that is standard on my vacuum. I ran a straight section across the ceiling with a couple sections running down in key areas in my workshop. I used sweeping connectors for smoother airflow and minimize places where dust can get caught. I held it all in place with perforated strapping tape and some screws. Most of the connections are just press fit. I didn't want to use cement in case I need to take it apart to clean it out, move it or do other sorts of maintenance. However, the sections that run down had a tendency to fall apart with just the friction fit so I put a short, self-taping screw in each one to hold them together. It's still pretty easy to remove the screw if I need to take them apart.

For the ports, I first looked at blast gates at the local wood working store. They were pretty expensive and not terribly well made. I really didn't think they were a very good value. I thought about making some blast gates of my own. I looked online and found some designs, but they were just more complicated to make than I wanted to deal with and I didn't have all the material I'd need in my scrap bin. So I made my own based on the design of the ports on the house's central vac system.

They're basically a hinged flap with a bit of foam to seal them and some magnets to hold them closed. They're epoxied to a standard plumbing fixture. The flex hose stays in with a press fit.

So that's pretty much it for the construction details. How well does it all work? I'll cover that in a future part 2 episode.

If you're interested in part 2 or other DIY type videos of this nature, click the Subscribe button and YouTube will let you know when they're released.

If you have any questions or comments, please leave them below. I'd love to hear from you.

Until next time, go make something. It doesn't have to be perfect, just have fun!