How to Make a Sound Baffle for Loud Shop Vacuums

Have a loud shop vac that you use for a stationary purpose, like sucking up chips off of the shopbot or dust collection for your table saw? This Instructable will show you how to create a sound baffle to minimize some of the noise. By the way, I made it at Techshop!

Step 1: Gather Materials, Preferably Scrap.

This project is meant to be functional rather than beautiful and is done with no budget, so the first order of business was to collect suitable scrap materials. I found 2 pieces of 2" scrap foam, 54" by 30", out by our container, and a few pieces of scrap ply board near the plastics station. (Actually, the availability of properly sized scrap foam was the impetus for this project.)

If you don't happen to have access to a giant pile of scrap or if you want to go out and buy new materials, you can follow this Instructable but make a much nicer looking final product. 

materials: 
2 sheets of 2" foam, 54" by 30", or whatever suits your purpose.   
4 pieces of 1/4" or 1/8" ply scrap (owsyp)
About 16' of 1.5" by 0.5" strips of board
Staple Gun
Drill with driver bit
Wood Screws 
(wood glue for the corner supports if you're not lazy like I was)

Step 2: Staple the Foam to the Boards

Lay a piece of your foam on a table. If your boards aren't already sized, cut them down so that the tall side of the boards is the same length as the width of the foam. Place the boards on top of the foam so that each board aligns itself along 3 edges of the foam. If there is a gap between your boards, put it in the center. This is what your staple job will look like when it's finished. Flip the whole thing over so that the foam is on top of the boards for easier stapling and fine-tune your alignment. Now staple the edges of the foam to the boards along the 3 outer edges. Repeat this step for both sets of foam and boards. 

Step 3: Make Corner Supports

Take your long, thin stretches of 1.5" board and cut them into  approximately 18" sections with 45 degree miter angles. Then assemble them as corner supports. You'll need 5 supports total. You may need to recut the length of one or more of the supports later to fit your final project. I stapled the outer corners then drove screws into the ends to make the supports. (Was too lazy to glue to corners, but that would be a good idea. If you're into joinery, do a better job than this.) Don't connect them to anything yet. That comes next. 

Step 4: Make 2 Ls

Connect one of your corner supports to one of your foam-boards to create a 90 degree L-shaped corner. Now attach a second support next to the first but spanning opposite ends of the board. (see picture). Now do the same procedure with your other foam-board combo so that you have 2 Ls, each with 2 supports. If you've done it right, 1 of the Ls will sit on it's side on the floor and the other will go over the top of it with only 1 short edge on the floor. that's the next step.

Step 5: Construct the Box

Lay the first L on it's side, so that both of it's long sides touch the floor. Now put the other L over the top and on the adjacent side, making a box with 1 open side. Carefully align the unattached ends of your supports so that the sides of your box are at 90 degree angles from each other. You may need to cut a notch out of the corner of the foam on the curved angle to make the top fit snugly. The pic shows the cut before it's screwed down tightly. Screw the vacant ends of the supports into the boards that are now underneath them. You may need to adjust your way around the box realigning the screws as it tightens up and gets closer to 90 degrees. When you feel the box is square, attach the 5th support to to connect the top of the box and the back of the box. (the back is the closed side opposite the open side). 

Step 6: Ready to Go

You'll notice that the support that spans the bent side of the box sits out just a bit. It's a perfect support cradle for the vacuum hose. (I installed another small wooden support where I put the hose through the cradle.) Just wind the hose through the cradle and tuck the baffle up to the side of the work bench. You should be able to easily access both the hose and the on/off switch.  I ran a sound level test using Sound Meter Lite on my Android phone. According to that app, the baffle reduced the dB level about 8 or 9 dBs between 2 feet and 15 feet from the vacuum.  Happy vacuuming and save your ears! If you happen to make a baffle like this, run your own dB test and post the results!!!