Recently I was comissioned to make a test bunch of acoustic pannels, so I documented the process, for myself to remember how I did it (probably I'm going to make more in future), and, probably, for everyone, who's interested to make some of those themselve.
Acoustic pannels are used to cover walls of home cinemas to improve the qualitie of the sound. They prevent the sound waves from bouncing from the wall surface, thus reducing unwanted sound distortions. The other function of soundpannels (rather really secondary one) is to sound insulate the room, thus making the living for everyone outside the home cinema much more calm and.... calm.
Step 1: Designing the Frame
The frame for the pannels is basycally a box. Owerall size (including the thickness of fabric) is 300x300mm, and there's a few variationd of depth: 50, 65, 80,95 mm. 10mm MDF was used to make these boxes, although plywood can be used as well. Ewen thinner material will do, but it requires coresponding changes to the dimmentions of parts.
So, the first thing to do is to cut the details, and since I do not have apropriate tools for doing this, that job was comissioned to the third party workshop. The sheet of paper they produced shows the diagram of cutting the details for 8 pannels out of single sheet of MDF. I'm including it since it may be somewhat usefull for somebody.
The sizes of deatails are shown on pictures represent the base piece and wall pieces of different hight.
For the next step you'll need a router table, I made mine out of scraps of laminated particle board. If you already have a router, look up for how to make a router table on the internet, there's a lot of great tutorials and designs out there.
With the router table you'll have to process the wall pieces, creating open grooves (English is not my first language and I'm not a professional carpenter, so if you can suggest appropriate term for this, just let me know in the comment section). You can see the dimmentions on the 3D diagram picture.
Process all the details, and make sure, you're making grooves on in the same configuration (on the same sides) on each detail.
When you have all wall pieces prepared, it's time to glue the details into boxes.
There's, probably, a bunch of ways you can perform the task according to the variety of tools you're possess. You can apply glue to the details and use pneumatic nail gun to secure the details, for example. But this is what I've came up with.
In the bicycle service workshop I bought a couple of used tires (one was punctured and the other one was torn in large area) It costed me almost nothing. I cut them into ~90cm long strips (one tire gives 4 of them, and it's ok if they're somewhat shorter). Then I glued them into rings using natural rubber based glue (follow the instructions on the package).
Also I cut a bunch of wooden blocks (I have rounded the corners so that they don't puncture the rubber), and made a simple jig out of scrap piece of particle board (drill 4 holes in the corners of ~32cm rectangle, and use nails as pins (or something suitable)).
Here's my set up for the gluing process. And here's the sequence of opperations:
- Insert pins into jig;
- pull the rubber ring onto pins;
- place the bottom piece of the pannel box inside the ring;
- take the wall piece and apply glue onto grooves (mne glue is latex based, but PVA based glue will also do the job (or do your own research));
- assamble the details around the bottom piece (on the last picture two neigbouring walls are shown from underneath; the recess for the bottom is creayed);
- insert wooden blocks between the rubber band and the walls of the pannel;
- remove pins (nails) one by one;
- adjust all the details to put them into place and close the gap;
- put the pannel onto plane surface for the glue to dry.
Here I want to say a few words about the design. There's a lot of ways to make a box like this, but I choose this one because it works perfectly with the way I'm gluing the details. Since the grooves provide self regestering structure I can use only a rubber band to clamp all pieces, because I know thet everything will be square anyway. and won't slide away under preassure. The wooden blocks serve to transfer the dirrection of the force applyed to the sides of the construction instead of it's corners. You can leave the pannels clamped with bands for a couple of hours untill the glue sets up, and then use the bands to clamp the next bunch.
The other advantage of this design is that every detail has the same dimmentions (for each dimmention-type pannel) and can be processed in the same way, which reduces the ammount of opperations. But again, this is my reasoning, and if you feel that something different will work better for you - go your own way.
Glue all the pannels.
After gluing I've been left with these recesses on the corners of the pannel boxes. I used a flush bit trimm those.
In the order for the pannels to work, the boxes has have to be filled with sound insulating material. I'm using 20mm thich acoustic mineral wool (it's denser than regular wool, and, probably, comes in thicker sheets; IDK if you can substitute it with regular mineral wool, make your own research).
To cut the sheets into desired pieces I'm using regular electric kitchen knife that has been installed underneath the table with blade sticking out abowe the table top surface. I made this contraption following Gregarious's instructable: THE BLADE RUNNER MULTI-MATERIAL ELECTRIC KNIFE. I've already had those two board screwed together at a right angle, so I just used them as a fence.
The rectancles I was cutting were a bit larger than the inner dimmentions of the box. I wanted them to fit inside snoggly, without being loose and rattling within.
Insert the wool rectangles to fill the box as close to the rim as posible. Use cut off pieces to fill between layers.
Out of Tyvek fabric cut a bunch (one for each pannel) of rectangular pieces, roughly 36x36cm in size.
Cut the corners off having in mind the rectangle of 30x30cm that fits inside.
Insert Tyvec rectangles into pannels the way shown in the video. Right moves come with practice, so expect it'll be only easyer with time.
The pourpouse of this detail is to create a membrain that prevents the particles of mineral wool escaping the pannel through the cover fabric (it may not be be very tight woven for this), thus creating airborn dust.
I'm not an expert on fabrics, and I was provided with the fabric for work by the person, who comissioned the job, so I'm not giving any recommendations on how to choose it. I believe, you'll be able to easily find this information on the internet or by consulting the right person.
Each pannel has 30x30cm (298x298mm to be precise) in base and the hight of the walls. Add a couple of centimetres to each wall, double that and add the basis to get the lenght of the side of the rectangle of fabric, you need to cut to cover the panel. So, if your pannel is 5cm high, take 7cm (5+2), double it (14cm) and add 30cm. You'll get 44x44cm rectangle of fabric to cut.
To properly stretch the fabric onto the case, put it underneeth the box and align the edges evenly (I mean even distance from the box). Fold then the middle of one side to the back of the box (as shown on the photo) and secure with a stepler, Pull then the opposite side (also on the middle) to create tension and secure the edge of the fabric on the back of the box. Do the same with two othwr sides. Add then two more staples beside the first on on one side. Pull the fabric on opposite side and secure it with staples in corresponding points. The same goes for two othe sides. Leave some clearence at the corners.
Pull the fabric at the corner and create a fold the way shown on the photo. Secure the fold with a staple on the side. Concidere, that at some height the pannel will be visible, so make sure that the staple is positioned pretty low (closer to the bottom). Do all the angles the same way, but take care to position folds on the case in simmetrical order. You can lightly tap the fold at the corner with hammer to flatten the fabric for mor accurate result.
There's a few ways, you can accomplish the fold of fabric on the corners, so I advice to experiment and find out, what looks best for you.
Now, on the photos, I'm showing, that Im cutting the excess fabric on the back of the pannel off. It's definitelly an option, but when I was making the next batch of pannels (the remaining four) I decided not to do so and work with what I had. It resulted in more accurate product eventually, so, once again, it's something for you to decide.
Pull the fabric and secure the edges at the cornes at the back of the pannel with stepler.
At first, whole your upholstering may look a bit sloppy. May this not dicourage you, since if you'll continue, you'll improve really quickly on the qualitie of your job.
One thing, I'm leaving a bit vague at the moment, is the way the pannels are supposed to be afixed onto the wall. At this poin't, I'm awaiting for the approval of the test batch, so that after I'll be able to continue the work ont the design. Newertheless I'm pretty sure, that the French Cleat system is optimal, and this is what will be used eventually (with two lines of connection for each pannel).
In any case, I'm going to update the instructable a bit later with photos, or atleat 3D plans on this part.
So, this is basically it. Obviously, you'll have to make a lot of pannels like this to properly upgrade your home cinema room (they have to cover two side wall completelly (or almost so)). In the future, I'll probably will have to make a lot of them, so I'll probably have some thoughts on making the process more efficient. Also there's some plans on implementing LED lights on the sides of the pannels, so it'll be another instructable.
This is it for now, though. Thanks for your attention, and have a nice cinema.
At the moment I don't have a propper job, and the projects like this is the main souce of income for me... which is not really much. So if you like, the content I'm sharing, please, concidere to support me on Patreon. Alse there's always something I'm creating besides the instructables site, so maybe, you'll find some stuff good for you on my Waldemar Sha Facebook page.