Intro: Recycled Timber Bluetooth Speaker
After being a long time viewer of this site and learning many new and exciting things, I have decided to upload my first Instructable :)
I have created a wireless Bluetooth speaker using recycled Jarrah and Pine. The Jarrah was sourced from old garden sleepers while the Pine was sourced from wooden pallets found at a industrial factory. I used a 2x50W Bluetooth Amplifier, powered by both mains power and three 3.7V Lithium Ion rechargeable batteries. Using the additional external battery board allowed the mains power to charge the lithium ion batteries and also provided overcharge protection. To ensure a quality sound was produced, I connected two full range Dayton Audio speakers.
I sourced most of my parts from online retailers and are shown with US Dollar values, the links are as follows;
Jarrah - 2400mm (l) x 150mm (w) x 50mm (h)
Pine - 500mm (L) x 150mm (w) x 21mm (h)
Bluetooth Amplifier ($40)
Aux In, USB Out Interface Board ($8)
I would not buy this again and will explain why in the build steps.
Battery Extension Board ($10)
3 1/2 Inch Full Range Speakers ($20 each)
2400mAh Li-Ion Battery ($8 each)
LED Push Button Latching Switch ($20)
Overall this first build was quite expensive but I am very happy with the outcome and the quality of the build. If planning this for the higher level classroom environment, I would ensure that I buy all of the parts from Aliexpress or a similar site as the total cost of parts would have be reduced heavily.
Step 1: Designs
When initially designing the speaker box, I started to research the science behind speakers and there sound efficiency. A good speaker enclosure will have minimal sound distortion but will allow a high amount of sound amplification.
Materials should be heavy enough that any vibrations or mechanical pressures are simply absorbed by the structure. It should also be rigid enough to allow heavy, bass sounds to be made without distorting the material.
I looked into such materials as Perspex, Colored Acrylic Sheet and Sheet-metal but decided against these as they do not match the requirements as discussed above, I decided to use a dense hardwood (Jarrah) for my speaker box with a pine speaker faceplate.
I then started researching the best dimensions for my speaker box that would allow for minimal sound losses. I found a free computer program called WinISD. This program allowed me to choose many types of speaker drivers available on the market, test them at different frequencies, it then printed out the ideal dimensions and internal volume (cubed meters) required for my speaker box design.
I started hand drawing designs for the speaker box using measurements that I thought would suit my idea the best. Plans were drawn up with overall dimensions of 400 (l) x 160 (h) x 140 (d)
I then transferred these ideas into CAD drawings using Fusion 360, attached are my drawings, models and and a animated video on how i would like the box to join together.
Step 2: Preparing the Jarrah Sleeper
The sleeper that I had chosen for the project was quite dirty and rough and needed to be cleaned up for use.
The sleeper had a length of 2.4m, a width of 150mm and total thickness of 50mm and unfortunately at time of production, my table saw was out of action and I did not have a way to cut the sleeper into two separate pieces that were 25mm thick.
I sanded down all faces of the sleeper first using a portable belt linisher, this was to remove any dirt and grit that could have ended up ruining the blades on the thicknesser I was going to use.
Using the surface planer and thicknesser, I slowly shaved the Jarrah sleeper down to a 19mm thickness, once I was happy with the finish, I then used a radial arm saw to cut two finished/clean end grains.
Step 3: Cutting to Size
After marking out the all of the surface sizes i needed, I proceeded to cut the Jarrah to the correct size using the now operational table saw. I set the blade to the correct height and tested using a scrap piece of timber first.
I double checked my markings on the timber to the measurement guide on the table saw, ensuring that the saw blade thickness was taken into account.
Once the sides were cut I then started to mark out the rebate joints.
Step 4: Rebating the Box
To ensure easy fitting of the front speaker plate and rear plate to the speaker box, I decided to rebate the 4 sides of the box.
I originally decided to use a hand router and table router to cut the rebates in the Jarrah sides, after setting up the router and making an initial pass, I decided that using the radial arm saw would be a more effecient option.
I set the radial arm saw to cut to a depth of 9mm (Adjustment made in the 2nd photo) and starting rebating to a 19mm width. This would allow the left and right hand box sides to fit nicely in the top and bottom sections of the box.
I then started rebating the left and right sides on the box to allow the front speaker plate and rear plare to fit flush inside the box.
Once all sections had been rebated, i used the backside of a chisel to smooth out any burrs then passed over with a fine grit sandpaper.
Step 5: Gluing Up the Speaker Box
I then started to glue the box together using PVA glue, adjustable rapid set clamps and some masking tape. I also used a fake front plate with identical dimensions to the real speaker plate to sit inside the box when initally gluing.
Using a wet cloth and PVA glue, I lathered the rebate joints with the glue and started to assemble the box, I then clamped the box together. While carefully wiping the excess glue away, I placed masking tape of the clamped sections of the box and after letting the glue set for one hour, i removed the clamps and used the masking tape as the sole clamping mechanism.
Step 6: Organising the Speaker Electrics
Organizing the position of all of the components
Once the speaker box had been glued and dry, I started to place the electrical components around my speaker box to see how the components best fit. I found that the Amplifier had to be placed a certain way as many of the cables were not long enough to fit to the battery board.
Designing and Laser Cutting the component mounts
I did not want the electrical boards to sit directly onto the timber, especially when being fastened down tight. To overcome this I created mounting spaces and plates using clear Acrylic sheet and a laser cutter. Attached is my mounting designs.
Soldering the DC Jack, Speakers and the On/Off LED switch.
The next part was probably the easiest of the project, I was able to set up a small soldering station with a extraction fan and fine tipped soldering iron. I placed heat shrink on all wires that were to be soldered and then continued to solder the connections using a fine sized solder. The addition of heat shrink gives a level of protection to the soldered connections and to any possible cross polarity arcing.
Once the speakers were soldered, I placed them into the front plate and secured them using four M3 screws per speaker. The screws were inserted on an angle to ensure they didn't drive through the newly chamfered section of the faceplate.
Attached is the mounting board template I created
Step 7: Creating the Front Speaker Plate
When creating the front speaker plate, I had designed a CAD template using Fusion 360. I did this as I was able to convert the CAD drawing to an Adobe Illustrator file and create a marking template a laser cutter.
I decided to create this template as it allowed me to easily mark the location of speaker holes into the blank front face plate and all drilling points that were required.
I used a small 5mm drill bit to drill out the center point of each speaker hole, this allowed the hole-saw to be located correctly when initially drilling. I then used a 86mm hole-saw to drill the speaker holes, this was the closest size to the 90mm i required.
Using the drill press, I clamped down the timber and I drilled out the speaker holes in the front plate. Once they were cut, I then removed any rough points with 240 grit sandpaper.
Finishing the Front Plate
I then moved over to the workbench and set up the hand router to cut a chamfer in the newly drilled holes. I collected the correct cove router bit and set up the router so the bearing of the bit was resting on the lowest point it could in the speaker hole. This would allow for maximum chamfer to be cut while still allowing the router to continue on a same plane as the bearing would set where the router cut.
Once the holes were chamfered, I then ran over the plate with an orbital sander set with a 400 grit sanding disc, this removed any rough points on the plate. Once that was completed, I glued the front plate into the speaker box.
Step 8: Creating the Back Plate
Cutting the back to accept the Electrical Components
Once I had cut up the back plate to the right dimensions in Step Three I then had to find i way to mark out and create the sections required. I decided to draw it out on Adobe Illustrator and laser cut a template on MDF. This allowed me to place all of my electrical components in a practice piece and evaluate their look before cutting my main backing.
Once i was happy, I needed to cut a section of my backing plate to a 3-5mm depth to allow the electrical components to correctly fit. To cut this section out I used the radial arm saw and made cuts similar to the rebates already made in previous steps.
Once the back section had been cut to the correct thickness, I placed it in the laser cutter and continued to etch and cut the text and holes that were required.
Fitting all Electrical Components
The hardest issue of this backing design was the fact that the accessory board to be fitted was not designed with all solder components flush with each other. The Aux In port was higher than the USB, these both were higher than the added standby switch. This made it very hard to mount correctly and look elegant, I would not have bought this board if i knew this and I would NOT recommend this board to anyone.
I decided to laser cut up some spacers using clear 1mm Acrylic sheet and placed these spacers over the accessory board until the right depth was made.
Attached to this step is the Backing file that I made on Illustrator.
Step 9: Sanding and Finishing
The final steps to complete the timber section of the speaker box was to sand down then stain the box to create a quality finish.
I used an orbital sander in progressions of 100 grit, 240 grit and then 400 grit to sand down the speaker box, ensuring that i did not roll over on the edges when sanding.
Once the box had a nice finish I wiped it down with a dry cloth and organized it to be stained, I used a Burnishing oil for the Jarrah sections of the box and a clear coar for the Pine front.
When applying the burnishing oil I applied it heavily using 1200 grit sandpaper and sanded it into the timber, I then moved up to 2000 grit sandpaper to ensure a high gloss finish was made. I carefully wiped of any excess oil with a dry cloth, the areas of over oiling was easy to tell as over oiled sections were very gluggy when you ran your hand over them.
I repeated this step three times over a one week period before i was happy with the end result.
I applied clear coat on the front section the speaker box using a paint brush, this made it easy to get around the curved section of the plate. I let the coat to dry for a period of 4 hours and then sanded it back smooth. I repeated this step three times until i was happy.
Step 10: Installing All the Electrics Component / Finished Product
Once the speaker box was fully stained, I carefully removed the back section and started to install all of the electrical components permanently. I tried to keep the wiring tight by using cable ties to clasp wiring together and routing it so it was clear of any pinch points when the back was removed.
Step 11: Evaluating My Speaker Box
I am very happy with my end product, The finish of the box is fantastic and I was very happy with the finish the burnishing oil gave to the Jarrah.
I was glad I put effort into researching speaker design and speaker types as the sound from the speaker is fantastic. The highs makes the room alive while any vocals in songs are crystal clear.
The best thing about this project is the effort and research to create it was immense I learnt many new and rewarding things. Having an exact idea of what I wanted it to look like even before I started gathering materials and parts was a big savior and my finished product looked pretty close to the one i designed on CAD. I am truly proud of that fact opened up my horizons and attempted this build.
I look forward to possibly bringing this into a Year 11 or Year 12 school curriculum and passing on my woodworking, advanced manufacturing and electronics knowledge base.