Introduction: 3D Hexagonal Dimple Hifi Speakers | CNC Front Baffle
I recently came across these wood textures on Pinterest and they peaked my interest into making some sort of 3D textured speaker build. I had also just set up my new Shapeoko 3 XXL so was looking for an excuse to make something with it.
So the scene was set, I set out to come up with a design for a solid wood speaker baffle that I could carve on my upgraded Shapeoko cnc machine.
Of the 4 textures, the honeycomb is my favourite and so this is what I set out to try and carve! Next step: figuring out how to cad and cam this up to get it made on the cnc.
If you enjoy this Instructable please do check out some of my other builds either here on Instructable or on my Instagram! I also upload some of the things I make to my Etsy so please do take a look! And please vote for this build in the audio contest! Thank you :)
Hardwood for baffles
MDF for cabinets
CNC Router for the textured surface
Step 1: CAD
To form the pattern of heaxgonal dimples, I first had to figure out the best approach for forming them in Fusion 360. I started out, naturally, with a close packed grid of 4 hexagons and off set a plane below them. On this plane, which was 4mm below the surface of the wood, I added a point in the middle of the hexagons. A loft function could then be used with smooth transitions to form the dimple shape, simple really!
Next, I used a rectangular pattern function to cover the entire surface of the baffle with the dimples. I had already dimensioned the baffles based on some calculations done in WinISD but I won''t go into too much detail on that for this build i'm afraid!
A cutout was made for the actual speaker driver and I revolved a chamfer around the speaker cut out as shown in the photos. Normally I would add some features to the backside of the baffle to make the speaker driver sit better against the baffle but I didn't feel it necessary from past experience with these drivers.
Lastly, using the baffle and the calculations for optimum volume I added the cabinet to visualize how the speaker would look when finished.
Step 2: CAM
The next step in Fusion 360 was to generate tool paths for the front baffle. Because the machining of the chamfer around the speaker would be carried out by the final finishing pass, I decided to cut out the circle for the speaker first. Then, I would run the finishing tool path to machine the hexagon dimples and finally run a contour operation to bring the baffle to final size.
The finishing tool path was done with a 6mm ball mill and a 0.3mm stepover to reduce the need for sanding afterwards. Due to the small stepover, this tool path could be run fast at around 3000mm/min on my shapeoko 3 xxl. This resulted in a cutting time of 1h30m per front baffle.
I also generated some simple tool paths for the back panel to cutout holes for the binding posts and the bass port.
Step 3: Material Prep
Normally, I would chose white oak for the front baffle material. However, I wanted to try something a bit darker, more exotic and something I hadn't worked with before. I settled on wild mango which I was able to get from my local timber supplier. This wood is nice and dark with intriguing orange tints throughout the grain pattern. I had a hunch that the dimples should accentuate the colour when oil is applied. I cut two blanks with a bit of margin around the outside for the CNC router to machine away.
For the cabinets, I find it quicker to build them the traditional way now I have a track saw and mitre saw. The process is quicker and more simple than using the CNC. MDF is my material of choice as it is consistent, easy to work with and cheap. I ripped lengths of MDF to the correct widths to make the cabinet components with the track saw.
Step 4: Machining the Baffles
The mango boards were attached on the spoilboard with the masking tape and super glue technique; this gives access to all sides for machining and removes the need for clamps and tabs. With the cutout for the speaker finished, I loaded a 6mm ball mill and then started the long 3d machining tool path. Normally I would leave the machine to do it's thing but this was one of the longest things I had run on my CNC so I kept myself busy in the workshop to keep an eye on it!
Once this was completed, I ran the final contour tool path to finalise the dimensions of the front baffle. I then used a chisel to clean up the chamfer around the speaker cutout to smooth the transition where the machining met the pre-cutout speaker cutout.
Wit that all done, the last thing to do at this point was to do a light sanding on the dimples before finishing. A foam sanding pad makes this super easy as it conforms to the contours of the machined features very well.
Step 5: Making the Cabinets
These were just simple, mitered edge, mdf boxes. All mitres were cut on the mitre saw set at 45 degrees with an electronic level. These parts where then assembled with masking tape to hold the edges tight as the glue dried. When the glue dried I then added dowels to strengthen the joints and flush trimmed the dowels before finishing.
Step 6: Cabinet Finishing
The cabinets were sanded up to 400grit and then blown down with compressed air. I primed and painted the cabinets with satin wall paint, applied with a soft foam roller.
Step 7: Routing Slot for Back Panel
Admittedly, I should have done this before painting but I then routed the rabbet for the back panel. This was done with the appropriate router bit, set at a depth matched to the thickness of the back panel. I intended to use a piece of dense laminate flooring for the back panel as it is essentially pre-finished!
Step 8: Mounting Baffle to Cabinet
First, the speaker was attached to the baffle as it is easier to do so now rather than when the cabinet is glued in place. With the speaker secured with super glue and screws, I used dowels to create good alignment between the baffle and the cabinet to make the glue up more reliable and allow for easy clamping without the two parts sliding around and out of alignment.
I then used normal wood glue to attach the two parts and clamps all around to ensure a tight seal. Padding was used to prevent the clamps from marring the dimples or painted surface of the cabinet.
Step 9: Rear Panel
Using the same tape and super glue technique to hold the stock down to the spoilboard, the back panel was machined with its two cutouts for the bass port and the binding posts.
Step 10: Attaching the Panel and Wiring.
I soldered the speaker up and then installed the back panel with white silicon. The binding posts could then be soldered onto the speaker wire. Last of all, the speaker could be stuffed with polyester stuffing and then I installed the bass tube. These back panel fittings all had a bead of silicon around them to completely seal any gaps.
Step 11: Finished! + What I Would Do Differently
Last thing to do was to test out the sound and get some beauty shots!
I love the way that the textured baffles really emphasize the wood grain and colour, this was the main purpose of the build and I think this aspect turned out the best. The sound is decent with strong bass and a good mid range. Because the drivers are coaxial and fairly cheap, the highs are a bit sharp but these could be swapped out in the future as they are a standard size.
Although the cabinets are quite nice I would like to add the textured paint that I have added to my other builds as I am still a huge fan of this finishing technique but I can always do this in the future.
I am keen to try out some different 3D textures in some future projects and also experiment with different woods more to see how the grain pattern interacts with the 3D textures.
I hope you enjoyed this quick build and please do check out some of my other projects here on Instructables or on Instagram!
Second Prize in the
Audio Challenge 2020