Following on from my first post on the design of my custom headphones, in this part I walk through the construction of the speaker housing. The most obvious place to start construction is in the piece that will hold the speakers. The idea here was to basically turn a box, with a 40mm internal diameter to take the speaker.
I chose some Padauk to make the speaker housings from, it's a really nice colour
The shavings were bright red!
The spaker will rest flat facing the bottom of the 'box' so I needed to drill holes to allow the sound through. The holes also provided a guide on the wall thickness of the base. So I was able to get a nice even and fairly thin base.
The 'lid' of the box will face out and I decided to engrave the letters 'L' and 'R' in the respective left and right ends. Being a turner I tried to keep a grain match so I needed to pay attention to what the orienatation of the box would be. The underside would need a small hole drilled to accept the speaker wire, and the cap would want the engraved letter vertical at the point the grain is alligned. Also the cap piece would be the pivot point when I made a ring to hold the speaker housings. So the cap pieces got a 6mm hole drilled through, at right angles to the orientation of the engraved letters on the end.
The last detail was a narrow groove a little in from the end that I intended the leater covering to pull into when stitched around. I just used my narrow parting tool and was careful not to go too deep. I'd come to far to accidentally chop the thing in half, so not a time to get careless.
In many ways this was easier than turning a real box since no one would see the interior so there was no finishing to be done there.
Whilst I was careful to measure the internal diameter it was not possible to check with the speaker until I completed the turning and finishing. Afterall, I couldn't risk the speaker getting stuck in place and not being able to turn it more with the speaker in place.
Fortunately I got a nice snug fit, and the speaker slid into place:
The next thing I made was a wooden former to fit around my ear. I actually started with a paper template, which I traced onto a piece of oak board. First I cut out the internal shape with a coping saw. Then I cut the exterior profile on the bandsaw. Lastly I used a drum sander gripped in my lathe chuck jaws, and used it to smooth the edges both inside and out.
Then I tested the assembly against my ear:
This let me figure out exactly where I wanted to glue the speaker box to the oak ring.
Before glueing the two pieces together I had to prepare the oak ring to be covered in leather. The idea was simple enough, drill holes at regular spacing around the outside through into the internal edge. These holes needed to be large enough for a needle and thread to pass through. So that I could literally stitch the leather onto the oak ring.
Also I fixed some foam to the face of the ring to provide padding. In my search for some suitable padding I hit upon the idea to just buy some large sponges (the kind used to was cars) and cut the padding I needed from them. This proved to be a reasonable choice, with just enough density to provide padding without being too hard.
I also turned the ring that would how the whole assembly to the headband, this was a simple oak ring, turned much as you might a bracelet. I just hot melt glued a block to a board, and turned a bead profile before hollowing to get the ring shape. I drilled 6mm holes at either end so that I could turn a 6mm diameter pin to go all the way through the ring and the end cap of the speaker housing, providing a pivot.
Here I test the pivot just using a screwdriver
And so I had the main piece assembled. Next I just had to break out the sewing kit...
I didn't remember to take and in progress pics, it took me about an hour I think, whilst watching tv. The material I chose was some leather. This came from a jacket I wore for well over 10 years, and now finds it's way into various projects where I need a tough but supple material. (It's good to recycle!)
The stitching isn't super neat, and the spacing wasn't terribly even, but it worked pretty well as I expected. I cut a circle in a piece of leather just smaller than the diameter at the bottom of the little grove I cut to take the back of the leather cover. Then kinda went on instinct with sewing, and cutting until I had a completely covered earpiece:
Once done, all I had to do was repeat the entire exercise for the left ear! I could have kept both in step, but it wasn't until I got to this point that I was confident I'd wind up with something that worked.
The second time through most things went quicker as I was familiar with the process. The only panic moment was when I mounted the main box section on my expanding jaws to get at the bottom. I turned on the lathe and heard a 'crack' when I stopped it again I found a split ran down the grain, through the small hole I'd drilled for the speaker wire. I dabbed a little superglue in the gap, then backed off the expansion on the jaws to let it seattle back shut. Then was super careful in remaining operations to avoid further problems. So basically 'keep calm and carry on'...
In the final instalment I'll cover what the wires coming out the top of the rings are for, and how the headband construction was done, leading to the final finished piece.