I volunteer at a teen makerspace at The Denver Public Library. There, we have some ten pairs of over-ear headphones. These headphones get much use and invariably wear out. The typical failure point is a little piece of plastic that connects the ear piece to the headband (see above). Our first repair method was to use an adhesive tape. This, however, would only hold together for a few days before slipping apart, and it severely limited the swivel movement, not to mention the gooey adhesive mess. What we needed was a custom-molded piece of rigid replacement plastic. While we have a 3-d printer, and may have been able to print this level of detail, affixing the printed-piece back to the cylinder would be very difficult. I then found sugru and decided to sculpt a custom piece, hoping that this material would bond strongly to the plastic cylinder and harden to a similar rigidity of plastic.
This particular headphone model is the Sennheiser HD 201. I have no idea if its construction follows any sort of industry standard. Thus, the following steps may not be applicable to your headphone repair needs, but at the least they should give you a good sense of my process and highlight a new and very useful repair product: sugru.
Step 1: What Is Sugru?
Sugru is a self-setting rubber, a pliable putty-like material that when warmed with your hands can be shaped and molded, and it adheres to nearly any surface. Once “set” (recommended 24 hour period) it acts as a rigid and durable rubber. Sugru comes in three primary colors, black, and white.
Clean the plastic cylinder well with rubbing alcohol. Then wash and dry your hands. With clean hands take a small chunk of of sugru and work it between your fingers. Eventually make a small cylinder that will fit inside the plastic cylinder. Push that yellow cylinder inside the plastic and let the overflow stick out of the top.
Now move back to the ear piece (A). Remove the cushion, it just snaps out. Then, unscrew the speaker from the plastic case (B). Next, remove the wishbone plastic piece; with little force, it snaps out of the track (C). Find the four screws on the wishbone, remove them, and then detach the two plates (D). We’ll call these the wishbone back plate and front plate, respectively as they lay left to right. The two wishbone plates (D) will be referenced often in this instructable. The headband cylinder fits into the hole of the wishbone back plate (E). Later, we'll come back to the front plate.
Find a straight and thin gauge (as rigid as possible) piece of wire. For this, I used the pin-back of a political candidate’s button. Cut two equal-length pieces from the wire. It is not necessary that they are sharpened like the picture below. These wire pieces will act as a T-shaped skeleton and will add rigidity to the rubber. Sink the parallel wire in the center of the yellow mass, and push it down until it bottoms out.
Insert the headband cylinder into the wishbone hole. You'll notice the tip of the wire peeping out of the yellow mass. As we move forward and sculpt the yellow mass, we will not be able to remove the headband cylinder from the wishbone back plate.
Now, flatten the yellow mass and place the top (of the T) wire atop the mass.
Add a pea-size chunk of sugru and completely cover the wire with the yellow mass.
Continue sculpting to create a T-shaped yellow mass. Add and remove sugru as necessary.
Keep sculpting, adding or removing mass so that you can easily fit the wishbone front plate back on. Of course this takes much trial and error. With too much sugru or too warm sugru, the mass will stick to the collar of the front plate. What we’re really aiming to do is to cast the mold from the front plate dimensions. This takes a good deal of time to complete. Once you find an appropriate shape, remove the wishbone front plate and let the sugru sit to cure for at least 24 hours, but surely the longer the better; I waited one week.
After the 24-hour curing process is complete, go ahead and reassemble. See step 3 ; reverse the sequence to reassemble.