Have you ever had a pair of ear buds fit perfectly out of the package? Probably not. Well, [Joe] decided to take matters into his own hands and cast his own silicone ear bud covers custom made for him.
The traditional route would have been to make an ear bud model, make a mold from it, cast a copy from it… etc, etc. But [Joe] wanted to try something else — he designed and 3D printed the two-part mold, and used plain old silicone caulking to fill it.
First he 3D modeled the ear bud covers in SolidWorks, then he had to learn how to design the mold for it, but luckily, there’s a handy tutorial. After printing the mold he opted to use 100% silicone caulking in order to make the part since he had some lying around the house. The problem is, this stuff can take days to cure — unless you mix in some cornstarch.
The golden ratio [Joe] found was about 5:1 silicone to cornstarch, which resulted in a cure time of about 20 minutes.
After curing you just need to trim off the excess silicone. In the molding process this is known as “flash”.
Since this is caulking he’s using, you’re going to want to wash off the part a few times because this type of silicone produces acetic acid as it cures.
The ear buds fit great and inspired [Joe] to try molding even more things, like a custom sleeping mask using the 3D scan of your own face!
Mold making is a hacking skill we see pop up around here from time to time. But rarely do we hear about problems in the process, and they must happen. Here’s proof. This Fail of the Week focuses on [Michael’s] unfortunate experience with failed mold making due to uncured silicone around the master mold. It’s worse than it may sound, since he lost about a pound of silicone to the fail, and we’re unsure of whether he can even use the master again (how do you clean uncured silicone off of something?). Not to mention the time lost from setting up the pour and waiting 20 hours for it to cure.
Soon after the issue presented itself [Michael] started researching to see what had gone awry and noticed that the master should have been sealed with acrylic lacquer. This gave him the opportunity to test several different finishes before making a run at the full mold once again. He picked up a variety of the paint products he could find locally, used them to coat some scraps, and globbed on some silicone to see which worked the best. He found a couple of different primers worked well, as did both glossy and matte acrylic coatings.
If you’ve never had a reason for mold making before, keep it in mind. You’d be surprised what kind of factory-production-type things can be pulled off by 3D printing a master, and casting a silicone mold of it.
Fail of the Week is a Hackaday column which runs every Wednesday. Help keep the fun rolling by writing about your past failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.
The folks at SC-3000 survivors have been working on a cartridge capable of storing dozens of games for the ancient Sega SC-3000 computer. The PCB works beautifully, but making a case for their cartridge left them with few options. They could use a 3D printer or simply collect a whole bunch of used cartridge cases, but making their own mold for a cartridge case was the best solution.
To create the mold for their multicart enclosure, the SC-3000 survivors first took an old, used case and made a silicone mold. While the first attempt at mold making was encouraging, several problems began to crop up due to the lack of vent holes and wiggling the mold before the resin had set. Before long, a proper technique to make resin casts was developed: use lots of resin, and don’t apply pressure or rubber bands to a curing mold.
We’re always impressed by what can be done with a few sheets of plastic, some Bondo, and the inordinate amounts of patience and sandpaper we see with other case mods and enclosure builds. the SC-3000 survivors put together an enclosure that rivals any Bondo build, and we’re happy they put out this tutorial.