Basic geocaching consists of following GPS coordinates to a location, then finding a container which is concealed somewhere nearby. Like any activity, people tend to add their own twists to keep things interesting. [Jangeox] recently posted a video of the OLED Snail 2.0 to show off his most recent work. (This is a refinement of an earlier version, which he describes in a blog post.)
[Jangeox] spices up geocaching by creating electronic waypoints, and the OLED Snail is one of these. Instead of GPS coordinates sending someone directly to a goal, a person instead finds a waypoint that reveals another set of coordinates and these waypoints are followed like a trail of breadcrumbs.
A typical waypoint is an ATTINY85 microcontroller programmed to display an animated message on the OLED, and the message reveals the coordinates to the next waypoint. The waypoint is always cleverly hidden, and in the case of the OLED Snail 2.0 the enclosure is the shell of a large snail containing the electronics encased in resin. This means that the devices have a finite lifespan — the battery sealed inside is all the power the device gets. Fortunately, with the help of a tilt switch the electronics can remain dormant until someone picks it up to start the show. Other waypoints have included a fake plant, and the fake bolt shown here. Video of the OLED Snail 2.0 is embedded below.
It may seem somewhat obvious to mix up resin in a disposable or reusable plastic cup. But not all cups are created equal. Polypropylene cups won’t outgas into your resin, but polystyrene will. If you use a silicone cup or any polypropylene food container marked #5/PP, cured resin will peel cleanly off of the cup walls.
For some reason, the giant jugs of resin [Botzen Design] uses don’t come with pumps. How do they expect someone to meter out exact amounts of resin and hardener while pouring them out of gallon jugs? Stadium-style condiment pumps at a restaurant supply store make things much simpler while avoiding costly spillage.
Our favorite tip (and seemingly [Botzen Design]’s as well) is the drip hammer. When air bubbles mature into craters, they can be filled easily and precisely with a drop or two of wet resin. A pipette would probably just get clogged, but an icicle of cured resin hanging from a stick makes the perfect drip applicator.
What do you do when someone gives you a Wurlitzer 3100 jukebox from 1969, but keeps all the records? If you are like [Tijuana Rick], you grab an Arduino and a Rasberry Pi and turn it into a really awesome digital music player.
We’ll grant you, making a music player out of a Raspberry Pi isn’t all that cutting edge, but restoration and integration work is really impressive. The machine had many broken switches that had been hastily repaired, so [Rick] had to learn to create silicone molds and cast resin to create replacements. You can see and hear the end result in the video below.
[Rick] was frustrated with jukebox software he could find, until he found some Python code from [Thomas Sprinkmeier]. [Rick] used that code as a base and customized it for his needs.
There’s not much “how to” detail about the castings for the switches, but there are lots of photos and the results were great. We wondered if he considered putting fake 45s in the machine so it at least looked like it was playing vinyl.
From animatronic dinosaurs to [Jeff Goldblum]’s prosthetic chest hair, Jurassic Park is known for its practical effects and props. While it’s not as fancy as a breathing triceratops, YouTube’s god of resin casting has recreated one of the more endearing props from this movie. [Peter Brown] and [Pocket83] made a replica of the amber-topped cane carried by John Hammond, and it took him two years to do it.
The ‘mosquito in amber’ walking cane prop from Jurassic Park is just what you think it is – a large mosquito-looking bug trapped in 100 million year old amber. Of course, finding such a chunk of amber with the included mosquito would cost a fortune, so [Peter] turned to polyurethane resin. This block of resin was cast in two halves, with a ‘mosquito eater’ (or a crane fly) embedded in the middle. It took two years for [Peter] to cast this block of amber, but really all but two weeks of that was waiting for a few adult crane flys to appear.
With a bug encased in resin, the project went over to [Pocket83] who turned the walking cane on his lathe. There’s not much to this part of the build except for drilling a three-foot long hole down the center of a piece of wood, although the finish does make this cane look spectacular.
The long wait for crane fly breeding season was worth it. This is one of the best looking functional props from Jurassic Park. You can check out the videos for this build below.
Some of us have looked at clear resin jewelry casting kits online and started to get ideas. Hackaday’s own [Nava Whiteford] decided to take the plunge and share the results. After purchasing a reasonably economical clear resin jewelry casting kit from eBay, a simple trial run consisted of embedding a solar lantern into some of the clear resin to see how it turned out. The results were crude, but promising. A short video overview is embedded below.
The big hangup was lack of a proper mold. [Nava]’s attempt to use a plastic bag and a cup as an expedient stand-in for a proper mold was not without its flaws, and the cup needed to be broken before the cured resin could be removed. Despite this, the results were good; the mixing needed careful measurement and the curing process was lengthy but the cured resin is as attractive as the advertisements promise. Mixing introduced many air bubbles into the mixture, but most of them seemed to disappear on their own during the curing process. The results of this quick test may not be pretty, but the resin seems to have held up its end of the bargain and delivered the expected smooth, clear finish.
If the [realjohnnybravo] is the one from the show, it appears he finally managed to get a girlfriend, marry her, and produce at least one son. As the old schoolyard rhyme goes, first comes love, then comes marriage, then comes filling the whole *!$&# backyard with brightly colored plastic garbage. One of these items, a Power Wheels quad bike, suffered a blow from planned obsolescence leaving behind a traumatized child. [realjohnnybravo] decided to fix it.
He made frequent mention of how one could go to a store and purchase replacement gears for the toy. Perhaps it’s a German thing. Regardless, he shows experience with internet comments by justifying his adventure in gear manufacturing with, paraphrased, “I’m having fun and learning so back off you pedantic jerks.”
Resin casting is great, and is often overlooked vs 3D printing. He purchased some hardware store RTV silicone and some slow-cure resin. The faster cure resin would get too hot with this much volume and potentially burn.
Materials procured he took apart both gearboxes from the machine. He first made a silicone mold of the broken parts (from the good copies out of the working gearbox) and removed the master. Without a vacuum or pressure casting chamber, the molds came out a little rough and bubbly, but it’s nothing some work with a carpet knife can’t fix. For big gears like this it hardly matters. Next he poured the two part resin into the molds and waited.
After some finishing with regular woodworking tools the parts fit right into the voids in the defective gearbox. His son can once again happily whir around the lawn, until the batteries die anyway.
Sometimes we need the look, feel, and weight of a metal part in a project, but not the metal itself. Maybe you’re going for that retro look. Maybe you’re restoring an old radio and you have one brass piece but not another. It’s possible to get a very metal like part without all of the expense and heat required in casting or the long hours in the metal fabrication shop.
Before investing in the materials for cold casting, it’s best to have practical expectations. A cold cast part will not take a high polish very well, but for brushed and satin it can be nearly indistinguishable from a cast part. The cold cast part will have a metal weight to it, but it clinks like ceramic. It will feel cool and transfers heat fairly well, but I don’t have numbers for you. Parts made with brass, copper, and iron dust will patina accordingly. If you want them to hold a bright shine they will need to be treated with shellac or an equivalent coating afterward; luckily the thermoset resins are usually pretty inert so any coating used on metal for the same purpose will do.
It is best to think of the material as behaving more or less like a glass filled nylon such as the kind used for the casing of a power tool. It will be stiff. It will flex a relatively short distance before crazing and then cracking at the stress points. It will be significantly stronger than a 3D printed part, weaker than a pure resin part, and depending on the metal; weaker than the metal it is meant to imitate.