Silicone Injector Gives Parts Production A Shot In The Arm

Many of us are happy to spend hours cooking up a solution that saves us seconds, if success means never having to do a hated task again. [frankensteinhadason] molds enough silicone parts that he grew tired of all the manual labor involved, so he built a silicone injector to do it for him. Now, all he has to do is push the handle in notch by notch, until silicone starts oozing from the vent holes in the mold.

The mold pictured above is designed to make little shrouds for helicopter communications connections like this one. His friends in the industry like them so much that he decided to sell them, and needed to scale up production as a result. Now he can make six at once.

He designed brackets to hold a pair of syringes side by side against a backplane. There’s a lever that pushes both plungers simultaneously, and adapters that keep the tubing secured to the syringe nozzles. Ejected two-part silicone travels down to a double-barrel mixing nozzle, which extrudes silicone into the top of the mold.

Naturally, we were going to suggest automating the lever operation, but [frankensteinhadason] is already scheming to do that with steppers and an Arduino. Right now he’s working on increasing the hose diameter for faster flow, which will mean changes to the adapter. Once that is sorted, he plans to post the STLs and a video of it pumping silicone.

Ever thought about doing the reverse, and using silicone to mold hot plastic? Yeah, that’s a thing.

Via r/functionalprint

DIY Watertight Junction Box For Serious Outdoor Sealing

Thingiverse user [The-Mechanic] shared a design for 3D printed enclosures that are made to house wire and cable junctions, which can then be rendered weatherproof by injecting them with a suitable caulking compound and allowing it to cure. It’s a cross between an enclosure and potted electronics. It’s also a one-way trip, because the result is sealed up like a pharaoh’s tomb. On the upside, it’s cheap, accessible, and easily customized.

The way it works is this: wires go through end caps which snap onto the main body, holding the junction inside. Sealant is then pumped in via the hole on the side, then the hole is plugged. Afterwards, all there is to do is wait until the sealant cures. [The-Mechanic] has a couple of companion designs, as well. For tubes of sealant that have threaded tops, one can more effectively save the contents of the tube for later with this design for screw-on caps. There are also 3D printed nozzles in a variety of designs.

One thing to keep in mind about silicone-based sealants is that thick gobs of it can take a really, really long time to cure fully. A thick gob of the stuff will tend to firm up on the outside but leave the inside gooey. If that will be a problem, maybe take a cue from Oogoo and mix in a bit of corn starch with the silicone sealant. The resulting mixture will be thicker, but it’ll cure throughout with no problems.

Project Egress: Two Ways To Latch The Hatch

With July slipping away and the deadline approaching, the Project Egress builds are pouring in now. And we’re starting to see more diversity in the choice of materials and methods for the parts being made, like these two latches made with very different methods by two different makers.

For the uninitiated, Project Egress is a celebration of both the 50th anniversary of Apollo 11 and the rise of the maker movement. Spearheaded by [Adam Savage], the idea is to engage 44 prominent makers to build individual parts from the Unified Crew Hatch (UCH) from the Apollo Command Module. The parts will be used to create a replica of this incredibly complex artifact, which will be assembled by [Adam] before a live audience at the National Air and Space Museum next week.

Both [Joel] from the “3D Printing Nerd” channel and [Bill Doran] from “Punished Props Academy” got the nod for one of the 15 latches needed, and both played to their respective strengths. [Joel]’s latch was executed in PLA on a Prusa I3 printer. [Bill] went a different route for his latch. He used a Form 2 SLA printer to print the parts, but used them only to make silicone molds. He then cast the parts from urethane resin, which should prove much stronger than the original SLA prints. We suspect the ability to quickly cast more latches could prove handy if any of the other latch makers should fail to deliver.

The latches [Joel] and [Bill] made joins the other parts, like the wooden latch being made by [Fran Blanche] and the hatch handle [Paul] cast in aluminum. We’re looking forward to more part builds, as well as the final assembly.

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Vintage Fairchild IC Proves Tough To Decap

You’d think that something called “white fuming nitric acid” would be more than corrosive enough to dissolve just about anything. Heck, it’s rocket fuel – OK, rocket fuel oxidizer – and even so it still it wasn’t enough to pop the top on this vintage Fairchild μL914 integrated circuit, at least not without special measures.

As [John McMaster], part of the team that analyzed the classic dual 2-input NOR gate RTL chip from the 1960s, explains it, decapping modern chips is a straightforward if noxious process. Generally a divot is milled into the epoxy, providing both a reservoir for the WFNA and a roughened surface for it to attack. But the Fairchild chip, chosen for dissection for the Maker Faire Bay Area last week specifically because the features on the die are enormous by modern standards, was housed in an eight-lead TO-99 case with epoxy that proved nigh invulnerable to WFNA. [John] tried every chemical and mechanical trick in the book, going so far as to ablate epoxy with a Nd:YAG laser. He eventually got the die exposed, only to discover that it was covered with silicone rather than the silicon dioxide passivation layer of modern chips. Silicone can be tough stuff to remove, and [John] resorted to using lighter fluid as a solvent and a brush with a single bristle to clean up the die.

We applaud the effort that this took, which only proves that decapping is more art than science sometimes. And the results were fabulous; as Hackaday editor-in-chief [Mike Szczys] notes, the decapping led to his first real “a-ha moment” about how chips really work.

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Building Keyboards With Resin Printers

Aside from putting a whole lot of tact switches on a board, no one has quite figured out how to make very small keyboards for wearable projects. [Madaeon] might have the answer, and it’s using a resin-based 3D printer to create a flexible keyboard without silicone.

The world of small keyboards is filled with what are effectively the squishy parts of a remote control. This uses a piece of silicone and tiny carbon ‘dots’ on the underside of each button. Press the button, and these carbon dots bridge two traces on a PCB, closing a switch. No one has yet mastered home-casting silicone, although the people behind the ESP32 WiPhone have been experimenting with aluminum molds.

Instead of going down the path of casting and curing silicone, [Madaeon] decided to use 3D printing, specifically resin 3D printing, using a very flexible resin. The build process is what you would expect — just some button-shaped objects, but this gets clever when it comes to bridging the connections on the keyboard matrix. This is done with conductive paint, carefully applied to the underside of each button.

Right now this is a viable means of getting a tiny keyboard easily. The color is a garish pink, and the labels on each button aren’t quite as visible as anyone would like, but the latter can be fixed with silkscreening, just like how it’s done on the silicone buttons for remote controls.

Need A Small Keyboard? Build Your Own!

If you want keyboards, we can get you keyboards. If you want a small keyboard, you might be out of luck. Unless you’re hacking Blackberry keyboards or futzing around with tiny tact switches, there’s no good solution to small, thin, customization keyboards. There’s one option though: silicone keyboards. No one’s done it yet, so I figured I might as well.

Unfortunately, there is no readily available information on the design, construction, or manufacture of custom silicone keypads. There is a little documentation out there, but every factory that does this seems to have copy and pasted the information from each other. Asking a company in China about how to do it is a game of Chinese Whispers. Despite this, I managed to build a custom silicone keypad, and now I’m sharing this information on how to do it with you.

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Reproducing Vintage Plastic Parts In Top-Notch Quality

Plastic is a highly useful material, but one that can also be a pain as it ages. Owners of vintage equipment the world over are suffering, as knobs break off, bezels get cracked and parts warp, discolor and fail. Oftentimes, the strategy has been to rob good parts from other broken hardware and cross your fingers that the supply doesn’t dry up. [Eric Strebel] shows us that’s not the only solution – you can replicate vintage plastic parts yourself, with the right tools.

In the recording industry there’s simply no substitute for vintage gear, so a cottage industry has formed around keeping old hardware going. [Eric] was tasked with reproducing VU meter bezels for a classic Neve audio console, as replacement parts haven’t been produced since the 1970s.

The first step is to secure a good quality master for replication. An original bezel is removed, and polished up to remove scratches and blemishes from 40+ years of wear and tear. A silicone mold is then created in a plywood box. Lasercut parts are used to create the base, runner, and vents quickly and easily. The mold is then filled with resin to produce the final part. [Eric] demonstrates the whole process, using a clear silicone and dyed resin to make it more visible for the viewer.

Initial results were unfortunately poor, due to the silicone and hardener used. The parts were usable dimensionally, but had a hazy surface finish giving very poor optical qualities. This was rectified by returning to a known-good silicone compound, which was able to produce perfectly clear parts first time. Impressively, the only finishing required is to snap off the runner and vents. The part is then ready for installation. As a final piece of showmanship, [Eric] then ships the parts in a custom laser-engraved cardboard case. As they say, presentation is everything.

With modern equipment, reproducing vintage parts like knobs and emblems is easier than ever. Video after the break.

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