Over-molding Wires With Hot Glue And 3D Printed Molds

August 2, 2024 by Dan Maloney 48 Comments

We’ve said it before and we’ll say it again: water always finds a way in. That’s particularly problematic for things like wire splices in damp environments, something that no amount of electrical tape is going to help. Heat shrink tubing might be your friend here, but for an electrically isolated and mechanically supported repair, you may want to give over-molding with a hot glue gun a try.

The inspiration for [Print Practical]’s foray into over-molding came from a video that’s making the rounds showing a commercially available tool for protecting spliced wires in the automotive repair trade. It consists of a machined aluminum mold that the spliced wires fit into and a more-or-less stock hot glue gun, which fills the mold with melted plastic. [Print Practical] thought it just might be possible to 3D print custom molds at home and do it himself.

His first attempt didn’t go so well. As it turns out, hot glue likes to stick to things — who knew? — including the PETG mold he designed. Trying to pry apart the mold after injection was a chore, and even once he got inside it was clear the glue much preferred to stay in the mold. Round two went much better — same wire, same mold, but now with a thin layer of vegetable oil to act as a release agent. That worked like a charm, with the over-mold standing up to a saltwater bath with no signs of leaking. [Print Practical] also repaired an iPhone cable that has seen better days, providing much-needed mechanical support for a badly frayed section.

This looks like a fantastic idea to file away for the future, and one that’s worth experimenting with. Other filament types might make a mold better able to stand up to the hot glue, and materials other than the ethylene-vinyl acetate copolymer found in most hot glue sticks might be explored. TPU over-molds, anyone? Or perhaps you can use a printer as an injector rather than the glue gun.

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Repairs You Can Print: Better Cable Splicing With 3D Printed Parts

February 16, 2018 by Brian Benchoff 20 Comments

A while back, [Marius] was faced with a problem. A friend of his lives in the middle of a rainforest, and a microphone was attacked by a dirty, greasy rat. The cable was gnawed in half, and with it went a vital means of communication with the outside world. The usual way of fixing a five- or six-conductor cable is with heat shrink, lineman’s splices, insulating tape, and luck. [Marius] needed something better than that, so he turned to his 3D printer and crafted his own wire splice enclosure.

The microphone in question is a fancy Jenal jobbie with a half-dozen or so conductors in the cable. A junction box was the obvious solution to this problem, and a few prototypes, ranging from rectangular to fancy oval boxes embossed with a logo were spat out on a 3D printer. These junction boxes have holes on either end, and when the cable ends are threaded through these holes, the wires can be spliced, soldered, and insulated from each other.

This microphone had to hold up to the rigors of the rainforest and rats, so [Marius] had to include some provisions for waterproofing. This came in the form of a hot glue gun; just fill the junction box with melted hot glue, pop the cover on, and just wait for it to cool. Like all good repairs, it works, and by the time this repair finally gives out, something else in the microphone is sure to go bad.

It’s a great repair, and an excellent example of how a 3D printer can make repairs easy, simple, cheap, and almost as good as the stock part. You can check out a few videos of the repair below.

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Repairs You Can Print: Fixing A Rat-Attacked Mic Cord

February 5, 2018 by Dan Maloney 23 Comments

We’ve all been there — a steamy night in the rainforest of Papua New Guinea, sweaty slumber disturbed by the unmistakable sounds of gnawing. In the morning we discover that a rodent of unusual tastes has chewed the microphone cable of our transceiver right half in two, leaving us out of touch with base camp. If we had a nickel for every time that’s happened.

It may sound improbable, but that’s the backstory behind [Marius Taciuc]’s 3D-printed mic cord repair. Even with more mundane failure modes, the retractile cords on microphones are notoriously difficult to fix. Pretty much any of the usual suspects, like heat-shrink tubing or electrical tape, are going to do very little to restore the mechanical stability lost once that tough outer jacket is breached. [Marius]’s solution was to print as small an enclosure as possible to mechanically support the splice. The fit is tight, but there was just enough room to solder the wires and stuff everything back in place. Cable ties provide strain relief where the cord exits the splice, and a liberal squirt of hot glue pots the joint. It’s not perfect — we’ll bet the splice acts as a catch point and gets a little annoying after a while — but if it gets you back on the air fast and cheap, it probably makes sense.

[Marius] entered this rat-race beating hack into the Repairs You Can Print contest. Do you have an epic repair that was made possible by a 3D printer? Let the world know about it and you might just win a prize.

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Hackaday Links: July 25, 2010

July 25, 2010 by Mike Szczys 20 Comments

Radio Receiver

If you never got the chance to build one as a kid [JoOngle] takes you through the steps to build your own radio receiver. Details are a bit scarce but it’s nothing your friend Google can’t help you out with.

Fixing a Blackberry trackball

If your Blackberry trackball stops working well you can try this non-technical fix. Remember when mice used to have a ball in them and you would need to clean out the gunk from time to time? Forcefully skidding your Blackberry across a piece of paper does a similar service.

Linux time lapse

Open source can be a great help to small businesses. Here’s a way to use a Linux machine to make time-lapse movies from surveillance camera feeds. We especially enjoy the use of a desktop wallpaper that has the terminal commands necessary to start recording.

Host a webpage with Dropbox

Here’s a way to host a simple webpage using Dropbox. It’s one of those easy ideas that you wouldn’t come up with yourself. When you place an HTML file in your Dropbox you can get a public URL which will be built as a webpage when visited with a browser.

Inline splicing

To round out the weekend here’s [Osgeld’s] tips on inline wire splicing. We laughed as he recounted spearing himself with stray strands. This is pretty simple stuff but he’s explained it well and who’s to pass up a good tip?