Print Your Own Magnetic Connector

If you have a late-model laptop, you’ve probably seen how the chargers magnetically snap into place. In theory, this should be easy to recreate for your own purposes. But why reinvent the wheel when [DarthKaker] has already done the work for you — assuming you only need two conductors.

The 3D-printed shells take the usual round magnets. Obviously, the north pole on one part should point to the south pole on the other part. In addition, if polarity matters, you should also have each housing contain one north-facing and one south-facing magnet so that the connectors will only mate one way.

It appears the project uses wires soldered or spot welded to the magnets. Heating magnets sometimes has bad effects, so we might try something different. For example, you could solder the wires to thin washers affixed to the magnets with epoxy, perhaps. Or use the magnets for alignment and make a different arrangement for the contacts, although that would take a different shell design.

We have talked about magnet soldering for connectors before. Don’t forget that you can build magnets into your prints, too.

Electromagnetic Actuator Mimics Muscle

Most electromagnetic actuators are rotating motors, or some variation on the theme, like servos. However, it’s possible to do linear actuation with electomagnetics, too. [Adrian Perez] demonstrates this with Linette, his design of a linear actuator that he was inspired to build by the structure of our own muscles.

The design uses a coil of copper wire in a 3D-printed plastic housing, surrounded by a claw full of strong magnets. When the coil is activated, the magnets are pulled towards the coil. When the coil is not energized, the magnets fall away. [Adrian] demonstrates the actuator under the control of an Arduino, which switches power to the coil to move it up and down.

He also notes that the design is similar solenoids and voice coil style actuators, though unlike most his uses discrete magnets rather than a single monolithic magnet. It’s possible to get more capacity out of the Linette design through stacking. You can parallelize the actuators to get more pulling force, with neighboring coils sharing the same magnets. Alternatively, you can stack them in series to get longer stroke lengths.

[Adrian] hasn’t put the design to a practical application yet, but we could see multiple uses for robotics or small machines. We’ve seen some other neat DIY magnetic actuators before, too. Video after the break.

A Teeny 3D-Printed Printing Press, Thanks Gutenberg

The printing press was first invented in 1440 AD by Johannes Gutenberg. It’s not so relevant to our day to day lives today, but it’s a technology that forever changed the path of human history. Now you can whip one up yourself using this teeny design from the [3DPrintingEnthusiast]!

Don’t expect to be making broadsheets with this thing—it’s a strictly table-top sized unit made on a 3D printer. Still, it does the job! The bed, frame, paper holder, and clamps are all 3D-printed. However, you will need some minor additional supplies to complete the carriage and inkballs.

As for your printing plates, you could go out and source some ancient lead type—or you could just 3D print some instead. The latter is probably easier if you’re living in 2024 like yours truly. Who knows, though. 2028 could be a banner year where printing presses roar back to prominence. Try not to think about the global scale disasters that would make that a reality.

In any case, there’s got to be some kind of irony about 3D-printing a printing press on a 3D printer? Perhaps, perhaps not. Debate it below!

3D Printing A Cassette Is Good Retro Fun

The cassette is one of the coolest music formats ever, in that you could chuck them about with abandon and they’d usually still work. [Chris Borge] recently decided to see if he could recreate these plastic audio packages himself, with great success.

He kicked off his project by printing some examples of an open source cassette model he found online. The model was nicely accurate to the original Compact Cassette design, but wasn’t exactly optimized for 3D printing. It required a great deal of support material and wasn’t easy to customize.

[Chris] ended up splitting the model into multiple components, which could then be assembled with glue later. He then set about customizing the cassette shells with Minecraft artwork. Details of the artwork are baked into the model at varying heights just 1/10th of the total layer height. This makes it easy to designate which sections should be printed with which filament during his multi-colored print. And yet, because the height difference is below a full layer height, the details all end up on the same layer to avoid any ugly gaps between the sections. From there, it’s a simple matter of transferring over the mechanical parts from an existing cassette tape to make the final thing work.

It’s a neat trick, and the final results are impressive. [Chris] was able to create multicolored cassettes that look great. It’s one of the better uses we’ve seen for a multi-colored printer. This would be an epic way to customize a mixtape for a friend!

We’ve seen some great 3D printed cassettes before, too, like these retro reel-to-reel lookalikes.

Continue reading “3D Printing A Cassette Is Good Retro Fun”

The $16 PCB Robot

It is a fun project to build a simple robot but, often, the hardest part these days is creating the mechanical base. [Concrete Dog] has a new open source design for stoRPer that uses a PC board as the base. The board has a Raspberry Pi Pico and motor drivers. The modular design allows you to add to it easily and use custom wheels. The video below shows some treaded wheels and some mechanum wheels with gears.

There are mounting holes for sensors and also a way to put another deck above to hold other circuits, power, or whatever you like. There’s lots you could do with this as a starting point.

Continue reading “The $16 PCB Robot”

Tricky 3D Printed Joinery Problem? Give Heat Staking A Try

When you just can’t 3D print something as a monolithic part, you’re going to have to join pieces together. In such cases, most of us instinctively include threaded inserts or nut slots in the design, or even reach for a tube of CA glue. But perhaps you should be thinking more along the lines of heat-staking your printed parts together.

Although you might not be familiar with the term, if you’ve looked inside anything made out of plastic, chances are good you’ve seen a heat-staked joint. As [Richard Sewell] explains, a heat-staked joint is nothing more than the classic mortise-and-tenon made from plastic where the tenon stands proud of the joint face so it can be softened with heat. The tenon spreads out so the joint can’t be pulled apart. A variant on the theme includes a mortise with a generous chamfer so the melted tenon can spread out, providing not only extra resistance to pull-out be also a more flush surface.

To melt the joint, [Richard] simply uses a soldering iron and a little pressure. To spread out both the heat and the force a bit, he uses the barrel of the iron rather than a tip, although we could see a broad chisel tip being used for smaller joints. Either way, a layer of Kapton tape helps keep the iron from getting gunked up with melted plastic. [Richard] lists a host of advantages for this kind of plastic joinery, including eliminating the need for additional hardware. But we think the best feature of this joint is that by avoiding monolithic prints, each aspect of a part can have its layer lines optimized.

While it probably isn’t applicable everywhere, heat-staking looks like a technique to keep in mind. We’d love to see [Stefan] over at CNC Kitchen do some of his testing magic on these joints, like he did for threaded inserts.

Reducing Poop On Multicolor Prints

While multicolor printing eliminates painting steps and produces vibrant objects, there are two significant downsides; filament consumption and print time. A single-nozzle filament printer needs to switch from one color to another, and doing so involves switching to the other filament and then purging the transition filament that contains a mixture of both colors, before resuming the print with the clean new color.

[teachingtech] tests out a variety of methods for reducing print time and waste. One surprising result was that purging into the infill didn’t result in significant savings, even when the infill was as high as 50%. Things that did have a positive effect included reducing the amount of purge per transition based on light to dark color changes, and printing multiple copies at once so that even though the total amount of waste was the same as a single part, the waste per part was reduced.

All of the tests were with the same model, which had 229 color changes within a small part, so your mileage may vary, but it’s an interesting investigation into some of the deeper settings within the slicer. Reducing filament waste and print time is an admirable goal, and if you make your own extruder, you can turn all of that purge waste into various shades of greenish brownish filament. Continue reading “Reducing Poop On Multicolor Prints”