Clock Mixes Analog, Digital, Retrograde Displays

Unique clocks are a mainstay around here, and while plenty are “human readable” without any instruction, there are a few that take a bit of practice before someone can glean the current time from them. Word clocks are perhaps on the easier side of non-traditional displays but at the other end are binary clocks or even things like QR code clocks. To get the best of both worlds, though, multiple clock faces can be combined into one large display like this clock build from [imitche3].

The clock is actually three clocks in one. The first was inspired by a binary clock originally found in a kit, which has separate binary “digits” for hour, minute, and second and retains the MAX 7219 LED controller driving the display. A standard analog clock rests at the top, and a third clock called a retrograde clock sits at the bottom with three voltmeters that read out the time in steps. Everything is controlled by an Arduino Nano with the reliable DS3231 keeping track of time. The case can be laser-cut or 3D printed and [imitche3] has provided schematics for both options.

As far as clocks builds go, we always appreciate something which can be used to tell the time without needing any legends, codes, or specialized knowledge. Of course, if you want to take a more complex or difficult clock face some of the ones we’re partial to are this QR code clock which needs a piece of hardware to tell the time that probably already has its own clock on it.

Adaptive Chef’s Knife Provides Better Leverage

[Colleen] struggled with using a chef’s knife to cut a variety of foods while suffering from arthritis in her wrist and hand. There are knives aimed at people with special needs, but nothing suitable for serious work like [Colleen]’s professional duties in a commercial kitchen.

As a result, the IATP (Illinois Assistive Technology Program) created the Adaptive Chef’s Knife. Unlike existing offerings, it has a high-quality blade and is ergonomically designed so that the user can leverage their forearm while maintaining control.

The handle is durable, stands up to commercial kitchen use, and is molded to the same standards as off-the-shelf knife handles. That means it’s cast from FDA-approved materials and has a clean, non-porous surface. The pattern visible in the handle is a 3D printed “skeleton” over which resin is molded.

Interested? The IATP Maker Program makes assistive devices available to Illinois residents free of charge (though donations in suggested amounts are encouraged for those who can pay) but the plans and directions are freely available to anyone who wishes to roll their own.

Assistive technology doesn’t need to be over-engineered or frankly even maximally efficient in how it addresses a problem. Small changes can be all that’s needed to give people meaningful control over the things in their lives in a healthy way. Some great examples are are this magnetic spoon holder, or simple printed additions to IKEA furnishings.

3D Printed Fidget Knife Snaps Back And Forth All Day Long

Fidget toys all have a satisfying mechanical action to engage with, and [uhltimate]’s OTF (out the front) “fidget knife” model provides that in spades. The model snaps open and closed thanks to a clever arrangement of springs and latches contained in only three printed pieces.

Here’s how it works: at rest, the mock blade (orange in the image above) is latched in the closed position. As one presses the slider forward, the bottom spring begins to pull up against the blade until it moves far enough to release the latch. When the latch is released, the tension built up in the spring propels the blade outward where it again latches in the open position. Retraction is the same essential process, just in the opposite direction (and using a latch on the opposite side of the blade, which faces the other direction.)

As you may imagine, effective operation depends on the material. The model is designed to be printed in PLA, but [uhltimate] also provides a part variation with a stiffer spring for those who find that basic model isn’t quite up to the task for whatever reason. Smooth surfaces are also helpful for hitch-free operation, but lubrication shouldn’t be necessary.

If this sort of thing is up your alley, don’t miss the satisfying snap action of this 3D printed toggle mechanism, either!

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A Vernier Take On A 3D Printer Extruder Indicator

A common way to visualize that a 3D printer’s extruder motor — which feeds the filament into the hot end — is moving is to attach a small indicator to the exposed end of the motor’s shaft. As the shaft turns, so does the attached indicator.

Small movements of the motor are therefore turned into larger movements of something else. So far, so simple. But what about visualizing very small extrusions, such as those tiny ones made during ironing?

[Jack]’s solution is a Vernier indicator for the extruder. Even the smallest movements of the extruder motor’s shaft are made clearly visible by such a device, as shown in the header image above. Vernier scales are more commonly found on measurement tools, and the concept is somewhat loosely borrowed here.

The usual way these lightweight indicators are attached is with a small magnet, and you can read all about them and see examples here.

This new design is basically the same, it simply has a background in a contrasting color added into the mix. [Jack]’s design is intended for the Bambu A1 printer, but the idea can be easily adapted. Give it a look if you find yourself yearning for a bit more visibility in your extruder movements.

Plasma Cutter Gets CNC Treatment At Low Cost

[Daniel] has been metalworking on a budget for a while now. Originally doing things like plasma cutting on old bricks, he used his original plasma cutter to make an appropriate plasma cutting table complete with a water bath which we presume was not only safer but better for his back. Since then he’s stepped up a little more with what might be the lowest-cost CNC plasma cutter that can reliably be put together.

The CNC machine uses a handheld plasma cutting torch as its base, which uses a blowback start mechanism making it usable in an automated CNC setup without interfering with the control electronics. This is a common issue with other types of plasma cutters not originally meant for CNC. The torch head only needs slight modifications to fit in a 3D printed housing designed for the CNC machine which involves little more than slightly changing the angle of the incoming copper tubing and wire and changing the location of the trigger.

With those modifications done, the tool head is ready to be mounted to the CNC machine. [Daniel] has put together a bill of materials for building the entire project for less than $400, which includes the sub-$200 plasma cutter. It’s an impressive bit of sleuthing to get the price down this low, but if you’re still using your plasma cutter by hand on bricks in the yard like [Daniel] used to do make sure to check out that DIY plasma cutting table he built a few years ago too.

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Corral Some Zippy Blue Flames Into 3D Printed Troughs

[Steve Mould] came across an interesting little phenomenon of blue flames zipping around a circular track. This led to diving down a bit of a rabbit hole about excitable mediums, ultimately leading him to optimize the shapes and come up with some pretty wild variations which he shows off in a video (also embedded below.)

After figuring out that the moving flame depended on combustion of fuel vapor in an environment that didn’t allow for the whole surface to stay lit at once, [Steve] tried to optimize the design of 3d-printed channels and raceways to encourage this effect, and he came up with some pretty novel ones. The 3D models are here if you’d like to try them for yourself (we especially like the “figure eight” and “rays” models.)

The video is an excellent show & tell of everything [Steve] dove into, complete with plenty of demonstrations of harnessing this effect to create some nifty running flames. Check it out in the video below, and if unintuitive physical effects are your thing, don’t miss [Steve]’s peeling apart of the turntable paradox.

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Alternate Threaded Inserts For 3D Prints

The usual way to put a durable threaded interface into a 3D print is to use a heat-set insert, but what about other options? [Thomas Sanladerer] evaluates a variety of different threaded inserts, none of which are actually made with 3D printing in mind but are useful nevertheless.

There are a number of other easily-available threaded inserts, including the rivnut (or rivet nut), chunky hex socket threaded inserts intended for wood and furniture, heli-coils or helical inserts (which resemble springs), self-tapping threaded inserts (also sold as thread adapters), and T-nuts or prong nuts. They all are a bit different, but he measures each one and gives a thorough rundown on how they perform, as well as offering his thoughts on what works best.

[Thomas] only tests M5 fasteners in this video, so keep that in mind if you get ideas and go shopping for new hardware. Some of the tested inserts aren’t commonly available in smaller sizes. Self-tapping threaded inserts, for example, are available all the way down to M2, but the hex socket threaded inserts don’t seem to come any smaller than M4.

These threaded inserts might be just what your next project calls for, so keep them in mind. Heat-set inserts are of course still a great option, and our own Sonya Vasquez can tell you everything you need to know about installing heat-set inserts into 3D printed parts in a way that leaves them looking super professional.

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