Author: Donald Papp

1263 Articles

One-Piece Tank Chassis Pushes Print-in-Place To New Heights

January 20, 2023 by 30 Comments

What’s better than 3D printing a tank chassis with working tracks? How about 3D printing the entire thing, moving parts and all, as a single piece? That’s [3D Honza]’s PiPBOT-1, and it’s the culmination of a whole lot of design work.

The design prints flat, then folds up into its final form.

[3D Honza] has been sharing progress pictures and videos on his Twitter account, and just recently released the first version of his design. Version 1.0 is just the mechanics, but he’s already at work on version 2.0 which includes the ability to attach servos to drive the treads. At this writing, the design is currently downloadable directly from his site and includes CAD files, which is great to see.

One part of the design we’d like to draw your attention to is the chunky hinge that doubles as a kind of axial structure making up the body. This allows the tank to print in an unfolded state with the treads and wheels flat on the print bed. After printing, the tank gets folded up a bit like a taco to attain its final form. It’s a clever layout that allows the unit to be printed according to a filament-based 3D printer’s strengths, printing as a single piece that transforms into a small tank chassis, complete with working treads, in a few seconds.

When it comes to vehicles and bots, whether to choose wheels or tracks is a serious question our own Lewin Day has explained thoroughly. And for those of you who choose tracks, this design is great for small devices but don’t forget it’s always possible to go bigger when it comes to 3D-printed tanks.

Continue reading “One-Piece Tank Chassis Pushes Print-in-Place To New Heights” →

LED Driver Circuit For Safety Hat Sucks Single AAA Cell Dry

January 19, 2023 by 21 Comments

[Petteri Aimonen] created an omnidirectional LED safety light to cling to his child’s winter hat in an effort to increase visibility during the dark winter months, but the design is also great example of how to use the Microchip MCP1640 — a regulated DC-DC step-up power supply that can run the LEDs off a single AAA cell. The chip also provides a few neat tricks, like single-button on/off functionality that fully disconnects the load, consuming only 1 µA in standby.

[Petteri]’s design delivers 3 mA to each of eight surface-mount LEDs (which he says is actually a bit too bright) for a total of about 20 hours from one alkaline AAA cell. The single-layer PCB is encased in a clear acrylic and polycarbonate enclosure to resist moisture. A transistor and a few passives allow a SPST switch to act as an on/off switch: a short press turns the unit on, and a long press of about a second turns it back off.

One side effect is that the “off” functionality will no longer work once the AAA cell drained too badly, but [Petteri] optimistically points out that this could be considered a feature: when the unit can no longer be turned off, it’s time to replace the battery!

The usual way to suck a battery dry is to use a Joule Thief, and while this design also lights LEDs, it offers more features and could be adapted for other uses easily. Interested? [Petteri] offers the schematic, KiCAD file for the PCB, and SVG drawing of the enclosure for download near the bottom of the project page.

Weatherproof Raspberry Pi Camera Enclosure, In A Pinch

January 18, 2023 by 17 Comments

The Raspberry Pi is the foundation of many IoT camera projects, but enclosures are often something left up to the user. [Mare] found that a serviceable outdoor enclosure could be made with a trip to the hardware store and inexpensive microscopy supplies.

A suitably-sized plastic junction box is a good starting point, but it takes more than that to make a functional enclosure.

The main component of the enclosure is a small plastic junction box, but it takes more than a box to make a functional outdoor enclosure. First of all, cable should be run into the box with the help of a cable fitting, and this fitting should be pointed toward the ground when the enclosure is mounted. This helps any moisture drip away with gravity, instead of pooling inconveniently.

All wire connections should be kept inside the enclosure, but if that’s not possible, we have seen outdoor-sealed wire junctions with the help of some 3D-printing and silicone sealant. That may help if cable splices are unavoidable.

The other main design concern is providing a window through which the camera can see. [Mare] found that the small Raspberry Pi camera board can be accommodated by drilling a hole into the side of the box, cleaning up the edges, and securing a cover slip  (or clover glass) to the outside with an adhesive. Cover slips are extremely thin pieces of glass used to make microscope slides; ridiculously cheap, and probably already in a citizen scientist’s parts bin. They are also fragile, but if the device doesn’t expect a lot of stress it will do the job nicely.

[Mare] uses the Raspberry Pi and camera as part of Telraam, an open-source project providing a fully-automated traffic counting service that keeps anonymized counts of vehicle, pedestrian, and bicycle activity. Usually such a device is mounted indoors and aimed at a window, but this enclosure method is an option should one need to mount a camera outdoors. There’s good value in using a Raspberry Pi as a DIY security camera, after all.

Make Your Own Pot And Encoder Knobs, Without Reinventing Them

January 14, 2023 by 10 Comments

Rotary potentiometers, switches, and encoders all share a basic design: adjustment is done via a shaft onto which a knob is attached, and knobs are sold separately. That doesn’t mean one knob fits all; there are actually a few different standards. But just because knobs are inexpensive and easily obtained doesn’t mean it’s not worth making your own.

A simple and effective indicator can be easily printed in a contrasting color.

Why bother 3D printing your own knobs instead of buying them? For one thing, making them means one can rest assured that every knob matches aesthetically. The ability to add custom or nonstandard markings are another bonus. Finally, there’s no need to re-invent the wheel, because [Tommy]’s guide to making your own knobs has it all figured out, with the OpenSCAD script to match.

By default, [Tommy]’s script will generate a knob with three shims (for interfacing to a splined shaft) when pot_knob(); is called. The number of shims can be adjusted by modifying potKnobDefaultShimCount. To give the knob a flat side (to interface with D-shafts), change flatted = false to flatted = true. And for adding a screw insert suitable for a set screw? Change tightenerDiameter = 0 from zero to the diameter desired.

The script is quite comprehensive and has sensible defaults, but it does require a bit of knowledge about OpenSCAD itself to use effectively. We have covered the basics of OpenSCAD in the past, and if you’re ready for a resource that will help you truly master it, here’s where to look.

DIY Magnet Handling Tool Puts An End To Placement Errors

January 14, 2023 by 10 Comments

I’m sure we can all agree that the worst time to find out a magnet is the wrong way around is after glue has been applied. With that in mind, [erick.siders] created the parametric Magnet Placer tool.

Color-coded tools, one for each polarity.

Picking up and placing magnets into assemblies can be an error-prone process, because magnet polarity cannot be directly identified or sensed by either sight or fingertips. This tool helps by acting a lot like a suction pickup tool — press the plunger down, and a magnet can be picked up, release the plunger, and the magnet lets go. Simple, and effective.

Since the tool is polarity-dependent (depending on which orientation the pickup magnet is mounted into the internal plunger), [erick.siders] suggests printing two tools and color-coding them. That way, one can choose the right tool based on the situation and be confident that the magnets are right-side-up, every time.

The tools use a long metric bolt, a magnet, and a spring, but none of those parts are particularly critical. We also love the way that the end result has no gaps or openings into the moving parts, which means nothing can get caught on or inside anything during use or storage.

It’s a parametric design and the CAD files (in both Fusion 360 and STEP flavors) are provided, so modification should be a breeze. And if you happen to be using PrusaSlicer, remember you can now drop STEP format files directly in for slicing.

Printable Case For Pinecil And TS100 Soldering Irons (Mis)Uses A 608 Bearing

January 7, 2023 by 61 Comments

[PjotrStrog]’s rugged Pinecil / TS100 storage case is the perfect printable accessory to go with a hacker’s choice of either the Pine64 Pinecil, or the Miniware TS100 soldering irons. There are some thoughtful features beyond just storing the iron, too!

A standard 608 bearing makes for a handy heat-resistant stand.

Some of you may have spotted a 608 bearing in the image above, and might be wondering what it is for. In proud hacker tradition of using things for something other than their intended purpose, the bearing makes a heat-resistant stand to hold the iron while in use.

This design has a pretty deep history that illustrates the value of sharing one’s designs and allowing others to remix and refine ideas. [PjotrStrog]’s work makes use of the earlier and highly thoughtful TS100, Pinecil, TS80 & TS80p cases with options by [Termiman], which themselves are based on bearing-equipped TS100 case by [Olvin] that we covered back in 2020.

We loved the Pine64 Pinecil soldering iron, and this looks like a fantastic printable storage and carry option. There are a few pieces of hardware needed to put the rugged version together, but [PjotrStrog] also offers a less rugged design with fewer hardware needs, so check that out as well.

3D Printed Light Pipe Turns Overly-Bright LED Into Design Harmony

December 22, 2022 by 14 Comments

There are a number of ways to efficiently and elegantly limit an LED’s brightness, but [Tommy] found that using a light pipe or diffuser can integrate better with a device, especially when the device itself is mostly 3D printed in the first place.

Infill has an effect on appearance. 20% infill on the left, 100% infill on the right.

For some problems the Goldilocks approach is the way to go. [Tommy] designed a small array of different LED cover options, and tested each to see what yielded the best results for his printed kit. Some of the biggest takeaways include:

  • 100% infill is best for even results (although interesting shadows happen at less than 100% infill.)
  • Interesting things happen with 7 to 11 mm of top layers of clear PLA, when illuminated from below with a 5 mm high-brightness LED. An even diffusion of light starts to give way to a circular gradient as the upper layer gets thicker.
  • LEDs emit their light mainly upward in a round pattern. Corners will always be darker, even more so if the guide is not round. This effect becomes noticeably more pronounced as the light guide grows in size, putting a practical upper limit on its effective dimensions.

[Tommy] explores these kinds of issues because he designs and builds electronic synth instruments, and they are mostly 3D printed. He explores efficiency and is always happy to share his findings about what works and doesn’t work.

Of course, the usual ways to deal with an overly-bright LED are to limit its current or control its brightness by driving it with a PWM signal. The right approach depends on the application and the scale of the design, and there are actually quite a few ways to crack this nut. Luckily, our own [Inderpreet Singh] is here to tell you all about how best to control LED brightness.