FreeCAD Takes Off With A Rocket Design Workbench

April 2, 2021 by Donald Papp 25 Comments

Here’s how FreeCAD works: the program’s design space is separated into different “workbenches”, each of which is intended for a particular set of operations, and a piece of work can be moved between them as needed. There is a sketching workbench, a part design workbench, and now a Rocket workbench has been added to the healthy ecosystem of FreeCAD add-ons. There’s even a series of video tutorials; ain’t open source grand?

It all started when [concretedog] posted on the FreeCAD forums, making a strong case for a Rocket-themed workbench. People got interested, and a short while later [DavesRocketShop] had some useful tools up and running. Here’s a blog post by [concretedog] which goes into detail and background, and while the Rocket workbench is available via FreeCAD’s add-on manager, the very latest experimental builds are available for manual installation on [Dave]’s GitHub repository.

This sort of development and utility is exactly the kind of thing our own Elliot Williams was describing when he made the point that one of open source’s greatest strengths is in the little things, like the FreeCAD ecosystem letting people scratch strange and specific itches, and the ability to share those solutions with others.

Electric Window Motor Becomes Mini Chainsaw

April 2, 2021 by Donald Papp 13 Comments

This mini handheld chainsaw by [Make it Extreme] is based around an electric motor from a car door, the same ones used to raise and lower car windows. They are common salvage parts, and with the right modifications and a few spare chainsaw bits attached, it turns out that the motor is more than capable of enough zip to cut through a variety of wood. Add a cordless tool battery pack, and the portable mini handheld chainsaw is born.

What’s really remarkable about the build video (embedded below, after the break) is not simply that it shows the build process and somehow manages to make it all look easy. No, what’s truly remarkable is that in the video it is always clear what is happening, and all without a single word being spoken. There’s no narration, no watching someone talk, just a solid build and demonstration. The principle of “show, don’t tell” is definitely taken to heart, here.

So, how well does it work as a chainsaw? It seems to work quite well! [Make it Extreme] does feel that a chain with smaller teeth and a higher motor speed would probably be an improvement, but the unit as built certainly can cut. You can judge for yourself by watching the build video, embedded below.

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Over-Engineered Incandescent Numerical Display Shows Great Workmanship

April 1, 2021 by Donald Papp 18 Comments

Back before LED technology came into its own, displays used incandescent bulbs. These vintage incandescent displays weren’t necessarily big; the Eaton 925H-C fiber optic display, for example, has numbers barely 7 mm tall and packs two of them into a tiny area. Of course, the depth of the display module itself is huge by today’s standards; those components have got to go somewhere, after all.

This particular device is, in [Industrial Alchemy]’s words, “[d]ripping with the spending excess that only a bottomless military budget can provide… the Eaton 925H-C may not be a practical device, but it is certainly an impressive one.”

The way the display works is this: individual incandescent bulbs light up fiber optic light guides, which terminate on the face of the display in small dots to make up a numerical display. With only fourteen bulbs, the dots we see here clearly aren’t individually addressable; the two digits are most likely broken up into seven segments each, with three dots making up each segment.

No expense seems spared in the design and manufacture of these displays. Even the incandescent lamps have individual shock absorbers.

The sheer amount of workmanship in these displays is remarkable, and their design makes them easy to retrofit with LED technology instead of replacing the tiny incandescent lamps. In a stark contrast to all of the machined aluminum and gold plated contacts seen here in the Eaton 925H-C, take a look at this Soviet-era seven-segment incandescent display whose construction is far less sophisticated, but shows off its own clever engineering. We’ve also seen more modern DIY takes on the concept, using LED light sources and cured UV resin light pipes to get that vintage look to the displays.

To Lovers Of Small Boxes: A 3D Printable Design Just For You

March 28, 2021 by Donald Papp 7 Comments

Print them at 50% scale for a far cuter (and much less useful) result.

[Jacob Stanton]’s design for 3D-printable, stacking and locking boxes is a great example of design for manufacturability (DFM). MicroStacks show how part of good DFM is taking the manufacturing method’s strengths and weaknesses into account. [Jacob]’s boxes are created specifically with 3D printing in mind, which is great design whether somebody is making one, or dozens.

The boxes have sturdy parts that all print without any need for supports, fasteners, or post-processing. In addition, since no two 3D printers are quite alike and some print better than others, the parts are also designed to be quite forgiving of loose tolerances. Even on a printer that is less well-tuned than it could be, the design should still work. The boxes also have a nice stacking feature: a sturdy dovetail combined with a sliding tab means that once boxes are stacked, they’re not coming apart by accident unless something breaks in the process.

The boxes as designed are about big enough to store AA cells. Not the right size for you? One nice thing about a 3D-printable design that doesn’t need supports is that it’s trivial to uniformly scale the size of the models up or down to match one’s needs without introducing any print complications in the process. You can watch [Jacob] assemble and demonstrate his design in the video, embedded below.

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Archery Release Becomes Reusable Balloon Cutdown Mechanism

March 27, 2021 by Donald Papp 12 Comments

A cutdown in high-altitude balloon (HAB) parlance refers to detaching a payload, and can refer to the act of severing a line or to the mechanism itself. How is this done? The most common way is the “hot wire” method: a segment of wire is heated rapidly with a high current, causing it to melt through something like a nylon line.

But there’s more than one way to solve a problem, and while documenting different cutdown methods, [KI4MCW] found that a caliper-style archery release plus hobby servo could be used as a high strength cutdown mechanism. An archery release (or bow release) is a tool to assist in holding the string of a bow in the drawn position, and cleanly release it at the touch of a lever or button. It occurred to [KI4MCW] that these features might be made to serve as a payload release as well, and you can see here the crude but successful prototype for a reusable cutdown.

The archery release [KI4MCW] obtained opens its jaws when a trigger-style lever on the side is pulled. The force required to trigger this is remarkably low, and a low-torque economical hobby servo easily does the job. In fact, the force needed to trip the release is so low that [KI4MCW] added a short rubber band to provide some opposing tension on the lever, just to be sure no spontaneous triggers occurred. The device hasn’t flown yet, but the prototype looks promising. Maybe a mechanism like this would be appropriate for a payload like dropping a high-altitude RC glider from a balloon.

Get A Better Look At E3D’s Tool-changing 3D Printer Kit

March 20, 2021 by Donald Papp 4 Comments

Want a closer, in-depth look at E3D’s motion system and tool-changing platform? [Kubi Sertoglu] shared his impressions after building and testing the system, which comes in the form of a parts bundle direct from E3D costing just under $3000 USD. The project took [Kubi] about 15 hours and is essentially built from the ground up. The system is definitely aimed at engineers and advanced prosumers, but [Kubi] found it to be of remarkable quality, and is highly pleased with the end results.

E3D Motion system and toolchanger, with four extruders

We first saw E3D’s design announced back in 2018, when they showed their working ideas for a system that combined motion control and a toolchanger design. The system [Kubi] built uses four 3D printing extruders for multi-material prints, but in theory the toolheads could just as easily be things like grippers, lasers, or engravers instead of 3D printing extruders.

One challenge with tool changing is ensuring tools mount and locate back into the same place, time after time. After all, a few fractions of a millimeter difference in the position of a print head would spell disaster for the quality of most prints. Kinematic couplings are the answer to being sure something goes back where it should, but knowing the solution is only half the battle. Implementation still requires plenty of clever design and hard engineering work, which is what E3D has delivered.

Want a closer look at the nitty-gritty? Check out E3D’s GitHub repository for all the details on their toolchanger and motion system.

New Part Day: Onion Tau LiDAR Camera

March 18, 2021 by Donald Papp 40 Comments

The Onion Tau LiDAR Camera is a small, time-of-flight (ToF) based depth-sensing camera that looks and works a little like a USB webcam, but with a really big difference: frames from the Tau include 160 x 60 “pixels” of depth information as well as greyscale. This data is easily accessed via a Python API, and example scripts make it easy to get up and running quickly. The goal is to be an affordable and easy to use option for projects that could benefit from depth sensing.

When the Tau was announced on Crowd Supply, I immediately placed a pre-order for about $180. Since then, the folks at Onion were kind enough to send me a pre-production unit, and I’ve been playing around with the device to get an idea of how it acts, and to build an idea of what kind of projects it would be a good fit for. Here is what I’ve learned so far.

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