OpenDog Version 3 Is Ready To Go Walkies

December 18, 2021 by Dave Rowntree 12 Comments

We’ve been following [James Bruton]’s open dog project for a little while now, and with his considerable pace of work – pandemic or no pandemic – development has been incredibly rapid. The latest milestone is the public release of version 3 (Video, embedded below.) This upgrade to the system adds 3D printed cycloidal gearboxes, removing the previous belt drives. [James] had immense fun tuning the motor controller parameters for these and admits they’re not completely dialed in yet. He notes that the wider gearbox body means that the robots geometry needed to change a little, and the previous belt-drive version may have a bit of an edge, but he’s confident he can make it work (and given his incredible previous robotics builds, we totally believe he’ll nail it!)

Silicone overmolding around a 3D printed former, using a 3D printed mould

Older versions struggled with slippery plastic feet; the advantage of a predictably smooth contact shape of a rounded foot is somewhat offset by the limited contact patch size, and that means not so much grip on some surfaces. [James] solution was obvious enough – just learn how to make 3D printed silicone moulds and cast a nice rubber foot around a plastic former, and problem solved! Unfortunately he neglected to add some recesses for a lever to get in between the mould halves, so it was a bit of a struggle to separate after curing. A beginner’s mistake that won’t be repeated, we’re sure.

Full source for openDogV3 is now available on the GitHub page. Here’s the playlist for the whole project, as well as direct links for the cycloidal drive development (part1, part2, part3.) But before you all go diving in to start 3D printing your own pooch, [James] tells us that the total cost would be around $2000 all in, with the bulk of that being the motors and ODrive units, so this one for the serious builder only!

We’ve covered robot dogs a fair bit, a particularly nice example is The Dizzy Wolf, and if you’re wondering just why on earth you’d want a robot dog, then Ask Hackaday has you covered as well.

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Tesla Model S Gets Boost With Jet Engine Upgrade

December 16, 2021 by Matthew Carlson 72 Comments

Tesla is well known for making cars that can accelerate quickly, but there’s always room for improvement. [Warped Perception] decided that his Tesla Model S P85D needed that little bit of extra oomph (despite the 0-60 MPH or 0-97 km/h time of 3.1 seconds), so he did what any sensible person would: add three jet turbines to the back of his car.

The best part of this particular build is the engineering and fabrication that made this happen. With over 200 pieces and almost all personally fabricated, this is a whirlwind of a build. The control panel is first, and there’s a particularly clever technique of 3D printing the lettering directly onto the control panel for the flat stuff. Then for the pieces with angles that would prevent the head from moving freely, he printed onto a plastic sheet in reverse, applied glue, then stuck the letters to the plate as a sheet. A top layer of clear coat ensures the letters won’t come off later.

Using a 3D printer to apply lettering on the control panel.

He installed the control electronics in the trunk with wiring strung from the car’s front to the rear. Three Arduinos serve as controllers for the jets. Afterward, came the bracket to hold the engines and attach it to the car’s underside. Unfortunately, supplies were a little hard to come by, so he had to make do with what was on hand. As a result it didn’t come out as strong as he would have hoped, but it’s still pretty impressive.

[Warped Perception] does a few tests before taking it out on the road. Then, he shifted the car into neutral and could drive the car solely on jet power, which was one of his goals. While we don’t love the idea of testing a jet engine on public roads, it certainly would discourage tailgaters.

Next, he finds a quieter road and does some speed tests. Unfortunately, it was drizzling, and the pavement was damp, putting a damper on his 0-60 standing times. Electric-only he gets 4.38 seconds, and turning on the jets plus electric shaves that down to 3.32 seconds. Overall, an incredible build that’s sure to draw a few curious glances whenever you’re out on the town.

If you’re looking to upgrade your Tesla, perhaps instead of jet engines, you might opt for a robot to plug it in for you?

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Adding Wire Races Improves 3D-Printed Bearings

December 13, 2021 by Dan Maloney 35 Comments

Like a lot of power transmission components, bearings have become far easier to source than they once were. It used to be hard to find exactly what you need, but now quality bearings are just a few clicks away. They’re not always cheap though, especially when you get to the larger sizes, so knowing how to print your own bearings can be a handy skill.

Of course, 3D-printed bearings aren’t going to work in every application, but [Eros Nicolau] has a plan for that. Rather than risk damage from frictional heating by running plastic or metal balls in a plastic race, he uses wire rings as wear surfaces. The first video below shows an early version of the bearing, where a pair of steel wire rings lines the 3D-printed inner and outer races. These worked OK, but suffered from occasional sticky spots and were a bit on the noisy side.

The second video shows version two, which uses the same wire-ring race arrangement but adds a printed ball cage to restrain the balls. This keeps things quieter and eliminates binding, making the bearing run smoother. [Eros] also added a bit of lube to the bearing, in the form of liquid PTFE, better known as Teflon. It certainly seemed to smooth things out. We’d imagine PTFE would be more compatible with most printed plastics than, say, petroleum-based greases, but we’d be keen to see how the bearings hold up in the long term.

Maybe you recall seeing big 3D-printed bearings around here before? You’d be right. And we’ve got you covered if you need to learn more about how bearings work — or lubricants, for that matter.

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Resin Stacking Proves Messy And Difficult

December 12, 2021 by Lewin Day 15 Comments

3D printers are typically the tool you use when you want a one-off quick prototype. However, more and more, they’re being used to produce things in quantity. [Uncle Jessy] decided to try out the resin stacking technique in order to quickly produce many figurines on his resin printer. However, not everything went exactly to plan.

The technique is simple. The idea is to produce many copies of an object in a single continuous print on a resin 3D printer. To achieve this, the object is cloned many times, and scaffolding is created to allow the stacking of multiple objects on top of each other. This must be done carefully to avoid ruining the geometry of the object, and similarly to support material, uses more resin in the process.

[Uncle Jessy] experimented several times, but ran into multiple issues with the process when trying to print out some small Magneto figurines. An initial experiment using a raft failed when the print fell off the build plate. With the raft removed, the second print failed as the scaffolding didn’t print quite right. Further tweaks and beefing up the scaffold improved things, and [Jessy] managed to print 93 figurines in a single operation.

It’s a useful technique if you want to print a ton of models on a resin printer in as short a time as possible. However, expect to spend plenty of resin as you refine the technique. You’ll also need a big wash tank to clean the prints during post-processing. Video after the break.

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Customize These 3D Printed Cases

December 12, 2021 by Al Williams 27 Comments

Building something, of course, requires your electronics skills. But packaging it is often an exercise in mechanics. You can buy off the shelf, of course, but sometimes it is hard to find just the right enclosure. You probably have a 3D printer, too, but sometimes 3D printing an entire case can be time consuming and isn’t always completely attractive. Enter [Johannes-Bosch] and Fusion 360. These 3D printed frames assemble into boxes and are easy to customize. The panels are aluminum, although we imagine you could substitute wood, acrylic, or even a 3D printed sheet of plastic, if you wanted to.

The video below shows some examples. If your German isn’t up to snuff, ask YouTube to automatically translate the subtitles and you’ll get the idea.

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A scaled down version of a pedestrian crossing signal

Don’t Walk Past This 3D Printed Pedestrian Crossing Light

December 1, 2021 by Chris Wilkinson 9 Comments

There’s just something so pleasing about scaled-down electronic replicas, and this adorable 3D printed pedestrian crossing light by [sjm4306] is no exception.

Although a little smaller than its real-world counterpart, the bright yellow housing and illuminated indicators on this pedestrian lamp are instantly recognizable due to their ubiquitous use throughout the United States. The handful of printed parts are held together using friction alone, which makes assembly a literal snap. The ‘safety grill’ with its many angles ended up being one of the most tedious parts of the build process, but the effort was definitely justified, as it just wouldn’t look right without it.

A suitably minuscule ATtiny85 drives a pair of LED strips that effectively mimic the familiar symbols for ‘Walk’ and ‘Don’t Walk’. [sjm4306] has designed the board and case in such a way to accommodate a variety of options. For example, there’s just enough room to squeeze in a thin battery, should you want to power this contraption on-the-go. If you don’t have an ATtiny85 on hand, the board also supports an ATmega328p or even an ESP8266.

All the build details are available over on Hackaday.io. While it’s billed as a ‘night light’, we think this could be an awesome platform for an office toy, similar to this office status light project. Or if you’ve somehow already got your hands on a full-size pedestrian lamp, why not hook it up to the Internet?

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Do You Really Need To Dry Filament?

November 29, 2021 by Dave Rowntree 49 Comments

There’s a lot of opinions and theories around the storing and drying of 3D printing materials. Some people are absolutely convinced you must bake filament if it been stored outside an airtight bag, even for a few days. Some others have ‘never had a problem.’ So it’s about time someone in the know has done some testing to try to pin down the answer to the question we’re all asking; How bad is wet filament really?

[Thomas Sanladerer] setup a simple experiment, using samples of three common types of filament, specifically PLA, PET-G and ASA. He stored the samples in three environments, on his desk, outside in the garden, and finally submerged in water for a full week. What followed was a whole lot of printing, but they all did print.

Different filaments will absorb water at different rates, depending upon their chemical composition and the environment, nylon being apparently particularly fond of a good soaking. It would seem that the most obvious print defect that occurs with increased water absorption is that of stringing, and other than being annoying and reducing surface quality somewhat, it’s not all that serious in the grand scheme of things. It was interesting to note that water absorption doesn’t seem to affect the strength of the final part.
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