3D Printing Omni-Balls For Robot Locomotion

May 20, 2021 by Lewin Day 6 Comments

Wheels are all well and good for getting around, but they only tend to rotate about a single axis. Omni-wheels exist, but they’re still a little too pedestrian for [James Bruton]. His latest project involved 3D printing custom omni-balls which roll in all directions. (Video, embedded below.)

The omniball concept comes from earlier work by Osaka University, which also produced a treaded tank-like vehicle by the name OmniCrawler as well. The spherical design, fitted with an axle and casters as well, allows rotation in multiple directions, allowing for a platform fitted with such omni-balls to easily rotate and translate in all directions.

[James] set about creating his own version of the design, which relies on grippy TPU filament for grip pads to give the 3D printed hemispheres some much needed grip. There’s also bearings inside to allow for the relative rotation between the hemispheres and the internal castor, necessary to allow the wheels to move smoothly when sitting on either pole of the hemispheres. Skate bearings were then used to assemble three of the omni-balls onto a single platform, which demonstrated the ability of the balls to roll smoothly in all directions.

While it’s just a demonstration of the basic idea for now, we can imagine these balls being used to great effect for a robot platform that needs to navigate in tight spaces on smooth surfaces with ease. The mechanical complexity of the omni-balls probably negates their effective use in dirtier offroad contexts, however.

We’ve seen [James]’s work before too – such as his compliant leg design for walking robots, and his active gyroscope balancer last week. When does [James] sleep?

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Toolchanging Printers Get A Nozzle Hanky Like No Other

May 18, 2021 by Sonya Vasquez 7 Comments

When it comes to toolchanging 3D printers, idle nozzles tend to drool. Cleaning out that nozzle goo, though, is critical before switching them into use. And since switching nozzles can happen hundreds of times per print, having a rock-solid cleaning solution is key to making crisp clean parts. [Kevin Mardirossian] wasn’t too thrilled with the existing solutions for cleaning, so he developed the Pebble Wiper, a production worthy nozzle wicking widget that’s wicked away nozzles thousands of times flawlessly.

With a little inspiration from [BigBrain3D’s] retractable purge mechanism, [Kevin] is first purging tools onto a brass brad. Rather than have filament extrude into free space, it collects into a small bloblike “pebble” that cools quickly into a controlled shape. From here, after one quick flick with a servo arm and a small wipe with a silicone basting brush, the nozzle is ready to use. The setup might sound simple, but it’s the result of thousands and thousands of tests with the goal of letting no residual ooze attach itself to the actual part being printed. And that’s after [Kevin] put the time into scratch-building his own toolchanging 3D printer to test it on first. Finally, he’s kindly made the files available online on Github for other hackers’ tinkering and mischief.

So how well does it work? Judging by the results he’s shared, we think spectacularly. Since adopting it, he’s dropped any sacrificial printing artefacts on the bed entirely and been able to consistently pull off stunning multimaterial prints flawlessly with no signs of residual nozzle drool. While toolchanging systems have been great platforms for hacking and exploration, [Kevin’s] Pebble Wiper takes these machines one step closer at hitting “production-level” of reliability that minimizes waste. And who knows? Maybe all those pebbles can be sized to be ground up, remade into filament, and respooled back into usable filament?

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Putting 3D Printed Chain Through Its Paces

May 15, 2021 by Lewin Day 15 Comments

One of the more frustrating things facing makers in decades past was the problem of power transmission. Finding things like belts, pulleys, sprockets, and chain for your projects could be difficult, particularly if you lived far from the shipping radius of suppliers like McMaster-Carr. These days, there’s no need to fuss, because you can simply 3D print whatever you need, as [Let’s Print] demonstrates by whipping up some chains.

The chains are a mixed design, combining plastic inner and outer links with bolts and nuts to fasten them together. [Let’s Print] tries out several combinations of ABS, PLA, and PETG, running them on 3D printed sprockets and determining that they are all functional, albeit at minimum load. The chains are also put through tensile testing by attaching a heavy brake disc to a length of chain and dropping the weight to see at which point the chains snap.

We’d love to see more 3D-printed chains; all-plastic snap-together designs, or even those that print pre-assembled are particularly tantalizing ideas. We’d also enjoy more testing done with the chain under some proper torque loads, rather than just spinning freely.

We’ve seen work from [Let’s Print] before, too – in the case of this awesome water pump. Video after the break.

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A Stackable Planetary Gearbox You Can Print At Home

May 14, 2021 by Lewin Day No comments

In one little corner of YouTube is a small but vibrant community sharing videos about gearboxes of their own design, particularly those with very high ratios or other quirky features. Adherents of the subculture are known as gearheads, and [Let’s Print] is among them. His latest creation is a 3D printed planetary gearbox design with a focus on easy assembly and versatile ratio choice. (Video, embedded below.)

The gearbox came about as [Let’s Print] grew weary of designing bespoke geartrains for each of their individual projects. The planetary design they landed on has the benefit of being stackable, with each reduction block fitted adding a 1:3 stepdown to the train.

For testing purposes, four stages were ganged up for a total reduction ratio of 1:81. The resulting gearbox was able to lift 40 kg before its output coupler failed, no mean feat for some plastic squirted out of a hot nozzle. It’s a common problem with huge ratio gearboxes made out of plastic – often, the very components of the gearbox can’t hold up to the huge loads generated.

Regardless of the limitations of the material, we’re sure the gearbox will prove useful in future projects from [Let’s Print]. We’ve seen other tough 3D printed gearbox builds before too, such as this anvil-lifter from the aptly-named [Gear Down For What]. Dive into the online gearbox subculture yourself.

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3D Printing Restores Bandsaw

May 13, 2021 by Al Williams 24 Comments

A great addition to a home shop is a bandsaw, but when [Design Prototype Test] got a well-used one, he found it wasn’t in very good shape. The previous owner put in an underpowered motor and made some modifications to accommodate the odd-sized blade. Luckily, 3D printing allowed him to restore the old saw to good working order.

There were several 3D printed additions. A pulley, a strain relief, and even an emergency stop switch. Honestly, none of this stuff was something you couldn’t buy, but as he points out, it was cheaper and faster than shipping things in from China. He did wind up replacing the initial pulley with a commercial variant and he explains why.

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Less Stinky Resin Two Ways

May 13, 2021 by Al Williams 12 Comments

After watching [Uncle Jessy’s] video about soy-based 3D printing resin from Elegoo and their miniature air purifiers, we couldn’t decide if the resin doesn’t smell as bad as some other resins or if the air purifier works wonders. Maybe it is a bit of both.

We’ve used Eryone super low odor resin and it has less smell than, say, paint. It sounds like the Elegoo is similar. However, we are always suspicious of claims that any resin is really made with natural ingredients. As [Brent], who apparently has a PhD in chemistry, pointed out, AnyCubic Eco resin makes similar claims but is likely only partially made from soy. Sure, a little less than half is soy-based, but then there’s the other half. Still, we suppose it is better than nothing. That video (also below) is worth watching if you ever wondered why resin solidifies under UV light or what a monomer is.

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Hybrid Rocket Engine Combines Ceramic Aerospike With 3D Printed Fuel

May 13, 2021 by Lewin Day 23 Comments

[Integza] has worked hard over the last year, crafting a variety of types of rocket and jet engine, primarily using 3D printed parts. Due to the weaknesses of plastic, all of which conflict with the general material requirements for an engine that gets hot, he has had less thrust and more meltdowns than he would have liked. Undeterred, he presses on, now with a hybrid rocket aerospike design. The goal? Actually generating some thrust for once!

The latest project makes the most of what [Integza] has learned. The aerospike nozzle is 3D printed, but out of a special thick ceramic-loaded resin, using a Bison 1000 DLP printer. This allowed [Integza] to print thicker ceramic parts which shrunk less when placed in a kiln, thus negating the cracking experienced with his earlier work. The new nozzle is paired with a steel rocket casing to help contain combustion gases, and the rocket fuel is 3D printed ASA plastic. 3D printing the fuel is particularly cool, as it allows for easy experimentation with grain shape to tune thrust profiles.

With the oxygen pumping, the new design produces some thrust, though [Integza] is yet to instrument the test platform to actually measure results. While the nozzles are still failing over a short period of time, the test burns were far less explosive – and far more propulsive – than his previous efforts. We look forward to further development, and hope [Integza’s] designs one day soar high into the sky. Video after the break.

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