Single Motor, Single Piece 3D Printed Hovercraft

RC hovercrafts offer all sorts of design options which make them interesting projects to explore. There are dual-motor ones where one motor provides lift while the other does the thrust. For steering, the thrust motor can swivel or you can place a rudder behind it. And there are single-motor ones where one motor does all the work. In that case, the airflow from the motor blades has to be redirected to under the hovercraft somehow, while also being vectored out the back and steered.

[Tom Stanton] decided to make a single-motor hovercraft using only a single 3D printed piece for the main structure. His goals were to keep it as simple as possible, lightweight, and inexpensive. Some of the air from the blades is directed via ducting printed into the structure to the underside while the remainder flows backward past a steering rudder. He even managed to share a bolt between the rudder’s servo and the motor mount. Another goal was to need no support structure for the printing, though he did get some stringing which he cleaned up easily by blasting them with a heat gun.

From initial testing, he found that it didn’t steer well. He suspected the rudder wasn’t redirecting the air to enough of a sideways angle. The solution he came up with was pretty ingenious, switching to a wedge-shaped rudder. In the video below he gives a the side-by-side comparison of the two rudders which shows a huge difference in the angle at which the air should be redirected, and further testing proved that it now steered great.

Another issue he attacks in the video below was a tendency for the hovercraft to dip to one side. He solves this with some iterative changes to the skirt, but we’ll leave it to you to watch the video for the details. The ease of assembly and the figure-eight drift course he demonstrates at the end shows that he succeeded wonderfully with his design goals.

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3D Printed Cookie Molds for the Best Speculoos

Experiencing nostalgia for the outstanding Belgian cuisine [Adam], currently stuck in Ohio, found himself in craving some home-made speculoos. For the uninitiated, speculoos is what those brown cookies usually served with coffee on planes dream of becoming one day.

To add some extra regional flavour, [Adam] decided to print his own molds featuring motifs from Brussels. The risks of 3D prints in the kitchen are the subject of a lively discussion. They are addressed in this project by recommending the use of food safe filament and sealant for the molds. The fact that the dough will be removed from the molds almost instantly and that the molds don’t go into the oven puts the risks in the vicinity of using plastic cutting boards in your kitchen.

[Adam]’s write up features solid, well illustrated baking instructions that should enable any of you to replicate this delicacy. Some links to additional references and two recipes are thrown in for good measure. The article finishes with detailed instructions for designing your own molds that take the properties of the medium into account, to ensure your custom motif will still be recognizable after baking. Line art with a stroke width of around 2-3 mm seems to work best. It is that time of year and we hope to see a lot more tricks to take your cookie and edible house designs to the next level so don’t forget to send in a tip.

With 3D printed molds having been used to shape resin, silicone and even metal, we are at a point where cookie dough looks like a natural progression.

Fastening 3D Printed Parts


Ever been curious on how to fasten 3D printed parts together? There are lots of ways to do it — but what’s the best way? [Chris Lopez] works in a machine shop and decided to do some testing of how best to tap 3D printed parts, so you don’t have to!

The typical ways to add fasteners in 3D printed parts include designing the thread right into the part (only works for big threads), adding a press-fit insert, drilling and tapping it like any other material, inserting a Heli-Coil, or even by using ultrasonic weld inserts. In fact, this Stratasys blog post actually goes into some good detail on the pros and cons of each!

But, there’s a much easier way. To tap a hole normally you need to locate it accurately, make a pilot hole with a center drill — ensuring it is straight and true — then drill through with the undersized tap drill, and finally, thread it with a tap. Luckily, your 3D printer takes care of almost all these steps. By simply designing your holes to be the tap drill size you can hand tap fairly strong threads in your 3D printed parts. Just make sure your wall thicknesses and or infill settings are high enough to make sure there is material to engage!

[Chris] also goes into some detail on creating captive nut geometry — but for that you’re going to have to check out his blog. And if you’re interested in another style of fastening 3D printed parts, why not inset magnets into them while they are printing?