Tips For 3D Printing Watertight Test Tubes

[DaveMakesStuff] uses 3D printed test tubes for plants and similar purposes, and he’s shared how to make them on a 3D printer, complete with different models each optimized for different nozzle sizes.

The slots in the model are a means of manipulating how the slicer creates a toolpath when printing in spiral vase mode. These areas end up denser and stronger than they otherwise would be.

It’s not too hard to get clear-looking prints in spiral vase mode by using a transparent filament, but the real value in his design is that it comes out reliably watertight, with an extra-strong base and rim.

How is this accomplished when using spiral vase mode, which extrudes only a single wall perimeter? By using fancy geometry on the part, which makes the nozzle follow a high-density path that turns back onto itself multiple times, in concept a little like a switchback trail. The result is extra-dense areas on both the rim and the bottom of the tubes. This helps make them not only watertight, but far stronger than a single wall.

This technique is reminiscent of an earlier method we saw of enhancing the strength of vase mode prints by modeling thin slots into an object. After slicing, the model still consists of a single unbroken spiral extrusion. But in practice, the extruded plastic forms what resemble structural ribs. Why? Because those technically-adjacent extruded lines are so close to one another that they end up sticking together. Something similar is being done here by [DaveMakesStuff] to ensure that the bottom and top of the tubes are extra strong.

You can see a short video (embedded below) that showcases the tubes, as well as some modular 3D-printable racks that [DaveMakesStuff] also makes. And should you want some tips on getting better transparency from your 3D prints, the essentials boil down to printing with transparent filament, slightly hotter, and with a slightly higher extrusion rate.

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You Wouldn’t 3D Print A Toilet…

[Emily The Engineer] wanted a 3D printing project, so naturally, she decided to print a working toilet. Check out the colorful contraption in the video below. At the start, we thought making it watertight might be a bit difficult, which proved to be a problem. However, some careful work with sealing and soldering irons did allow her to make a working flushable toilet.

Mercifully, we don’t get to see the device in actual use, and, as far as we can tell, she never actually connected it to the plumbing in her home. But it did fill from a garden hose, shut itself off, and flush 3D printer waste, toilet paper, and other material out of its drain. It doesn’t appear that the designs have been made public, but since something of this size would likely take hundreds of print hours to complete, we aren’t sure anyone would really want to do this anyway.

However, some of the techniques might come in handy if you are working on something that has to handle water. If you do replicate this for actual use, consider that many 3D printed plastics aren’t considered food-safe because you can’t adequately clean the little ridges from the layer lines. If you were really using this for its intended purpose, cleaning would be a high priority.

Towards the end, the over-engineering bug hit, and you get to see an add-on bidet, armrests, and even mobile casters. A fun project, even if a bit impractical. As an art installation, though, we’ve definitely seen worse.

A mobile toilet is a unique idea, right? Um — maybe not. If [Emily] does a second version, we’d suggest making the TP roll holder heated.

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Scratch Built Subnautica Sub Explores The Pool

In Subnautica, players explore an alien underwater landscape with the help of a number of futuristic tools and vehicles. [Robert Cook] found himself particularly enamored with the large submarine you unlock towards the later parts of the game, so much so that he decided to build his own real-life version.

Even though the RC version of the Cyclops [Robert] has designed is only big enough to explore swimming pool sized alien landscapes, it’s by no means a simple build. In fact, the sub’s internal watertight compartment holds an impressive array of electronics and systems that are arguably overkill for what’s essentially a toy. Not that we’re complaining, of course.

Beyond the electronics and a few key components, almost every part of the RC Cyclops has been 3D printed. From the bulkheads that cap off the internal watertight acrylic tube to the hull itself, there’s a lot of plastic aboard this ship. Which might explain why it takes nearly two kilograms of lead weight to get the sub close to neutral buoyancy. From there, a clever ballast tank arrangement made from a syringe and peristaltic pump allow the vehicle to dive and surface on command.

[Robert] is in the process of releasing the STL files for all the submarine’s 3D printed components, and has done an excellent job of documenting the roughly four months he’s spent working on the project in a series of videos on his YouTube channel. The videos contain a wealth of fascinating tips and tricks regarding DIY submersible vehicles, such as selecting the proper radio frequencies for maximum penetration through water and counteracting the permeability of 3D printed parts with a generous coating of epoxy.

Modern RC hardware makes it easier than ever to cobble together a “submarine”, but there’s still something to be said for a project that takes the long way around and actually implements features like a functioning ballast system.

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3D Printing Watertight Containers

Most normal 3D prints are not watertight. There are a few reasons for this, but primarily it is little gaps between layers that is the culprit. [Mikey77] was determined to come up with a process for creating watertight objects and he shared his results.

The trick is to make the printer over extrude slightly. This causes the plastic from adjacent layers to merge together. He also makes sure there are several layers around the perimeters.

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Pelican Case Xbox 360


[Ben Heck] has put the final touches on his Pelican case Xbox 360. This prototype was constructed for use by troops stationed overseas. When he announced the project in October, he already knew some of the hurdles he would face. An industrial Velcro style product is used for all component mounting so the air/water-tight seal of the case remains intact. He sanded the surface so that it would stick better. [Ben] mentions that he ended up using less Velcro than he planned on because it held so well. Not being able to cut the case meant the DVD drive had to be converted to top-loading. The tray movement limit switches have been relocated so they now respond to lid position. He regrets not being able to motorize the lid, but let it go since this is still just the first attempt. Extra copper was added to all of the heat sinks to improve cooling. This Xbox is for sale and he’d love to hear from anyone that wants to put it into production. The write-up has a ton of pictures and you can see a video of it below.

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