Whiteboard Plotter Rocks Three Colors And An Eraser

May 18, 2020 by Donald Papp 11 Comments

AutoWhiteboardBot’s business end, with three markers.

[td0g]’s AutoWhiteboardBot is not just any 3D printed whiteboard plotter, because it also sports a triple-marker carrier and on-board eraser! The device itself hangs from stepper motors, which take care of moving the plotter across the whiteboard, and the trick to making the three colors work was to incorporate retractable dry-erase markers. A spherical Geneva drive-based assembly on the plotter rotates the pen cartridge, and a plunger activates the chosen color. Erasing, arguably the easiest thing to do on a whiteboard, is done by a piece of felt. 3D printed parts are on Thingiverse and [td0g] says software is coming soon. It’s a clever device, especially the method of accommodating multiple colors with retractable markers.

AutoWhiteboardBot hangs from motors which pull it around, but we’ve also seen a SCARA-type robot writing away on a whiteboard. Watch the video embedded below, which begins with sped-up footage of AutoWhiteboardBot drawing in different colors as it slides across the board surface.

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Take A 3D Printed Brushless Motor Demo For A Spin

May 18, 2020 by Al Williams 9 Comments

It used to be a staple of junior high physics class to build some sort of motor with paperclips or wire. A coil creates a magnetic field that makes the rotor move. In the process of moving, brushes that connect the coil to the rest of the circuit will reverse its polarity and change the magnetic field to keep the rotor turning. However, brushless motors work differently. The change in magnetic field comes from the drive controller, not from brushes. If you want to build that model, [Rishit] has you covered. You can see his 3D printed model brushless motor running in the video below.

Usually, you have a microcontroller determining how to drive the electromagnets. However, this model is simpler than that. There are two permanent magnets mounted to the shaft. One magnet closes a reed switch to energize the coil and the other magnet is in position for the coil to attract it, breaking the current. As the shaft turns, eventually the second magnet will trip the reed switch, and the coil will attract the first magnet. This process repeats over and over.

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Look Ma, No Support For My Floating Holes!

May 17, 2020 by Jenny List 21 Comments

Do you find supports to be annoying, when you use a 3D printer? A lot of time breaking away surplus pieces of plastic and then cleaning up the resulting ragged edges on your prints is certainly an unwelcome chore. But printing in free space is beyond the capabilities of even the most expensive printer, so it seems we’re stuck with supports for the foreseeable future. [Adam Haile] may have a solution to some support woes though, in the form of a clever technique for printing inset holes without support. His designs have a significant quantity of screw holes with inset heads, too far for the printer to bridge over so his technique breaks down the bridge into manageable smaller distances.

In the video below the break he shows how its done, with successive single layers that contain polygons bridging chords across the circle, with each layer approximating further to the final hole and the last holding the hole itself. Over a few layers the hole is created, without any support but with the minor inconvenience of a not perfectly flat inset. It’s a very clever idea, and one that we’d be interested to see further expanded upon by others.

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Fusing Plastic Sheets With A 3D Printer (Sort Of)

May 14, 2020 by Tom Nardi 17 Comments

If you want to experiment with pneumatic devices, you’ll likely find yourself in need of custom inflatable bladders eventually. These can be made in arbitrary 2D shapes by using a soldering iron to fuse the edges of two plastic sheets together, but it’s obviously a pretty tedious and finicky process. Now, if only there was some widely available machine that had the ability to accurately apply heat and pressure over a large surface…

Realizing his 3D printer had all the makings of an ideal bladder fusing machine, [Koppany Horvath] recently performed some fascinating experiments to test this concept out in the real-world. Ultimately he considers the attempt to be a failure, but we think he might be being a bit too hard on himself. While he didn’t get the sheets to fuse hard enough to resist being pulled apart by hand, we think he’s definitely on the right track and would love to see more research into this approach.

For these early tests, [Koppany] wrapped the hotend of his Monoprice Maker Select Plus with some aluminum foil, and covered the bed with a piece of cardboard. Stretched over this were two sheets of plastic, approximately 0.5 mil in thickness. Specifically, he used pieces cut from the bags that his favorite sandwiches come in; but we imagine you could swap it out for whatever bag your takeout of choice is conveyed in, assuming it’s of a similar thickness anyway.

There were problems getting the plastic pulled tight enough, but that was mostly solved with the strategic placement of binder clips and a cardboard frame. Once everything was in place, [Koppany] wrote a Python script that commanded the printer to drag the hotend over the plastic at various speeds while simultaneously adjusting the temperature. The goal was to identify the precise combination of these variables that would fuse the sheets of plastic together without damaging them.

In the end, his biggest takeaway (no pun intended) was that the plastic he was using probably isn’t the ideal material for this kind of process. While he got some decent seams at around 180 °C , the thin plastic had a strong tendency towards bunching up. Though he also thinks that a convex brass probe inserted into the hotend could help, as it would smooth the plastic while applying heat.

We’ve already seen some very promising results when using LDPE film in a CO2 laser cutter, but if a entry-level 3D printer could be modified to produce similar results, it could be a real game changer for folks experimenting with soft robotics.

3D Printed Train Set Aims For Speed

May 12, 2020 by Lewin Day 32 Comments

For most involved in the hobby, model trains involve buying track from off-the-shelf suppliers, and lots of delicate painting and finishing. Conversely, [Ivan] just wanted to make something fast and fun, busting out the 3D printer in due course.

While the title of “World’s fastest toy train” is somewhat dubious, the build has its value as an interesting way of doing things. The train is 3D printed, with pressed-in ball bearings and metal shafts for the bogies. Differing from usual practice, this train carries its power supply on board, in the form of a LiPo battery. It’s hooked up to a brushless motor and controlled by a standard RC car setup.

The track is an impressive structure, consisting of 3D printed rails and supports. These are assembled and then screwed down to plywood baseplates, which are hot glued to the flat concrete floor of [Ivan]’s workshop. Strings were used to align everything as straight and true as possible. The track features a steep banking which helps with cornering. However, the straights remain banked in an effort to avoid the complex modelling of a transition. This leads to some derailments at higher speeds on the flat sections.

While it’s not yet perfect, [Ivan] has done a great job of demonstrating a quick and easy way to build a model railway out of almost entirely 3D printed components. We can’t wait to see improvements to the rails and railcars, and hope to see speeds increase significantly in future tests. 3D printing tends to bring some interesting results to bear on the model train world, such as this vertical hanging setup. Video after the break.

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Combine Broken Drone Propellers For A Second Spin

May 6, 2020 by Danie Conradie 8 Comments

If you’ve ever flown or watched anyone fly a racing drone for any length of time, you know that crashes are just part of the game and propellers are consumables. [Adam] knows this all to well, decided to experiment with combining multiple broken propellers into one with a 3D printed hub.

A damaged propeller will often have one blade with no damage, still attached to the hub. [Adam] trimmed the damaged parts of a few broken props, and set about designing a 3D printed hub to attach the loose blades together. The hubs were designed let the individual blades to move, and folding out as the motors spin up, similar to the props on many photography drones.

Once [Adam] had the fit of the hubs dialed in, he mounted a motor on a piece of wood and put the reborn propellers through their paces. A few hubs failed in the process, which allowed [Adam] to identify weak points and optimise the design. This sort of rapid testing is what 3D printing truly excels at, allowing test multiple designs quickly instead of spending hours in CAD trying to foresee all the possible problems.

He then built a test drone from parts he had lying around and proceeded with careful flight testing. The hubs were thicker than standard propellers so it limited [Adams] motor choices to ones with longer shafts. Flight testing went surprisingly well, with a hub only failing after [Adam] changed the battery from a 3 cell to a 4 cell and started with some aerobatics. Although this shows that the new props are not suitable for the high forces from racing or aerobatics/freestyle flying, they could probably work quite well for smoother cruising flights. The hubs could also be improved by adding steel pins into the 3D printed shafts, and some carefully balancing the assembled props.

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An All Lead Screw 3D Printer You Can Build Yourself

April 30, 2020 by Jenny List 35 Comments

There was a time when the curious hardware hacker had to build their own 3D printer, because commercial models were so expensive as to be unaffordable except by well-funded institutions. We’re fortunate then to live in an era in which a good quality off-the-shelf machine can be had without breaking the bank, but that is not to say that home-made 3D printers are a thing of the past. Instead the community of rapid prototyping experimenters continue to push the boundaries of the art, and from that we all benefit. An example comes from [Morgan Lowe], whose 3DLS lead screw driven 3D printer joins the freely downloadable designs to be found on Thingiverse.

If at first sight you think it looks a little familiar, you are correct, as it takes its frame design from the popular AM8 metal frame upgrade for the Anet A8 off-the-shelf printer. It draws heavily from other A8 upgrades, and brings in some parts such as the extruder and bed from the Creality Ender3. This is the beauty of incremental open source, and the result is a belt-free printer that does a decent-looking Benchy on the bench, and as a party piece manages to print a slightly more hairy little plastic boat when suspended at 45 degrees by a rope from the ceiling.

When dipping a toe into the world of home made 3D printers it’s interesting to take a look into some of the earlier Hackaday RepRap posts, and see how far we’ve come.