3D Printed Switch Uses Paperclip

May 21, 2020 by Al Williams 11 Comments

We live in a time when all manner of electronic components are practically a mouse click away. Still, we like to see people creating their own components. Maybe a stock part won’t fit or isn’t immediately available. Or maybe you just want to build it yourself, we get that. [Aptimex] shows off a design for a 3D printed slide switch that uses a paperclip for the contact material.

Of course, it had better be a metal paperclip and we’d make sure the shiny metal was pretty conductive. Of course, you could probably use thick wire to get the same effect. It sounds like [Aptimex] was inspired by an earlier Hackaday.io project that created a few different kinds of switches using similar techniques.

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Bricking Your 3D Printer, In A Good Way

May 20, 2020 by Dan Maloney 15 Comments

In our vernacular, bricking something is almost never good. It implies that something has gone very wrong indeed, and that your once-useful and likely expensive widget is now about as useful as a brick. Given their importance to civilization, that seems somewhat unfair to bricks, but it gets the point across.

It turns out, though, that bricks can play an important role in 3D-printing in terms of both noise control and print quality. As [Stefan] points out in the video below, living with a 3D printer whirring away on a long print can be disturbing, especially when the vibrations of the stepper motors are transmitted into and amplified by a solid surface, like a benchtop. He found that isolating the printer from the resonant surface was the key. While the stock felt pad feet on his Original Prusa i3 Mk 3S helped, the best results were achieved by building a platform of closed-cell packing foam and a concrete paver block. The combination of the springy foam and the dampening mass of the paver brought the sound level down almost 8 dBA.

[Stefan] also thoughtfully tested his setups on print quality. Machine tools generally perform better with more mass to damp unwanted vibration, so it stands to reason that perching a printer on top of a heavy concrete slab would improve performance. Even though the difference in quality wasn’t huge, it was noticeable, and coupled with the noise reduction, it makes the inclusion of a paver and some scraps of foam into your printing setup a no-brainer.

Not content to spend just a couple of bucks on a paver for vibration damping? Then cast a composite epoxy base for your machine — either with aluminum or with granite.

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Bolt-On Clog Detection For Your 3D Printer

May 19, 2020 by Tom Nardi 19 Comments

Desktop 3D printing technology has improved by leaps and bounds over the last few years, but they can still be finicky beasts. Part of this is because the consumer-level machines generally don’t offer much in the way of instrumentation. If the filament runs out or the hotend clogs up and stops extruding, the vast majority of printers will keep humming along with nothing to show for it.

Looking to prevent the heartache of a half-finished print, [Elite Worm] has been working on a very clever filament detector that can be retrofitted to your 3D printer with a minimum of fuss. The design, at least in its current form, doesn’t actually interface with the printer beyond latching onto the part cooling fan as a convenient source of DC power. Filament simply passes through it on the way to the extruder, and should it stop moving while the fan is still running (indicating that the machine should be printing), it will sound the alarm.

Inside the handy device is a Digispark ATtiny85 microcontroller, a 128 x 32 I2C OLED display, a buzzer, an LED, and a photoresistor. An ingenious 3D printed mechanism grabs the filament on its way through to the extruder, and uses this movement to alternately block and unblock the path between the LED and photoresistor. If the microcontroller doesn’t see the telltale pulse after a few minutes, it knows that something has gone wrong.

In the video after the break, [Elite Worm] fits the device to his Prusa i3 MK2, but it should work on essentially any 3D printer if you can find a convenient place to mount it. Keep a close eye out during the video for our favorite part of the whole build, using the neck of a latex party balloon to add a little traction to the wheels of the filament sensor. Brilliant.

Incidentally, Prusa tried to tackle jam detection optically on the i3 MK3 but ended up deleting the feature on the subsequent MK3S since the system proved unreliable with some filaments. The official line is that jams are so infrequent with high-quality filament that the printer doesn’t need it, but it does seem like an odd omission when even the cheapest paper printer on the market still beeps at you when things have run afoul.

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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.