Bolt-On Clog Detection For Your 3D Printer

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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Ventilators 101: What They Do And How They Work

Treating the most serious cases of COVID-19 calls for the use of ventilators. We’ve all heard this, and also that there is a shortage of these devices. But there is not one single type of ventilator, and that type of machine is not the only option when it comes to assisted breathing being used in treatment. Information is power and having better grasp on this topic will help us all better understand the situation.

We recently wrote about a Facebook group focused on open source ventilators and other technology that could assist in the COVID-19 pandemic. There was an outpouring of support, and while the community is great when it comes to building things, it’s clear we all need more information about the problems doctors are currently dealing with, and how existing equipment was designed to address them.

It’s a long and complicated topic, though, so go get what’s left of your quarantine snacks and let’s dig in.

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Prusa Advises On Printed Medical Devices, Releases Face Shield

Like everyone else, hackers and makers want to do something to help control the spread of COVID-19. The recent posts on Hackaday dealing with DIY and open source approaches to respirators, ventilators, and masks have been some of the most widely read and commented on in recent memory. But it’s important to remember that the majority of us aren’t medical professionals, and that even the most well-meaning efforts can end up making things worse if they aren’t done correctly.

Which is exactly what [Josef Průša] wanted to make clear about 3D printed medical equipment in his latest blog post. Like us, he’s thrilled to see all the energy the maker community is putting into brainstorming ways we can put our unique skills and capabilities to use during this global pandemic, but he also urged caution. Printing out an untested design in a material that was never intended for this sort of application could end up being more dangerous than doing nothing at all.

The nested design lends itself to mass production.

To say that he and his team are authorities in the realm of fused deposition modeling (FDM) would be something of an understatement. They know better than most what the technology is and is not capable of, and they’re of the opinion that using printed parts in respirators and other breathing devices isn’t viable until more research and testing is done

For example, how can we ensure the porous plastic parts are sterilized and not just serving as a breeding ground for bacteria? It’s hardly a new concern; the debate about printed objects in food contact applications has been going on for years.

The safest option is to only use printed parts for structural components that don’t need to be sterile. To that end, [Josef] used the post to announce a newly published design of a printable face shield for medical professionals. Starting with an existing open source design, the Prusa Research team used their experience to optimize the headband for faster and easier printing. They can produce four headbands at once on each of the printers in their farm, which will allow them to make as many as 800 shields per day without impacting their normal business operations. The bottleneck on production is actually how quickly they can cut out the clear visors with their in-house laser, not the time it takes to print the frames.

It’s easy to get excited when success stories featuring 3D printed medical devices are in the news, but that doesn’t mean you should be cranking out lifesaving devices with that roll of bargain PLA you’ve had sitting around the shop. As difficult as it may be for some of us to admit, the safest thing might be to let our spare CPU cycles do battle with COVID-19 instead.

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Hackaday Podcast 047: Prusa Controversy, Bottle Organ Breakdown, PCBs Bending Backwards, And Listen To Your LED

Hackaday editors Mike Szczys and Elliot WIlliams get together for the 47th and final Hackaday Podcast of 2019. We dive into the removable appendix on Prusa’s new “Buddy” control board, get excited over the world’s largest grid-backup battery, and commiserate about the folly of designing enclosures as an afterthought. There’s some great research into which threaded-inserts perform best for 3D-printed parts, how LEDs everywhere should be broadcasting data, and an acoustic organ that’s one-ups the traditional jug band.

Take a look at the links below if you want to follow along, and as always tell us what you think about this episode in the comments!

Direct download (63 MB)

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Annealing 3D Prints: A Scientific Approach

We’ve all been taught the scientific method: Form a hypothesis, do some experiments, gather some data, and prove or disprove the hypothesis. But we don’t always do it. We will tweak our 3D prints a little bit and think we see an improvement (or not) and draw some conclusions without a lot of data. Not [Josef Prusa], though. His team printed 856 different parts from four different materials to generate data about how parts behaved when annealed. There’s a video to watch, below.

Annealing is the process of heating a part to cause its structure to reorganize. Of course, heated plastic has an annoying habit of deforming. However, it can also make the parts firmer and with less inner tension. Printed parts tend to have an amorphous molecular structure. That is to say, they have no organization at all. The temperature where the plastic becomes soft and able to reorganize is the glass transition temperature.

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Prusa Dares You To Break Their Latest Printer

Two months after its surprise reveal at the 2019 East Coast RepRap Festival, the Prusa Mini has started shipping out to the first wave of early adopters. True to form, with the hardware now officially released to the public, the company has begun the process of releasing the design as open source. In their GitHub repository, owners can already find the KiCad files for the new “Buddy” control board and STLs for the machine’s printable parts.

But even so, not everyone feels that Prusa Research has made the Mini as “open” as its predecessors. Some concerned owners have pointed out that according to the documentation for the Buddy board, they’ll need to physically snap off a section of the PCB so they can flash custom firmware images via Device Firmware Upgrade (DFU) mode. Once this piece of the board has been broken off, which the documentation refers to as the Appendix, Prusa Research will no longer honor any warranty claims for the electronic components of the printer.

For the hardcore tinkerers out there, this news may come as something of a shock. Previous Prusa printers have enjoyed a fairly active firmware development community, and indeed, features that started out as user-developed modifications eventually made their way into the official upstream firmware. What’s more, certain hardware modifications require firmware tweaks to complete.

Prusa Research explains their stance by saying that there’s no way the company can verify the safety of community developed firmware builds. If thermal runaway protections have been disabled or otherwise compromised, the results could be disastrous. We’ve already seen it happen with other printers, so it’s hard to fault them for being cautious here. The company is also quick to point out that the installation of an unofficial firmware has always invalidated the printer’s warranty; physically breaking the board on the Mini is simply meant as a way to ensure the user understands they’re about to leave the beaten path.

How much support is a manufacturer obligated to provide to a user who’s modified their hardware? It’s of course an issue we’ve covered many times before. But here the situation is rather unique, as the user is being told they have to literally break a piece off of their device to unlock certain advanced functionality. If Prusa wanted to prevent users from running alternate firmware entirely they could have done so (or at least tried to), but instead they’ve created a scenario that forces the prospective tinkerer to either back down or fully commit.

So how did Prusa integrate this unusual feature into their brand new 32-bit control board? Perhaps more importantly, how is this going to impact those who want to hack their printers? Let’s find out.

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Josef Prusa Wants You To Change File Formats

We’ve all been there. You find that cool cat model on Thingiverse — we won’t judge. You download the STL, all ready to watch the magic of having it materialize on your print bed. But the slicer complains it isn’t manifold or watertight or something like that. What a let down. Part of this is due to shortcomings in the STL file format. There’s a newer format available, 3MF, and Josef Prusa and Jakub Kočí would like you to start using it.

STL — short for stereolithography — is a simple format that just holds a bunch of triangles. If you need any information about the part — like colors or materials. Worse still, as in our hypothetical example, there are no definition about how the triangles relate so you can create “bad” STL files. Even properly formed files can be tough to work with. You might scale for inches and the file is set for millimeters, for example.

Turns out 3MF is actually a ZIP archive and it can contain lots of information. The file can contain one or more models, colors, slicing data, copyrights, images, and lots more. The ZIP file is often shorter, too because of the compression. The big deal, though, is that the file format won’t allow nonmanifold models and removes ambiguity so that everything nicely prints. If your slicer stores data into the file — as the Prusa one does — other people using the same software can grab your settings, too.

The format isn’t really that new — it appeared around 2015 — but it hasn’t seen widespread adoption yet. Prusa encourages you to upload models in 3MF even if you also add an STL copy for people who haven’t made the switch yet.

So will you start using 3MF? Or are you already? The file format is open, they say. So if your favorite tool doesn’t like 3MF, you could always add support for it yourself.

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