MRRF 17: True Color 3D Printing

3D printing has evolved to a point where dual extrusion isn’t really that special anymore. A few years ago, a two-color frog print would have been impressive, but this isn’t the case anymore. The Midwest RepRap Festival is all about the bleeding edge of what 3D printers are capable of, and this year is no exception. This year, we were graced with a few true multicolor filament-based 3D printers. The biggest and best comes from [Daren Schwenke]. His Arcus 3D printer is a full color, CMYKW mixing printer that’s able to print in any color imaginable.

The bizarre mixing hotend, powered by a brushless motor

The electronics for this printer are, to say the least, very weird. The controller board is a CRAMPS with a few extra bits to control six stepper motors. The hotend is bizarre, feeding six PTFE tubes into a weird water-cooled assembly that mixes and squirts filament out of the nozzle with the help of a small brushless motor. Thanks to a clever design, the end effector of the hotend weighs only about 150 grams – about the same as any other delta printer out there – and this printer is able to move very fast.

Over the last year, we’ve seen a lot of improvements in the state of multi-material and multi-color extrusion for 3D printers. At last year’s Maker Faire NY, Prusa’s i3 quad extruder made an appearance alongside the ORD Solutions RoVa4D printer. These are two completely different approaches to multicolor 3D printing, with the RoVa mixing filament, and the Prusa merely extruding multiple colors. Both approaches have their merits, but mixing extruders are invariably harder to build and the software stack to produce good prints isn’t well-defined.

Even though we’re still in the early years of full-color filament-based printing, this is still an awesome result. In a few years, we’ll be able to look back on [Daren]’s efforts and see where our full-color 3D printers came from – open source efforts to create the best hardware possible.

[Daren] has been working on this printer for a while, and he’s been uploading all his project updates to hackaday.io. You can check out the build log here.

Oscillating Fan Controller Used As Relay

The most brilliant hacks we see aren’t always the thousand-dollar, multi-year projects spanning every facet of engineering. Rather, the most ingenious projects are ones that take an everyday thing and use it in a simple but revolutionary way. By that measure, it’ll be hard to top [Robert]’s latest hack which uses the controller board from an everyday oscillating fan to build a three-way remote-controlled relay board.

Most oscillating fans have a speed selector switch. What that does might be somewhat different between different types of fan, but in general it will select either a smaller portion of the fan’s motor to energize or switch in a resistor which will have the same speed-lowering effect. [Robert]’s fan had little more than a triple-throw switch on the control board, so when he decided the fan wasn’t worth keeping anymore, he was able to re-purpose the control board into a general-use relay. As a bonus, the fan could be controlled by infrared, so he can also remote control whatever he decides to plug into his new piece of equipment.

While this simple hack might not change the world, it may give anyone with an old fan some ideas for other uses for its parts. If you want to do a little more work and get the fan itself running again, though, it is possible to rebuild the whole thing from the ground up as well.

CNC Turns Empty Cans into Action Figures

[apollocrowe] at Carbide 3D (a company that does desktop CNC machines) shared a project of his that spent years being not-quite-there, but recently got dusted off and carried past the finish line. His soda can robot action figures were originally made by gluing a paper design to aluminum from a soda can, but [apollocrowe] was never really able to cut the pieces as reliably or as accurately as he wanted and the idea got shelved. With a desktop CNC machine to take care of accurate cutting, the next issue was how to best hold down a thin piece of uneven metal during the process. His preferred solution is to stick the metal to an acrylic wasteboard with hot glue, zero high enough and cut deep enough to account for any unevenness, and afterwards release the hot glue bond with the help of some rubbing alcohol.

Assembly involves minor soldering and using a few spare resistors. A small spring (for example from a retractable pen) provides the legs with enough tension for the figure to stand by itself. The results look great, and are made entirely from a few cents worth of spare parts and recycled materials. A video of the process is embedded below, and the project page contains the design files.

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Printing Nintendo Portables With SLA

Downing] is no stranger to building portable consoles, employing all manner of techniques in the process. However, when it came time to start on this commission, [Downing] decided to take a different tack – employing a Form 2 SLA printer in this Nintendo 64 portable build.

Modifying home consoles to become portables often involves tricks like Frankencasing – hacking together original factory parts such as controllers, cases, and accessories, and using body filler and a lot of sanding to create a template for vacuum moulding, which then results in a seamless final product. It’s possible to get some really impressive results, but it does limit the builder to relying on existing parts.

By using the Form 2, [Downing] was able to take advantage of the SLA printer’s ability to create parts with good surface finish that would normally require a lot of post-print finishing when 3D printed with more common FDM technology. This was particularly useful as it allowed the creation of custom buttons and small parts that “just fit” – normally such parts are made from stock pieces that are then modified.

The build also features a few other cool features – there’s a breakout box which allows the connection of extra controllers, as well as hosting AV out for hooking up to a television. The breakout box connects to the portable over an HDMI cable. It’s a tidy choice – it’s a standard cable that has an abundance of conductors available so you don’t have to be particularly tricky to get 3 controllers and a few analog signals talking over it.

In the end, [Downing] wouldn’t use SLA printing again for the case itself – the process was too slow and expensive. In this respect, FDM may require more work after printing but it still comes out ahead in terms of time and money. But for small custom parts like buttons and structural brackets, the Form 2 is the machine for the job.

Video after the break.

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How to Play the Bass With Marbles

Stringed instruments make noise from the vibrations of tuned strings, using acoustic or electronic means to amplify those vibrations to the point where they’re loud enough to hear. The strings are triggered in a variety of ways – piano strings are hit with hammers, guitar strings are plucked, while violin strings are bowed. Meanwhile, [Martin] from the band [Wintergatan] is using marbles to play a bass guitar.

[Martin] starts out with a basic setup. The bass guitar is placed on the workbench, while a piece of wood is taped to a tripod. The wood has a hole drilled through it, and marbles are dropped through the aperture in an attempt to get them to land on the string. Plastic containers are used to easily alter the angle the bass guitar sits at, relative to the bench, while an acrylic guide sits around the string to try to guide the marbles in the desired direction. These guides are important to make sure the marbles hit the top of the string, and bounce cleanly in the desired direction afterwards.

The initial setup is too inconsistent, so [Martin] places a notch in the wood and builds a lever system to hold the marbles and then release them in a controlled manner. [Martin] then checks that the system works by analysing footage of the marble drop with slow motion video.

The video covers the CAD design of an eight-slot guide so the four strings of the bass can be played more rapidly than in their previous build. Two guides per string allow each string to play two notes in quick succession without having to worry about marble collisions from playing too quickly.

It’s a great build, and we’ve seen [Wintergatan]’s work before – namely, the incredible build that was the original Marble Machine.

Thanks to [Tim Trzepacz] for the tip!

MRRF 17: E3D Introduces Combination Extruder And Hotend

Since the beginning of time, or 2006, the ‘hot glue gun’ part of our CNC hot glue guns have had well-defined parts. The extruder is the bit that pushes plastic through a tube, and the hot end is where all the melty bits are. These are separate devices, even though a shorter path from the extruder to hotend is always better. From Wade’s gear extruder to a nozzle made from an acorn nut, having the hotend and extruder as separate devices has become the standard.

This week at the Midwest RepRap Festival, E3D unveiled the Titan Aero. It’s an extruder and hotend rolled into one that provides better control over the filament, gives every printer more build height, and reduces the mass of a 3D printer toolhead.

 

The aluminum thermal block of the Titan Aero

The Titan Aero, revealed on the E3D blog yesterday, is the next iteration of E3D’s entry into the extruder market. It’s a strange mashup of their very popular V6 hotend, with the heat break coupled tightly to the extruder body. A large fan provides the cooling, and E3D’s thermal simulations show this setup will work well.

The core component of the Aero extruder is a fancy and complex piece of milled aluminum. This is the heatsink for the extruder and provides the shortest path possible between the hobbed gear and the nozzle. This gives the Aero better control over the extrusion of molten plastic and makes this the perfect extruder and hotend setup for hard to print materials.

Combine the Aero with a smaller ‘pancake’ stepper motor, and you have a very small, very light hotend and extruder. This makes it perfect for the small printers we’re so fond of and for printers built for fast acceleration. I can easily see a few end effectors for Delta-style printers built around this extruder in the near future.

E3D’s Volcano nozzle sock

Also at the E3D booth were a few prototypes of nozzle socks. Late last year, E3D released silicone nozzle covers – we’re calling them nozzle socks – for their V6 hotend. These are small silicone covers designed to keep that carbonized crap off of your fancy, shiny hotend. It’s not something that’s necessary for a good print, but it does keep filament from sticking to your hotend, and you get the beautiful semantic satiation of saying the words nozzle socks.

E3D’s other hotend, the Volcano, a massive and powerful hotend designed to push a lot of plastic out fast, did not get its own nozzle sock at the time. Now, the prototypes are out, and the E3D guys expect them to be released, ‘in about a month’.

A Red Teamer’s Guide to Pivoting

What is hacking and what is network engineering? We’re not sure where exactly to draw the lines, but [Artem]’s writeup of pivoting is distinctly written from the (paid) hacker’s perspective.

Once you’re inside a network, the question is what to do next. “Pivoting” is how you get from where you are currently to where you want to be, or even just find out what’s available. And that means using all of the networking tricks available. These aren’t just useful for breaking into other people’s networks, though. We’ve used half of these tools at one time or another just running things at home. The other half? Getting to know them would make a rainy-day project.

Is there anything that ssh and socat can’t do? Maybe not, but there are other tools (3proxy and Rpivot) that will let you do it easier. You know how clients behind a NAT firewall can reach out, but can’t be reached from outside? ssh -D will forward a port to the inside of the network. Need to get data out? There’s the old standby iodine to route arbitrary data over DNS queries, but [Artem] says dnscat2 works without root permissions. (And this code does the same on an ESP8266.)

Once you’ve set up proxies inside, the tremendously useful proxychains will let you tunnel whatever you’d like across them. Python’s pty shell makes things easier to use, and tsh will get you a small shell on the inside, complete with file-transfer capabilities.

Again, this writeup is geared toward the pen-testing professional, but you might find any one of these tools useful in your own home network. We used to stream MP3s from home to work with some (ab)use of netcat and ssh. We keep our home IoT devices inside our own network, and launching reverse-proxies lets us check up on things from far away without permanently leaving the doors open. One hacker’s encrypted tunnel is another man’s VPN. Once you know the tools, you’ll find plenty of uses for them. What’s your favorite?

Thanks [nootrope] for the indirect tip!