Ground plastic bits go in one end, finished 3D-prints come out the other. That’s the idea behind [HomoFaciens]’ latest build: a direct-extrusion 3D-printer. And like all of his builds, it’s made from scraps and bits most of us would throw out.
Take the extrusion screw. Like the homemade rotary encoders [HomoFaciens] is known for, it appears at first glance that there’s no way it could work. An early version was just copper wire wrapped around a threaded rod inside a Teflon tube; turned by a stepper motor, the screw did a decent job of forcing finely ground PLA from a hopper into the hot end, itself just a simple aluminum block with holes drilled into it. That worked, albeit only with basically powdered PLA. Later versions of the extruder used a plain galvanized woodscrew soldered to the end of a threaded rod, which worked with chunkier plastic bits. Paddles stir up the granules in the hopper for an even flow into the extruder, and the video below shows impressive results. We also picked up a few tips, like using engine gasket paper and exhaust sealant to insulate a hot end. And the slip coupling, intended to retract the extruder screw slightly to reduce stringing, seems brilliant but needs more work to make it practical.
Open-Source Extruded Profile systems are a mature breed these days. With Openbuilds, Makerslide, and Openbeam, we’ve got plenty of systems to choose from; and Amazon and Alibaba are coming in strong with lots of generic interchangeable parts. These open-source framing systems have borrowed tricks from some decades-old industry players like Rexroth and 80/20. But from all they’ve gleaned, there’s still one trick they haven’t snagged yet: affordable springloaded T-nuts.
It would be really hard to go through a typical day in the developed world without running across something made from ABS plastic. It’s literally all over the place, from toothbrush handles to refrigerator interiors to car dashboards to computer keyboards. Many houses are plumbed with pipes extruded from ABS, and it lives in rolls next to millions of 3D-printers, loved and hated by those who use and misuse it. And in the form of LEGO bricks, it lurks on carpets in the dark rooms of children around the world, ready to puncture the bare feet of their parents.
ABS is so ubiquitous that it makes sense to take a look at this material in terms of its chemistry and its properties. As we’ll see, ABS isn’t just a single plastic, but a mixture that takes the best properties of its components to create one of the most versatile plastics in the world.
Conventional 3D printing and other additive manufacturing methods are highly effective at producing parts of irregular geometries that are difficult or impossible to create with other methods. However, there is a whole set of compromises that come with it – material uniformity, strength, and size are just some that come to mind. There are, however, other techniques that can be used in conjunction with these technologies, and the use of so-called “extruded elements” may be one of them.
The idea is to break up large models into a series of smaller mutually interlocking pieces of an extruded form. This is done by importing an STL model into OpenSCAD and processing it with a special script. This script essentially intersects a matrix of extruded forms upon the original part geometry, allowing it to be printed as a series of seperate pieces that can later be assembled. The instructions are long and detailed, but are an accurate guide of how to create your own extruded element parts.
There are options to customise the process, allowing for filled and skeleton type extrusions and various ways of interlocking the parts. There are interesting implications for this technology, thanks to the benefits of interlocking parts. Particularly, it could have great benefits for the repair of damaged structures and for building objects that exceed the size of the build platform on a smaller 3D printer. The technique looks especially good for building up lightweight cores for big objects. [Toby] is working on a stand-up paddle board.
We look forward to seeing how this particular project develops. We’ve seen other techniques to build large printed structures, before, too – like this giant RC F1 car.
A camera slider is a popular and simple project — just a linear slide, a stepper, and some sort of controller. Adding tilt and pan axes ups the complexity until you’ve got three motors, a controller, and probably a pretty beefy battery pack to run everything. Why not simplify with an entirely mechanical pan-tilt camera slider and leave all that heavy stuff at home?
There’s more than one way to program motion control, and [Enza3D]’s design uses adjustable rails to move the gimballed pan-tilt head through two axes of motion. One rail adjusts vertically to control tilt, while the other adjusts in and out relative to the slider to control pan. Arms ride on each rail and connect to the gimbals to swivel the camera in both dimensions while it travels down the manually cranked slide. It’s pretty clever and results in some clean, dynamic shots as in the video below.
Our quibble is that the “program” is only linear since the control rails are straight lengths of aluminum extrusion; seems to us that some sort of flexible control rails might make for more interesting shots. [Enza3D] has amply documented the build and is looking for feedback, so comment away. And if you don’t have a 3D printer to make the parts, wood works for a slider too.
We all know what the ultimate goal of 3D printing is: to be able to print parts for everything, including our own bodies. To achieve that potential, we need better ways to print soft materials, and that means we need better ways to support prints while they’re in progress.
That’s the focus of an academic paper looking at printing silicone within oil-based microgels. Lead author [Christopher S. O’Bryan] and team from the Soft Matter Research Lab at the University of Florida Gainesville have developed a method using self-assembling polymers soaked in mineral oil as a matrix into which silicone elastomers can be printed. The technique takes advantage of granular microgels that are “jammed” into a solid despite being up to 95% solvent. Under stress, such as that exerted by the nozzle of a 3D printer, the solid unjams into a flowing liquid, allowing the printer to extrude silicone. The microgel instantly jams back into a solid again, supporting the silicone as it cures.
[O’Bryan] et al have used the technique to print a model trachea, a small manifold, and a pump with ball valves. There are Quicktime videos of the finished manifold and pump in action. While we’ve covered flexible printing options before, this technique is a step beyond and something we’re keen to see make it into the hobby printing market.
A lot of homebrew CNC machines end up being glorified plotters with a router attached that are good for little more than milling soft materials like wood and plastic. So if you have a burning need to mill harder materials like aluminum and mild steel quickly and quietly, set your sights higher and build a large bed CNC machine with off-the-shelf components.
With a budget of 2000 €, [SörenS7] was not as constrained as a lot of the lower end CNC builds we’ve seen, which almost always rely on 3D-printed parts or even materials sourced from the trash can. And while we certainly applaud every CNC build, this one shows that affordable and easily sourced mechatronics can result in a bolt-up build of considerable capability. [SörenS7]’s BOM for this machine is 100% catalog shopping, from the aluminum extrusion bed and gantry to the linear bearings and recirculating-ball lead screws. The working area is a generous 900 x 400 x 120mm, the steppers are beefy NEMA23s, and the spindle is a 3-kW VFD unit for plenty of power. The video below shows the machine’s impressive performance dry cutting aluminum.
All told, [SörenS7] came in 500 € under budget, which is a tempting price point for a machine this big and capable.