We’ve seen a lot of homebrew filament extruders, but [Stefan] at CNC Kitchen shows off a commercial desktop filament extruder in his latest video, which you can see below. The 3DEVO extruder is pretty slick but at around $7,000-$8,000 we probably won’t rush out and buy one. We might, though, get some ideas from it for our next attempt to build something similar.
In concept, any machine that creates filament is pretty straightforward. Melt pellets and push them out of a nozzle. Cool the filament and wind it up. Easy, right? But, of course, the problems are all in the details. Die swell, for example, means you can’t just assume the nozzle’s hole size will give you the right size filament. Continue reading “Machine Extrudes Filament”→
Recycling plastic into filament normally involves chopping it into tiny pieces and pushing it through a screw extruder. [JRT3D] is taking a different approach with PetBot, which cuts PET bottles into tape and then turns it into filament. See the videos after the break.
Cutting the tape and extrusion happens in two completely separated processes on the same machine. A PET bottle is prepared by cutting off the bottom, and the open rim is pushed between a pair of bearings, where a cutter slices the bottle into one long strip, as a driven spool rolls it up. The spool of tape is then moved to the second stage of the machine, which pulls the tape through a hot end very similar to that on a 3D printer. While most conventional extruders push the plastic through a nozzle with a screw, the PetBot only heats up the tape to slightly above its glass transition temperature, which allows the driven spool to slowly pull it through the nozzle without breaking. A fan cools the filament just before it goes onto the spool. The same stepper motor is used for both stages of the process.
We like the simplicity of this machine compared to a conventional screw extruder, but it’s not without trade-offs. Firstly is the limitation of the filament length by the material in a single bottle. Getting longer lengths would involve fusing the tape after cutting, or the filament after extrusion, which is not as simple as it might seem. The process would likely be limited to large soda bottle with smooth exterior surfaces to allow the thickness and width of the tape to be as consistent as possible. We are curious to see the consistency of the filaments shape and diameter, and how sensitive it is to variations in the thickness and width of the tape. That being said, as long as you understand the limitations of the machine, we do not doubt that it can be useful. Continue reading “PetBot: Turn PET Bottles Into Filament”→
Metal 3D printers are, by and large, many times more expensive than their FDM and resin-based brethren. It’s a shame, because there’s plenty of projects that would benefit from being able to produce more heat-resistant metal parts with additive fabrication methods. [Integza]’s rocketry projects are one such example, so he decided to explore turning a MIG welder into a 3D printer for his own nefarious purposes. (Video, embedded below.)
The build is as simple as you could possibly imagine. A plastic adapter was printed to affix a MIG welding nozzle to an existing Elegoo Neptune 2 3D printer. Unfortunately, early attempts failed quickly as the heat from the welding nozzle melted the adapter. However, with a new design that held the nozzle handle far from the hot end, the ersatz metal 3D printer was able to run for much longer.
Useful parts weren’t on the cards, however, with [Integza] facing repeated issues with the steel bed warping from the heat of the welding process. While a thicker steel base plate would help, it’s likely that warping could still happen with enough heat input so more engineering may be needed. It’s not a new concept by any means, and results are typically rough, but it’s one we’d like to see developed further regardless.
Even if you’ve got a decent sized workshop, there’s only so much stuff you can have sitting on the bench at one time. That’s why [Eric Strebel], ever the prolific maker, decided to build this slick cart for his fairly bulky Ultimaker 3 Extended printer. (Video, embedded below.) While the cart is obviously designed to match the aesthetics of the Ultimaker, the video below is sure to have some useful tips and tricks no matter which printer or tool you’re looking to cart around the shop in style.
[Eric] made a second video on sketching out the design.On the surface this might look like a pretty standard rolling cart, and admittedly, at least half of the video is a bit more New Yankee Workshop than something we’d usually be interested in here on Hackaday. But [Eric] has built a number of neat little details into the cart that we think are worth mentally filing away for future projects.
For example, we really liked his use of magnets to hold the plastic totes in place, especially his method of letting the magnets align themselves first before locking everything down with screws and hot glue. The integrated uninterruptible power supply is also a nice touch, as it not only helps protect your prints in the event of a power outage, but means you could even move the cart around (very carefully…) as the printer does its thing.
But perhaps the most interesting element of the cart is that [Eric] has relocated the Ultimaker’s NFC sensors from the back of the printer and into the cart itself. This allows the printer to still read the NFC chip built into the rolls of Ultimaker filament, even when they’re locked safely away from humidity in a sealed box.
Now all you’ve got to do is apply for the loan it will take to pay for all of the MDF you’ll need to build your own version. At this point, we wouldn’t be surprised if encasing your 3D printer in metal would end up being cheaper than using wood.
The process starts with the design and printing of a wall hook, with [Brian] taking care to include the proper draft angles to allow the pattern to be properly removed from the mold. The print is carefully sanded down and post-processed to be highly smooth, so that it doesn’t spoil the mold when its removed for the casting process. From there, a sand casting mold is built around the pattern using sodium silicate in a 3-4% mix by weight with fine masonry sand. Once ready, the pattern is removed, and the mold is assembled, ready for the pour.
[Brian] completes the process with a simple gravity casting method using molten aluminium. The part is then removed from the mold, and filed down to improve the surface finish from the sand casting process. It’s then polished up to a nice shine and hung on the wall.
[Brian] does a great job of explaining the basics of what it takes to get gravity casting right; draft angles in particular are something often ignored by beginners, yet are crucial to getting good results. You needn’t just settle for casting inanimate objects though; we’ve featured DIY casting processes for gears before, too. Video after the break.
A common CAD operation is to take a 2D shape and extrude it into a 3D shape. But what happens if you take a gear and replicate it along a sphere and then rotate it and do it again? As you can see in the video below, you wind up with a porcupine-like ball that you can transfer power to at nearly any angle. There’s a paper describing this spherical gear as part of an active ball joint mechanism and even if you aren’t mechanically inclined, it is something to see.
The spherical gear — technically a cross spherical gear — is made from PEEK and doesn’t look like it would be that difficult to fabricate. There’s also a simpler version known as a monopole gear in the drive system that provides three degrees of freedom.
Game developer and eternal learner [David Tucker] just posted a project where he’s making linear flexures on a 3D printer. Tinkerer [Tucker] wanted something that would be rigid in five of the six degrees of freedom, but would provide linear motion along one axis. In this case, it is for a pen or knife on a CNC flatbed device. [David]’s design combines the properties of a 1-dimensional flexure and a spring to give a constant downward force. Not only is this an interesting build in and of itself, but he gives a good explanation and examples of more traditional flexible constructs. He also points out this site by MIT Precision Compliant Systems Lab engineer [Marcel Thomas] which provides a wealth of information on flexures.
