3D printers now come in all shapes and sizes, and use a range of technologies to take a raw material and turn it into a solid object. We’re most familiar with Additive Manufacturing – where the object is created layer by layer. This approach is quite useful, but has a down side of being time consuming. Two professors at the University of Michigan have figured out a way to speed this process up, big time.
They start off with a VAT additive printing approach. These work by using an ultraviolet laser to harden or cure specific areas in a vat of resin, layer by layer, until the object is complete. The resin is then drained revealing your 3D printed object. Traditionally, VAT printing has been limited to small objects because the resin needs to have a relatively low viscosity.
The clever professors at U-M were able to get around this problem by adding a second laser that keeps the resin in a liquid state. By combining a curing laser with an ‘uncuring’ laser, they’re able to use resins that are more viscous, allowing them to print more durable parts. And do so about 100 times faster than traditional printers!
Thanks to [Baldpower] for the tip!
3D printers, like most CNC machines, reward careful thought and trial and error. It’s important to use the correct machine settings and to prepare the build environment properly in order to get good results. Fused Filament Fabrication printers rely on melting plastic just so in the production of parts, and have their own set of variables to play with. [Mysimplefix] has been exploring various solutions to bed adhesion and found something that seems to work perfectly, right in the pantry.
That’s right, this solution to the problem of bed adhesion is more commonly stirred into your coffee every morning – it’s sugar. [Mysimplefix] shares their preferred process, consisting of first mixing up a sugar/water solution in the microwave, before applying it to the bed with a paper towel and allowing the water to evaporate off.
Several test prints are then shown, with major overhangs, to show the adhesive capabilities of the sugar. The results are impressive, with parts sticking well while the bed is hot, while being easy to remove once cool. The video deals with PLA, but we’d be interested to see the performance with other materials as well.
It’s a tidy solution, and we’d love to know your thoughts and experiences in the comments. We’ve had a good long think about adhesives ourselves, too.
Continue reading “Sugar As A Bed Adhesive For 3D Printing”
[Mark Rehorst] has been busy with his Ultra MegaMax Dominator (UMMD) design for a 3D printer, and one of the many things he learned in the process was how not to design a 3D printed belt clamp. In the past, we saw how the UMMD ditched the idea of a lead screw in favor of a belt-driven Z axis, but [Mark] discovered something was amiss when the belts were flopping around a little, as though they had lost tension. Re-tensioning them worked, but only for a few days. It turned out that the belt clamp design he had chosen led to an interesting failure.
The belts used were common steel-core polyurethane GT2 belts, and the clamp design uses a short segment of the same belt to lock together both ends, as shown above. It’s a simple and effective design, but one that isn’t sustainable in the longer term.
The problem was that this design led to the plastic portion of the belt stretching out and sliding over the internal steel wires. The stretching of the polyurethane is clear in the image shown here, but any belt would have had the same problem in the clamp as it was designed. [Mark] realized it was a much better idea to use a design in which the belts fold over themselves, so the strain is more evenly distributed.
[Mark] has been sharing his experiences and design process when it comes to building 3D printers, so if you’re interested be sure to check out the UMMD and its monstrous 695 mm of Z travel.
One of the interesting benefits of the 3D printing revolution is the dramatic increase in availability of prosthetics for people with virtually any need. With a little bit of research, a 3D printer, and some trial and error, virtually anyone can build a prototype prosthetic to fit them specifically rather than spend thousands of dollars for one from a medical professional. [Dominick Scalise] is attempting to flesh out this idea with a prosthetic hand that he hopes will be a useful prosthetic in itself, but also a platform for others to build on or take ideas from.
His hand is explained in great detail in a series of videos on YouTube. The idea that sets this prosthetic apart from others, however, is its impressive configurability while not relying on servos or other electronics to control the device. The wearer would use their other hand to set the dexterity hand up for whatever task they need to perform, and then perform that task. Its versatility is thanks to a unique style of locks and tensioners which allow the hand to be positioned in various ways, and then squeezed to operate the hand. It seems like a skilled user can configure the hand rapidly, although they must have a way to squeeze the hand to operate it, or someone will need to develop an interface of some sort for people without needing to squeeze it.
To that end, the files for making your own hand are available on Thingiverse. [Dominick] hopes that his project will spark some collaboration and development, using this hand as a basis for building other low-cost 3D printed prosthetics. There are many good ideas from this project that could translate well into other areas of prosthetics, and putting it all out there will hopefully spur more growth in this area. We’ve already seen similar-looking hands that have different methods of actuation, and both projects could benefit from sharing ideas with each other.
Thanks to [mmemetea] for the tip!
Continue reading “Dexterity Hand is a Configurable Prosthetic Hand”
If you’ve ever tried to cut a piece of acrylic with a tool designed to cut wood or metal, you know that the plastic doesn’t cut in the same way that either of the other materials would. It melts at the cutting location, often gumming up the tool but always releasing a terrible smell that will encourage anyone who has tried this to get the proper plastic cutting tools instead of taking shortcuts. Other tools that heat up plastic also have this problem, as Gizmodo reported recently, and it turns out that the plastic particles aren’t just smelly, they’re toxic.
The report released recently in Aerosol Science and Technology (first part and second part) focuses on 3D printers which heat plastic of some form or other in order to make it malleable and form to the specifications of the print. Similar to cutting plastic with the wrong tool, this releases vaporized plastic particles into the air which are incredibly small and can cause health issues when inhaled. They are too small to be seen, and can enter the bloodstream through the lungs. The study found 200 different compounds that were emitted by the printers, some of which are known to be harmful, including several carcinogens. The worst of the emissions seem to be released when the prints are first initiated, but they are continuously released throuhgout the print session as well.
Perhaps it’s not surprising that aerosolized plastic is harmful to breathe, but the sheer magnitude of particles detected in this study is worth taking note of. If you don’t already, it might be good to run your 3D printer in the garage or at least in a room that isn’t used as living space. If that’s not possible, you might want to look at other options to keep your work area safe.
Thanks to [Michael] for the tip!
It’s hard to pass up another lesson in good machine design brought to us by [Mark Rehorst]. This time, [Mark] combats the relentless forces of bed deformation due to thermal expansion.
Did you think your printer stayed the same size when it heated up? Well, think again! According to [Mark’s] calculations, when heated, the bed can expand by as much as half a millimeter in the x/y direction. While x/y deformation seems like something we can ignore, that’s not always true. If our bed is rigidly fixed in place, then that change in dimension will only result in a warped bed as it tries to make space for itself.
Don’t give up yet though. As sinister as this problem may seem, [Mark] introduces a classic-but-well-implemented solution: and adjustable kinematic coupling. The kinematic coupling holds the bed at the minimum number of points to keep it rigid while exposing thumbscrews to dial in a level bed. What’s special about this technique is that the coupling holds the bed perfectly rigid whilst allowing it to thermally expand!
This is the beauty of “exact constraint” design. Parts are held together only by the minimum number of points needed to guarantee a specific relationship. Here that relationship is coplanarity between the the nozzle’s x/y plane and the bed. Even when the bed expands this relationship holds. Now that is magic.
With such a flood of 3D printed parts on the market, building a printer has never been easier! Nevertheless, it’s easy to pin ourselves into a corner re-tuning a poor design that skips a foundation on the base principles. If you’re curious about more of these principles behind 3D printer design, check out [Mark’s] thorough walkthrough on the CoreXY design.
With the proliferation of 3D printing in the new millennium, stepper motors are no longer those idle junkbox inhabitants you pulled out of a dot matrix in 1994 and forgot about ever since. NEMA standard parts are readily available and knocking about just about everywhere. Now, you can readily turn a stepper motor into a peristaltic pump with just a few simple 3D printed parts.
The pump consists of a bracket that fits on to a standard NEMA-14 stepper motor frame. A rotor is then fitted to the motor shaft, constructed out of a 3D printed piece fitted with a series of standard roller bearings. These bearings roll against the tubing, pumping the working fluid.
The design uses the bearings to squeeze outwards against the tube’s own elastic resistance. Frictional wear is minimised by ensuring the tube is only pressed on by the bearings themselves, avoiding any contact between the tubing and hard plastic surfaces.
While the design is in its early stages of development, we’d be interested to see a pump performance comparison against other 3D printed peristaltic designs – we’ve seen a few before!
[Thanks to Baldpower for the tip!]