One of the limitations of the conventional Cartesian CNC platforms is that the working area will usually be smaller than its footprint. SCARA arms are one of the options to get around this, as demonstrated by [How To Mechatronics], with his SCARA laser engraver.
This robot arm is modified from the original build we featured a while back, which had a gripper mounted. It uses mainly standard 3D printer components with 3D printed frame parts. The arms lengths are sized to fold over the base and take up little table horizontal space when not in use. It can work in a large semi-circular area around itself, and if a proper locating and homing method is implemented, it can be moved around and engrave a large area section by section.
One of the challenges of SCARA arms is rigidity. As the cantilevered arm extends, it tends to lean over under its weight. In [How To Mechatronics]’s case, it showed up as skewed engravings, which he managed to mitigate to some degree in the Marlin firmware.
We’ve all seen videos of blisteringly fast SCARA arms working on assembly lines, and more than a few of us have fantasied about having that same kind of technology for the home shop. Unfortunately, while the prices for things like 3D printers and oscilloscopes have dropped lower than what many would have believed possible a decade ago, high-performance robotics are still too pricey for the home player.
Unless of course, you’re willing to build it yourself. The PyBot designed by [jjRobots] is an open source robotic arm that should be well within the means of the average hardware hacker. One could argue that this is a project made entirely possible by desktop 3D printing; as not only are most of the structural components printed, but most of the mechanical elements are common 3D printer parts. Smooth rods, linear bearings, lead screws, and NEMA 17 motors are all exceptionally cheap these days thanks to the innumerable 3D printer kits that make use of them.
Those who’ve researched similar projects might notice that the design of this arm has clearly been influenced by the Mostly Printed SCARA (MPSCARA). But while that robot was designed to carry an extruder and act as a 3D printer, [jjRobots] intends for the PyBot to be more of a general purpose platform. By default it features a simple gripper, but that can easily be changed out for whatever tool or gadget you have in mind.
In the base of the arm is a custom control board that combines an Arduino M0, an ESP8266, and a trio of stepper motor drivers. But if you wanted to build your own version from the parts bin, you could certainly wire up all the principle components manually. As the name implies, the PyBot is controlled by Python tools running on the computer, so it should be relatively easy to get this capable arm to do your bidding.
One of the side effects of the rise of 3D printers has been the increased availability and low cost of 3D printer components, which are use fill for range of applications. [How To Mechatronics] capitalized on this and built a SCARA robot arm using 3D-printed parts and common 3D-printer components.
The basic SCARA mechanism is a two-link arm, similar to a human arm. The end of the second joint can move through the XY-plane by rotating at the base and elbow of the mechanism. [How To Mechatronics] added Z-motion by moving the base of the first arm on four vertical linear rods with a lead screw. A combination of thrust bearings and ball bearings allow for smooth rotation of each of the joints, which are belt-driven with NEMA17 stepper motors. Each joint has a microswitch at a certain position in its rotation to give it a home position. The jaws of the gripper slide on two parallel linear rods, and are actuated with a servo. For controlling the motors, an Arduino Uno and CNC stepper shield was used.
The arm is operated from a computer with a GUI written in Processing, which sends instructions to the Arduino over serial. The GUI allows for both direct forward kinematic control of the joints, and inverse kinematic control, which will automatically move the gripper to a specified coordinate. The GUI can also save positions, and then string them together to do complete tasks autonomously.
The base joint is a bit wobbly due to the weight of the rest of the arm, but this could be fixed by using a frame to support it at the top as well. We really like the fact that commonly available components were used, and the link in the first paragraph has detailed instructions and source files for building your own. If the remaining backlash can be solved, it could be a decent light duty CNC platform, especially with the small footprint and large travel area. Continue reading “3D Printed SCARA Arm With 3D Printer Components”→
With the roughly 20-day wide launch window for the Mars 2020 mission rapidly approaching, the hype train for the next big mission to the Red Planet is really building up steam. And with good reason — the Mars 2020 mission has been in the works for a better part of a decade, and as we reported earlier this year, the rover it’s delivering to the Martian surface, since dubbed Perseverance, will be among the most complex such devices ever fielded.
“Percy” — come on, that nickname’s a natural — is a mobile laboratory, capable of exploring the Martian surface in search of evidence that life ever found a way there, and to do the groundwork needed if we’re ever to go there ourselves. The nuclear-powered rover bristles with scientific instruments, and assuming it survives the “Seven Minutes of Terror” as well as its fraternal twin Curiosity did in 2012, we should start seeing some amazing results come back.
No prior mission to Mars has been better equipped to answer the essential question: “Are we alone?” But no matter how capable Perseverance is, there’s a limit to how much science can be packed into something that costs millions of dollars a kilogram to get to Mars. And so NASA decided to equip Perseverance with the ability to not only collect geological samples, but to package them up and deposit them on the surface of the planet to await a future mission that will pick them up for a return trip to Earth for further study. It’s bold and forward-thinking, and it’s unlike anything that’s ever been tried before. In a lot of ways, Perseverance’s sample handling system is the rover’s raison d’être, and it’s the subject of this deep dive.
We see a lot of 3D printers here at Hackaday, but as over the years the 3D printer has moved from being an exciting item in its own right to being an everyday tool, it’s increasingly rare for us to feature a build of one as a project. It’s especially rare for us to see a 3D printer that isn’t a variation of either an XYZ Cartesian design or a delta printer, but that’s what [bondus] has done with a printer based upon a parallel SCARA mechanism. If SCARA isn’t something you’re familiar with, it’s a design used in the world of industrial robots in which an almost humanoid jointed arm works in two dimensions, with the third being provided by raising or lowering the whole construction. It has the advantage of greater speed than Cartesian designs, at the expense of higher quality joints being required to maintain accuracy of positioning.
This is the second SCARA printer he’s built, and has a sturdy set of aluminium arms and substantial bearings. Drive comes via a pair of belts to some very large pulleys, and calibration is extremely important to ensure that both arms are in exactly the same plane. The curcular bed is on a lead screw that provides the Z axis.
The results are certainly impressive, both is speed and in print quality. We’ve placed a video of it in action below the break. Whether or not SCARA printers improve to the point of being ubiquitous isn’t something we can supply an answer to, but we’ve featured a small number of them in the past. Particularly memorable is this one using an industrial robotic arm.
[Ignacio]’s VIRK I is a robot arm of SCARA design with a very memorable wooden body, and its new gripper allows it to do a simple pick and place demo. Designing a robot arm is a daunting task, and the fundamental mechanical design is only part of the whole. Even if the basic framework for a SCARA arm is a solved problem, the challenge of building it and the never-ending implementation details make it a long-term project.
When we first saw VIRK I in all its shining, Australian Blackwood glory, it lacked any end effector and [Ignacio] wasn’t sure of the best way to control it. Since then, [Ignacio] has experimented with Marlin and Wangsamas support for SCARA arms, and designed a gripper based around a hobby servo. It’s as beautiful to see this project moving forward as it is to see the arm moving ping-pong balls around, embedded below.
The average 3D printer is a highly useful tool, great for producing small plastic parts when given enough time. Most projects to build larger 3D printed objects use various techniques to split them into smaller parts which can fit inside the limited build volume of most Cartesian-based printers. However, there’s no reason a printer need sit inside a box, and no reason a printer can’t roam about, either. Hence, we get the RepRap HELIOS on wheels.
[Nicholas Seward] created the HELIOS and entered it into the Hackaday Prize in 2017, using a SCARA arm to build a printer with a large build volume and no moving steppers. One of [Nicholas]’s students then did a test, in which the HELIOS was mounted on an angled motorized cart, giving the printer potentially infinite build volume in one axis.
[Nicholas] expects the current basic setup to be capable of prints 200mm wide, 100mm high, and theoretically infinite length. There’s also potential to enable the device to create large curved parts by allowing the printer to steer itself with independently controlled motors.
There’s more work to be done, particularly to allow the printer to locate itself relative to its work space to avoid dimensional issues on large prints, but the preliminary results are highly impressive. We’ve seen other infinite volume printers, too – like this build using a conveyor belt design. Video after the break.