Perhaps the humble block and tackle — multiple parallel pulleys to reduce the effort of lifting — is not such a common sight as it once was in this age of hydraulic loaders, but it remains a useful mechanism for whenever there is a lifting task. To that end [semi] has produced a 3D-printed block and tackle system, which as can be seen in the video below the break, makes lifting moderately heavy loads a breeze.
It’s a simple enough mechanism, with the 3D printer supplying pulleys, chocks, and attachment points, and steel bolts holding everything together. It’s demonstrated with a maximum weight of 20 kilograms (44 pounds), and though perhaps some hesitation might be in order before trusting it with 200 Kg of engine, we’re guessing it would be capable of much more that what we’re shown. Should you wish to give it a try, the files can be found on Thingiverse.
The block and tackle should hold a special place in the hearts of engineers everywhere, as the first product manufactured using mass-production techniques. It shouldn’t be a surprise that this early-19th century factory came from the work of Marc Brunel, father of Isambard Kingdom Brunel who we’ve made the subject of a previous Hackaday piece.
Continue reading “A 3D-Printed Block And Tackle For Those Annoying Lifts”
Even the oldest of mechanisms remain useful in modern technology. [Skyentific] has been messing with robotic joints for quite a while, and demonstrated an interesting way to use a pulley system in a robotic joint with quite a bit of mechanical advantage and zero backlash.
Inspired by the LIMS2-AMBIDEX robotic arm, the mechanism is effectively two counteracting sets of pulley, running of the same cable reel, with rollers allowing them to act around the bend of the joint. Increasing the mechanical advantage of the joint is simply a matter of adding pulleys and rollers. If this is difficult to envision, don’t work as [Skyentific] does an excellent job of explaining how the mechanism works using CAD models in the video below.
The mechanism is back drivable, which would allow it to be used for dynamic control using a motor with an encoder for position feedback. This could be a useful feature in walking robots that need to respond to dynamically changing terrain to stay upright, or in arms that need to push or pull without damaging anything. With properly tensioned cables, there is no backlash in the mechanism. Unfortunately cables can stretch over time, so it is something that needs to be considered when using this in a project.
Pulley systems have been with us for a very long time, and remain a very handy tool to have in your mechanical toolbox. A similar arrangement is used in the Da Vinci surgical robots to control their tiny manipulators. It would also be interesting to see this used in the already impressive robots of [James Bruton]. Continue reading “Cable Driven Robotic Joint”