Every once in a while we get sent a link that’s so cute that we just have to post it. For instance: this video from [Ludic Science]. It’s a wind-up chicken toy that kicks a pendulum back and forth. No more, no less.
But before you start screaming “NOT A HACK!” in the comments below, think for a second about what’s going on here. The bird has a spring inside, and a toothed wheel that is jammed and released by the movement of the bird’s foot (an escapement mechanism). This makes the whole apparatus very similar to a real pendulum clock.
Heck, the chick toy itself is pretty cool. It’s nose-heavy, so that under normal conditions it would tip forward. But when it’s wound up, tipping forward triggers the escapement and makes it hop, tipping it backward in the process and resetting the trigger. The top-heavy chicken is an inverted pendulum!
And have a look, if you will indulge, at the very nice low-tech way he creates the pivot: a bent piece of wire, run through a short aluminum tube, held in place by a couple of beads. Surely other pivots are lower-friction, but the advantage of using a rod and sleeve like this is that the pendulum motion is constrained to a plane so that it never misses the chicken’s feet.
Our only regret is that he misses (by that much) the obvious reference to a “naked chick” at the end of the video.
Continue reading “Chicken-powered Pendulum”
Electronics are undoubtedly the basis for our modern society. Leaving out transistor-based devices, and a mechanical clock would be one of the most intricate devices man has come up with. As a Mechanical Engineer, I thought it would be a fun challenge to design and build my own gear-driven clock.
Because clocks have obviously been invented, I wouldn’t be starting from scratch, and I don’t think I could have figured out an escapement on my own. I explain my initial clock escapement and gear reduction design thoughts in this post, and originally getting the escapement to work was my biggest fear.
As seen in the first video after the break, the escapement gear is still a big problem, but not really for the reason I expected. The shaft that the gear sits on seems to be bent, so it allows the escapement to “go free” for part of it’s cycle, losing any sense of accurate timekeeping. Be sure to also check out the second video, especially around 1:50 when I show what happens when an escapement gear goes much faster than a normal clock. Continue reading “Designing and Building a Wooden Mechanical Clock”
Here’s an art exhibit that does its own painting. The Senseless Drawing Bot (translated) uses the back and forth motion of the wheeled based to get a double-pendulum arm swinging. At the end of the out-of-control appendage, a can of spray paint is let loose. We’re kind of surprised by the results as they don’t look like a machine made them.
The video after the break gives a pretty good synopsis of how the robot performs its duties. The site linked above is a bit difficult to navigate, but if you start digging you’ll find a lot of build information. For instance, it looks like this was prototyped with a small RC car along with sticks of wood as the pendulums.
We can’t help but be reminded of this robot that balances an inverted double pendulum. We wonder if it could be hacked to purposefully draw graffiti that makes a bit more sense than what we see here?
Continue reading “Double-pendulum spray gives this graffiti bot some style”
[Frank] sent in a link to this fantastic wooden clock. The design was dreamed up by [Clayton Boyer] and he’s got full-sized templates for sale on his site. We’ve marveled at his creations in the past, having featured his useless machine that was made from wooden gears. This “Bird of Paradise” clock steps up the complexity quite a bit, creating a timepiece without a case to show off the beauty of all of those teeth.
We wondered what goes into building one of these yourself. From the FAQ page it seems you could get by with a scroll saw, drill press, Dremel, and sander. That’s the medium-tech method, but you could opt to scan the plans in order to laser cut your parts, or just use hand tools. But in addition to building tips, there’s advice on how to fine tune clocks that don’t want to keep running, thoughts on finishing the wood parts, sanding, tweaking the teeth, and much more. It’s no secret we have a love for digital clock projects, but there’s something very seductive about a design like this that uses no electricity. Don’t miss the clip after the break to see what we mean.
Continue reading “Do you have what it takes to make lumber keep time?”
[Stephen Hobley] has been experimenting with an electromagnetic pendulum in order to build himself a clock. Through the course of his experiments, he has learned quite a bit about how pendulums function as well as the best way to keep one moving without the need for chains and weights, which are typically associated with these sorts of clocks.
His first experiments involved driving a simple pendulum with a pulse motor. He discovered that the easiest way to keep the pendulum moving was to use a coil to detect when the it reached the equilibrium point, pushing it along by sending a small pulse to that same coil. He noticed that he could keep the pendulum moving at a pretty good tick if he triggered the magnetic coil every third pass, so he implemented an Arduino to keep count of passes and apply the appropriate force when needed.
He has been making pretty decent headway since his first experiments and now has nearly all of the clock works assembled. Crafted out of wood, he uses a 15-tooth primary drive ratchet, which powers two 60-tooth gears responsible for keeping track of seconds, as well as a pair of larger gears that track the minutes and hours.
It’s looking good so far, we can’t wait to see it when finished.
Stick around to see a quick video demonstration of the clock with all of its gearing in action.
Continue reading “Building an electromagnetic pendulum clock”
Put a case around it and it would be a grandfather clock but for now it’s a pendulum clock made from LEGO pieces. The video after the break shows a great overview of the build. You can see the workings at several different angles, as well as a clip that has been sped up to show the movement of the weights over time. One weight, made from dead AA batteries, drives the clock and the other weight switches the winding motor. That motor acts to automatically wind the clock when the drive weight reaches the end of its rope.
This is a nice departure from the majority of clock projects we see as it utilizes mechanical concepts instead of electronic. Most of [Pmroskelly’s] build details are shared as comments on the Picasa album found at the link above. There are also some other videos such as the one showing how the escapement works.
Continue reading “LEGO pendulum clock”
The robot above can balance an inverted pendulum. But wait, it gets better. It can balance an inverted pendulum that is articulated in the middle like the one seen above. Wait, wait, wait… it gets even better. It can start with the pendulum hanging below the sliding carriage, flick back and forth to get the two segments swinging, and then come to equilibrium with the pendulum as seen above. Once there, it can recover from a bit of a shove, like some of the big boys. Very impressive, even when compared to two-wheeled balancers. See for yourself after the break.
We don’t have very much information on how this works. We do know that it was a seminar paper from a student at the University of Stuttgart but the rest is pretty much a mystery. Does it use visual processing? What kind of controller is driving this thing? We want to know the details but haven’t yet found a copy of the paper. If you know where we can get our mitts on it please leave a comment below.
Continue reading “Balancing inverted pendulums”