[Jacob] has put a slightly new twist on the levitating ball trick with his ping-pong ball levitation machine. We’ve all seen magnetic levitation systems before. Here on Hackaday, [Caleb] built a Portal gun which levitated a Companion Cube. Rather than go the magnetic route, [Jacob] levitated a ping-pong ball on a cushion of air.
Now, it would be possible to cheat here, anyone who’s seen a demonstration of Bernoulli’s principle knows that the ball will remain stable in a stream of air. [Jacob] proves that his system is actually working by levitating ping-pong balls with different weights.
A Parallax Ping style ultrasonic sensor measures the distance between the top of the rig and the levitating ball. If the ball gets above a set distance, [Jacob's] chipKit based processor throttles down his fans. If the ball gets too low, the fans are throttled up. A software based Proportional Integral Derivative (PID) loop keeps the system under control. A graph of the ball distance vs fan speed is displayed on an Android tablet connected to the controller via USB.
When [Jacob] switches a heavy ball for a light one, the lighter ball is pushed beyond the pre-programmed height. The controller responds by reducing the fan speed and the ball falls back. Who said you can’t do anything good with a box of corn dogs?
Continue reading “The Old Ping-Pong Ball Levitation Trick”
This is one of the simplest CNC builds we’ve seen but it still functions quite well. It’s a clone of the EggBot, but is aimed at printing on spherical Ping Pong balls rather than oblong eggs. [Chad] calls it the Spherebot, but you should be careful not to confuse it with the morphing sphere robot which can walk around like a hexapod.
The project is both mechanically and electronically simple. The body of the printer is made up of three acrylic plates, which we’re sure were clamped together when drilling holes to guarantee proper alignment. Threaded rod and nuts are used to mount the plates to one another, as well as to hold the sphere in place while printing. One stepper motor turns the ball while the other pivots the pen mount. A servo motor is responsible for lifting the pen. The entire thing is driven by an Arduino along with two stepper motor driver boards. Don’t miss [Chad's] presentation embedded after the break.
Continue reading “CNC ping pong printer uses simple construction”
Next time you’re in a Nerf gun battle, you better hope you’ve got this absurdly powerful ping pong ball gun. It shoots common celluloid spheres at over 400 meters per second, or Mach 1.2.
This ping pong gun is the work of [Mark French], [Craig Zehrung], and [Jim Stratton] at Purdue University. As you would expect, the gun is powered by compressed air housed in a length of 3 inch schedule 80 PVC pipe. One end of the pressure vessel is sealed with a PVC end cap, while the other is closed off with a doubled up piece of duct tape to contain the pressure.
The interesting bit of the build is a de Laval nozzle between the pressure vessel and the barrel. Just like a rocket engine nozzle, this bit of machined PVC compresses the air coming through the burst duct tape seal and allows it to expand again, propelling the muzzle-loaded ping pong ball at supersonic speeds.
The guys have written a report on their gun, you can grab that over on arxiv.
[Ian Lee, Sr.] made something special for his daughter’s birthday party. It’s pretty common for girls of this age (this was her 5th birthday) to be enthralled with stories of princesses so he made a blinky princess wand for each party guest. The motivation came when she asked what special thing he was going to do for her celebration. You may remember seeing the LED badge kits that were featured at her brother’s party earlier this year. From the look of the party guests he surely satisfied her desire for a memorable party.
The project is very inexpensive, extremely easy to assemble, and might make a perfect kit for supervised Kindergarteners. It’s basically an LED throwie with a stick and a feather added. [Ian] used CR2032 batteries along with an LED and current limiting resistor to light things up. He clipped off one leg of the LED and replaced it by soldering the LED in place. The remaining leads were then pressed to either side of the coin cell and the whole thing was shoved into a slit cut in the end of a balloon rod. The whole thing was wrapped tightly in with a rubber band before being crowned with a ping pong ball. To trim it out he hot glued a feather at the base of the ball.
The only think that has us worried is what he’s going to do next year to top these parties.
What should you do with your down time between sophomore and junior year at MIT? You better build something awesome. [Christian Reed] didn’t disappoint with his newest creation. He calls it the Ping Pong Mauler and we think that’s an appropriate name. It doesn’t just lunch a ball, it belches forth a relentless barrage.
He certainly has no shortage of ammo. A few garbage bags full of the white orbs number at least 3000 strong, and the plastic drum he’s using as a hopper has room for them all. Jamming is an issue and in the image above you can see him working the agitator with his right hand to prevent a clog. The system is mobile, but the shop vacuum used to propel the balls needs AC power. This means there is a tether that keeps it from roaming too far from home. [Christian] included an air tank in the design but apparently the pressurized air doesn’t do much to help with launch speed. That’s good because pressurized ball guns can be scary.
Check out the video after the break to see the ping pongs fly. We bet they’ll be mowing over some strays out in the yard for at least the rest of this summer.
Continue reading “Ping pong ball barrage”
[Andrew] and his brother had some time (and a lot of ping pong balls) on their hands, so they decided to have some fun and built a remote-controlled ping pong ball turret.
Arduino aside, the turret is cheap and easy to build as [Andrew’s] writeup explains. The firing mechanism was constructed using a pair of foam wheels and motors, which is used to launch the ping pong balls much like a baseball pitching machine. The balls are stored above the wheels in a cardboard tube and released by a mechanical flap when triggered.
When [Andrew] is ready to release the turret’s payload, he sends a command to his computer over VNC, which relays the command to the Arduino over a serial connection, triggering the flap. While the control scheme could certainly benefit from direct, wireless phone-to-Arduino communications, it seems to work well enough for [Andrew's] needs.
Check out the video dramatization below to see [Andrew] “surprise” his brother with a hail of ping pong balls after the jump.
Continue reading “Rapid fire, remote controlled ping pong ball turret”
Induction cook top provides power too
We’re familiar with induction cook tops but we never thought to power a microcontroller with one. [Thanks Hadez]
We’ve been big fans of the chain reaction demonstration using ping-pong balls and mouse traps ever since we saw [Mr. Wizard] do it back in the day. If you don’t know what we’re talking about, check out this demonstration that is analogous of a fission reaction. [Thanks nateL]
Phone tripod enclosure
If you’re interested in using your smart phone for some photography, [Mike] has a nice wood and elastic mount for an iPhone which you might try yourself.
Bicycle snow tires
Admittedly we’re a bit late on this one. But keep it in mind for next year: you can use some zip ties for added traction on your bike when it snows. [Thanks Rob]
Now you can BE mario
A little Kinect script lets this gentleman play Super Mario Bros. with his body. Now you can have all the fun that goes along with being a pixellated character stuck in a two-dimensional environment (plus, there are shrooms). [Thanks Das_Coach via Slashdot]