We are fascinated by the hybrid rocket engine which [Ben Krasnow] built and tested in his shop. It is actually using a hollow cylinder of acrylic as the fuel, with gaseous oxygen as an oxidizer. We’re already quite familiar with solid rocket propellant, but this hybrid approach is much different.
When a rocket motor using solid propellant is lit it continues to burn until all of the fuel is consumed. That is not the case with this design. The acrylic is actually burning, but if the flow of oxygen is cut off it will go out and can be ignited later. This also opens up the possibility of adjusting thrust by regulating the pressure of the oxygen feed.
[Ben] milled the test rig in his shop. It’s a fat acrylic rod through which he bored a hole. There are two aluminum plates which complete either end of the chamber. The intake has a fitting for a valve which connects to the oxygen tank. There is a nozzle on the outflow end. Check out the video after the break to see a full description. You’ll also get a look at the toll the combustion heat takes on the rig.
Continue reading “Hybrid rocket engine uses acrylic as fuel”
Here [Catarina Mota] is showing off a ring of magnetic ink printed on a piece of paper. It’s strong enough to hold a disc magnet in place when the paper is raised vertically. This strength comes from mixing your own batch of ink.
Magnetic ink has been around a long time and is most often used in banking. The account number and routing number on the bottom left of paper checks are printed in magnetic ink to allow for automated recognition. Iron oxide is charged by the reader as it passes through. In this case, magnetite is used as the doping agent as it has very strong ferromagnetic properties. By mixing it with acrylic medium in a vortex mixer you end up with a homogeneous ink.
There’s a quick demo after the break that shows how well this printed ring holds the magnet. What are some things for which you would use this ink? Leave a comment to let us know.
Continue reading “Make your own magnetic ink”
[Simon Inns] is showing off the Raspberry Pi case which he built out of acrylic. It provides a lot more protection than a flimsy film case, but it is also a little bit more involved to fabricate. No, this doesn’t need to be laser cut, but to get the nice edges [Simon] used a band saw which many don’t already have in their shop. Ask around, or poke your head in at the local Hackerspace. It only takes a few minutes to cut out the parts.
It sounds like either 8mm or 6mm acrylic will work for this project. Aluminum pipe serves as a spacer to keep the two main sheets in place. The RPi board itself is held in position by a few well-place acrylic chunks super glued in place. You can see the entire build process, including rounding cut edges with a torch, in his video embedded after the break.
Continue reading “Acrylic RPi case you can make without a CNC machine”
As a retired industrial designer, [Dave] has a lot of time to do what we’d all like to do: sit around in a workshop and make stuff. His latest project, an acrylic light display of an Indian motorcycle looks fantastic and betrays his designer heritage.
The base of the light display is made up of a laminate of a few 1/4″ pieces of Poplar carved on [Dave]’s CNC machine. These pieces were glued together with a slot routed into the top for the arcylic panel. Instead of going with a few LEDs for the light source, [Dave] used a small cold cathode fluorescent lamp with the requisite inverter tucked away inside the base. This is the same setup he used in an earlier project, and judging from that the Indian motorcycle display looks great on the inside.
After giving the wooden base a few coats of lacquer, [Dave] milled a piece of acrylic with an Indian motorcycle motif he created himself. It’s a great piece of work, sure to brighten up his very awesome workshop.
[BadWolf’s] girlfriend wanted him to build her a lamp for Christmas and he didn’t disappoint. What he came up with is a water-filled color changing lamp with bubbles for added interest. See for yourself in the clip after the jump.
The color changing properties are easily taken care of by some waterproof RGB LED strips. [BadWolf] went the Arduino route for this project but any microcontroller will be able to fill the role of color cycling. The enclosure is all hand-made from acrylic sheets. He grabbed some chemical welding liquid from the hardware store and applied it to the acrylic with a syringe. That’s easy enough when attaching the edges to one side of the enclosure. But it gets much tougher when it’s time to seal up the other side. He recorded a video of this which shows the syringe taped to a rod so he can get it down in there, pushing the plunger with a second extension device.
Bubbles are supplied by a small aquarium pump. We’re wondering if this will need frequent cleaning or if you can get some pool chemicals to keeps it nice and clear (or just a teaspoon of bleach)? Continue reading “Hacking together a color changing water wall”
Although [Danman] was right on time with his home-hacked Valentines day gift, this article comes to you a little late. With the message on the heart changed, however, it could be a perfect “Sorry I forgot Valentines Day again” gift, so it may still be useful.
The concept isn’t that complicated, simply a strip of LED lights around a piece of acrylic. A battery holder and switch rounds out this build. It’s a neat way to light things up, but what we thought was especially interesting was the way it was engraved and cut out with a minimum of traditional tools.
Sure, [Danman] had access to a bandsaw, but as for actually engraving the outline he used a modified electric toothbrush! We’d love to see that build written up. If that wasn’t enough, the lettering was “ghetto blasted”, as he puts it, using a compressed air nozzle, a pen tube, and a styrofoam cup full of ceramic dust! Macgyver would be proud!
[Will] didn’t pick up a card, rose, and bottle of wine for Valentine’s Day like most guys. Nope, he planned way ahead and built this color-selectable glowing Valentine. When we first saw it, we figured he threw some LEDs together with a microcontroller and edge-lit a piece of acrylic. While that is technically what happened, there was a lot more design and craftsmanship at play here than you might think.
First off, the controller board is a beautifully designed two-sided PCB which he etched rather than throwing a mess of wires and hot glue into an enclosure. Speaking of enclosures, he grabbed a wooden picture box from the big box store and used a piece of brass plate stock to serve as the control panel. The enclosure was finished with tinted polyurethane after having a slit added to the top for the acrylic. The message itself was milled using an engraving bit and a Dremel tool. This was done by hand and we think achieves a finished look that is comparable to the CNC milled ornaments we’ve seen in the past.
Get a good look at the device and a demonstration of its features in the clip after the jump.
Continue reading “A lot of love went into this glowing Valentine”