Ketan's Home

November 30, 2016

Parametric 3D Printable Wheels And Treads

Filed under: Uncategorized — ketan @ 6:15 PM

When it comes to robotic platforms, there is one constant problem: wheels. Wheels have infinite variety for every purpose imaginable, but if you buy a wheeled robotic chassis you have exactly one choice. Even if you go down to the local Horror Freight, there’s only about five or six different wheels available, all of which will quickly disintegrate.

To solve this problem, [Audrey] created OpenWheel, a system of parametric, 3D-printable wheels, tweels, tires, and tracks for robotics and more.

Like all good parametric 3D-printable designs, OpenWheel is written in OpenSCAD. These aren’t 3D designs; they’re code that compiles into printable objects, with variables to set the radius, thickness, diameter of the axle, bolt pattern, and everything else that goes into the shape of a wheel.

Included in this toolset are a mess of wheels and gears that can be assembled into a drivetrain. 3D-printable track that can be printed out of a flexible filament for something has been almost unobtanium until now: completely configurable 3D-printable tank treads. All we need now is a 3D-printable tank transmission, and we’ll finally have a complete hobby robotics chassis.

Filed under: 3d Printer hacks

from Hack a Day

November 28, 2016

A Review of Template Engines: What Next After Velocity?

Filed under: Uncategorized — ketan @ 6:22 AM

Let’s dive into the Template engine problems of MVC based frameworks.

This post will shed light on the mystery of different templating possibilities supported by the Spring Boot framework.

from Javalobby

November 27, 2016

“Alexa, Make My ESP8266 Do Something”

Filed under: Uncategorized — ketan @ 10:59 AM

“Alexa, Make My ESP8266 Do Something”

The Amazon Echo and its diminutive Dot cousin have the handy feature of being able to control some home automation devices. If you own the right manufacturer’s hardware you can bend your home to your will using the power of your voice alone.

The trouble is, if your hardware isn’t on the list of supported devices or if you make your own, you’re out of luck.

[Xose Pérez] had been sidestepping this problem by using a server running a set of scripts emulating a Belkin WeMo device, which Echo supports. The server could issue commands to his microcontrollers, but he wanted more. Why not cut out the middle man to incorporate the WeMo emulation directly on the ESP8266 that did the work?

He took the Fauxmo Python WeMo emulator he had been using, and ported it to an ESP8266 library that can be incorporated in existing code to make it appear to the world as a WeMo device. With the code itself he has provided full instructions on its BitBucket page as well as on the page linked above.

He admits that he is not the first person to have achieved this aim, and points to this earlier project. However his requirement for a library to be incorporated in another piece of software were not satisfied by it, hence his work.

We like this project, but it’s probably worth reminding readers that Alexa does have an SDK in the form of the Alexa Skills Kit. You can use it to do all sorts of clever things with your Echo or Dot… or you can make it the brains of a Big Mouth Billy Bass novelty ornament.

from Hack a Day

Malware uses Facebook and LinkedIn images to hijack your PC

Filed under: Uncategorized — ketan @ 10:38 AM

Malware doesn’t always have to attack your computer through browser- or OS-based exploits. Sometimes, it’s the social networks themselves that can be the problem. Researchers at Check Point have discovered that a variant of known ransomware, Locky, is taking advantage of flaws in the way Facebook and LinkedIn (among others) handle images in its bid to infect your PC. The trick forces your browser to download a maliciously coded image file that hijacks your system the moment you open it. If you do, your files are encrypted until you pay up.

While the actual Locky code is relatively pedestrian and easy to avoid if you’re aware (just don’t open the file), it’s the delivery mechanism that has analysts worried. Many security apps explicitly trust big social networks, and many people aren’t used to worrying about their downloads at sites like Facebook.

Check Point says it told Facebook and LinkedIn about the exploit in September, but it’s not clear that there are fixes in place. We’ve reached out to both companies to find out what the situation is right now. Whether or not you’re in the clear, this is a reminder that you can’t take the safety of social sites for granted — it’s a good idea to be wary of any downloads you weren’t expecting.

[Thanks, Kristy]

Via: Ars Technica

Source: Check Point

from Engadget

November 26, 2016

How to Make Fidget Spinner Toys

Filed under: Uncategorized — ketan @ 1:52 AM

I’d never even heard of a “fidget spinner” until Donald Bell mentioned them on his Maker Update show. Suddenly, I’m seeing them everywhere, and having developed a seriously nervous tick in the past week, I think I need one now.

In this video from Kris’ Workshop, inspired by Jimmy DiResta videos, Kris fashions a fidget spinner from an old skate bearing, a piece of oak off-cut, and some solder.

I love how many young makers have spinner projects online. Here, 14 year old Slingshot King makes a handsome wooden spinner out of some African Padauk wood, aluminum rod, and a skate bearing.

Brian, a young Filipino maker, has a channel called Brains techKnowlogy. In this project video, he builds two spinners using little more than Popsicle sticks, some coins, skate bearings, and the most basic household tools.



Here’s the

Thingiverse project page

that Donald Bell talked about on

Maker Update

. There are dozens of interesting 3D printable spinner designs here, just add skate bearings.

You can find a whole slew of fidget spinner projects on YouTube and on Instructables. One of the more fun things about these little fidget toys is that they can be made out of so many different materials. You’ll find them made out of everything from plastic, wood, paper, and metal using parts from the hardware store, the kitchen trash, and the loose change in your pockets. And, if you’re lazy and just want to buy one, there are plenty of different models of them available on Etsy.

from MAKE Magazine

November 11, 2016

Web Matrix Control Proves Power of ESP8266

Filed under: Uncategorized — ketan @ 9:26 AM

Web Matrix Control Proves Power of ESP8266

LED matrix projects are all over the place, but this one is interesting for its simplicity: it’s an LED matrix that is driven straight from an ESP8266 board. [Ray] put it together as a quick project for his students to teach the basics of LED programming.

It’s built using a WS2812 LED matrix board he designed himself and his own ESPToy ESP8266 dev board. But the gist of the hardware is simply an ESP8266 and some WS2812’s. Where this gets interesting is with the user interaction side of things. The ESP makes WiFi and web serving easy, and [Ray] has build a simple HTTP GET API into the firmware. This is a great combination for the web dashboard and JavaScript-based animation programs [Ray] is demonstrating in the video below.

Just get on the same network and load up the module’s WiFi address for a graphical representation of the 5×7 LED matrix. Pick a color, turn pixels on or off, or choose a predefined pattern and send it to the hardware. This is a powerful way to get use input and with this as a guide it’s fast to set up for pretty much an application you can think of. Just work your way through the documents he put together for the workshop (Zip file link), including all of the code and the slides he used to run the workshop.

from Hack a Day

Stealth Cell Tower Inside This Office Printer Calls to Say I Love You

Filed under: Uncategorized — ketan @ 9:07 AM

If you look around the street furniture of your city, you may notice some ingenious attempts to disguise cell towers. There are fake trees, lamp posts with bulges, and plenty you won’t even be aware of concealed within commercial signage. The same people who are often the first to complain when they have no signal it seems do not want to be reminded how that signal reaches them. On a more sinister note, government agencies have been known to make use of fake cell towers of a different kind, those which impersonate legitimate towers in order to track and intercept communications.

In investigating the phenomenon of fake cells, [Julian Oliver] has brought together both strands by creating a fake cell tower hidden within an innocuous office printer. It catches the phones it finds within its range, and sends them a series of text messages that appear to be from someone the phone’s owner might know. It then prints out a transcript of the resulting text conversation along with all the identifying information it can harvest from the phone. As a prank it also periodically calls phones connected to it and plays them the Stevie Wonder classic I Just Called To Say I Love You.

In hardware terms the printer has been fitted with a Raspberry Pi 3, a BladeRF software-defined transceiver, and a pair of omnidirectional antennas which are concealed behind the toner cartridge hatch. Software comes via  YateBTS, and [Julian] provides a significant amount of information about its configuration as well as a set of compiled binaries.

In one sense this project is a fun prank, yet on the other hand it demonstrates how accessible the technology now is to impersonate a cell tower and hijack passing phones. We’re afraid to speculate though as to the length of custodial sentence you might receive were you to be caught using one as a private individual.

We’ve considered the Stingray cell phone trackers before here at Hackaday, as well as looking at a couple of possible counter-measures. An app that uses a database of known towers to spot fakes, as well as a solution that relies on an SDR receiver to gather cell tower data from a neighbourhood.

[via Hacker News]

from Hack a Day

November 7, 2016

Mastering Ball Screws

Filed under: Uncategorized — ketan @ 7:41 AM

Most inexpensive 3D printers use a type of lead screw to move some part of the printer in the vertical direction. A motor turns a threaded rod and that causes a nut to go up or down. The printer part rides on the nut. This works well, but it is slower than other drive mechanisms (which is why you don’t often see them on the horizontal parts of a printer). Some cheap printers use common threaded rod, which is convenient, but prone to bad behavior since the rods are not always straight, the threads are subject to backlash, and the tolerances are not always the best.

More sophisticated printers use ACME threaded rod or trapezoidal threaded rods. These are made for this type of service and have thread designs that minimize things like backlash. They typically are made to more exacting standards, too. Making the nut softer than the rod (for example, brass or Delrin) is another common optimization.

However, when lead screws aren’t good enough, mechanical designers turn to ball screws. In principle, these are very similar to lead screws but instead of a nut, there is a race containing ball bearings that moves up and down the screw. The ball bearings lead to less friction.

Misumi recently posted a few blog articles about ball screws. Some of the information is basic, but it also covers preloading and friction. Plus they are promising future articles to expand on the topic. If you prefer to watch a video, you might enjoy the one below.

In general,

  • Lead screws cost less than ball screws
  • Unlike ball screws, lead screws are self-locking and do not require a braking system
  • Ball screws can have difficulty with vertical operation
  • Ball screws are more efficient allowing less torque and smaller motors than a lead screw, which also will generate more heat
  • Lead screws require more frequent replacement than ball screws

The Misumi catalog, by the way, is a marvel of mechanical engineering toys. If you’ve followed Hackaday for a while, you might know that all ball screws don’t have threads. While ball screws are uncommon in 3D printers, they show up pretty often in CNC machine designs.

Filed under: 3d Printer hacks, robots hacks

from Hack a Day

DIY I2C Devices with ATtiny85

Filed under: Uncategorized — ketan @ 7:31 AM

DIY I2C Devices with ATtiny85

[Pawel] has a weather station, and its nerve-center is a Raspberry Pi. He wanted to include a light sensor but the problem is, the Pi doesn’t have a built-in ADC to read the voltage off the light-dependent resistor that he (presumably) had in his junk box. You can, of course, buy I2C ADC chips and modules, but when you’ve already got a microcontroller that has ADC peripherals on board, why bother?

[Pawel] wired up a tremendously simple circuit, downloaded some I2C slave-mode code, and added an LED for good measure. It’s all up on GitHub if you’re interested.

Bright by Day, Dark by Night!

We’re covering this because we rarely see people coding for I2C slave devices. Everyone and their mom uses I2C to connect to sensors, for which the Arduino “Wire” library or “i2c-tools” on the Pi do just fine. But what do you do when you want to make the I2C device? [Pawel]’s project makes use of TinyWireS, a slave-mode SPI and I2C library for AVR ATtiny Arduino projects.

Here, [Pawel] just wanted a light sensor. But if you’re building your own devices, the sky is the limit. What’s the most esoteric I2C sensor that you can imagine? (And is it really the case that we haven’t seen an I2C slave device hack since 2010?)

from Hack a Day

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