Man Builds Concrete 3D Printer In His Garage

[Andrey Rudenko] is building a house in his garage. Not with nails and lumber, but with concrete extruded by his 3D printer. We’ve seen concrete 3D printers in the past, but unlike those projects, [Andrey] isn’t part of a of a university or corporation. He’s just a contractor with a dream. His printer is directly derived from the RepRap project. It’s even commanded by Pronterface.

[Andrey] started with an Arduino Mega 2560 based RepRap RAMPS style controller. His big printer needed big NEMA34 stepper motors, far beyond the current capacity of the stock RAMPS stepper drivers. [Andrey] got in touch with [James] at MassMind who helped him with an open source THB6064AH based driver. [James] even came up with an adaptor cable and PCB which makes the new drivers a drop-in replacement.

Now that his printer was moving, [Andrey] needed a material to print. Concrete chemistry is a science all its own. There are many specialty blends of concrete with specific strength and drying times. Trucking in custom mixtures can get expensive. [Andrey] has come up with his own mixture based on bags of regular concrete mix, sand, and some additives. [Andrey’s] special sauce doesn’t cure especially quickly, but it is viscous enough to print with.

Every piece of [Andrey’s] printer had to be designed and refined, including the nozzle. The concrete printer works somewhat like a frostruder, extruding concrete in 20mm wide by 5mm tall layers. He’s even managed to print overhanging layers and arches exactly like a giant RepRap Mendel.

The printer’s great unveiling will be this summer. [Andrey] plans to print a playhouse sized castle over the course of a week. He’s looking to collaborate with architects, builders, and other like-minded folks. We’d suggest uploading the project to  Hackaday.io!

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Physical Keys Not Just For Doors Anymore, Now Available For Windows

Physical Key Locks and Unlocks Windows Computer

If you have ever forgotten your computer password after a long weekend or maybe you can remember it but just can’t seem to type it correctly, [Thomas] has a project for you. It’s a physical key that locks and unlocks your PC.

So how does it work? The heart of the project is an Arduino Leonardo. You may recall that this board is a bit different from the preceding Arduinos as it can enumerate on a host computer as a Human Interface Device (HID), such as a keyboard or mouse. The Arduino sketch continually reads an input pin using an internal pull-up resistor to make it logic high with the key switch connecting the signal to ground. When the Arduino sees the pin change from high to low, it sends out a keyboard command consisting of the Windows Key and “L”, which is the keyboard shortcut for locking the computer.

When the physical key is turned again, the Arduino sees the pin change back to a high state and it again emulates a keyboard but this time enters your password. You do have to include your password in the Arduino sketch for this to work. In addition, there are two LED’s wired up to show if the computer is locked or not, but you’ll be able to tell pretty quick when trying to get back to work.

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