Half-tone CNC with man-powered Z axis

We think this is an intriguing take on half-tone art. It’s a CNC machine that uses an Arduino and two stepper motors to draw on a paper-covered drum. But you’re not just going to set it and forget it. To simplify the device, the Z-axis is not mechanized, but requires the dexterous opposing digit of a person to actuate.

The first prototype used a frame cut from plywood, but the developers moved to some attractive laser-cut Lexan for the final version. The rotating drum was inspired by observing the off-set printing process. It greatly simplifies the build when compared to a flat CNC bed. But including a Z-axis solution that could account for differently sized dots really opens a can of worms. Because of this, the choice was made not to automate that task, but to leave it up to the user. A clickable Sharpie does the marking. When the pen is in place, you click the plunger to hold the felt tip against the paper until a dot of the appropriate size has leeched onto the paper.

It’s not a bad solution to the problem. Especially if you don’t have the high-end milling equipment necessary to do this on a piece of plywood.

[Thanks Dron]

Spaduino heats up a used hot-tub

[Ryan] and the roomies decided that a hot tub was just what they needed to spice up the place. They hit Craig’s List and found one for the right price. After acquisition and setup they were pleased to find that the jets and pump worked great. But you’re not going to want to stick as much as your big toe into this ice-cold cryogenics experiment. Some poking around in the control system exposed the dead relays which are responsible for switching the heater. Instead of swapping the parts, [Ryan] began building a control system that will replace the twenty-year-old original.

The heating element still works, but it’s rated at 5.5 kW and here’s no way to automatically switch it on and off. [Ryan] found a 60 Amp solid state relay which can handle the load, and plays nicely with his Arduino. Initial tests got the tub up and running again. Obviously you want the tub to maintain temperature and so a thermistor was added to take readings from the heater core. There’s also a potentiometer to adjust the temperature, and an LCD screen to show the current settings. But [Ryan] hopes to add more features over time, like incorporating jet control, and adding wireless communications via an Xbee module.

Kitchen Hacks: [Dino's] egg tricks

[Dino's] latest weekly hack plays right into our Kitchen Hacks theme. He’s sharing some obscure tips and tricks involving eggs.

It should come as no surprise that he knows a thing or two about using eggs. After all, he keeps chickens and you’ve can’t just let good eggs go to waste. Which is where his first tip comes in. Eggs will keep for weeks, but if you don’t know if they’re still good you can put them in a bowl of water before cracking them. Eggs that float are on the way out!

Need some scrambled eggs but don’t have a pan to cook them in? His next feat is to cook up a breakfast of steamed eggs using the steamer nozzle on his espresso machine. It’s messy (egg seems to be flying everywhere) but the final product does look appetizing.

The rest of the video (embedded after the break) shows his methods of making Hollandaise sauce for Eggs Benedict, and how to blow the innards out of an egg-shell.

Now we have a picture in our minds that [Dino's] daily routine is surrounded by eggs… like the egg farmers in Napoleon Dynamite.

[Read more...]

Bluetooth enabled breathalyzer

[Al] at Open Gadgets just put the finishing touches on his Android breathalyzer. It’s the perfect thing to install on ex-girlfriends’ phones to prevent 2 a.m. drunk dialing.

The project started off as a talking breathalyzer connected to a computer that tweeted your BAC, gave weather and stock readouts, and functioned as a photo booth. Since the first reveal of his project, [Al] moved from the desktop world to the mobile domain.

The breathalyzer itself is contained entirely in an Altoids tin. The build is based on the IOIO board that recently got support for Bluetooth. An alcohol sensor in the project measures the alcohol content of the surrounding atmosphere and reports this back to a phone over Bluetooth. There’s no word if the Android version of [Al]‘s breathalyzer has the Twitter and photo booth functions, they would be relatively easy to add.

While a wirelesss, tweeting breathalyzer lends itself to a competition for a high score, [Al]‘s project could have a few very good implantation; a DIY auto ignition interlock would be a very useful device for some people. Check out the videos of [Al]‘s builds after the break.

[Read more...]

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