Add Slots And Tabs To Your Boxes In FreeCAD

FreeCAD is a fairly sophisticated, open-source, parametric 3D modeler. The open-source part means that you can bend it to your will. [Alexandre] is working on a module that lets him easily add tabs, finger joints, and t-slots to models (YouTube link, embedded down under).

Right now the plugin is still experimental, but it looks usable. In the video demo, [Alexandre] builds up a simple box, and then adds all manner of physical connective pieces to it. You’ll note that the tabs look like they’re pieces added on to the main face — that’s because they are! He then exports the outlines to SVG and erases the lines that separate the tabs from the sides, and hands these files off to his laser cutter. Voilà! A perfect tab-and-t-slot box, with only a little bit of hand-work. ([Alexandre] mentions that it’s all still very experimental and that you should check out your design before sending it to the laser.)

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Improving Rice Cooker Efficiency

Looking at the plate on the bottom of his electric rice cooker, [AC_Hacker] was surprised to find that it was rated to consume 400 watts. Furthermore when he measured its consumption he found that it consumed 385 watts without even having a cooking cycle initiated. The circuit to keep cooked rice warm was always on – even when the cooking circuit wasn’t engaged.

Something clearly had to be done, so he set about modifying the cooker for better economy. Removing the base revealed that disabling the warming circuit was as simple as disconnecting it. [AC_Hacker] also noticed that the device had no thermal insulation. There was plenty of space between the inner and outer walls, so he packed it with glass wool. The final modification was to reduce the power taken by the heater by installing a half-wave rectifier diode. The cooker still reached the desired temperature, it just used half the power.

You might think that would be the end of it, given that the modifications significantly reduced the cooker’s power consumption without detriment to its rice cooking ability. Rice now took a little longer to cook, so there was still room for improvement. The moment of inspiration came when [AC_Hacker] realized that the cooking time was proportional to the amount of water used in a cooking cycle. He could safely reduce the water without affecting the cooked rice. A 30% water reduction led to a proportional cooking time reduction, and rice cooked using a lot less power.

Surprisingly this seems to have been Hackaday’s first rice cooker hack. Perhaps that’s because you’ve been so busy supplying us with sous vide hacks to write about.