Small-Scale Projects Use Snail-Mail Mail-Scale scale offers a free USB scale when you sign up for their service. The first versions of this scale did not have a display. In order to find the weight of an object the scale had to be connected to a computer running the software. If you happen to have one of these old scales or are able to pick one up cheap, you may be interested in using it outside of the service. There are several options on how to do that.

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Hacking Digital Scales for the Disabled


[Jan] works with both physically and mentally disabled individuals, some of whom cannot read, making many of their tasks more difficult. Although [Jan] is not in a position to teach reading or writing skills, he was able to build an add-on device for the scales used in repackaging sweets to provide simple feedback that the user can interpret.

The device has three LEDs—red, green, and yellow—to indicate the package does not weigh enough (red), weighs too much (yellow), or lies within an acceptable range (green). The industrial scales at [Jan’s] workplace each have a serial output to connect to a printer, which he used to send data to the device. An ATMega8 controls the lights and an attached LCD, with the usual trimpot to change the display’s contrast and a rotary encoder to adjust the device’s settings. Everything fits snugly into a custom-made frosted acrylic enclosure, laser-cut at a local hackerspace.

[Jan] provides a rigorous guide to approaching each step on his Instructables page, along with source code and several pictures. See a video overview below, then enjoy another scale hack: building one from scratch.

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Adding digital readout to a non-CNC mill

In the quest to add a digital readout to his mill, [Yuriy] has done a lot of homework. He’s sourced a trio of very capable scales, researched what kind of hardware his DRO should be based on, and even built a very cool display using seven-segment LEDs. After nearly a year of work, [Yuriy] finally hit upon something that works well: an Arduino and an Android tablet, perfectly matched for one of the prettiest machine shop displays we’ve ever seen.

[Yuriy] based his build off a trio of digital scales he bought from Grizzly. These scales bolt on to the frame of his mill and send data to their own display. An Arduino was used to pull the data off these scales and sent via Bluetooth to a Nexus 7 Android tablet.

Considering a DRO solely based on an Arduino and a character LCD would look a little chintzy – and the fact Arduinos can’t do floating point arithmetic – we’re really impressed with [Yuriy]’s very elegant solution.

Thanks [Lee] for sending this one in.