Making A Concrete Sign

While paging through the feed a few days ago our attention was caught by something a little away from the ordinary in Hackaday terms, a DIY video about creating cast concrete signage from [Proper DIY] which we’ve placed below the break. A deceptively easy-looking mould-making process has a few tricks that  will make the difference between a hard-wearing sign that lasts for years, and a lump of concrete.

So, to make a cast concrete sign, you throw together a mould with some letters, and chuck in some concrete? Not so fast, because the key appears to be preparation, and ensuring that there are no 90-degree corners on the mould parts. The letters are carefully shaped and sealed with varnish before being attached to the mould with silicone adhesive, and all the corners are beveled. Finally a light oil is used as a release agent, and hefty vibration takes care of any air bubbles.

The result is a set of signs, but we can see these techniques finding uses outside signage. For example, how about casting using a 3D printed mould?

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Cast-in-Concrete Clock Upgraded After Thirteen Years

Proving that an old design cast in concrete can indeed be changed, [Hans Jørgen Grimstad] has revisited his Nixie clock from 2008, cleaned up the electronics and packaging, and turned it into a kit. Not that he has plans to enter the kit-making business, but he just thought it would be fun to learn how to make kits. In the video below the break, he’s a bit embarrassed to reveal the inside of his first Nixie clock design, housed in a cast-concrete electronics enclosure. Although it still works, the internal wiring is a flaky, untidy, and perhaps a bit dangerous.

But [Hans] has improved his game over the years, making a number of different clock designs. The latest incarnation is pleasant to look at, built on a PCB which is visible inside a custom acrylic case. Three versions are available to support different types of tubes. The documentation he prepared for the project and the kit is very thorough. He walks you through the unboxing and assembly process in the videos below. Firmware is in C, and runs on a Raspberry Pi Zero W. If you are interesting in making electronics kits, [Hans]’s project would be a good example to follow.

All the necessary information to build the clock is published on the project’s GitHub repository. If you’re looking for enclosure ideas other than concrete or acrylic sheet, check out this write-up on hand-forging artistic Nixie clock enclosures.

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