For quite some time now we’ve seen people casting their own countertops and other surfaces out of cement. It’s a combination of mold-making and surface finishing that produces a smooth and durable surface at quite a low cost, if you don’t factor in damage done to your back when lifting the thing for installation.
This offering is a little bit different. [Elliott Spelman] built his own touch sensitive cement table top. When you place your grubby hands on the polished surface, a loop of neon lighting is switched on. This is thanks to a 4:1 mix of quick setting cement and iron oxide powder. Bare copper wire was laid around the edges of the surface to be encased by the cement for making connections later.
There were some sad moments when [Elliott] was removing the cast surface from the mold. He ended up cracking it and suggests others be liberal with their use of both wax on the mold before casting, and patience in removing the cement afterward. We might also suggest a strengthening agent like fiber reinforcement. The edges and surface can be sanded to the finish desired and in this case, attaching table legs was easy since the wooden underside of the mold remains on the bottom of the cement.
The neon lighting adds a retro touch to this build. It’s sad to see this technology dying away, so a resurgence of artisanal neon is great in our book. [Elliott] found a Bay Area arts collective called the Crucible which does a lot of art glass education to help him make two hoops of glass tube and fill them with the appropriate gasses. A capacitive touch sensor (once Atmel, now Microchip part) AT42QT2120 (datasheet) monitors the wire coming from the slab and switches the power supply for the tubes using a combination of relay board and Arduino Uno.
We find the prospect of positional sensing in doped cement fascinating. Anyone have ideas for adapting this technique so that a more long and narrow slab could have positional awareness within, say, a few inches? Let us know in the comments.
[Geeksmithing] wanted to respond to a challenge to build a USB hub using cement. Being a fan of Mario Brothers, a fitting homage is to build a retro-gaming console from cement to look just like your favorite Mario-crushing foe. With a Raspberry Pi Zero and a USB hub embedded in it, [Geeksmithing] brought the Mario universe character that’s a large cement block — the Thwomp — to life.
[Geeksmithing] went through five iterations before he arrived at one that worked properly. Initially, he tried using a 3D printed mold; the cement stuck to the plastic ruining the cement on the face. He then switched to using a mold in liquid rubber (after printing out a positive model of the Thwomp to use when creating the mold). But the foam board frame for the mold didn’t hold, so [Geeksmithing] added some wood to stabilize things. Unfortunately, the rubber stuck to both the foam board and the 3D model making it extremely difficult to get the model out.
Next up was regular silicone mold material. He didn’t have enough silicone rubber to cover the model, so he added some wood as filler to raise the level of the liquid. He also flipped the model over so that he’d at least get the face detail. He found some other silicone and used it to fill in the rest of the mold. Despite the different silicone, this mold worked. The duct tape he used to waterproof the Raspberry Pi, however, didn’t. He tried again, this time he used hot glue – a lot of hot glue! – to waterproof the Pi. This cast was better, and he was able to fire up the Pi, but after a couple of games his controller stopped working. He cracked open the cement to look at the Pi and realized that a small hole in the hot glue caused a leak that shorted out the USB port on the Pi. One last time, he thought, this time he used liquid electrical tape to waterproof the Pi.
The final casting worked and after painting, [Geeksmithing] had a finished cement Thwomp console that would play retro games. He missed the deadline for the USB Hub Challenge, but it’s still a great looking console, and his video has a lot of detail about what went wrong (and right) during his builds. There’s a great playlist on YouTube of the other entries in the challenge, check them out along with [Geeksmithing]’s video below!
[EssentialCraftsman] is relatively new to YouTube, but he’s already put out some impressive videos. We really enjoyed an episode dedicated to a fixture in his shop, his large custom blacksmith’s forge.
The forge is a custom cast vault of refractory that sits on a platter of fire bricks suspended on a heavy-duty rotating frame. Two forced air natural gas burner provide the heat. The frame is plasma CNC cut steel welded together.
A lot of technical challenges had to be solved. How does one hold a couple hundred pound piece of refractory in such a way that it can be lifted, especially when any steel parts exposed to the heat of the forge would become plastic and fail? When the forge turns off, how do you keep the hot air in the forge from rising into the blowers and melting them? There were many more.
We were really impressed by the polished final appearance of the forge, and the cleverness of its design. Everything is well thought out, and you can even increase the height of the forge by propping it up on more fire bricks. We hope [EssentialCraftsman] will continue to produce such high quality videos. We also enjoyed his episode on Anvils as well as a weirdly informative tirade on which shape of stake (round or square) to use when laying out concrete jobs. Videos after the break.
[Dan] had a bunch of concrete mixing to do. Sure, it was possible to stand there and mix concrete and water in a wheelbarrow for hours and hours but that sounds like a tedious task. Instead, [Dan] looked around the shop to see if he had parts available to make a concrete mixer. As you may have guessed, he did. Instead of stopping at just a concrete mixer, he decided to make a concrete mixing wheelbarrow!
The frame is built out of plywood left over from a past canoe project. The frame holds a mixing barrel that was also hanging around the shop. From the photo, the drive system looks simple but it is not. First, the small motor pulley spins a larger pulley that is in-line with the barrel. Gearing down the drive this way increases torque available to spin the barrel, and that gear reduction is necessary to spin the heavy concrete slowly. What you can’t see is a planetary gear system that gears down the drive train again. The gears are cut out of plywood and were designed in this Gear Generator program. The sun (center) gear of the planetary setup is supported by another scavenged part, a wheel bearing from a Chevy minivan.
Now [Dan] can mix all the concrete he wants, wheel it over and dump it wherever he needs it. With the exception of the drive belt and some miscellaneous hardware, all the parts were recycled.
For those unfamiliar with it, Bocce Ball is an outdoor game played with a set of heavy grapefruit-sized balls. We’ve never really thought of making our own set, but as you can see above, it can be done. These are six Bocce balls produced at home by [Horvitz444].
It seems the commercially available balls have a cement or clay core covered in a layer of high-impact epoxy. [Horvitz444] was able to recreate this starting with some vacuum forming. He built his own former out of peg board and a shop vac. The plastic stock he used was a light panel from the home store. After heating it up in the oven he formed a mold using what looks like two halves of Bocce balls. The mold halves were melted together using a soldering iron. After pouring in the secret concoction of cement ingredients and letting them harden, he removed the orbs from the molds and ground down the seams until smooth. They were covered in epoxy and painted. Most of these details were gleaned from his comments in the Reddit thread.