Conductive Concrete Confounds Circuitry

November 12, 2017 by Tom Nardi 21 Comments

There’s a fairly good chance you’ve never tried to embed electronics into a chunk of concrete. Truth be told, before this one arrived to us via the tip line, the thought had never even occurred to us. After all, the conditions electronic components would have to endure during the pouring and curing process sound like a perfect storm of terrible: wet, alkaline, and with a bunch of pulverized minerals thrown in for good measure.

But as it turns out, the biggest issue with embedding electronics into concrete is something that most people aren’t even aware of: concrete is conductive. Not very conductive, mind you, but enough to cause problems. This is exactly where [Adam Kumpf] of Makefast Workshop found himself while working on a concrete enclosure for a color-changing barometer called LightNudge.

While putting a printed circuit board in the concrete was clearly not workable, [Adam] was hoping to simplify manufacturing of the device by embedding the DC power jack and capacitive touch sensor into the concrete itself. Unfortunately, [Adam] found that there was a resistance of about 200k Ohm between the touch sensor and the power jack; more than enough to mess with the sensitive measurements required for the touch sensor to function.

Even worse, the resistance of the concrete was found to change over time as the curing process continued, which can stretch out for weeks. With no reliable way to calibrate out the concrete’s internal conductivity, [Adam] needed a way to isolate his electronic components from the concrete itself.

Through trial and error, [Adam] eventually found a cheap method: dipping his sensor pad and wire into an acrylic enamel coating from the hardware store. It takes 24 hours to fully cure, and two coats to be sure no metal is exposed, but at least it’s an easy fix.

While the tip about concrete’s latent conductivity is interesting enough on its own, [Adam] also gives plenty of information about casting concrete parts which may be a useful bit of knowledge to store away for later. We have to admit, the final result is certainly much slicker than we would have expected.

This is the first one we’ve come across that’s embedded in concrete, but we’ve got no shortage of other capacitive touch projects if you’d like to get inspired.

The Engineering That Survives Hurricanes

September 27, 2017 by Bryan Cockfield 84 Comments

Florida is a great place to live, especially around January when it’s sunny and 24 degrees outside (76F) while all of your friends from back home are dealing with scraping ice off of their windshields every morning. In the late summer, though, this pleasant tropical paradise can sometimes take a turn for the worse, because Florida is one of the handful of places that frequently see some of the worst storms on the planet: hurricanes. As a Floridian myself, perhaps I can shed some light on some of the ways that the various local governments and their residents have taken to mitigate the destruction that usually accompanies these intense tropical storms when it seems that, to outsiders, it might be considered unwise to live in such a place.

Continue reading “The Engineering That Survives Hurricanes” →

3D Print Your Next Dwelling In A Day

March 11, 2017 by James Hobson 51 Comments

What’s the shortest amount of time in which a 400 square foot home can be built? A few weeks? Try a fully printed structure in 24 hours for a little over $10,000.

This radial residence was materialized out of concrete in Stupino, Russia by [Apis Cor], and six collaborating companies, as a prototype. As opposed to traditional — such as it is for tech largely in its infancy — assembly of pre-printed or fabricated pieces, the building was printed as a whole, with the printer removed by crane before finishing the rest of the construction. It features a bathroom, hallway, living room, and a compact kitchen — everything a bachelor or bachelorette needs.

Continue reading “3D Print Your Next Dwelling In A Day” →

Bulking Up A Lightweight Lathe With A Concrete Cart

March 5, 2017 by Dan Maloney 21 Comments

When it comes to machine tools, a good rule of thumb is that heavier is better. A big South Bend lathe or Bridgeport mill might tip the scales at ludicrous weight, but all that mass goes to damping vibration and improving performance. So you’d figure a lathe made of soda cans could use all the help it could get; this cast concrete machine cart ought to fit the bill nicely

Perhaps you’ve caught our recent coverage of [Makercise]’s long and detailed vlog of his Gingery lathe build. If not, you might want to watch the 5-minute condensed video of the build, which shows the entire process from melting down scrap aluminum for castings to first chips. We love the build and the videos, but the lightweight lathe on that wooden bench never really worked for us, or for [Makercise], who notes that he was never able to crank the lathe up to full speed because of the vibrations. The cart attempts to fix that problem the old fashioned way – more mass.

There are a few “measure twice, cut once” moments in the video below, as well as a high pucker-factor slab lift that could have turned into a real disaster. We might have opted for a countertop-grade concrete mix that could be dyed and polished, but that would be just for looks. When all is said and done, the cart does exactly what it was built to do, and there’s even room on it for the shaper that’s next on the build list. We’re looking forward to that.

Continue reading “Bulking Up A Lightweight Lathe With A Concrete Cart” →

Touch Sensitive Cement With Just A Dash Of Neon

February 22, 2017 by Mike Szczys 11 Comments

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.

Continue reading “Touch Sensitive Cement With Just A Dash Of Neon” →

Custom Keyboard Makes The Case For Concrete

October 4, 2016 by Kristina Panos 38 Comments

One of the worst things about your average modern keyboards is that they have a tendency to slide around on the desk. And why wouldn’t they? They’re just membrane keyboards encased in cheap, thin plastic. Good for portability, bad for actually typing once you get wherever you’re going.

When [ipee9932cd] last built a keyboard, finding the right case was crucial. And it never happened. [ipee9932cd] did what any of us would do and made a custom case out of the heaviest, most widely available casting material: concrete.

To start, [ipee9932cd] made a form out of melamine and poured 12 pounds of concrete over a foam rectangle that represents the keyboard. The edges of the form were caulked so that the case edges would come out round. Here’s the super clever part: adding a couple of LEGO blocks to make space for the USB cable and reset switch. After the concrete cured, it was sanded up to 20,000 grit and sealed to keep out sweat and Mountain Dew Code Red. We can’t imagine that it’s very comfortable to use, but it does look to be cool on the wrists. Check out the gallery after the break.

Concrete is quite the versatile building material. We’ve seen many applications for it from the turntable to the coffee table to the lathe.

Continue reading “Custom Keyboard Makes The Case For Concrete” →

One Man’s Journey To Build Portable Concrete 3D Printer Produces Its First Tiny House

June 28, 2016 by Gerrit Coetzee 71 Comments

[Alex Le Roux] want to 3D print houses. Rather than all the trouble we go through now, the contractor would make a foundation, set-up the 3D printer, feed it concrete, and go to lunch.

It’s by no means the first concrete printer we’ve covered, but the progress he’s made is really interesting. It also doesn’t hurt that he’s claimed to make the first livable structure in the United States. We’re not qualified to verify that statement, maybe a reader can help out, but that’s pretty cool!

The printer is a very scaled gantry system. To avoid having an extremely heavy frame, the eventual design assumes that the concrete will be pumped up to the extruder; for now he is just shoveling it into a funnel as the printer needs it. The extruder appears to be auger based, pushing concrete out of a nozzle. The gantry contains the X and Z. It rides on rails pinned to the ground which function as the Y. This is a good solution that will jive well with most of the skills that construction workers already have.

Having a look inside the controls box we can see that it’s a RAMPS board with the step and direction outputs fed into larger stepper drivers, the laptop is even running pronterface. It seems like he is generating his STLs with Sketch-Up.

[Alex] is working on version three of his printer. He’s also looking for people who would like a small house printed. We assume it’s pretty hard to test the printer after you’ve filled your yard with tiny houses. If you’d like one get in touch with him via the email on his page. His next goal is to print a fully up to code house in Michigan. We’ll certainly be following [Alex]’s tumblr to see what kind of progress he makes next!