Hack Safely: Fire Safety in the Home Shop

Within the past two months we’ve covered two separate incidents of 3D printing-related fires. One was caused by an ill-advised attempt to smooth a print with acetone heated over an open flame, while the other was investigated by fire officials and found to have been caused by overuse of hairspray to stick prints to the printer bed. The former was potentially lethal but ended with no more than a good scare and a winning clip for “Hacking’s Funniest Home Videos”; the latter tragically claimed the life of a 17-year old lad with a lot of promise.

In light of these incidents, we here at Hackaday thought it would be a good idea to review some of the basics of fire safety as they relate to the home shop. Nowhere was this need made clearer than in the comments section on the post covering the fatal fire. There was fierce debate about the cause of the fire and the potential negative effect it might have on the 3D-printing community, with comments ranging from measured and thoughtful to appallingly callous. But it was a comment by a user named [Scuffles] that sealed the deal:

“My moment of reflection is that it’s well past time I invest in a fire extinguisher for my workstation. Cause right now my fire plan pretty much consists of shouting obscenities at the blaze and hoping it goes out on its own.”

Let’s try to come up with a better plan for [Scuffles] and for everyone else. We’ll cover the basics: avoidance, detection, control, and escape.

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Retrofitting Smoke Alarms With Bluetooth

Everybody should have a few smoke alarms in their house, and everyone should go check the battery in their smoke alarm right now. That said, there are a few downsides to the traditional smoke alarm. They only work where you can hear them, and this problem has been solved over and over again by security companies and Internet of Things things.

Instead of investing in smart smoke alarms, [Johan] decided to build his own IoT smoke alarm. It’s dead simple, costs less than whatever wonder gizmo you can buy at a home improvement store, and reuses your old smoke alarm. In short, it’s everything you need to build an Internet-connected smoke alarm.

Smoke alarms, or at least ionization-based alarms with a tiny amount of radioactive americium, are very simple devices. Inside the alarm, there’s a metal can – an ionization chamber – with two metal plates. When smoke enters this chamber, a few transistors sound the alarm. If you’ve ever taken one apart, you can probably rebuild the circuit from memory.

Because these alarms are so simple, it’s possible to hack in some extra electronics into a design that hasn’t changed in fifty years. For [Johan]’s project, he’s doing just that, tapping into one of the leads on the ionization chamber, measuring the current through the buzzer, and adding a microcontroller with Bluetooth connectivity.

For the microcontroller and wireless solution, [Johan] has settled on TI’s CC2650 LaunchPad. It’s low power, relatively cheap, allows for over the air updates, and has a 12-bit ADC. Once this tiny module is complete, it can be deadbugged into a smoke alarm with relative ease. Any old phone can be used as a bridge between the alarm network and the Internet.

The idea of connecting a smoke alarm to the Internet is nothing new. Security companies have been doing this for years, and there are dozens of these devices available at Lowes or Home Depot. The idea of retrofitting smarts into a smoke alarm is new to us, and makes a lot of sense: smoke detectors are reliable, cheap, and simple. Why not reuse what’s easy and build out from there?

Audio-coupled Smoke Alarm Interface Sends Texts, Emails

The Internet of Things is getting to be a big business. Google’s Nest brand is part of the trend, and they’re building a product line that fills niches and looks good doing it, including the Nest Protect smoke and CO detector. It’s nice to get texts and emails if your smoke alarm goes off, but if you’d rather not spend $99USD for the privilege, take a look at this $10 DIY smoke alarm interface.

The secret to keeping the cost of [Team SimpleIOThings’] interface at a minimum is leveraging both the dirt-cheap ESP8266 platform and the functionality available on If This Then That. And to keep the circuit as simple and universal as possible, the ESP8266 dev board is interfaced to an existing smoke detector with a simple microphone sensor. From what we can see it’s just a sound level sensor, and that should work fine with the mic close to the smoke detector. But with high noise levels in your house, like those that come with kids and dogs, false alarms might be an issue. In that case, we bet the software could be modified to listen for the Temporal-Three pattern used by most modern smoke detectors. You could probably even add code to send a separate message for a CO detector sounding a Temporal-Four pattern.

Interfacing to a smoke detector is nothing new, as this pre-ESP8266 project proves. But the versatile WiFi SoC makes interfaces like this quick and easy projects.

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Beefing up a smoke alarm system with video, temperature, and connectivity

Here’s a little smoke detector hack which [Ivan] has been working on. He wanted to extend the functionality of a standard detector and we’re happy to see that he’s doing it with as little alteration to the original equipment as possible (this is a life-saving device after all). He sent all the build images for the project to our tips line. You’ll find the assembly photos and schematic in the gallery after the break.

As you can see his entry point is the piezo element which generates the shrill sound when smoke as been detected. He connected this to his own hardware using an optoisolator. This allows him to monitor the state of the smoke alarm on his server. It then takes over, providing a webpage that display’s the board’s temperature sensor value and streams video from an infrared camera.

Of course this is of limited value. We’ve always made sure that our home was equipped with smoke detectors but the only time they’ve ever gone off was from normal cooking smoke or after an extremely steamy shower. But still, it’s a fun project to learn from and we’ve actually got several of the older 9V battery type of detectors sitting in our junk bin.

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Leaking water detector from an old smoke alarm

[Thomas Clauser] had his basement flood last year when a hurricane swept over New England. The problem with flooding or leaking water is that chances are you won’t notice until it’s too late. He decided to protect against this in the future by building his own leaking water detector. It’s a simple device that sits on the floor of his basement and triggers an audio alarm if water begins to cover the floor.

He used an old smoke detector for the build; a nice choice since it’s loud, and designed for long-term battery operation. It also has a button for testing if the detector is working. [Thomas] removed the PCB from the smoke detector case and soldered wires onto the test button contacts. He cut a sponge to squeeze it inside of a PVC pipe connector housing. That sits against the floor, with the wires for the test button contacts placed through the sponge. If water is soaked up by the sponge it completes the circuit and triggers the alarm.

A few other design features really make this a nice setup. He notched out the bottom of the PVC connector so that water can flow freely, and added a switch to one of the probe wires lets him kill the alarm when inspecting the damage.