Making A Metal Hand Doorknob

Regular doorknobs are widely reviled for their bare simplicity, but by and large society has so many other problems that it never really comes up in day to day conversation. Fear not, however, for [Matthew] has created something altogether more special: a doorknob in the shape of his own outstretched hand.

The build was inspired by a similar doorknob at the WNDR museum in Chicago, and its one you can recreate yourself, too. It’s achieved through a multi-stage mold making process. [Matthew]’s first step was to make a flexible mold of his hand using Perfect Mold alginate material to do so.

Once solidified, [Matthew’s] hand was removed and the mold filled with wax. The wax duplicate of [Matthew]’s hand was then used to create an investment plaster mold for casting metal. Vents were added in the end of each fingertip in the mold to allow molten metal to effectively fill the entire cavity.

Once the investment mold was solid and dry, the wax was melted out and it was ready for casting. A propane furnace was used to melt the casting metal and fill the mold using a simple gravity casting method. [Matthew] ended up making two hands, one in aluminium and one in copper. Some cleanup with grinders and a wire wheel, and a replica of [Matthew]’s hand was in his hands!

The finished piece looks great attached to a door knob, and we’re sure it’s quite satisfying shaking hands with your hefty metal self every time you open the door. It bears noting that the same techniques can be used with 3D printing, too! If you pull off your own great home casting project, be sure to drop us a line. Video after the break.

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Physical Security Hack Chat With Deviant Ollam

Join us on Wednesday, June 3 at noon Pacific for the Physical Security Hack Chat with Deviant Ollam!

You can throw as many resources as possible into securing your systems — patch every vulnerability religiously, train all your users, monitor their traffic, eliminate every conceivable side-channel attack, or even totally air-gap your system — but it all amounts to exactly zero if somebody leaves a door propped open. Or if you’ve put a $5 padlock on a critical gate. Or if your RFID access control system is easily hacked. Ignore details like that and you’re just inviting trouble in.

Once the black-hats are on the inside, their job becomes orders of magnitude easier. Nothing beats hands-on access to a system when it comes to compromising it, and even if the attacker isn’t directly interfacing with your system, having him or her on the inside makes social engineering attacks that much simpler. System security starts with physical security, and physical security starts with understanding how to keep the doors locked.

join-hack-chatTo help us dig into that, Deviant Ollam will stop by the Hack Chat. Deviant works as a physical security consultant and he’s a fixture on the security con circuit and denizen of many lockpicking villages. He’s well-versed in what it takes to keep hardware safe from unauthorized visits or to keep it from disappearing entirely. From CCTV systems to elevator hacks to just about every possible way to defeat a locked door, Deviant has quite a bag of physical security tricks, and he’ll share his insights on keeping stuff safe in a dangerous world.

Our Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, June 3 at 12:00 PM Pacific time. If time zones have you down, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.

A Simple App Controlled Door Lock

[Adnan.R.Khan] had a sliding door latch plus an Arduino, and hacked together this cool but simple app controlled door lock.

Mechanically the lock consists of a Solarbotics GM3 motor, some Meccano, and a servo arm. A string is tied between two pulleys and looped around the slide of a barrel latch. When the motor moves back and forth it’s enough to slide the lock in and out. Electronically an Arduino and a Bluetooth module provide the electronics. The system runs from a 9V battery, and we’re interested to know whether there were any tricks pulled to make the battery last.

The system’s software is a simple program built in MIT App Inventor. Still, it’s pretty cool that you can get functionally close to a production product with parts that are very much lying around. It also makes us think of maybe keeping our childhood Meccano sets a little closer to the bench!

Automating Your Door For $20

We love the doors on Star Trek’s Enterprise. We should have known they were human-operated though because they were too smart. They would wait for people, or fail to open when someone was thrown against them during a fight. [SieuweE] has a much more practical automatic door that he calls ArduDoor.

You might guess from the name it uses an Arduino. It also uses a windshield wiper motor which is perfect since it is high-torque and low speed. You might even be able to pick one up for little or nothing if you frequent the junkyards.

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Jeep Wrangler Dome Light Mod

If you’re the owner of a Jeep Wrangler, you may have experienced some frustration with the interior dome light. For those not in the know, removing the doors on a warm day or for a bit of fun can lead to a dead battery. This happens because the Wrangler’s light stays on unless the fuse or light are removed, or a custom shutoff switch is added — at the expense of troublesome wiring. You could say it’s a Jeep Thing. [Tim Nummy] offers a solution with minimal modifications.

First off, pop the switch out of the door and set it aside. As a replacement, [Tim Nummy] has managed to salvage a door light switch from an old Mercedes. In addition to the same momentary-off function as the Wrangler’s stock switch, the button on the new one can be pulled out and locked for a secondary off position. Many machines and appliances use this same type of switch in their safety interlocks as a service position. [Tim] didn’t want to cut apart the wiring in the Wrangler in case something goes awry down the line, so for now he has filed down some spade terminals to slot into the Mercedes plug. He’s also 3D printed a nut to nicely secure the new switch in place. Check out his how-to video after the break!

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Fridge Alarm Speaks, And Saves Power & Food

One of the most power-hungry devices in our homes, besides the air conditioner or heater, is our refrigerator and freezer. It’s especially so if the door doesn’t close all the way or the magnetic seal doesn’t seat properly. [Javier] took to solving a recurring problem with his personal fridge by attaching an alarm to the door to make sure that it doesn’t consume any more power than it absolutely needs.

At its core the device is straightforward. A micro switch powers a small microcontroller only when the door is open. If the door is open for too long, the microcontroller swings into action. The device then powers up a small wireless card (which looks like a variant of the very well-documented ESP module), that communicates with his microwave of all things, which in turn alerts him with an audible, spoken alarm that the refrigerator hasn’t closed all the way. It’s all powered with a battery that will eventually need to be recharged.

While there are certainly easier ways to implement an alarm, the use of the spoken alarm is a nice touch for this project, and the power savings that can be realized are not insignificant. There’s also the added benefit that [Javier] can prevent his freezer from frosting over. If you’re in the mood for other great fridge hacks, there are other exciting, novel, and surely one-of-a-kind ways to trick out your refrigerator.

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Opening The Door To Functional Prints

If you are going to do something as a joke, there is nothing to say that you can’t do a nice job of it. If you’re like [Michael], a whimsical statement like “Wouldn’t it be funny to put Gründerzeit-style doors on the server cabinet?” might lead down a slippery slope. True to his word, [Michael] not only installed the promised doors, but he did a darn nice job of it.

Buying new doors was the easy part because the door frame and hinges were not standardized back then, so there was nothing on the server cabinet to his mount doors. He walks us through all the steps but the most interesting point was the 3D printed door hinges which [Michael] modeled himself and printed in steel. His new hinges feature his personal flair, with some Voronoi patterning while matching the shape of the originals. We love seeing 3D printed parts used as functional hardware, and hinges are certainly a piece of hardware meant to hold up under pressure.

This is not the first 3D printed door hardware we’ve seen. Check out this innovative latch printed as a single piece and here’s the skinny on making flexible objects yourself.

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