Whether the inspiration came from geckos, insects, spiders, or Spider-Man, people have been fascinated by the ability to stick to walls. Humans aren’t going to evolve this ability any time soon, but we have the next best thing; gloves that use magnetism to stick to walls so you can climb up them! You’ve probably seen them in movies like Mission Impossible 4 and games like Call of Duty: Advanced Warfare, two series with seemingly infinite sequels.
Well, the Hacksmith team brought a pair to life! Well, they’re more like clamps, but they will stick you to a wall, as long as it’s a metal wall… See how they were built, how they work, and how much weight they can hold in the video below!
Warning: High Voltage!
As stated in the video, the climbing clamps were based on the electromagnets used for Captain America’s shield, which were very powerful. Since these electromagnets use high voltage (72 Volts DC!), safety is very important. It wouldn’t be responsible to show the public how to make high powered electromagnets without emphasizing safety, so the majority of this project is centered around LCDs used to monitor heat and current. If you do attempt to make your own electromagnetic climbing clamps, please consult the Hacksmith team for advice on constructing and using them safely. Like Spider-Man says, “With great power comes great responsibility”, and these clamps put out some great power!
The clamps have LCD screens on them so you can monitor the battery voltage voltage, the temperature of the magnets (They are prone to overheating), the adjustable power setting and how long the magnets have been active. While the LCDs aren’t necessary for the clamps to work, they are very helpful for using them safely and maintaining their durability. This display will let you know if current is running through them so you don’t crush your hand under the magnet, or if they are overheating so they don’t give out on you while you’re hanging on stuff. Now that the disclaimers out of the way, let’s see how they were made!
How Do They Work?
You probably have a pretty good idea of how electromagnets work. Some of their more pesky properties caused issues when the team used them to make Captain America’s shield. Electromagnets are large inductors that do not like to be switched. While testing the electromagnets for the shield, they burnt out several switches because they would arc across the contacts. So this time, they used a MOSFET with a snubber instead of a mechanical switch. A MOSFET also allows for pulse width modulation incase the full 1,500 pounds (Together, the clamps can hold 3,000 pounds) lifting force isn’t needed.
Even with the MOSFETs substituting for the switches, the high voltage (6 times the rated voltage!) can cause issues, mainly, overheating. They needed a way to measure the temperature and alarm the user in case of overheating. A thermistor was used to measure the magnet’s temperature, display it on the LCD and ring a buzzer if it gets too hot.
The electromagnets were made from a lot of coiled up copper wire, current runs through the wire, which magnetizes them. The electromagnets are housed in 3D printed clamps with handles. The batteries required are too big to fit inside the clamps, so the clamps have long wires to connect to an external power source. If James ever wants to use the clamps for some kind of heist, he’d need some kind of backpack enclosure. This would probably be too bulky of a setup for a heist, so we wouldn’t recommend using them for crime, on top of more obvious reasons.
The voltage is measured by the resistor and the heat is measured through the thermistor. The measurements are transmitted from the Arduino NANO to the LCD screen. The NKK push-button switches power the electromagnets on and off so you don’t stay stuck to walls. You can see the BOM and schematic for the LCD monitoring circuit below.
Bill of Materials (For the LCD Circuit)
You can get a closer look at this in Scheme-It