Brilliant door closer :-)

thingiverse

Calling it "brilliant" might be a bit overdone, but the design is so simple and elegant that it comes close to brilliant! It really helped me out with solving an annoying habit of my kids - leaving doors open whenever they used them. I've tried several other solutions before, including installing an automatic door closer with infrared sensors, but they all had their drawbacks. This one is surprisingly efficient in design, which is why I'm amazed I never came across it before. It consists of 2 pulleys, a piece of rope that you attach to the door, and a counterweight that gently closes the door when you release it. Mechanical door closers on the market are often difficult to open due to the tension on the spring and close the door with too much force, which I don't like. The pulleys can be printed as one piece - usually just 2 are needed. My FLSUN printer isn't the best, but it still managed to print the pulleys with a 1mm margin without the wheel sticking to the axle. Of course, you need to use supports everywhere, and I used only 10% support density since it's not essential for the design to look perfect, but it is crucial that the supports are easy to remove after printing. The openings in this design are quite small, so removal can be difficult at times, making it better to have fewer supports. I printed mine with PLA, and I tried ABS as well, but it got completely messed up due to the printer's inability to handle the supports using ABS. Large nuts make great counterweights - I designed a cylinder around them for storage. Iron nuts have a relatively high specific weight compared to sand, so by using iron, I could keep the cylinder as small as possible. Using large washers would enable you to use a smaller designed counterweight since they hold more iron relative to their volume.