Brilliant door closer :-)

thingiverse

Ok, ok, calling it ' brilliant' might be a bit overdone but the design is so simple, so small, elegant and fully printable that it comes close to brilliant :-) and it helped me a lot with solving an annoying habit of my children, leaving doors open whenever they used them. I have tried several other solutions, even installed an automatic door closer at some point with infrared sensors etc. but they all have their drawbacks. This one is so simple and efficient in design I am surprised I have never come 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 available on the market often are both quite difficult to open because of the tension on the spring and subsequently close the door with too much force to my liking. The pulleys are to be printed as one piece. You usually would need only 2. The FLSUN this is printed on is definitely not the best printer but still it could print the pulleys with the 1 mm margin without the wheel sticking to the axle. Of course you absolutely need to use supports everywhere. I used only 10% support density as it is not important that this design looks perfect, but it IS important you can remove the supports easily after print. The openings in the design are quite small so removal is sometimes difficult so the less you need to remove, the better. I printed mine in PLA. I tried ABS but that got fully messed up. The printer could not cope with the supports using ABS. I used large nuts as counterweights. I basically designed a cylinder around them to store them in. Iron nuts have a relative high specific weight, much higher than sand for example. 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 as they hold more iron relative to their volume.