Building Instructions for Gravity-Powered Door Closer
By: Advit Deepak
Tags: Projects, Physics, DIY, Room Decor, Lego

These are the building instructions for my Automatic, Gravity-Powered Door Closer, hyperlinked and described in further detail here. Although this is one specific way to implement this device, it can be easily modified if you’re missing some of these pieces. All that’s important is the basic principles — the pulley, fishing line, and weight system.

Component 1 — Door Attachment

The following are the required pieces:

To begin, we will use these pieces:

Combine the two red 1 X 3 Cross Blocks with four blue Axle to Pin Connectors,

Attach 7 black Technic Pins to one red 1 X 15 Beam,

Attach the other red 1 X 15 Beam on top,

Attach the two red 1 X 3 Cross Blocks from earlier to the end of the beams,

Here is our completed first part of Component 1,

Now, we will need the following pieces for the second part of Component 1,

Attach two blue 3L connectors to two red 1 X 15 beams exactly as follows,

Combine two red 2 X 4 Bent Beams with four black Long Pin with Bushings,

Attach these two our finished first part of Component 1 from earlier,

Push the bottom black pins in for both sides,

Attach our two red 1 X 15 beams with blue pins,

Attach two blue 3L pins to two red 2 X 4 Bent Beams as follows (notice that they’re not symmetrical!)

Combine these two as follows, pushing so the blue pins enter all the way,

Take the black 1 X 4 axles and insert into the top red 2 X 4 Bent Beam,

Combine the two red 1 X 3 Cross Blocks with four grey Axle to Pin 2L Connectors,

Insert them into the following locations,

For the final part of Component 1, we start with the following,

Combine as follows,

Next, attach four black 2L pins with two red Double Bent Beams,

Attach as follows,

Attach our black 1 X 3 Cross Block (this is where the fishing line will tie to),

Add our other red Double Bent Beam from before,

And voila, we’re done with Component 1!

This component will be attach to the top of the door as follows:

The fishing line will be tied to the top black 1 X 3 Cross Beam (just a simple knot will suffice). The screws will go through the four red 1 X 3 Cross Beams.

Now, onto Component 2.

Component 2 — Horizontal Pulley

The following are the required pieces:

To being, combine two black 1 X 3 Cross Beams with the following pins and axles,

Attach two blue 2 X 4 Bent Beams,

Add the blue 1 X 9 Beam,

Combine one black 1 X 3 Cross Beam with the following pins and attach as shown,

Attach one black 3 X 3 T-Shaped Beam to the bottom,

Attach one black Hole with Pin,

Finally, use the grey 1 X 4 axle and remaining pieces,

Attach the screws into the holes at the bottom,

And that’s Component 2!

The fishing line will go through the horizontal pulley (the small grey wheel piece) as shown below.

Now, onto Component 3.

Component 3 — Vertical Pulley + Guiding Piece

The following are the required pieces:

To begin, attach six blue 3L pins into one red 1 X 11 Beam,

Add two red 1 X 3 Beams to each end,

Using the grey 1 X 7 axle, two bushels, and wheel (our pulley),

Attach two green 1 X 3 Cross Blocks to either end,

Attach this to our beam from earlier,

Add the other red 1 X 15 Beam on top,

Using the two black 1 X 3 Cross Blocks,

The screws will go through the two black 1 X 3 Cross Beams as shown below,

The fishing line will go through the vertical pulley (the medium grey wheel piece).

For the Guiding Piece, we will need the following,

Simply attach two black 2L Pins to one of the red 1 X 5 Beams,

Attach the other beam on top,

Instead of screws, this piece can simply be attached using adhesives (for example, Velcro strips). This is because no direct force is exerted on the Guiding Piece. Instead, the fishing line simply runs through the center hole to ensure the wooden weight does not swing.

Finally, we can put the system together.

Component 4 — Wooden Block + Finished System

For the weight, anything can be used. In my case, I used a small wooden block with a clip screwed on, allowing me to attach the fishing line.

Put together, the components look like the following:

Once more, this is merely one way to implement a Gravity-Powered Door Closer. If you don’t have the required pieces, feel free to play around with different designs. There is no right way to build any of these.

All that matters is the theory behind the device — the relations among the pulleys, fishing line, and weight. How these components are designed is up to the builder.

Enjoy building!

For more details, kindly refer to the original Medium article. Don’t hesitate to leave any questions. I’ll be happy to help!