Automatic Mechanical Door Closer




About: Rob Douglas
If you are like me, you hate getting out of your bed to turn off yoru lights and or close your door. I guess you could call it being lazy... but it was fun to build.

There are a few steps, and depending on how many walls away door is, construction will differ. In this instructable, you will learn how to make an automatic door closer, controlled by pulleys . Almost every Item Listed is from home depot. I did not show pictures of the molleys and dry wall screws, because that is all preferance based.

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Step 1: The Door Closer

In this first step you are going to prepare everything you need so that construction is made simple. It is difficult to determine how many pulleys you need depending on how many walls you are going to cross.

1. Drill the four holes on opposing corners.
2. Remove all copper staples
3. Unhinge the bottom where the arm of the rat trap holds the springs.
4. Remove and discard the safe guard holder where you put the cheese.

Picture 2:

1. Cut the broom stick about 2 feet away from the handle. It depends where you put the rat trap, but it shouldnt be more than 2 feet.

2. Dremmel out enough space to place the toy car wheel( reduces friction when riding on the door.
3. Drill an axis for the whell, where the arrows indicate. You want to make sure there is enough room left for the wheel to spin.

4. place the wheel in the handle, and slide a nail through the axis holes you drilled. If the wheel wobbles when spun,take the nail out, and place a staw on both sides of the wheel for bearing. Cut the end of the nail off with wire cutters. Your finished product should look like Picture 3.

Step 2: Door Closer Continued

Here we will assemble the door closer, by sliding the broom arm built in the previus step onto the rat trap arm, and then nailing it back into the original trap.

1. Drill a hole on the bottom of the broom arm. Make it large enough so that it will be able to slide onto the rat trap arm.
2. In my picture I used wood and covered it with wire hider. To hold the wire hider in place I sprayed a little spray glue on the shaft of the broom.
3. Before you assemble the rat trap, make sure you look at the picture for assembly instructions, it can get confusing with the springs.
Assembly: Place on of the springs onto the seperated rat trap bar first so that the arm with a slight hook is on top of the bar arm( as seen in the picture). This part is a little confusing...Place the arm of the broom onto the rat trap bar, but make sure the broom goes under the upper part of the rat trap, as seen inthe pic.

Now close off the rat trap metal bracket by pinching together the two copper endings. Place the arm back onto the wooden plank and nail it down with the wire holders, as seen in teh picture( Try and keep it in the middle). Place the holders over the springs so that the unit is now held down to the wooden part. It may be tricky to hold it down and hammer it in with the springs now cocked, so you may need to clamp it down and hammer it in that way. Now the fun part comes.

Step 3: Door Placement

This depends on where your door is in relation to your bed...and how your door opens... but generally speaking, you want the wheel of the newly constructed rat trap to be roughly dead center of the door fully closed door. So that it looks like picture one when the springs are released.

You need to take the mouse trap and place it on your wall where your think it will have the best leverage. It will depend on the kind of door you have and the way it opens, For a door like mine. The actual rat trap is place about 5 inches away from the molding on the left

Line up the trap, wiht the door, and drill 4 holes into the wall. If you have plaster walls make sure to put molleys where the holes are. If your wall is not liek mine, I can suggest ideas on how to place the trap, but generally if your going to palce the trap on the same wall as the door ( unlike me ) Your going to want to raise the trap so that the arm can fully extend.

Test yoru rig out. Open your door, and if it closes automatically then you are good to go, If it does not close all the way, I would put some WD40 on the hinges of the door and the handle, to loosten things up.


Step 4: Setting Up the Pulley System

This layout worked for me:

To place the broom holder ( used to keep the door open ) fully open yoru door and mark off where the broom touches the wall. Make sure that the broom holder is put at about at least 2 inches away from the broom handle with the wheel. MAKE SURE the LARGER LIP of the broom holder is DOWNWARDS.

Once you mark that off, hold the the broom holder in place and drill it to the wall(drywall,Molley's. etc). There should be two holes drilled.

To make sure this works , let your door close fully, and then open it to full extension. If the broom locks in and the door does not move, then we are good to go. If your broom misses the mark, then you may need use some epoxy and move the broom arm a little ( to avoid having to redrill holes).

Your system is now ready for setup.


Step 5: System Setup: 2

Here we will fully delve into the pully system setup:

On the broom holder, you need to drill a hole large enough so that the twine(masenry twine) will be able to fit through the hole. Dont tie a knot yet. Depending on how many walls you cross, there will be a variance in the piping used.

zero walls: 0 piping
one wall: 1, 8 inch peice
two walls : 2, 8 inch peices
three walls: 3....

Do not cut the twine, leave it on the reel.

I crossed three walls, so took the clear bendable piping and place three 8" sections on the twine( just leave them on the twine for later. Take the end of the string, and snake it through the back of(behind) the broom holder...There should be enough space.

Then put the line through one of the unaltered pulleys (Home Depot) so that the line is coming out from the bottom of the pulley(closer to the hole).

NOW you can tie the twine onto the broom holder where you previously drilled a hole.

Take the pulley you placed on the line before and place it about one inch away from the knotted twine. Make sure it is placed exactly below it on the wall, or you will loose mechanical strength. Dril into wall ( molley,Screw)

Step 6: System Setup:3

You are now going to setup the pulleys.

Your first step will be to get the pulley's out of there casing( the home depot ones have a casing). To do this, I used a dremmel and dremmeled the axis off of the pulley.

Make sure the rattrap arm is fully extended, you dont want to pull the latch and have the arm smash you in the face...(I learned the hard way)

Pull up the string and place it on a pulley, line the pulley up with the broom holder and drill it into the wall(molley,screw) MAKE SURE IT IS STRAIGHT.(It really does not matter how far away this pulley goes, I personally like keeping things close.

For me, my next step was crossing a wall, here is where the tubes come in handy... They reduce alot of friction and are easy to install.

Wall Cross:
1: Your going to want to take two wire holders and drill holes through them.
2: Take the plastic tube, and make sure it placed where the two walls meet. MAKE IT SO THAT IT IS STRAIGHT.
3: Drill the wire holders into the wall(molley,screw)(as seen in the picture.
4: Take a de-cased pulley, and drill it fairly close and PARRALEL to the tubing, MAKE SURE IT IS PARRALEL. Line up the twine, and DRILL the PULLEY in (screw, MOLLEY

Small Ledge: IF you are going to cross a small ledge should use one of the pulley's on the metal holder as seen in picture 4

Every time that you want to switch a wall use the tubes... but plan ahead so that your not stuck wiht a closed pulley system, but still one more wall to go.

For every 2-D direction change, use the de-cased pulleys.

On my wall, I went from one end to the other without any pulleys, and just used the tubing with barely any mechanical loss.

Step 7: Finalizing

For aesthetic purposes I used adhesive wire holders, to avoid an ugly droopy line.

I had cabinetry near my bed, but since it was away from the wall, I used an unaltered pulley to change the direction so that I coudl have the mechanical advantage of pulling downwards to close the door.

For the handle:
I took an old shovel handle, wrapped the twine around it, put a dab of epoxy, and placed it right near my bed.

When your system is finished, open the door fully, and lock it into position, go over to your bed, and pull yoru handle, Give it a good tug. IF everything is set up right it should close your door. The system closes your door when it is partially open also, Go ahead, test it out. lock the arm into position, and open your door a smidge. Go over to your bed and release the lever. You should hear a loud thump followed by the swift motion of your door closing.



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    33 Discussions


    9 years ago on Introduction

    Nice instructable been looking for a good one of these for a while!!!! also it would be a great help if you could post the light switch one!

    2 replies

    Reply 9 years ago on Introduction

    There are a bunch of different ways you can do this. This was my first shot at it, and looking back I think I would have changed it up a little... I liked using a rat trap 'cus it's soooo cheap, but you could use a motor if you wanted... but I guess that would get pretty messy.


    Reply 9 years ago on Introduction

    I'd like to not involve electronics, because when you do that everything gets messy as you said. I like this one because it's self powered and not to hard to build (I think) this coming weekend i think I will build it if I had enough time.


    10 years ago on Introduction

    I love how we put more time and hard work into making something so we can be lazy. Ironic.


    10 years ago on Introduction

    Did you know that you can buy spring hinges? We use them on our bathroom doors and they work great. They replace the standard hinges and they have a spring inside the assembly that makes the hinge close automatically.

    8 replies

    My lease won't allow me to change any hardware in my building. But I am allowed to screw stuff to the wall. This is the answer to children who can't remember to close a door after they open it.


    Reply 10 years ago on Introduction

    it closes at about 1 mph... and the door isn't too heavy. It doesn't close automatically, so the person pulling the lever would be responsible... but you could rig it to intentionally hit people... but that just seems wrong.


    Reply 10 years ago on Introduction

    1 mph? That's fat fora clsing oor but to hit someone real hard, try closing it at the speed i normally do, 10 mph it makes a giant bang!


    Reply 10 years ago on Introduction

    yeah... but that's no fun... and besides, that won't let me close the door when i'm in bed.

    you could make it so the door latches to the wall and then just undo the latch from bed, and if you were truly lazy you would go for the easier thing

    That's what it does... i would need spring loaded hinges in order for that to work, in this case i used the spring force from a rat trap


    Reply 10 years ago on Introduction

    Haha ok then. I used to have a string and pulley system rigged up to turn off my lights from in bed, so I guess i can't say too much.

    I was thinking about this the other night, a way too close my door from my bed as you mentioned and i wasn't sure what i would do so i went to instructables and found this! thanks so much


    10 years ago on Introduction

    great idea, but I think this would make a better "face smasher" than a door closer. Just hang the contraption in a hallway/doorway/ceiling and when your victim comes walking by, pull the string ( a trip wire would also be easy with your design.) Just make sure to video tape it. // joking, or am I? /// anyway you have a great idea, thanks