Hi, everyone! Welcome to my first instructable! I hope it will be helpful to anyone who wants to make an automatic door closer with this design, using sheaves and internal counterweight. I'd like to apologize for any grammar or english errors, because i'm brazilian and i am also trying to learn english while publishing some few ideas that i was able to put in practice!

Well, let's go to the instructable:

Bill of Materials:

Well, I didn't take any picture of all the material that I used in this instructable, but here is a list of the most important that were used:

   -> 0,5m of " U" Beam (35x10mm) for office divider panels;
   -> Two 50A1 sheaves (Diameter 50, A1 channel);
   -> One 60A1 sheave (Diameter 60, A1 channel);
   -> 2 pieces of M8x50 DIN933 screws;
   -> 14 pieces of M8 DIN934 nuts;
   -> 2 pieces of M8 DIN125A washers;
   -> 1 piece of M8x95mm cut of threaded rod;
   -> 2m of wire/rope. I used clothes line rope, here;
   -> 6 sets of 6mm steel screws for concrete fixturing;
   -> One bottle for counterweight.
   -> 6 pieces of aluminium rivets 3,2x12,7mm

Materials left to get other level of finishing:
   -> 700mm of sewer PVC pipe of 75mm diameter;
   -> One cap of 75mm PVC sewer pipe.


Tools that I needed to make this instructable:

   -> Power Drill
   -> 8mm concrete drill bit
   -> 3,5mm HSS drill bit
   -> Angle grinder for cutting the "U" beams;
   -> Hand riveter for 3,2mm rivets;

Step 1: Making the sheave supports

Cut two U beams with 120mm length and one U beam with 195mm length with the angle grinder.

For the two "L" supports, cut only the beam laps at 60mm of the border. This will allow you to bend the "U" channel easily, and precisely, using your hands. The drawing will give you the dimensions of this part that I made. Do the same for the "U" support with the 195mm piece of "U" channel. Forget about the 45º cut that the drawing represents, i just messed up one part when I made that because i didn't realize that the beam was so easy to bend!

Before bending the parts, make sure you've drilled the fixture holes of 6 and 8mm of diameter.

After bending, you will need to place two rivets on the laps of the "U" channel, to make sure it will not unbend with the counterweight and the forces involved on the operation of the assembly.
Hi Fernando and thanks for this! <br>Here's a more rational design (I think): <br>Skip the Return sheave and simply twist the Couterweight sheave 90 degrees to the right and stick it to the other wall. And shorten the string of course. <br>Thoughts? <br>Again, thank you!
me and my brother built something similar a few years ago, we had to close the door the opposite way, used fishing line for a bungy effect so when the bottle reaches its lowest point the line flexes a little and doesnt send it crashing into the wall. we used a mountain dew bottle filled with pennies and drilled a hole through the top of the bottle instead of just tying it so it would come down straight, room air pressure [whether the window was open or not] was an obstacle because if the window was opened the door would slam so we had to have a small spring between the door and the jamb so it wouldnt slam
Good job! Just a suggestion, could you describe the inverting sheave a little bit more in detail?
Thank you! Of course, here it is below: <br> <br>Let's suppose that you didn't have put that sheave. Then the rope would have to connect directly to the &quot;return sheave&quot;, and it would cause it to face towards the wall opposed to the door. <br>This way, when the weight falls down, it will generate a tension force on the rope that would, in the point where it is fixed in the door, point towards the inside of the room. Then it would open the door, not close it! And my mechanism would so be called &quot;Automtic door opener&quot;, hehehe! <br> <br>So I had to put that &quot;inverting sheave&quot;, that will make the rope tension force point towards the outside of the room, in a way that it closes the door. <br> <br>Let's say that you had put the mechanism on the other room, then it would not be necessary, because the tension force is already pointing towards the closing movement of the door. <br> <br>Hope this explanation helped you!
i've done that with a few doors i built in Afghanistan, except waaaay simpler, just a couple of U nails and some 550 cord and some water bottles. is simple and it works, just dont get your hand caught in it it doesnt feel too great
I did the same in my dorm room at university. Epic. :)
Can you post another video. i cant see whats going on here. <br>
Very nice. Simple and effective design.
Nice work... <br> <br>Am i the only one who instantly thought of ferris bueller's day off?
This is a nice complication, and very impressively executed (great instructable!! :-) would be simpler with the rope attached above the door, and a pulley/sheave on the top edge of the door, with the weight hanging down the back of the door. <br> <br>This way does allow you to put the weight in the corner and more out of the way however. <br> <br>Good work, <br> <br>Giles
The weight next to the door means it will knock against it.
I know what you mean, however when I tried it, the weight rarely hit the back of the door. That does not seem to be intuitive (according to my level of physics anyway), but you had to push the door really hard/quickly in order to make the weight hit the door. <br> <br>However I would agree that the solution here, although more complicated, is a much neater way of closing the door.
We used to do that for all of our doors when I was in Iraq to keep our cool air in, but yours works and looks much nicer. We would just drive a nail halfway in, and then bend it into a hook. Also, I think we had our water bottles on the other side of the door so they would close all the way, but they tended to make the door bang shut. Good work!
Cool, I use one of those stretchy curtain cables, it's like a long spring in a white sleeve, a screw hook in the door frame by the hinge and a screw eye in the door on the handle side, both at the top of the door it does close a bit quick and the girlfriends dog gets stressed when it's head gets stuck :/
I made a similar one years ago using fishing line, pulleys from an old radio (the tuning dial mechanism) and two &quot;D&quot; size batteries as the weight. Three would have worked better, and when someone commented that it did'nt work very well, I said it was because the batteries were flat. ;-)
From the photo it seems that it would work well until the last few cm because of the angle and does not hold the door firmly closed. How did you get that to work?
I'd attach a short stub out from the door so that the string pulls at the same angle the whole time. Could do away with the left-most pulley too.
Great !&hellip; <br>A nice way to remember us that older easy mechanisms can replace sophisticated expensive engineering &hellip; <br>However, when the soda bottle has been drunken, what happens ?&hellip; <br>LOL &hellip;
Very nice
Bom trabalho! Exatamente o dia de hoje minha esposa estaba falando pra mim sobre como manter a porta da habitacao das minhas filhas fechada pra evitar o ingreso dos mosquitos, eu pensei en colocar um fecha-portas hidraulico que tenho por algum lugar da minha casa.. ha ha! pero agora vou fazer uso da sua ideia... Obrigado desde Asuncion, Paraguay, South America. <br> <br>Good work! Just today my wife was talking to me, about keeping the door closed in my daughters' room to avoid mosquitoes, I thought putting an hydraulic door closer that I have somewhere in my house .. ha ha! But now I'll make use of your idea ... Thanks from Asuncion, Paraguay, South America.
Well done, i need one of this thing but it is hard to find . <br> <br>Muito bom, tava querendo um aqui destes que se v&ecirc; em escrit&oacute;rio, nunca pensei que poderia ser feito assim, valeu.
Looked lik a door opener to me until I watched the video ^^
Very nice, I had a similar pulley system on my bedroom door growing up.
Thanks for sharing this project. One question: where do you get the &quot;sheaves&quot;. Is this some part of a machine or can you buy them &quot;of the shelf&quot;?
Thanks for the comment! <br>I bought them on a hardware store, here in brazil, it was very cheap (about $5 each). These are single channel pulleys for &quot;V&quot; belts, I think it is easier to get there in USA than here!
Would not the project work better if the door swung the other direction? However the demonstration of the theory is marvelous.
Thanks for the comment! Surely it would be easier if it was on the other side, but in my case it was impossible because I couldn`t invert the door. Also, this way the counterweight stays hidden behind the door while it is being opened, preventing accidents while it`s moving.

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