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.
Tooling:
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;
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.
Tooling:
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;
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Signing UpStep 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.
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.
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Here's a more rational design (I think):
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.
Thoughts?
Again, thank you!
Let's suppose that you didn't have put that sheave. Then the rope would have to connect directly to the "return sheave", and it would cause it to face towards the wall opposed to the door.
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 "Automtic door opener", hehehe!
So I had to put that "inverting sheave", that will make the rope tension force point towards the outside of the room, in a way that it closes the door.
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.
Hope this explanation helped you!
Am i the only one who instantly thought of ferris bueller's day off?
This way does allow you to put the weight in the corner and more out of the way however.
Good work,
Giles
However I would agree that the solution here, although more complicated, is a much neater way of closing the door.
A nice way to remember us that older easy mechanisms can replace sophisticated expensive engineering …
However, when the soda bottle has been drunken, what happens ?…
LOL …
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.
Muito bom, tava querendo um aqui destes que se vê em escritório, nunca pensei que poderia ser feito assim, valeu.
I bought them on a hardware store, here in brazil, it was very cheap (about $5 each). These are single channel pulleys for "V" belts, I think it is easier to get there in USA than here!