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.