A pulley is a grooved wheel over which a rope is slung to provide a reduction in the force needed to move a weight by creating a larger distance for the force to be spread over. You can build a simple pulley system consisting of one or more pulleys using simple items you probably already have lying around. Your homemade pulley can be used for lifting small items for fun, practical or experimental purposes.
Make a small hole through the centre of both of the bottle caps with a power drill. The hole should be big enough to accommodate the bolt you are using.
Hold one of the metal straps over a drilled bottle cap so one end of the strap is 1 inch past the bottle cap.
Drill through the metal strap directly above the hole in the bottle cap. Make another hole in the same position at each of the straps.
Slip the bolt through one hole in one of the straps and pass several washers against the strap. Start with 5 or 6 washers and remove them if needed.
Tighten the washers in place with a nut and pass a bottle cap onto the bolt. The cap should go on the bolt with the inside facing the nut and washers. The cap should be touching the strap. Remove washers until the cap and strap touch.
Pass the second bottle cap onto the bottle so the outside of the first cap touches the outside of the second cap. Secure the second cap with a nut inside.
Slide several washers onto the bolt to fill the second cap and place the second strap onto the bolt. The strap should be perfectly flat against the washers and the cap.
Secure the second strap onto the bolt with a nut. Make sure that both of the straps are pointing in the same direction.
Slide the ends of the straps around a post or ceiling joist to secure it in place. If you don't have a joist or something similar, bend the drilled parts of the straps to a 90 degree angle to attach the straps to a ceiling.
Attach the straps to the ceiling or joists using screws and a screwdriver. The bottle caps should be pointing directly downward.
Pass the rope over the bottle caps so it rests on the joist between the caps. Attach the load to one end of the rope and add a weight to the other end.
You can make several pulleys and attach them on alternate planes, like up and down, to create an even more effective pulley system.
Do not use this pulley for lifting furniture or other heavy items.