How to Build Simple Machines

The six simple machines are the fundamental mechanisms of physics. They are the wedge, lever, pulley, inclined plane, wheel, and screw. The devices themselves and their principles have been understood since antiquity, and it can easily be said that every machine on Earth is simply a combination of simple machines. Making some of these machines is a simple matter, because they are present in even the most basic tools. Others require more assembly, but are still a relatively simply matter to build.

Things You'll Need

• Pole, board, or crowbar
• Wooden block or oblong stone
• Wood-splitting wedge or doorstop
• Shovel
• Wheel
• Pole
• Rope
• Drill
• 2 Bolts
• 2 x 4s
• Pocketknife
• Hand saw
• Handblock sander
• Sledgehammer
• Cylinder
• Wider covers
• Rod and handle
• Screws or glue
• Pivot joint
• Rotating handle
• Large screw with bolt head
• Socket wrench
• Hollow tube

Instructions

Gathering: the Lever, the Wedge, and the Inclined Plane

1. 

   Find a pole, board, crowbar, or something similar, and also a wooden block or oblong stone. You now have a lever and a fulcrum, which gains you mechanical advantage in lifting objects.

2. 

   Find or buy a wood-splitting wedge. One of the simple machines is simply known as the wedge. The wedge works by converting force that is applied to the blunt end into force applied along the lengths of its side. In the case of a splitting wedge, hitting the wedge with a hammer drives logs apart.

3. 

   Find a ramp, take a shovel and make one out of dirt, or simply locate a hill. Ramps and hills are examples of the simple machine known as the inclined plane. The inclined plane reduces the amount of force necessary to raise an object by exchanging it for the distance traveled. In other words, you travel a longer distance in order to gain altitude, but expend less energy in doing so, just as walking up a 60 foot hill is easier than climbing a 60 foot ladder.

Building a Wheel and Axle

1. 

   Find or buy an old wheel and a wooden pole.

2. Insert the pole into the wheel hub, drill holes into the pole on either side of the hub, and secure the pole with bolts.

3. Drill another hole to the far end of the wooden pole. Thread the rope through this and tie a knot big enough through the other end to secure it.

4. Saw one end of both of the 2x4 into a point.

5. Whittle channels into the top of the 2x4s that fit the end of wooden pole, and sand the channels to reduce friction.

6. Use the sledgehammer to drive the 2x4s into the ground, making sure the tops are level, and that they are spaced so that the wheel lay outside them.

7. Place the wooden pole into the channels in the top of the 2x4s. The wheel should be on the outside, so it can be readily turned. You know have a light duty wheel and axle crank, where the rope converts rotational motion into lifting motion.

An Example of a Pulley: The Rope Winch

1. 

   Consider your parts carefully. A winch is as simple as a spool and hand crank. But, what you make those parts from and how you attach may prove insufficient if you intend to bear heavy loads on your winch. Do not expect to be able to reel in 1,000 pounds on a hand crank attached by screws that can only bear 200 pounds.

2. Pick out your cylinder and covers. Keep in mind that you will be winding your rope up around the cylinder, and therefore the surface area of your cylinder and the width of the end covers has a direct bearing on how much rope you can spool up. There are no hard and fast rules for this, but a short, skinny cylinder will need large covers on the ends to handle a lot of rope, for example.

3. Attach your covers to the cylinder. This can be done with heavy-duty glue, bolts, or screws, depending on how sturdy you need the winch to be. This is now your spool.

4. Assemble and attach your hand crank. Take a rod as a lever. Attach a rotating handle to one end, and a fixed disk to the other. Attach the crank to one end of the spool. Whether you use bolts, screws, or glue is once again a matter for how heavy a load you intend to put on the winch.

5. Attach the remaining, unused end of the spool to your mounting point for the entire winch. This is the base for the winch. The moving parts in a correctly assembled winch are in the handle and the base. Whether you use bolts, screws, or glue is once again a matter for how heavy a load you intend to put on the winch.

Archimedes Screw

1. 

   Find a large screw that has the biggest threads you can find.

2. Find a tube that is a good fit for the width of the bolt, and in length is a bit shorter. The tip of the screw should extend a little beyond the tube, and the bolt head should be fully outside the tube. You may need to cut a tube to fit with the hand saw.

3. Attach the socket wrench to the screw to serve as a handle.

4. Place the end of the tube, with its exposed screw tip, underwater. Turn the screw using the wrench. The screw uses rotational force and the inclined planes of the screw's threads to raise water up the tube and out the top.

Resources

• Read this Article in Spanish
• Mechanical Advantage and Simple Machines
• MCAT Prep and Simple Machines