Tech to improve grinding wheels

We’ve covered some of the technical components that are spinning inside a humble garbage disposer, but the real action takes place in the grinding system. At the same time, the tech challenge is how to make this operate as quietly as possible!

The high-end units will use multiple grinding wheels to crush food waste to a pulp. They also use special materials and baffles to reduce the sound.

InSinkErator-EvolutionIf you rely on a garbage disposal unit – and millions of homes in the US do – then you might be interested to understand how much engineering know-how goes on inside the discreet casing.

Take, for example, one of the best-selling models, the InSinkErator Evolution Excel, which is designed for busy kitchens and has multiple grinding stages and a special noise-reduction system.

(As an aside, if you are looking for a new unit and are confused with the choice, take a look at this review site that compares features from the best garbage disposal units and provides a useful comparison chart.)

A key selling point of the Excel is its high-end grinding system: other models might include a single grinding setup (with  one set of grinding wheels), but the Excel includes a 3-stage grinding system to crush and pulp even the toughest chicken bones.

This model also includes what InSinkErator say is a unique sound-reduction technology that cuts the noise from the unit to acceptable levels so you can still hear normal conversation whilst it’s running. This is thanks to the special sound-reduction baffles and low-friction materials such as nylon bushes, that together make up the unique SoundSeal system.

To help you find out more about the technical features, the spec and the components used in this Excel model and by other manufacturers, visit the site I used for this initial research – which provides background technical articles together with reviews of almost all the garbage disposal units on the market – plus it helps you choose the right model for your needs.

Technology of Fuel Injection

techron fuel injector cleanerFuel injection is commonly used in car and truck engines to deliver the fuel to the combustion chambers. Around 20years’ ago, it was more common to find carburetors doing the same job, but since then carbs have gradually been replaced in all but the simplest engines (eg in a lawn mower tractor engine will often still use a carb).

The main difference between an engine that uses a carburetor versus fuel injection is that fuel injection system pumps the fuel through a small nozzle to atomize it at high pressure, so delivering a fine spray of fuel into the combustion chamber. In contrast, a carburetor relies on suction to draw the fuel into the chamber.

Fuel injection systems work with both gas and diesel fuel – and the injectors are designed specifically for the type of fuel being used.

There are several benefits to using a fuel injection system instead of a carb-based setup. These include smoother and more predictable engine response, easier starting, smoother engine idle and running, and increased fuel efficiency.

And lastly, a car with a fuel injection system does not have a choke, which on carburetor-equipped vehicles must be operated when starting the engine from cold and then adjusted by the driver as the engine warms up.

Check out the articles and guides at for more information.

Science: What Happens When Knife Blades Are Hardened?

Heating steel with a medium to high carbon content to a high temperature and then cooling it rapidly imparts hardness to it. Back yard steel workers are able to perform hardening with some precision by following specific steps. But what happens to the metal when it undergoes hardening?

Hardening: Step by Step

Demonstration of the hardening process is available on the internet; there are several videos. In one, the narrator holds a steel knife blade at a 90 degree angle with a pair of pliers in his gloved hand. Then he takes an oxyacetylene torch, set to a neutral flame, and heats the blade to a red hot state. Heat is applied evenly to the surface, so no melt spots or other structural defects are imparted to the steel.

When the entire blade is glowing cherry red, the narrator immediately plunges the knife into a waiting can of old motor oil for rapid cooling, a method called quenching. The blade is swirled around in the oil, so it cools evenly even as flames shoot up and out. When the flames stop and the blade has visibly cooled, it finishes cooling in the air. After the blade has cooled to the touch, the narrator demonstrates the hardness with a file. The file, although able to grip and file the non-hardened shaft, can do nothing more than slide across the surface of the blade; the blade hardened.

Atomic Changes in the Metal

When steel, a combination of iron and carbon, is heated to the critical point (named the Curie point for the temperature at which a material’s permanent magnetism becomes induced magnetism), the crystals in the iron change from ferrite (magnetic) to austenite (non-magnetic). When the crystals become austenite, they can hold more carbon. The carbon dissolves when it’s heated, filling in empty spots around the iron crystals. At the point of saturation, the steel is quenched.

Slow cooling of steel is called annealing. Steel is annealed to make it softer and more easily worked. Annealing also helps smooth out any machining deformities. A knife blade can have its cutting edge put on after the steel is annealed; then it is heated to cherry red and quickly cooled. During quenching, when the temperature cools to a low enough point, the steel tries to return to its low temperature crystal structure, but carbon atoms have taken up the free space of the crystal lattices, so the metal cannot return to its previous state. This phase is called martensite. It is extremely hard.

Why Tempering is Necessary

There are tradeoffs to the hardening, however. When steel is hardened, atoms that could previously slip and slide across and around each other when force was applied can no longer do so. Instead of bending and giving, the metal now breaks or shatters. With hardness comes brittleness. Tempering the steel takes out some of the hardness and gives back toughness.

As soon as the hardened steel has cooled to room temperature, it is tempered. In tempering, the steel is heated for a longer time with a low temperature, and then it is slowly cooled. A standard home oven is often used, since it can reach the low temperature range needed. Ideally, the steel develops the balance of toughness and hardness as required for the uses of that particular steel.

Steel is a versatile metal with an interesting atomic structure. The back yard steel worker can create his perfect knife blade with only a small amount of knowledge of the atomic changes each processing step is creating. Annealing, hardening and tempering are all stages steel can go through on its way to becoming the perfect metal for the job.

Further information

Batteries and Battery Science Explained

A useful everyday item whose intricacies are rarely understood is the battery. In technical terms, a battery is any self-contained unit that generates and stores power through an electrochemical reaction. Batteries are manufactured from a wide range of materials and are used in a multitude of applications. In fact, all organic bodies store and produce a small amount of charge, so by definition are batteries, including the famous 1.2 volt potato battery seen in science fairs the world over.


In 1800, the Italian physicist Alessandro Volta invented the first electrochemical cell called a voltaic pile. Over the next 200 years, scientists delved into the problem of creating less dangerous and more reliable and portable batteries.

Some of the significant contributions to this technology have come from both physicists and chemists seeking to improve the voltaic pile, developing a number of wet cell batteries, including the Daniel’s, Porous Pot, Gravity, and Chromic Acid cells. The earliest rechargeable battery was the lead-acid cell, invented by Gaston Planté in 1859. Lead-acid batteries are still used in automobiles and other applications where their heavy weight is not a concern.

Wet cell batteries had some drawbacks; they produced caustic and dangerous liquids like sulfuric acid, or gave off toxic fumes, or were simply too fragile to move. The solution was to develop an electrochemical cell that did not use a liquid solution as a medium and thus became more portable and less volatile, called a dry cell. The first dry cell battery was the zinc-carbon cell invented by Georges Leclanche in 1866, although his design had to be refined before it was commercially successful. Electrochemical dry cell technology continued to be perfected and new batteries came into production in the twentieth and twenty-first centuries.

Primary Cells

Batteries are not only dry or wet; they are also categorized as primary or secondary cells. Primary cells are disposable because their components are depleted through use. They are very stable, maintaining capacity over time when stored. They commonly power things like flashlights, toys, and many other portable devices and tools. The most commonly used types of primary cells include the following:

  • Atomic: power cells that use a radioactive source to generate power, include betavoltaics, optoelectric nuclear batteries and nuclear micro-batteries; very costly but have a high energy density and long lifespan making these batteries ideal in machines that are not regularly or easily maintained, such as on spacecraft, in wind turbines, in pacemakers and remote scientific research stations.
  • Lithium: have a long life but are very costly; they have many applications, including in pacemakers, small portable electronic devices, laptops, calculators and remote automobile door locks, to name but a few.
  • Zinc-Carbon: these are the most common and least expensive of the primary batteries and are often sold with electronic devices.

Secondary Cells

Secondary cells are rechargeable because the electrochemical reaction can be reversed, but they can lose capacity quickly when in use. There are a number of types, the most common being the following:

  • Lithium-Ion and Lithium-ion polymer: commonly sold in electronics because they lose their charge slowly when not in use; however, there is considerable health and environmental risk if damaged.
  • Nickel: including Nickel-metal hydride and Nickel-cadmium cells that have a high energy density and rapid recharge.

Batteries are in use everywhere in contemporary technology. Thus, understanding their structure and function is both pragmatic and interesting. For a comprehensive list of battery types, see Wikipedia’s List of battery types; for a list of battery and electricity related science projects, see’s comprehensive library.

Electric motor science and technology explained

Although the invention is nearly 200 years old, the electric motor has actually enjoyed increasing popularity over the years. The main reason for this is its versatility. With fewer moving parts, quiet operation, easy scalability, and precise control, electric motors can be used in many more applications than any other type of motor. To get a better idea of how they do this, an understanding of the science behind them can help.

Electro-magnet Basics

In the 18th century, early experimenter Andrew Gordon discovered that electrical currents in wires made them behave like magnets. It wasn’t until the 19th, though, that French scientist Andre-Marie Ampere figured out the actual relationship and developed the mathematical formulas, Ampere’s Force Law and Circuital Law, on which later advancements were based. Ampere discovered that electro-magnetic field intensity increased when electric current increased. He also found that magnetic polarity was connected to the direction the electric current was moving. Another key concept needed for electric motors was provided by Michael Faraday. Faraday discovered electro-magnetic induction whereby a magnetic field passes through a conductor and generates an electrical current in it.

Electricity Gets Moving

With this basic understanding established, it was Hungarian inventor Anyos Jedlik who built the first working electric motor with the primary components that are still present in some modern electric motors. In order to generate rotating movement, Jedlik invented the commutator. If you use an device with a rotating electric motor, for example an electric drill (read more info at TheDrillGuy), then you’ll be using a device that has not changed in its principle physics since the early discovery!

In its simplest form, the commutator consists of a metal ring with two gaps at opposite ends. The ring transfers electricity to the moving rotor by making contact with wire brushes attached to two parallel cables carrying power in opposite directions. When the rotor is repelled from one end of the fixed electro-magnet or stator and pulled towards the other end, the gap in the commutator allows the rotor to lose contact with one power line and draw power from the other line. This reverses the magnetic field, insuring the continuous movement of the rotor as it’s repelled from one end of the stator after the other.

To avoid the problem of brushes wearing out, most modern DC motors use external switches to reverse the polarity of the rotor or armature.

Alternating Current

This type of construction works when the primary electric current is going in only one direction, such as with batteries. The electrical grid, though, uses an alternating current. Two inventors, Nikola Tesla and Galileo Ferraris, developed induction motors in the 1880s that could produce motion from AC power. They accomplished this by utilizing Faraday’s discovery. Since an alternating current drops to zero before building back up to full strength in the opposite direction, it provides the needed fluctuating magnetic field to induce an electric current in a secondary conductor in the rotor. This secondary current, in turn, creates its own magnetic field. The secondary magnetic field will always match the primary one, north to north or south to south, and will be repelled. As long as the current alternates, the rotor will continuously move.

Expanding Future

While the invention of induction motors and expansion of the electrical grid led to a huge array of new devices like vacuum cleaners and dish washers, things didn’t end there. Computer advancements have made such things as printers or even robotics possible. Both rely on DC stepper motors. Likewise, improvements in battery technology make electric cars more practical over time. As important as electric motors are now, they’ll have an even bigger future.

Useful sites

Technology used in digital security cameras

Digital security cameras have become one of the most commonly used tools in catching criminals and deterring potential crimes. The cameras keep a constant eye on areas that might otherwise be prime targets for theft, and they’re always on.

Despite their apparent simplicity, there are actually a number of different components used in security cameras to let them do their job. Outside of the basics of a lens, let’s take a look at what makes modern security cameras so useful.

Digital Storage

Storage is the basis of any camera system, but digital cameras rely on digital storage. This is superior to film in a number of ways. It has a much longer lifespan, it can be duplicated easily and inexpensively, and the picture quality is generally better. Some cameras rely on solid-state (SSD) storage that’s stored locally, while others can use a LAN or Internet connection to store footage on a network drive or other remote hard drive. This is the preferred method, as it prevents destruction by an intruder.

Night Vision Technology

Although it’s possibly to put together a pretty serviceable camera without it, night vision technology makes any digital security camera that much better. There are a couple universal components that security cameras can use to achieve night vision.

The most important component of a night vision sensor is an infrared (IR) light sensor. IR light is invisible to the human eye, but cameras with IR sensor can use the spectrum to light up the picture being recorded.

An IR cut filter is also important to producing a good night vision setup. An IR cut filter essentially lets the camera know when to ignore the IR spectrum. Without a cut filter, cameras will produced washed out images that are over saturated during the day. Thus, a cut filter lets the camera produce the best picture it’s technically capable of both during the day and at night.

Motion Triggers

The most advanced cameras have the capability to sense motion and send an alert back to the operator of the camera. This alert can be an audible or visible alert if the camera is being used by a security team, or it can be a text message or phone call for private operators.

There are a few different ways that motion detectors can function. The most common in digital systems is photo-sensitivity. A beam of light is used and focused across a particular part of the area that the camera is being used in. When that beam is broken by an intruder or other object, the change of light is detected and the camera knows to send a trigger. Another common method is to use infrared or photo-analysis. This method looks at changes in the overall image being captured by the camera. It then sends alerts if there is a significant change in what the camera is looking at. The parameters can be adjusted here so that an indoor camera will alert for an intruder, but not for the family dog moving around.

An Internet Connection

For most digital cameras, this is the most obvious need. Using a wired or wireless (Wi-Fi) Internet connection, cameras can be placed online. This allows operators to view the image on the camera remotely, and it also lets the camera send out alerts over the Internet. It also lends a new set of control to the camera – many now have pan, tilt and zoom controls. These let the owner of the camera adjust its field of view remotely, allowing for fewer cameras to be put in place and for better images to be captured.

It’s interesting to see how existing systems work together. Motion detectors, IR light sensors and Internet connectivity aren’t anything new or revolutionary on their own. When brought together, though, they make for one of the most efficient crime-stopping tools that has ever been invented. Digital security cameras are a straightforward idea, but as with all technology, there’s more going on under the hood than meets the eye.

LED Flashlights: Technology and Effectivness

While the flashlight’s basic design remains unchanged, LEDs are an innovative addition that provide significant benefits. The LED, or light emitting diode, was invented in 1962 by Nick Holonyak for General Electric. It wasn’t until 1999, however, that the Lumileds Corporation succeeded in creating a practical LED flashlight. See how the technologies within this device work together to illuminate your world.

LED Flashlights

The flashlight is a relatively simple electronic device. In fact, the first patent for the flashlight was issued in 1899. This was only a few years after the first dry-cell battery was invented. All battery powered flash-lights consist of a battery, a spring, a contact strip and a light source. When you turn the switch to the ON position, you complete an electric circuit between the light source and the battery. This circuit causes electrons to drain from the battery and flow into the LEDs. The electrons flow because of a differential between the positive and negative electrodes within the battery.

The circuit itself consists of two conductive strips. The first is connected to the switch and makes contact with the battery. The second strip is connected to the LEDs. When you turn the flashlight off, you break the circuit between these two strips and stop the flow of electrons.

When the electrons reach the LEDs, the LEDs begin to glow with a bright white light. This is because they convert the electrical energy into photonic energy. LEDs are extremely efficient as they only require 60 milliwatts of power to produce light. They are substantially more efficient than normal tungsten-based lights and shine more brightly to boot. However, the light produced by these diodes is dim and must be bounced off of a reflective surface within the lens of the flashlight to produce a strong beam. Once amplified in this way, LED flashlights provide comparable luminosity to standard flashlights at a fraction of the power consumption. Note that not all flashlights are battery powered. Some come with cranks that convert mechanical energy into electricity.


A light-emitting diode is constructed of two-surfaces sandwiched together. The first surface is replete with electrons while the second is electron-hungry. When electrons flow into these layers an energy buildup occurs. The LED—a closed system—must resolve this energy buildup and does so by releasing photons. Manufacturers can control the amount and color of the light produced by altering the chemical makeup of the two semiconductive layers.

Individual LEDs are packaged together on a dye to create a usable amount of light. There are two primary types of LED arrays: pixelated and diffused. Pixelated arrays consist of a layer of visible LEDs while diffused arrays utilize lenses that create a uniform appearance. Diffused arrays simulate natural lighting and are more commonly used in home applications while pixelated arrays see more frequent use in industrial applications.


Some scientists believe that the earliest use of the battery occurred in Mesopotamia more than one thousand years ago. These simple devices consisted of a conductive metal such as copper dipped into a pot of wine. The wine, an electrolyte, built up an electrical charge in the presence of the copper. Whether or not these devices were actually used to store energy is unknown, but the science is sound. The ancient devices may have been used to plate objects with gold, although many scientists doubt this interpretation.

Batteries consist of three parts: an anode, a cathode and an electrolyte. The anode is negatively charged while the cathode is positively charged. The electrolyte serves as a bridge through which electrons flow from the cathode to the anode when energy is supplied to the system. As energy builds up in the battery, an electrical differential occurs. When a conductor connects the cathode and the anode together, by-passing the electrolyte, electrons rush out of the battery, nullifying this differential. In practical terms, the battery is said to be “discharging.” Batteries eventually go bad because the electrodes within them corrode, and because the electrolytes leach into the battery’s casing.


The LED flashlight is an efficient innovation and is particularly useful in survival situations. LEDs last longer and are not as prone to failure as their tungsten-based counterparts. They use less power and can provide a powerful beam when properly amplified by a reflective material.

The Technology Behind Kitchen Sink Garbage Disposals

Some of us have them, and most of us have at least used one. We are talking about the kitchen sink garbage disposal, of course. However, how many of us really know about the technology that makes this kitchen powerhouse actually work?

What Is a Garbage Disposal?

insinkerator septic assistBefore we get into the technology behind the garbage disposal, let’s break down what this device is. A garbage disposal, sometimes referred to as a waste disposal, is an electrically powered device that typically sits under your kitchen sink. The units itself is placed between the sink and the drain. The purpose of it is to catch the food waste that homeowners put down the drain and shred it into small enough pieces to fit down your plumbing. The general standard is for garbage disposals to cut waste into 2 millimeter pieces so that it can safely fit down your pipes. Take a look at for more information – this site notes that garbage disposal units are not very common outside of America, which could mean we are much more likely to waste food than other countries.

The Inventor: John W. Hammes

Despite the fact that garbage disposals are still considered a luxury, the very first one was invented in 1927 by John W. Hammes. After coming up with the idea for the device, he filed for a patent for technology in 1935. The world saw the very first commercial garbage disposal in 1940, developed by Hammes’ company, InSinkErator. It took some time for this device to get off the ground because there were regulations in place to prevent the disposal of food down sink pipes in the 30s and 40s. Hammes faced an uphill battle the whole way with getting cities to lift these restrictions. For the most part, however, he was extremely successful.

Garbage Disposal Technology

Now that you know a bit about the history, it is time to break down how this device works. The garbage disposal is an insulated electric motor with a high-torque. The great torque is needed to get the blades up to speed quickly to chop the waste into small pieces before they make their way through the unit and down your plumbing. Some units use induction motors, but these models usually have a low starting torque. These units also suffer from the added weight that comes with using an induction motor. As a result, they can only be used as domestic units in homes that have sinks that are big enough to support them. It is also generally recommended that these units be turned on first before the waste is added to give the blades time to get up to speed.

Although all garbage disposals have different ratings, most are rated at 250 to 800 watts, with around 1 horsepower for domestic units. Nearly all garbage disposals have a circular turntable in which impellers are installed horizontally. Most universal garbage disposals have a motor that runs at speeds around 2,800 RPM. In comparison, induction motors only run about 1,600 RPM on average. The one advantage that induction motors have over insulated motors is the fact that they are much quieter. This is due to the great torque that is put out by the insulated motors.

Once the waste goes down the garbage disposal hole, it enters the grinding chamber, where there are two metal impellers that swivel on the turntable. These are used to push the food against the grind ring. This is a process that happens repeatedly and very quickly until the food is small enough to pass down the pipe. The rubber lining at the entrance to the grinding chamber helps prevent food from being flung back out of the grinding chamber by the metal impellers. The main difference between commercial and domestic garbage disposals is that most commercial units have an additional blade installed under the turntable. The blade is great at breaking down “stringy” food that sometimes gets passed domestic units.


The technology behind the garbage disposal is pretty simple, yet it is more complex than what the average person might give it credit for. The most remarkable part is the fact that the technology has been around since the 1930s. So the next time you use a garbage disposal, remember that you are using technology that came out in the 30s and is still being used today.


Technology and the Science of Lenses and Optics in Binoculars

The easiest way to describe binoculars as two telescopes, one for each eye, that have been stuck together in one convenient unit. However, this might be not be the most helpful explanation, especially if a person does not know how telescopes work. This article will seek to explain how such a device works in the context of binoculars.

Types of Lenses

A convex lens is a piece of glass that has been curved so that the outside edges are thicker than the middle of the glass. When light hits this piece of glass in its middle, it is forced to slow down and bend. This allows the glass to take objects that are far away and make them appear as though they are closer than they actually are.

A concave lens is a lens that is thicker around the edges and thin in the middle. This causes light, when it enters the lens, to spread out around the edges like how a firework expands. This allows light to cover a larger area when it goes through the lens.

How Telescopes Work

Telescopes are specifically intended to magnify the image of an object that is in the distance. Inside of a telescope’s casing, there are two convex lenses. The first lens takes the light that comes in and captures that image right behind the second lens. It is known as the objective lens because it is focused on the object that is being looked at. The second lens captures the image that is inside of the telescope and makes it bigger.

How Lenses and Prisms Work in Binoculars

Because binoculars are basically two different telescopes that are attached so that they are side by side, there is one for each eye. The main problem with just the two lenses is that the rays, when passing through a lens that is considered to be convex, is that sometimes the images become flipped upside down since the rays are crossing. In order to fix this problem, there are two chunks of glass in each telescope that are put into the binocular.

These wedges are known as prisms that take the image and cause it to flip upside down 180 degrees. The first prism will flip the image by 90 degrees. The second will flip it an additional 90 degrees. These prisms can be located at 90 degree angles from one another, which is known as a Porro formation. They can also be located back to back, which is called the roof prism formation.

Prisms are what makes the binoculars heavy because they are such large wedges. The reason why field lenses are lighter than binoculars is because they only use lenses to flip the image upside down. Because prisms are not used, the image that is produced by field glasses tends to be of a poorer quality.

How do the Numbers Work?

Binoculars tend to have a set of numbers that are separated by an “x” on them.

  • The first of these two numbers describes how many times closer the image will be. If there is a five for the first number, then the image will be five times closer.
  • The second number is the size of the objective lens, which describes the size of the image that is able to be captured.

This brief overview of field glasses provides a basic explanation of the science of binoculars and an introduction to how optics work within binoculars . More information can be found at and