COMPUTERS

'To compute' means to count. So the literal meaning of 'Computer' is a counting machine, or a calculator. But a computer performs many more functions than a calculator. It sorts out, compares, analyses, arranges information systematically, reasons logically, draws conclusions or gives the information in the desired form. It can handle vast amount of facts and figures and solve complicated problems at incredibly high speed. It can also store information for future use.

Although a computer can do many things, it cannot think. It should be instructed by a human operator. The operator should give detailed instructions to the computer about what it should do. He must put into a computer the information with which a computer can do its work or solve a problem. Putting information into a computer is called feeding or programming. This is done through an input device.

The inner part of the computer called the central processing unit receives the information, stores it, and processes it by means of mathematical calculations or logical operations. The processed data is finally translated into the form which the operator can understand and presented through an output device.

Computers are indispensable for large establishments and projects which require the combined co-operation of hundreds or thousands of persons to take innumerable complex decisions or to solve innumerable complex problems. Thus computers are a must to the big industries, government, municipality, military and space projects. But for the computers, man would never have been able to land on the moon.

They are used everywhere for various purposes. Whether it is the small-sized personal computer used to keep household accounts or the sophisticated machine used to keep track of spacecrafts, computers have become an Indispensable part of modern life.

Some people are afraid that in the long run, computers will control man. Man will become a slave of the computer. But this fear has no basis. Any computer, however sophisticated, will require man to operate it.

Development of Bluetooth techmology

Bluetooth history

Bluetooth takes its name from a character in history called Harald Bluetooth. He was the king of Denmark born in 910AD and was responsible in 940AD of uniting Denmark and Norway which is where Bluetooth technology gets its conception from. The founders of Bluetooth took the name of Harald Bluetooth because of the way he united two countries together and in the same way Bluetooth unites two dissimilar components. The use of Bluetooth technology has the ability of linking the different technologies like , computers, mobile phones, printers, headsets etc.

The first to try and discover a way to provide low cost, low power interfaces was a company called Ericsson Mobile Communications. They started looking into ways of linking cell phones and computers without wires in 1994. A group of like minded companies joined forces in 1998 to form and association called the Bluetooth Special Interest Group (SIG) in Lund Switzerland. This group consisted of companies from different backgrounds including one leader in digital signal processing, two of them were market leaders in the cell phone industry, and the other two were leading laptop manufacturers. These companies where Ericsson, IBM, Microsoft, Motorola, Nokia, Intel, Toshiba, and Agere. Today research and development into the Bluetooth technology is led by these companies.

Two employees of Ericsson Mobile Platforms developed the Bluetooth specifications, they where Jaap Haartsen and Sven Mattisson. Enabling various components from different industries to Connect Bluetooth technology was developed in Scandanavia. Based on a frequency hopping spread spectrum it is a wireless technology that combines and simplifies multiple forms of communication into a common secure available radio signal.

The Bluetooth Special Interest Group made a firm commitment to have Bluetooth technology installed in various devices and by 2002 Bluetooth technology was installed in PC’s, notebooks, desktop computers and over 100 million mobile phones had the technology as well as millions of other communications devices.

What exactly is Bluetooth?

Bluetooth is a wireless communications network which operates on a short-range radio frequency. Bluetooth technology has the ability to has the ability to be used on any equipment that has its built in features and can exchange information between various device like mobile phones and computers. Due to its very low power it is medically safe to use, the information it carries using short wave radio and narrow bandwidth know as ISM is scientifically sound and very secure.

Devices have to be compatible and anyone wanting to use it will have to have Bluetooth profiles to be able to connect to one another. You can use things like mobile phones, hands free headsets, printers with wireless network communications, keyboards and a mouse, provided the profiles have been enabled.

Versions of Bluetooth

There have been many different versions of Bluetooth and a lot has changed since version1.0 in 1998 which had many teething problems, like most technology. The main problem being a lack of devices being able to communicate.

Version 1.1 saw great improvements and it became a truly operable product with devices being able to communicate properly.

Version 1.2 saw all round improvement with vastly superior voice qualities, and many extra benefits.

Version2.0 saw more improvements and features and now version 3.0 is able to communicate with several devices using a Bluetooth master device in which the slave can become the master at any given time. The master has the ability to switch between devices very fast.

Other similar technology Such as Wi-Fi is on the market but use different technology although Wi-Fi has a greater operating range. The Bluetooth advantage is in its costs, much cheaper than the more expensive hardware used by Wi-Fi. The Bluetooth setup of its services between many devices is simpler, can be automated and security is easier. Wi-Fi is more complicated to set up and needs to have devices configured to set up shared resources which are more for Ethernet networking. Bluetooth is more powerful and has better connections whilst Wi-Fi is better suited for operating larger networks. 

For operating Bluetooth on a computer it requires Microsoft Windows XP with Service Pack 2 or higher. If you run an Apple computer it has been supported by Bluetooth technology since 2002. Nearly all computers now have Bluetooth installed but if not then if your computer has Windows XP with Service pack 2 then a device called a dongle can be purchased. The dongle device allows various devices to communicate with your computer.

The future of Bluetooth is bright and it has become the world wide wireless standard system. In the future High quality audio and video data will have a much higher quality as Bluetooth improves and the alternative for transporting Bluetooth profile data is MAC PHY. Automatic configuration will be carried out by using Topology Management, and broadcast channelling, which will enable Bluetooth in other devises. Manufacturers are now jumping on the bandwagon and using Bluetooth technology and as more components use it the technology will grow. Bluetooth technology is here to stay.

Where can I get more information about Used Macintosh Computers?

Because they've had other owners, used computers might be what you'd expect. Often, items listed online are being offered at a great reduction from their original cost. Used computers are an excellent way to get a great PC at a reasonable price. Take note that I did not write high spec computer. Let's be realistic, you are not going to get a top-spec computer at a used price, OK. This spec machine delivers best service at best price.

Something a first time buyer may want to consider is purchasing used Macintosh computers.

All used Macintosh computers from reputable online dealers are thoroughly inspected, repaired and or cleaned to be in perfect operating condition by an experienced, certified technician. There is a money back guarantee and unless they work properly you can get back your money. The period of this warranty is 30 days, a good enough time. Often second-hand computers that are name brands come with a warranty of 3, 6 or as much as 12 months, so be sure to ask the salesperson.

A lot of people mistakingly believe used computers require additional work. That is certainly not the case. Many mechnical parts, including the keyboard and mouse, have usually been replaced with either new or refurbished ones. Often, when you work through the costs, you'll find it is more cost efficient to keep replacing used computers than it is to buy a new PC over a slightly longer period. Don't forget this.

You can find great prices on used computers by searching the Internet. Businesses who lease computers usually lease for a year or more prior to upgrading; this explains why so many previous model computers are available. Then these almost new computers are made available. It's a great situation for someone on a budget.

Buying used Macintosh computers from a shop isn't usually recommended, not only because is it difficult to find a reputable dealer, but also because a good warranty isn't offered and the computer may not have been checked to find out if it works properly. Similarly, I'd give the personal ads a miss too as you won't get any warranty at all. That's why I've been pushing you towards online dealers. They have a system in place to deal with the inspection, repair and cleaning of used computers as well as being able to offer you a warranty.

So if they don't have a guarantee, go somewhere else online. When purchasing anything online, be sure to review exactly what you are buying. Read the small print and find out whether you are getting a monitor or not and whether you have Windows installed. Make sure that you check because sometimes that isn't the case.

Tips for Milling Machine Parts and CNC Milling Machines

CNC

When you are looking for CNC Milling machine parts and components there are a variety of places where you can find them. The best price and a lot of research can be found on the Internet at a variety of websites.

Depending on the type of CNC Mill machine you need the price can be steep but there are many small machines that can do the same job if you are looking at this as part of a small business or a hobby. Also, you can buy a machine to cut metal or wood, to do fancy scroll work or to do engraving on metals and other applications.

You can decide whether you will purchase a brand new machine or a used one. Most people do not suggest buying a used one because you aren't sure what you are getting but buying other types of machines like CNC routers seem to be a good idea because of the cost.

All CNC Milling machines contain the following parts:

§ Axis -- depending on the type of CNC milling machine it could have anywhere from one to six axis which will also determine the size and what it is supposed to do.

§ Column -- the column is what travels along an axis that holds the part that mills or cuts.

§ Control panel -- the part that holds the computer keyboard (sometimes small, other times large) where you program the G-Codes into the machine.

§ Cutting tool -- the cutting tool is attached to the column and is the part that actually cuts the piece in the way that the operator specifies.

§ Spindle -- the spindle holds the cutting tool in place.

Coolant Supply Tubes -- Just like the name says these tubes are where coolant is pumped through to keep the tool lubricated.

§ Table -- the table is the area that the workpiece will be attached to either using a clamp or a vacuum. This is where the workpiece will sit while being milled.

There are several different types of CNC Milling machines that can be found and they are small or large depending on what they do. Here are a few:

Vertical CNC mills have a vertical spindle axis. This means that the cutters that do the milling are held vertically in the spindle and they rotate on the spindle's axis. In this type you can extend the spindle or the table to make drilling or plunge cuts. Bed mills and Turret mills fall into this category.
Horizontal CNC mills have the same type of table as vertical CNC mills but their cutters are mounted on an arbor that sits across the table horizontally.

Hobbyists will most likely use a box mill which is mounted to a bench and basically moves up and down. One thing thats really nice about a knee mill is that you have an x-y table that moves up and down the column. It can be adjusted with what is called a vertically adjustable knee. Many larger industries use the C-Frame mill because it is the most conducive for larger work. They are only vertically mobile and it used a fixed spindle head for that movement.

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CNC Mill Basics and CNC Milling Machine

CNC

A machine tool that shapes metal and other types of solid materials is called a milling machine. A CNC milling machine does this automatically once a computer sets up the specifications for the machine, it uses a rotating cutter to work like a drill to cut the material.

There is a difference between a drill and a milling machine however. A milling machine will use a cutter that rotates around a spindle axis and the table by which the piece of work is attached. A drill only moves along an axis and can only drill in one direction. A milling machine can move sideways and in and out like a drill.

The CNC milling machine can be controlled evenly by what is put into the computer. Miling Machines can actually work in different ways as some milling machines the table moves around the cutter. If you want a milling machine that can be operated manually versus with a computer then you will not want a CNC Milling Machine but just a Milling Machine.

A CNC Milling machine makes the operator's work easier because it can do a number of operations like panning, rebating, drilling, routing and more. Often a cutting fluid has to be used at the site of the cut because it needs to keep the metal cool and the cut lubricated; also it is used to move the sluice out of the way.

In CNC Mill you will have a block of material that will be cut through by a rotating tool attached to the machine. You can actually move the piece in three dimensions all together so that you get the cut and shape that you want.

An operator can produce many different shapes with a CNC milling machine. For instance, if you have a 2D shape with an intricate pattern you can program the machine to do this pattern and repeat it as needed. The machine will also do 3D shapes, do different types of punches and even use a laser (usually a CNC Plasma Cutter).

Most metals and hard plastics are the best materials to use with a CNC milling machine because they can withstand the rigors of how the machine cuts. Softer materials are not able to stand up to the pressure of the process.

The CNC Mill machine is best used when you need a short run of materials to be produced. This process also needs only a software program to do the tooling and some type of jig to hold the work down while it is being cut. The machine is programmed using G-Codes for more precision.

Today, CNC milling machines are being produced that can do a variety of things. As an example, Datron Dynamics sells a CNC milling machine that does all of the milling needs but also does industrial engraving. This machine can engrave on most metals including
Aluminum, graphite and stainless steel, but it can also engrave on ceramics and plastics.

The CNC Milling machine is a versatile machine and it can create many different parts while saving the company and the operator time and money.

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Information on Injection Molds

Rapid Prototype

Approximately 30% of all plastic products in the world are produced by an injection molding Rapid Prototype process. Within this another 30% are produced using a custom injection molding Rapid Prototype technology. You can make as many steps as you want for the injection molding process, but most people will recognize that there are 6 basic steps in the molding process. The first step is the clamping of the mould, the clamping unit makes for one of the three units of the molding machine. The other two being the injection unit and the mold, once the clamping unit holds on to the mold, the molten plastic is injected into the mold by the injection unit. The plastic is fed in the form of tiny pellets onto a hopper. The next process is that of which these items are put into a cylinder where they are heated for a long time until they melt and can be injected into the mold. The steps that follow are referred to as dwelling phase. Rapid Prototype basically involves making sure all the cavities in the mold are fully filled. The next step is that the mold is allowed to cool but its important to do this as the clamping is still intact. Finally the mold is opened and the component is ejected out. The biggest advantage of plastic injection molding is the cost factor of the produced parts, especially when you need large number of parts.  The disadvantage is the cost of manufacturing the molds; a simple injection mold can cost you $3000 while the bigger complex ones can run into several hundreds of thousands.

Rapid Prototyping: This process bacially automates certain types of manufacturing using a technology called solid freeform fabrication. They are used in a wide range of applications, everything from medical to fine art. Rapid Prototyping machine works by taking virtual models from software and then converting it into extremely thin, horizontal cross-sections and then goes onto create each of the cross-section in physical space in a cyclic manner until the model is completed. Rapid Prototyping is a WYSIWYG process in which the virtual model bears identical resemblance to the finished physical model. Additional fabrications allows the machine to lay down layers of sheet, liquid or powder material and build up a series of cross-sections These layers are finally automatically fused together to render the final product. The main advantage of rapid prototyping is the ability to create any shape no matter how complex the geometry is. The commonly used data interface between the machine and the software is the STL format. It works by approximating the geometry of a part using triangular facets, smaller the facets higher will be the surface quality. The word “rapid” is used relative top conventional methods which take days to construct a model depending upon its complexity.  Rapid prototyping can create the model within a few hours, though it is highly dependent of the type of machines and the size of the model. There have been several new technologies available for rapid prototyping including Fused Deposition Modeling, Selective laser sintering, 3D printing, and Electron Beam Melting.  

Prototyping Injection Molding is a specialized method of combining traditional plastic injection molding. CAM software are able to combine rapid tooling and plastic injection molding  in order to quickly create small quantities of any thermoplastic part.

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Cast Prototyping and Precise Cast Prototyping, and the PCPro Technique

rapid prototyping

Researchers have developed a new Rapid Prototyping technique that blends traditional casting methods with CNC milling which allows faster prototyping; the best thing is that it happens in a single machine. This technique become public when it was invented and named Precise Cast Prototyping by a group of researchers in Germany at the Institute for Material and Beam Technology. Half of the mold is machine using CNC machining, then silicon or polyurethane material is poured into fill half the mold, this will be the lower half to render the shape of one half of the part, while the part still in the CNC mill. When the material is cured and hardened, the upper side of the component is milled. The process is targeted at components with simple geometry such as housings whose one side can be fairly easily machined on aluminum or epoxy mold half and the other complicated half is on the opposite side where it can be milled into the soft plastic.

Cost Saving: The Rapid Prototyping technique is touted to be an enormously cost effective as only one half of the tool is made and that too for low pressure casting. There are no runners; gate, venting and parting lines to be taken care of and besides these can be manufactured by toolmakers with lesser experience. Another Rapid Prototyping advantage is that one half casting allows the air bubbles to escape freely; this translates into a more dense part and better surface finish. The casting can be machined again which is nice because then you can get some great features such as threads and undercuts worked into your design. The casting method shapes the outer surface of the component while precision CNC milling renders the inner contours. The fact that he casting can be milled allows for parts with totally different dimension to be manufactured from the same mold. This is because the second half of the mold exists only as a CAD/CAM model and tool path programming. Geometrical changes can be altered by just changing the parameters.

Time saving: Since the outer surface of the component are not machined the process saves a lot of time .Moreover the inner dimensions gain closer tolerances compared to prototypes manufactured by vacuum casting. The reason for this is that the finishing takes palce after the curing and shrinkage in conventional prototyping while in casting it’s done before the casting shrinks. CNC allows for achieving of tighter tolerances compared to casting technologies. Besides all the machining is done in a single setting so there is no chance of non-alignment of the outer and inner features. The PCPro technique manufactures a prototype in just 6 steps, while the vacuum method takes 15 steps. A potentially major application of PCPro is to make housings for cell phones and similar electronic products; this is because of the technique’s ability to deliver flawless, close tolerance free-form surfaces. This machine, which was designed and patented by Fraunhofer, is a machine that is a blend of a casting and milling machine. However it has to be said that highly complex features are difficult to manufacture by this method.

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