Engineering 

What is the situation when an engineer will use jacking at one end only and from both ends in prestressing work?

During prestressing operation at one end, frictional losses will occur and the prestressing force decreases along the length of tendon until reaching the other end. These frictional losses include the friction induced due to a change of curvature of tendon duct and also the wobble effect due to deviation of duct alignment from the centerline. Therefore, the prestress force in the mid-span or at the other end will be greatly reduced in case the frictional loss is high. Consequently, prestressing, from both ends for a single span i.e. prestressing one-half…

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Lathe Machine 

What is fiddle-bow lathe?

Fiddle-Bow lathe was used mostly for small work, generally metal work, was called a “fiddle-bow lathe,” on account of the method of driving it. In this lathe, which is shown in the figure below. The same idea of propulsion is used, that of a cord passing around either the piece to be turned or a rotating part of the mechanism by which the piece was revolved. In this case, however, instead of the resistance of the flexible limb of a tree or of a “spring pole” acting to keep the…

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Lathe Machine 

What are the basic principles of wood turning?

It must be noted, however, that although skill can only be acquired by practice, by “making shavings” as the saying goes, it is futile practising unless the basic principles are being applied. The basic principles are comprised of four main elements: The choice of the correct tools The use of properly sharpened tools A good stance The use of correct cutting techniques Consideration must also be given to safety. Safe working habits should become habitual and are as much part of basic principles as the four points covered above. Unsafe…

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Lathe Machine 

How to develop wood turning skill?

In the case of woodturning there is a bit more to it than motor skills because, with the right attitude of mind, it is within the power of the individual to alter the shape of the learning curve. The key to skill is attitude. What does this mean? To begin with it means developing an understanding of the correct basic techniques. If the turner does not get the basics right then, however much he practises, he will not improve. In contrast he may develop a lot of bad practices which…

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Engineering Engineering Drawing General Knowledge Lathe Machine Mechanical Engineering 

How to make a curve?

Turning requires manual dexterity, visual judgement and the co-ordination of hand and eye. In this respect it is similar to games like tennis. Such activities require the development of what psychologists term ‘motor skills’. The learning and development of these skills require relatively long periods of practice. It has been said that it can take seven years, working full-time, for a turner with aptitude to reach the peak of his abilities and become fully skilled. But again this should not deter the beginner. What does ‘fully skilled’ mean? It means…

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Lathe Machine 

The art of woodturning

Woodturning is an art not a science. Each skilled practitioner has his own particular way of doing things. The reason for this is that wood unlike, say, metal or plastic, is not an homogeneous substance. No two pieces of wood are identical even when cut from adjacent positions in the tree. In contrast, consider a piece of steel to be used in a motor car. Numerous metallurgists, and other specialists, will have been employed in the production and testing of the steel, to ensure that it has the required characteristics,…

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Lathe Machine 

GENERAL SAFETY RULES FOR OPERATING MACHINERY

1. KNOW YOUR MACHINE. Read the manual carefully. Learn the machines applications and limitations, as well as the specific potential hazards peculiar to it. 2. KEEP GUARDS IN PLACE and in working order. 3. EARTH ALL MACHINES. If the machine is equipped with three-pin plug, it should be plugged into a three-pin electrical socket. Never remove the earth pin. 4. REMOVE ADJUSTING KEYS AND WRENCHES. 5. KEEP WORK AREA CLEAN. Cluttered areas and benches invite accidents. 6. DON’T USE IN DANGEROUS ENVIRONMENT. Don’t use machinery in damp or wet locations,…

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