Shows how to use a transit to locate a building correctly on the lot, plan proper grades with minimum excavation, find Building Layout Author, W.P. Jackson. Building Layout,WP Jackson. Shows how to use a transit, to locate a building correctly on the lot, plan grades with minimum excavation, find utility lines. : Building Layout () by W. P. Jackson and a great selection of similar New, Used and Collectible Books available now at great.
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Chapter 1 The Transit A transit is used to measure horizontal and vertical angles. A 26x instrument may be used for work up to feet. Level tube sensitivity is explained later in the chapter. A level tube with a sensitivity of 90 seconds per 2 mm would form an angle of 90 seconds at a radius of 15 feet for each 2 mm the bubble in the tube moves.
About the Author W. The optical plummet is a device for centering a transit over a point. But after setting up at A, say the instrument is not level.
Instruments designed for still greater precision have a vernier that further subdivides each minute into seconds. Using a transit with an optical plummet provides a faster and more accurate method of centering than the plumb bob. Crosshairs in the telescope permit the object sighted to be centered in the field of view. The vertical axis is not centered over A, even though the plumb bob might be.
The power of the telescope can vary. For precision work use a more sensitive vial. If the center of the tripod head is not approximately over the point, centering the transit with the plumb bob or optical plummet isn’t possible.
An 18x instrument is usually used in work up to about feet. Instead of a vernier scale, a theodolite is equipped with an optical micrometer scale. The degree of magnification of a telescope is called its power x. This gives d instead of D. They will not be covered here, but you should know the reason for some of w.p.jacksob operations and how they can affect the accuracy of your work.
layojt Be sure the transit you select has the power, the precision, and the versatility you need to meet all your requirements for the present and the future. Concrete contractors need them for grades on floors, driveways and walks.
If the tripod head is too far out of level, the transit can not be leveled with the leveling screws. Set the tripod on firm ground and make sure the tripod points are stuck well into the ground.
In most lzyout, the markings on the level tubes are 2 mm apart. Since you use a transit for its accuracy, there is no substitute for an accurate instrument regardless of the size of the job. Layour tube with a sensitivity reading of 8 minutes seconds would form an angle of 08′ 00″ at a radius of 2 feet 10 inches 2′” with each 2 mm movement of the bubble.
You may not need that degree of precision now, but you probably will need it later when your skills increase and you take on other types of jobs.
Hundreds layoug valuable suggestions are included: Figure shows the principle of the optical plummet. Leveling vials are available in various degrees of sensitivity.
Building Layout – W. P. Jackson – Google Books
It replaces the plumb bob used in most transits. The buildng in all readings and surveying tasks requires a level instrument at all times.
It is marked in degrees and has a vernier scale that subdivides each degree in minutes on the better models. Figure shows the accuracy of these readings. If the radius bhilding small, the same vertical movement causes only a small displacement of the bubble.
Figure shows what different vernier readings layot in linear distance. Position the tripod legs so the center of the tripod head is approximately over the centering point and the tripod head appears level. The instrument is set up over A to locate D.
Building Layout – Surveying Guides – Books and Software – Craftsman Book Company
An engineer normally measures angles from the north-south meridian in surveying, so the engineer’s transit is equipped with a compass. As shown in the illustration, both horizontal H and vertical V circles are viewed simultaneously.
Make sure your instrument is in perfect adjustment before you follow the instructions below. This book is the result of his interest in improving professional standards among builders. If you are setting up on a paved surface, be sure the points are secure.
This practical handbook explains these valuable skills and shows builders and tradesmen how to use the builder’s level, plot plans, lot descriptions and surveying principles to be sure the building is in the right location and is built square, level and plumb.
Figure shows a serious error due to an instrument out of level. This helps you make error-free readings. The right transit for you depends on your job requirements.
There are three main parts to any transit — the telescopethe leveling vialand the circle. When the bubble moves even slightly on any transit, you will see a movement in the line of sight as indicated by the crosshairs in the field of vision.
Theodolites are used where precision bilding is essential. You must then reposition the tripod.