# Sine bar

﻿
Sine bar

A sine bar is a tool used to measure angles in metalworking.

It consists of a hardened, precision ground body with two precision ground cylinders fixed at the ends. The distance between the centers of the cylinders is precisely controlled, and the top of the bar is parallel to a line through the centers of the two rollers. The dimension between the two rollers is chosen to be a whole number (for ease of later calculations) and forms the of a triangle when in use. The image shows a 10 inch and a 100 mm sine bar.

When a sine bar is placed on a level surface the top edge will be parallel to that surface. If one roller is raised by a known distance, usually using gauge blocks, then the top edge of the bar will be tilted by the same amount forming an angle that may be calculated by the application of the sine rule.

*The hypotenuse is a constant dimension &mdash; (100 mm or 10 inches in the examples shown).
*The height is obtained from the dimension between the bottom of one roller and the table's surface.
*The angle is calculated by using the sine rule. $sin left\left(angle ight\right) = \left\{opposite over hypotenuse\right\}$

Angles may be measured or set with this tool.

Principle

Angles are measured using a sine bar with the help of gauge blocks and a dial gauge or a spirit level. The aim of a measurement is to make the surface on which the dial gauge or spirit level is placed horizontal. For example, to measure the angle of a wedge, the wedge is placed on a horizontal table. The sine bar is placed over the inclined surface of the wedge. At this position, the top surface of the sine bar is inclined the same amount as the wedge. Using gauge blocks, the top surface is made horizontal. The sine of the angle of inclination of the wedge is the ratio of the height of the gauge blocks used and the distance between the centers of the cylinders.

Types

ine centre

A special type of sine bar is sine centre which is used for conical objects having male and female parts.it cannot measure the angle more than 45 degrees.

ine table

Sine table is used to measure angles of large workpieces.

Compound sine table

It is used to measure compound angles of large workpieces. In this case, two sine tables are mounted one over the other at right angles. The tables can be twisted to get the required alignment.

Wikimedia Foundation. 2010.

### Look at other dictionaries:

• sine bar — noun : a device that consists of a steel straightedge at whose extremities buttons are attached with their centers equidistant from the straightedge and that is used to locate work at desired angles on angle plates …   Useful english dictionary

• Sine hebdo — Siné Hebdo  Siné Hebdo Pays …   Wikipédia en Français

• Siné-Hebdo —  Siné Hebdo Pays …   Wikipédia en Français

• Siné Hebdo — Pays  France Langue Français …   Wikipédia en Français

• Siné Hebdo — Sine Hebdo es un periódico satírico francés fundado y dirigido por el dibujante Siné que se publica todos los miércoles desde el 10 de septiembre de 2008. Sus 16 pàginas de formato tabloide contienen artículos de opinión, investigación y viñetas… …   Wikipedia Español

• Wrench — For other uses, see Wrench (disambiguation). A set of chrome vanadium metric wrenches, open at one end, box/ring at the other. This type is commonly known as a combination wrench. A wrench or spanner is a tool used to provide grip and mechanical… …   Wikipedia

• Forging — This article is about the metalworking process. For specific hot forging hearth, see forge. For the act of counterfeiting, see forgery. Hot metal ingot being loaded into a hammer forge Forging is a manufacturing process involving the shaping of… …   Wikipedia

• Metalworking terminology — This article is a list of terms commonly used in the practice of metalworking. Contents 1 Processes 1.1 Casting 1.2 Forge work 1.3 Heat treating …   Wikipedia

• Combination square — with standard head A Combination Square consisting of the rul …   Wikipedia

• Milling cutter — Milling cutters are cutting tools typically used in milling machines or machining centres (and occasionally in other machine tools). They remove material by their movement within the machine (e.g., a ball nose mill) or directly from the cutter s… …   Wikipedia