A sine bar, often referred to as a precision angle device, is a specialty instrument for precise measurement in metrology and machining. It is employed to measure and establish angles with a high level of precision and accuracy.
To guarantee the exact alignment and machining of workpieces at particular angular inclinations, they are frequently used in machine shops, quality control labs, and manufacturing sectors.
Well, in this reading, we explore what a sine bar is, its application, diagram & part, construction, types, and working principle. We’ll also explore the advantages & Limitations.
Let’s get started!
What is Sine Bar?
A sine bar is a precision tool for extremely accurate angle measurement and calibration. It is made of a hardened and ground steel bar with two precisely positioned rollers at its extremities. The rollers are set with high precision to determine the exact distance between their centres, allowing users to achieve precise angular measurements and calibration.
Sine bars are made of high-chromium corrosion-resistant steel that is hardened, precision ground, and stabilised. Two cylinders of equal diameter are positioned at the ends of the bar, and their axes are parallel to each other as well as parallel to and equally spaced from the upper surface of the sine bar. A sine bar is used in conjunction with slip gauge blocks for precise angular measurement.
Application
Following are the applications of sine bars:
- Sets or determines workpiece at a given angle.
- Checks measurement of unknown angles in workpiece.
- Mounts workpiece for conical-shaped machining.
- Checks unknown angles on heavy components.
- Checks taper key angles.
- Checks surface flatness.
Diagram & Parts
Construction of Sine Bar
The stiff steel gauge body of the sine bar is made up of two rollers of identical size with parallel axes and parallel construction. The length of the sine bar, which is precisely adjusted at 100 mm, 200 mm or 300 mm, corresponds to the distance between the roller centres, while the top of the steel bar runs parallel to a line joining them.
Its weight is decreased by the thoughtful placement of relief holes. A sine bar is used in combination with slip gauges and elevation gauges since it is ineffective when used alone to measure angles.
Surface Plate
The sine bar and related parts are arranged on a surface plate, which guarantees a precise horizontal reference surface for the bar. The sine bar’s top surface must be parallel to the horizontal planes of the surface plate for alignment to be effective.
Dial Gauge
In order to verify surface parallelism with its base, dial gauges are used to measure surface uniformity. They record zero deflections during traversal. Dial gauges are essential in the sine bar configuration for measuring the angle of the tapered sine or confirming that the workpiece’s upper surface aligns with the surface plate.
Block Gauges or Slip Gauges
The precision of sine bar installations is enhanced by block gauges, often referred to as slip gauges, which act as exact standards for height and length measurements.
Vernier Height Gauge
The height of the sine bar rollers is measured using vernier height gauges, which makes it easier to measure the angles of bigger parts of the setup.
Types Of Sine Bar
Sine bars come in various types, including the simple sine bar, compound sine bar, and universal sine bar, each offering unique capabilities for angle measurement and precision machining tasks.
The different types of sine bars are:
1. Sine Centre
This type of sine bar is used to measure the angles of conical objects with both male and female components, although it should be noted that the sine centre is limited and cannot measure angles more than 45 degrees.
2. Sine Table
A unique variation of the sine bar, the sine table has a broader and bigger form. Its locking system, which allows for safe placement and workpiece stability during operations, is what distinguishes it.
3. Compound Sine Table
In terms of measuring the angles of large workpieces that a regular sine bar cannot handle, the compound sine table is useful. It is made up of two sine tables that are perpendicular to one another. To get the required angle measurements, these tables can be rotated as necessary.
Working Principle
The basic ideas of trigonometry form the basis of a sine bar’s action. A triangle is formed by the sine bar, surface plate, and slip gauge when one of the rollers is placed on a surface plate and the other roller is adjusted to the height of the slip gauge.
The sine bar itself, which was produced by combining vertical slip gauges with the surface plate base, is the hypotenuse of this triangle. The sine ratio may be written as H divided by the angle L theta, assuming that the slip gauge height is represented by H and the sine bar length by L.
Thus, to ensure accurate angular measurements, the angle θ may be found by computing the inverse sine (sin−1) of H divided by L. The purpose of a measurement is to measure the surface on which the dial gauge or spirit level is placed horizontally.
For instance, to measure the angle of a wedge, the wedge is placed on a horizontal table, and the sine bar is placed over its inclined surface. At this position, the top surface of the sine bar is inclined the same amount as the wedge, and the top surface is made horizontal using gauge blocks. The sine of the wedge’s angle of inclination is the ratio of the height of the gauge.
Advantages
The advantages of using a sine bar
• High Accuracy: Provides precise angle measurements for accurate machining.
• Repeatable: Ensures consistent angle measurements and machining operations.
• Versatility: Can measure and set various angles.
• Simple Operation: requires minimal operator skill.
• Cost-effective: Offers a cost-effective solution for accurate angle measurement and machining.
Limitation Of Sine Bar
Sine Bar Drawbacks
• Limited to specific angles based on length.
• Requires additional tools for precise measurements.
• Not suitable for measuring small or large angles.
• Susceptible to wear and damage affecting accuracy.
• Requires complex setup compared to simple protractors.
FAQs
What is a sine bar used for?
A sine bar is used either to measure an angle very accurately or face locate any work to a given angle. Sine bars are made from a high chromium corrosion resistant steel, and is hardened, precision ground, and stabilized. Two cylinders of equal diameter are placed at the ends of the bar.
What is Sinbar?
SINBAR is a selective residual herbicide for weed control in apples, peaches, lucerne seed crops and peppermint.
What are the different types of sine bars?
Sine bars come in various types, including the simple sine bar, compound sine bar, and the universal sine bar, each offering unique capabilities for angle measurement and precision machining tasks.
What is a sine block?
A sine block is a precision measurement tool built of finely ground or lapped steel, used to measure angles for parts or for measuring angled parts. A sine block is a sine bar that is wider than 1 inch, but not wide enough to be a sine plate. Sine blocks are built and function identically to sine bars.