ROSS Combination Square - 300mm
Product Description
- A combination square is a multi-use measuring instrument which is primarily used for ensuring the integrity of a 90° angle, measuring a 45° angle.
- Measuring the centre of a circular object, find depth, and simple distance measurements.
- It can also be used to determine level and plumb using its spirit level vial.
- Steel scriber and a steel blade.
- Etched mm graduations.
Terminology
- Before using a combination square, one must first be familiar with the structure and terminology of the square itself.
- A combination square consists of a rue-type blade attached to a handle.
- The handle is composed of two parts, a shoulder and an anvil.
- The shoulder is placed at an angle of 45° between itself and the blade.
- It is therefore used for the measurement and layout of miters.
- The anvil is placed at a 90° angle between itself and the blade.
- The handle contains an adjustable knob which allows it to move freely horizontally along the edge of the ruler so that it may be tailored towards any size job.
- Additionally, contained within the head of the handle is a scriber used for marking measurements and a vial which may be used for measuring plumb and level.
Testing for Accuracy
- Regardless of the job being undertaken, the first step when using a combination square is to check the square to ensure its accuracy.
- This task can be easily accomplished by first taping a white piece of paper to a board with a perfectly straight edge.
- Place the anvil of the square against this edge and draw a line on the outside edge of the blade.
- Once this is complete, turn over the square and draw a second line at least 1/32 in, away from the first line drawn.
- If the two lines drawn are parallel with each other, then it can be said that the combination square is accurate.
- To test the accuracy of the shoulder, one may simply gauge the angle it makes with the blade against a 45° drafting triangle.
- If the angle between the shoulder and the blade is the same as that of the triangle, then the square is accurate.
How To Use a Combination Square
- Place the shoulder of the square against the edge of the working surface you wish to cut.
- Draw a line along the blade edge until your pencil reaches the shoulder of the combination square.
- Once completed, the line should be a perfect 45° angle with the edge of the working surface.