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close this book Village-Level Brickmaking
View the document Preface
View the document Minimum Conditions Necessary To Produce Fired Clay Bricks
close this folder Standardization
View the document Introduction
View the document Form
View the document Size
View the document Quality
View the document Strength
View the document Using Bricks In Construction
View the document Moulds
View the document Extraction
close this folder Clay Preparation
View the document Tempering
View the document Mixing
close this folder Moulding
View the document Slop Moulding
View the document Sand Moulding
View the document Principle Elements Of Sand Moulding
View the document How To Mould Bricks
View the document Transporting bricks to drying area
View the document Drying
View the document Problems
close this folder Building A Field Kiln Which Uses Firewood As Fuel
View the document How To Layout The Kiln
View the document Construction Of The Kiln
close this folder Firing A Field Kiln With Firewood
View the document Firewood
View the document Organization Of The Kiln Site
View the document The Workers
View the document The Firing Process
View the document Temperature
View the document Control Of Air Flow
View the document Summary Of Firing Stages
View the document Problems With Fired Bricks
View the document Firing A Field Kiln: An Example
View the document Time Estimate For Building And Firing A Field Kiln
View the document Firing Principles - (Points To Remember)
close this folder Building And Firing A Coal-Fired Brick Kiln
View the document How To Lay Out The Kiln
View the document Construction Of The Kiln
View the document Firing The Kiln
close this folder Appendices
View the document Appendix 1 - Clay Testing
View the document Appendix 2 - Making A Hinge Mould And Moulding Table
View the document Appendix 3 - The 3: 4: 5 Method
View the document Appendix 4 - Pyrometric Cones
View the document Appendix 5 - Woodlots
View the document Appendix 6 - References
View the document Acknowledgements

Appendix 3 - The 3: 4: 5 Method

The 3:4:5 method is a simple way to ensure that corners are right angles or 90 and can be used when laying out a building or field kiln.

The 3:4:5 rule states that when a triangle has one side (AB) 3 units long, another side (BC) 4 units long, and the hypotenuse (AC) is 5 units long, the angle ABC will be 90 or a right angle.


Figure

This method requires that you use some unit of measurement. This unit could be the length of your foot, the distance between two knots tied in a string, or a length of one metre as measured on a tape measure. The length of the unit can be anything you choose but you will find that a unit measurement of one metre is ideal for marking the corners of a field kiln.

For example, if a triangle has one side 3 metres long, another 4 metres long and a hypotenuse 5 metres long, the angle ABC will be 90 or a right angle. This rule also holds true if the measurements are multiples of 3:4:5, such as 6 metres: 8 metres: 10 metres or 9:12:15.

Example: Laying out a corner of the field kiln

1. Select your unit of measurement which should be one metre or more in length. The most accurate method is to use a 5 metre tape measure. Note: If you do not have a tape measure, make one with a long piece of cord or string. First tie a knot close to one end of the cord and holding the knot in one hand, stretch your other arm out as far as possible as shown in the diagram. Tie a second knot at that point on the cord. For most people this distance is about one metre. Hold the second knot and measure that same distance again and tie a third knot. Continue until you have six knots with equal spaces between them. The distance between the first and last knot will be 5 units or approximately 5 metres.

2. Mark the first side of the kiln. Drive a large nail or spike into the ground where the comer of the kiln will be. Tie a string to the spike and stretch the string in the same direction as the length of the kiln (the side with the tunnel openings). Fix the string in this position. Using a tape measure (or the cord that was made to measure units), measure four metres from the comer along the string and drive another spike into the ground at that point.


Figure

3. Mark the second side of the kiln. Tie another string to the first spike (where the corner will be) and stretch it out in the direction of the kiln width (the side without tunnel openings). Using a tape measure or measuring cord, measure 3 metres from the corner along the string and tie a knot in the string at that point.


Figure

4. Mark the hypotenuse. Attach another string to the spike that marks the 4 metre point on the first side. Measure 5 metres on this third string and tie a knot. This string will form the hypotenuse of the triangle.

Stretch the knot on the 5 metre string towards the knot on the 3 metre string. Move both strings until the 5 metre knot and the 3 mete e knot are exactly on top of each other. Both strings should be taut.


Figure

5. Fix the 3 metre string in this position and the 5 metre string can be removed.

If you have followed all the steps and measured accurately, the angle or corner formed by the 4 metre string and the 3 metre string should be 90 or a right angle.