Scales algebra (simple explanation) The representation of objects to their natural size is not possible when they are very large or very small.
In the first case, it would require unwieldy size formats and in the second because it would lack clarity in their definition.
This solves the problem of SCALE, applying the enlargement or reduction necessary in each case the objects are clearly represented in the picture plane. SCALE
is defined as the ratio between the size drawn on its real dimension, ie E =
drawing / reality
If the numerator of this fraction is greater than the denominator, it is a level of enlargement and reduction will be otherwise. 1:1 scale corresponds to an object drawn to actual size (full scale). GRAPHIC SCALE
Based on Thales' Theorem uses a simple graphical method to scale.
See, for example, the case for E 3:5
1 º) Arising in an arbitrary point O plotted two lines forming rys any angle.
2 º) r on the line lies the denominator of the scale (5 in this case) and on the line s number (3 in this case). The ends of these segments are A and B.
3 º) situated on any real scale r will be converted into the drawing by a simple parallel to AB .. STANDARD SCALES
Although, in theory, be possible to apply any scaling value, in practice it is recommended the use of certain standard values \u200b\u200bin order to facilitate the reading of dimensions through the use of rules or scalimeter.
These values \u200b\u200bare: Magnification: 2:1, 5:1, 10:1, 20:1, 50:1 ...
Reduction: 1:2, 1:5, 1:10, 1:20, 1:50 ... However, in special cases (particularly in construction) will use certain intermediate stops such as: 1:25, 1:30, 1:40, etc ...
PRACTICAL EXAMPLES EXAMPLE 1
You want an A3 represent the floor of a building 60 x 30 meters.
The scale more suitable for this case is 1:200 to provide a dimension of 30 x 15 cm, very appropriate for the size of the format.
EXAMPLE 2:
We want to represent in a piece of A4 Clock 2 x 1 mm dimensions.
scale 10:1 would be appropriate
EXAMPLE 3:
on a chart to 1:50000 E measured a distance of 7.5 cm between two islands, what actual distance between them?
be solved with a simple rule of thumb: if 1 cm
are 50000 cm drawing actual drawing will be 7.5 cm X cm X real
= 7.5 x 50000 / 1 ... and this results in 375,000 cm, equivalent to 3.75 km. USE
Scalimetre
The most common form of scale ruler is a ruler of 30 cm in length, with section 6 Starry facets or faces. Each of these facets is Graduated with different scales, which usually are: 1:100, 1:200, 1:250, 1:300, 1:400, 1:500 These scales are also valid for values \u200b\u200bthat result from multiply or divide by 10, and by example, the scale is 1:300 scale drawings for use in 1:30 or 1:3000, etc.
Examples of use:
1 º) For a plane E 1:250, was applied directly to the scale of 1:250 scale ruler and the figures indicating that it is read are real meters represents the drawing.
2 °) In the case of a plane E 1:5000, 1:500 scale will apply and must be multiplied by reading the scale ruler 10. For example, if a dimension of the plane has 27 points in the scale ruler, we are actually measuring 270 m.
Of course, the scale of 1:100 is also the scale of 1:1, which is normally used as a ruler in cm.
