Technical Drawing in Photonics

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Lesson 2

Primitive notions of geometric space. Base techniques of drawing.

TAMOP-4.1.1.C-12/1/KONV-2012-0005 project

„Preparation of the concerned sectors for educational and R&D activities related to the Hungarian ELI project”

Dr. Zsolt István Benkő

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Technical drawing in Photonics Lesson 2

The primitive notions of geometric space are:

• points,

• lines,

• planes.

All are undefined terms.

The point is the most fundamental object: it has zero dimension (no size), it is represented by a dot and named by a capital letter.

P point P

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Technical drawing in Photonics

The line consists of infinitely many points. It is a one dimensional object. It has infinite length but has no width and height. It extends to infinitely far in two opposite directions. It is named usually by a small letter. A line segment may be named by the letters of the two endpoints.

A

B

line e line segment AB

e

Every two distinct points denote a line and a line segment as well.

If a third point fits to the line denoted by two points, then the points are called collinear.

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A plane is an infinite set of points forming a connected flat surface.

It extends infinitely far in all directions. It is a two dimensional object: it has infinite length and infinite width but no height. It is represented usually by a four sided figure and named by a capital letter.

plane S

A plane can be denoted by two intersecting lines or by a line and a non-fitting point or by three not collinear points.

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Some tools are needed for drawing :

• two square rulers (preferably a 45^o and a 30^o)

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• a pair of compasses

• a mechanical pencil (0.5 mm) – for the thin line

• a pencil (B or 2B; blunt) – for the thick line

(ideally a pair of corresponding mechanical pencils should be used, e.g. 0.35 mm and 0.7 mm)

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Drawing parallel lines

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Drawing perpendicular lines

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Of course there are other methods to draw parallel and perpendicular lines.

The methods shown previously are accepted in technical drawing and they are fast.

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Bisecting a line segment

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Bisecting a line segment

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Bisecting an angle



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Bisecting an angle

/2

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Dividing a line segment to N equal parts

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Dividing a line segment in given ratio

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3

2

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3

2 3

2

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Drawing a 60 angle.

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Drawing a 60^o angle.

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Drawing a 60 angle.

60^o

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References

1. Ocskó Gy., Seres F.: Gépipari szakrajz, Skandi-Wald Könyvkiadó, Budapest, 2004

2. Lőrincz P., Petrich G.: Ábrázoló geometria, Nemzeti Tankönyvkiadó Rt., Budapest, 1998

3. Pintér M.: AutoCAD tankönyv és példatár, ComputerBooks, Budapest, 2006