Technical drawings provide clear and accurate information how an object is to be manufactured. It shows and describes clearly and accurately the information required to build or manufacture a product.

The technical drawing is a form of design communication based on line symbols recognized and understood worldwide. Hence, technical drawing is often referred to as a universal language understood (readable) by anyone regardless of the language they speak.

Contractors, estimators, tradesmen, and builders rely totally on technical drawings for the information they need to build, construct and manufacture a product. To work in the design and manufacturing industries, the study of technical drawing; ability to prepare, read and interpret technical drawing is essential.

Line symbols used in technical drawing are often referred to as ALPHABET OF LINES. The use of line symbols enables engineers/designers to express the features of designed products clearly and accurately.  Line features vary not only by width but also by how they are graphically represented in a drawing.

Line significance is conveyed by line weight or thickness of the line. Every line is drawn at different thicknesses and darkness to express contrast as well as importance. Lines that are less important are thin and light. The key to successful drafting is to have a good technical knowledge of these various line characteristics – to understand where and when to apply them in technical drawing.

ALPHABET OF LINE

1. OBJECT OR VISIBLE LINES – Thick dark line use to show outline of object, visible edges and surfaces.

2. CONSTRUCTION LINE – Very light and thin line use to construct layout work.

3. DIMENSION LINE – Thin and dark lines use to show the size (span) of an object with a numeric value. Usually terminates with arrowheads or tick markings.

4. HIDDEN LINE – Short dash lines use to show non visible surfaces. Usually shows as medium thickness.

5. CENTER LINE – Long and short dash lines. Usually indicates center of holes, circles and arcs. Line is thin and dark.

6. EXTENSION LINE – Thin and dark line use to show the starting and ending of dimension.

7. CUTTING PLANE LINE – Extra thick lines use to show cutaway views or plane of projection where a section view is taken. Arrow indicates the direction of view.

8. SHORT AND LONG BREAK LINES –Short and long medium line use to show cutaway view of a long section.

9. LEADER LINE – Medium line with arrowhead to show notes or label for size or special information about a feature.

10. PHANTOM LINE – Long line followed by two short dashes use to show alternate position of a moving part.

11. SECTION LINE – Medium lines drawn at 45 degrees use to show interior view of solid areas of cutting plane line.

SOME ADDITIONAL INFO GRAPHS

alphabet-of-line-12
alphabet-of-lines-diagram

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Ricky
Ricky
2 years ago

Thank you School work helper.. It helps a lot!

Beasty
Beasty
4 years ago

I still need another one!!!!!

miko
miko
5 years ago

yeah im 100 for my assigment

Lauren Einstle D. Ternora
Lauren Einstle D. Ternora
1 year ago

this is really good and helped me

Ram
Ram
4 years ago

It let me choose the answer for the latter, I have no idea?

Yacchan Y.
Yacchan Y.
2 years ago

this really helped me

Usian W
Usian W
3 years ago

centre?

Matt L.
Matt L.
3 years ago

Cool thanks for the information!

Cristal mae ang
Cristal mae ang
Reply to  Matt L.
2 years ago

Yeah its cool

Li Sho
Li Sho
3 years ago

Incredible!!!!!!!

Lisa
Lisa
Reply to  Li Sho
1 year ago

Yes

Kelvin Ernest
Kelvin Ernest
4 years ago

I appreciate this it’s real needed

Julia
Julia
4 years ago

So thankful for this info

Saoud
Saoud
4 years ago

Sir what is meant of symbolic representation in engineering drawing

Kobe
Kobe
2 years ago

is there an example for a Lamp line and a battery?

Michel
Michel
5 years ago

Thank you, and perfect site

Lisa
Lisa
1 year ago

It helps a lot

Ayo
Ayo
5 years ago

need help please how thick is hatching line

Nani N.
Nani N.
5 years ago

great help!

J. Alphonso Perkins
J. Alphonso Perkins
6 years ago

It help me a lot. Thanks

eliz
eliz
6 months ago

incredible

Ash
Ash
10 months ago

It helps me with my report. Thank you.