Technical lettering

 Technical Lettering

Syllabus: 

1. Introduction to lettering and its necessity. Demonstrate the construction details of English alphabets and numerals in 7:4 ratio and free hand in parallel lines 2. Sheet no.3 practice of single stroke vertical English alphabets and numerals (0-9) – uppercase letters (Height14mm and 20mm lettering in 7:4 ratio) in single stroke Sheet no.4 practice of single stroke inclined English alphabets and numerals (0-9) – uppercase letters (Height14mm and 20mm lettering in 7:4 ratio)

INTRODUCTION


https://youtu.be/bsutdDrPrKw

Technical Lettering is a barren piece of engineering drawing. It gives data concerning measures, and guidelines, as notes and measurements. On a drawing, the entire of the composed data is consistently through lettering. It isn't manually written. Likewise, it very well might be added here, that Lettering is fitting and right words however not (Printing implies the creation of literature on a print machine)

·                     Lettering

The writing of alphabets and numerals such as A, B, C, D…………………….Z and 1, 2, 3……………9, 0 respectively is called Lettering.

Mainly, there are two types of lettering most commonly used in engineering drawing viz. Gothic Lettering and Roman Lettering.

Single Stroke Letters

Single stroke letters are simplest form of letters and are used to write titles, dimensions, notes and other information on a drawing. Lettering using single stroke letters has been recommended by Bureau of Indian Standards (BIS) and described in IS:9609-1990. The word “single stroke” indicates that the thickness of lines used in letters should be such as obtained in single stroke of pencil. It does not mean that letter written in single stroke without lifting the pencil. The single stroke letters may be of two types e.g., vertical and inclined letters.
The vertical letters are used for general purpose lettering in engineering drawing. Height to width ratio of such letters varies. But for all practical purposes the letters with height to width ratio may be taken as 7:5 or 6:5 for all capital letters except I, J, L, M and W. For M and W the suitable ratio is 10:8 and for I, this ratio is taken as 10:2. For numerals such ratio may be taken as 7:4 or 6:3. Single stroke vertical upper and lower case letters and numerals are shown in Fig. 1.17. The inclined/italics letters are written

at an angle of 75o from horizontal towards right. Fig illustrates typical inclined

letters and numerals. The size of letters and numerals is specified by their heights ‘h’. The

standard heights of letters and numerals for practical use are 1.8, 2.5, 3.5, 5.7, 10, 14 and

20 mm as recommended by BIS. The letters size 5 mm-10 mm may be used for main title

of drawing. For sub-titles, letter size of 3.5 mm or 5 mm may be used conveniently. The

letters and numerals having size 2.5, 3.5 or 5 mm are suitable for writing notes,

dimensions etc. The single stroke letters may be of A type or B type. In A type letter,

height of letter is divided into fourteen parts whereas in B type letter, the height is divided

into 10 parts. The recommended ratio, spacing between letters and thickness of lines

(stems) of letters are summarized in Table  and are explained in Fig

Gothic Letters  

When the stem of letters are given more thickness, such letters are called as gothic letters.These letters are used for writing the main title for ink drawing. Thickness of stem maybe taken as 1/5th to 1/10th of the height of letters.

General Rules for Lettering

(a) Select the size of letters suitable to given drawing.

(b) Draw horizontal guide lines keeping the distance between them equal to the

height of letters.

(c) Width of letters may be taken equal to the height of the letter. Complete the

lettering with the standard dimensions.

(d) Do not erase the guide lines.

·                     Height Of Lettering

The height "h" of the capital letter is taken as the base of dimensioning.
The main requirement of lettering on engineering drawing are legibility, uniformity, ease and rapidity in execution.
Both upright and inclined letter are suitable for general use. All letters should be capital, except where lower case letters are accepted internationally for abbreviations.
The recommended size of lettering is as under :-

ITEM	SIZE h, mm
Drawing number in Title Block and letters denoting Cutting Plane Section	10, 12
Title of Drawing	6, 8
Sub-titles and Headings	3, 4, 5, 6,
Notes, such as Legends, Schedules, Material list, Dimensioning	3, 4, 5
Alteration, Enteries and Tolerances	2, 3

·                     Guide Lines

The light thin lines drawn to obtain uniform and correct height of letters are called Guide Lines.
Guide line should be drawn very light and thin, so that, they need not be erased after the lettering is finished. To erase guide lines after finishing the lettering is not easily possible. Guide line for capital and lower case lettering

·                      How To Draw Graph For Lettering

The letters are drawn in a graph. Before drawing the alphabets or numerals of 7:4, 5:4 or any other ratio, a graph is needed.

·                     First of all take the height of  the lettering and draw two parallel horizontal lines.

·                     Draw an inclined line at A and mark, 7 or 5 or as required number of vertical squares or rhombii, parts of any suitable size. Join B1 with B.

·                     Draw parallel line to B1B from 1, 2, 3, 4, 5, 6 meeting the line AB at A1, A2, A3, A4, A5 and A6.

·                     From A1, A2, A3, A4, A5 and A6 draw horizontal line.

·                     From point B draw line at 45' to the horizontal.

   Draw the vertical line for making lines for making squares and inclined line at an angle of 75' for making graph for inclined letters.

Problems For Practice SHEET NO: 3

1.             Rewrite the following in vertical up right printing. Take height of letters = 10 mm. "GROW MORE FOOD"

2.            Rewrite in inclined lettering technique 10 mm height in capital  letters the following :- DIFFERENT MATERIALS SHOULD BE INDICATED BY NOTES ON DRAWING

3.             Write your name and the name of your institution in  single stroke vertical lettering, taking height of letters as 3 mm, 5 mm, 8 mm, 10 mm and 12 mm.

4.             Rewrite the following in free hand vertical upright and inclined lettering. I AM PROUD OF MY COUNTRY, take height of letters = 3 mm,4 mm,6 mm, 8 mm and 12 mm.

5.             Draw single stroke vertical capital letters of ratio 7 : 4 and 6 : 5, INDIAN STANDARD INSTITUTIONS.

6.             Print the single stroke vertical letters in height 28 mm in 7 : 4 ratio, BUY NATIONAL SAVING CERTIFICATES.

           7.Draw freehand sketch &write short notes on the following images in lowercase alphabets.                             

(a) Hexagonal nut

(b) Wing nut

(c) Spur gear

BEG Week 2 Session1 Dimensioning Exercises

BEG – WEEK 2 SESSION 1 Dimensioning

 BEG – WEEK 2 SESSION 1

STUDY MATERIALS

Syllabus

ü  1. Demonstrate the dimensioning and its necessity, methods, and principles,

ü  2. Sheet no.2  Dimensioning of overall sizes, circles, threaded holes, chamfered surfaces, angles, tapered surfaces, holes, equally spaced on P.C.D., countersunk holes, counterbored holes, cylindrical parts, narrow spaces and gaps, radii, curves, and arches.

https://anchor.fm/s.deivanai/episodes/Dimension-e1c1vcs

Dimensioning

Principles of Dimensioning

The following are the basic principles of dimensioning:

1. All dimensional information necessary to define a part clearly and completely shall be shown directly on a drawing.

2. Each feature shall be dimensioned once only on a drawing.

3. Dimensions shall be placed on the view or section that shows clearly, the corresponding features

4. As far as possible, on a drawing, dimensions should be expressed in one unit only, preferably in millimeters, without showing the unit symbol (mm). Unit on the drawing, however, may be shown in a note

5. No more dimensions than are necessary to define a part shall be shown on the drawing. No feature of a part shall be defined by more than one dimension in any one direction

 

https://youtu.be/HNlsbYi_Uvc

 

BEG - Week 1 Session 2 Lines and Material conventions

 Lines and Material conventions

1.  Demonstration of various lines and material conventions

2. Sheet no 1. Draw the conventions of lines and materials

When you are preparing drawings, you will use different types of lines to convey information. Line characteristics, such as widths, breaks in the line, and zigzags, all have definite meanings.

Construction Lines

Usually, the first lines that you will use on a drawing are construction lines. These are the same lines that you used to layout your drafting sheet. They will also be used to layout the rest of your drawing. Line weight for construction lines is not important since they will not appear on your finished drawing. They should be heavy enough to see, but light enough to erase easily. A 4H to 6H pencil with a sharp, conical point should be used. With the exception of light lettering guidelines, all construction lines must be erased or darkened before a drawing is reproduced

.

Centerlines

Centerlines are used to indicate the center of a circle, arc, or any symmetrical object. 

Centerlines are composed of long and short dashes, alternately and evenly spaced, with a long dash at each end. They should extend at least one-fourth in. outside the object. At intersecting points, center lines should be drawn as short dashes. A very short centerline may be drawn as a single dash if there is no possibility of confusing it with other lines. Centerlines may also be used to indicate the travel of a moving center, 

Visible Lines

The visible edge lines of the view are drawn as solid, thick lines. These include not only the outlines of the view but lines defining edges that are visible within the view. 

Hidden Lines

Hidden edge lines are drawn with short dashes and are used to show hidden features of an

object. A hidden line should begin with a dash in contact with the line from which it starts,

except when it is the continuation of an unbroken line. 

To prevent confusion in the interpretation of hidden edge lines, you must apply certain standard techniques in drawing these lines. A hidden edge line that is supposed to join a visible or another hidden line must actually contact the line, ; The incorrect procedure is shown in the lower views.

Extension Lines

Extension lines are used to extend dimensions beyond the outline of a view so that they can be read easily. These thin, unbroken lines are started about one-sixteenth of an inch from the outline of the object and extend about one-eighth of an inch beyond the outermost dimension line. They are drawn parallel to each other and perpendicular to the distance to be shown.  

In unusual cases, extension lines may be drawn at other angles if their meaning is clear. As far as practical, avoid drawing extension lines directly to the outline of an object. When it is necessary for extension lines to cross each other, they should be broken (exceptions to this rule have been adopted since the development of CAD software).

Dimension Lines

A dimension line, terminating at either end in a long, pointed arrowhead, is inserted between each pair of extension lines. Occasionally, when the radius of an arc is to be indicated, there is an arrow at only the end of the line that touches the arc. The other end, without an arrow, terminates at the point used as the center in drawing the arc.

The arrowhead on a dimension or leader line is an important detail of a drawing. If these arrowheads are sloppily drawn and vary in size, the drawing will not look finished and professional.

The size of the arrowhead used on a drawing may vary with the size of the drawing, but all arrowheads on a single drawing should be the same size, except occasionally when space is very restricted. The arrowheads used on Navy drawings are usually solid, or filled in, and are between one eighth and one-fourth of an inch long, with the length about three times the spread. 

With a little practice, you can learn to make good arrowheads freehand,  first define the length of the arrowhead with a short-stroke as shown at A. Then draw the sides of the arrowhead as indicated at B and C. Finally, fill in the area enclosed by the lines, as shown at D.

Leaders

Leaders are used to connecting numbers, references, or notes to the appropriate surfaces or lines on the drawing. From any suitable portion of the reference, note, or number, a short line is drawn parallel to the lettering. From this line, the remainder of the leader is drawn at an angle (dog-leg) to an arrowhead or dot. In this way, the leader will not be confused with other lines of the drawing. If the reference is to a line, the leader is always terminated at this line with an arrowhead,  However, a reference to a surface terminates with a dot within the outline of that surface.

Break Lines

The size of the graphic representation of an object is often reduced (usually for the purpose

of economizing on paper space) by the use of a device called a break. Suppose, for example, you want to make a drawing of a rectangle 1 ft wide by 100 ft long to the scale of 1/12, or 1 in. = 1 ft. If you drew in the full length of the rectangle, you would need a sheet of paper 100 in. length. By using a break, you can reduce the length of the figure to a feasible length, 

 

On the original object, the ratio of width to length is 1:100. You can see that on the drawing the ratio is much larger (roughly about 1:8). However, the break tells you that a considerable amount of the central part of the figure is presumed to be removed. The thick, wavy lines shown in view (A), are used for a short break. A short break is indicated by solid, freehand lines, and is generally used for rectangular sections. For wooden rectangular sections, the breaks are made sharper (serrated appearance) rather than wavy. For long breaks, full, ruled lines with freehand zigzags are used, as shown in view (B),  For wider objects, a long break might have more than one pair of zigzag lines. For drawings made to a large scale, special conventions are used that apply to drawing breaks in such things as metal rods, tubes, or bars. 

Phantom Lines

Phantom lines are used most frequently to indicate an alternate position of a moving part,

The part in one position is drawn in full lines, while in the alternate position it is drawn in phantom lines. Phantom lines are also used to indicate a break when the nature of the object makes the use of the conventional type of break unfeasible. 

Section Lines

Sometimes the technical information conveyed by a drawing can best be shown by a view that represents the object as it would look if part of it were cut away. A view of this kind is called a section. 

The lower view is a section, showing the pipe sleeve as it would look, viewed from one side if it were cut exactly in half vertically. The surface of the imaginary cut is crosshatched with lines called section lines. According to DoD-STD-100C, “section lining shall be composed of uniformly spaced lines at an angle of 45 degrees to the baseline of the section. On adjacent parts, the lines shall be drawn in opposite directions. On a third part, adjacent to two other parts, the section lining shall be drawn at an angle of 30 to 60 degrees.”

The cross-hatching  used on any drawing of parts made of only one material (like machine parts, for example, which are generally made of metal). Cross-hatching is the symbol for metals and may be used for a section drawing of any type of material.

A section which goes all the way through and divides the object into halves, is called a full section. If the section showed the sleeve as it would look if cut vertically into unequal parts, or cut only partway through, it would be a partial section. If the cut followed one vertical line part of the way down and then was offset to a different line, it would be an offset section.

Viewing or Cutting Plane Lines

VIEWING PLANE LINES are used to indicate the plane or planes from which a surface or several surfaces are viewed.

CUTTING PLANE LINES are used to indicate a plane or planes in which a sectional view is taken.

Section views are used to give a clearer view of the interior or hidden feature of an object that normally cannot be clearly observed in conventional outside views. A section view is obtained by cutting away part of an object to show the shape and construction at the cutting plane. Notice the CUTTING PLANE LINE AA in figure 3-38, view A. It shows where the imaginary cut has been made. The arrows point in the direction in which you are to look at the sectional view.

Note that hidden lines behind the plane of projection are omitted in the sectional view. These lines are omitted by general custom, the custom is based on the fact that the elimination of hidden lines is the basic reason for making a sectional view. However, lines that would be visible behind the plane projection must be included in the section view.

Cutting plane lines, together with arrows and letters, make up the cutting plane indications. The arrows at the end of the cutting plane lines are used to indicate the direction in which the sections are viewed. The cutting plane may be a single continuous plane, or it may be offset if the detail can be shown to a better advantage. 

All cutting plane indications should be identified by the use of reference letters placed at the point of the arrowheads. Where a change in direction of the cutting plane is not clear, reference letters may also be placed at each change of direction. Where more than one sectional view appears on a drawing, the cutting plane indications should be lettered alphabetically.

The letters that are part of the cutting plane indication should always appear as part of the title; for example, SECTION A-A, SECTION B-B, If the single alphabet is exhausted, multiples of letters may be used. The word SECTION may be abbreviated if desired. Place the title directly under the section drawing.