learning guide5 bar bending tech drawing2
DESCRIPTION
TECHNICAL DRAWINGTRANSCRIPT
Federal Democratic Republic of EthiopiaMinistry of Education
Amhara National Regional StateTVET Bureau
Ethiopian TVET-System
Bar Bending and ConcretingLevel III
Learning Guide #5
Unit of Competence: Prepare Technical Drawing
Module Title: Prepare Technical DrawingLG Code: CON BBC3 01 0211
MO1 LO2TTLM Code: CON BBC3 01 0211
TTLM 1011v1 Developed by: JEFFREY P. YAP Date: Current Date Page 1 of 53
Federal Democratic Republic of EthiopiaMinistry of Education
Amhara National Regional StateTVET Bureau
LO2: Create Simple Sketches, Orthographic Drawings and Sectional Views
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Amhara National Regional StateTraining, Teaching and Learning Materials
Introduction Learning Guide 5
Instruction Sheet Learning Guide #4This learning guide is developed to provide you the necessary information regarding the following content coverage and topics –
Symbolic Lines
Line Weights
Line Types
Line Quality
Dimension Lines
This guide will also assist you to attain the learning outcome stated in the cover page. Specifically, upon completion of this Learning Guide, you will be able to –
identify the different types of symbolic lines use in technical drafting
construct the alphabet of lines
make the drawing more expressive and easier to read
present the lines in different thickness and shape
draw quality lines
identify the basic parts of dimension lines
know how to apply proper dimensioning in the drawing
Learning Activities
1. Read the specific objectives of this Learning Guide.
2. Read the information written in the “Information Sheet 1”.
3. Accomplish the “Self-check 1” in page 5.
4. If you earned a satisfactory evaluation proceed to “Information Sheet 2”. However, if your rating is unsatisfactory, see your teacher for further instructions or go back to Learning Activity #2.
5. Submit your accomplished Self-check. This will form part of your training portfolio.
6. Read the information written in the “Information Sheets 2-4”.
7. Accomplish the “Self-check 2” in pages 13-14.
8. If you earned a satisfactory evaluation proceed to “Information Sheet 3”. However, if your rating is unsatisfactory, see your teacher for further instructions or go back to Learning Activity #3.
9. Accomplish the “Self check 3” in page 19.
10. Read the information written in the “Information Sheet 4”.
11. Accomplish the “Self-check 4” in page 33-34.
12. If you earned a satisfactory evaluation proceed to “Operation Sheet” in page 41. However, if your rating is unsatisfactory, see your teacher for further instructions or go back to Learning Activity #4.
13. Read the “Operation Sheet”, try to understand the description or procedures discussed and practice the exercises illustrated. Go to your teacher if you need clarification or you want answers to your questions or you need assistance in understanding a particular step or procedure.
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Amhara National Regional StateTraining, Teaching and Learning Materials14. Request you teacher to observe your demonstration of the exercises and give you feedback.
15. Do the “LAP test” in page 41 (if you are ready) and show your output/performance to your teacher. Your teacher will evaluate your output/performance either satisfactory or unsatisfactory. If unsatisfactory, your teacher shall advice you on additional work. But if satisfactory you can proceed to Learning Guide #6 or await instructions from your teacher.
Information Sheet-1 Symbolic Lines
The "Alphabet of Lines" refers to the different styles of symbolic lines used in drafting such as to show different features about an object that is drawn: hidden. construction, cutting-plane, visible (object), dimension, extension, phantom, center, section, and border.
Lines in technical drawings are part of a specialized graphic language that is standardized throughout industry. Each type of line has a very precise symbolic meaning. Correct usage of this “alphabet of lines” is essential whether you use traditional drafting methods or CAD. In Drafting, or Computer Aided Drafting (CAD) -- the alphabet of lines are the different lines that draftsmen, architects, engineers, et al use when constructing a drawing.
For example, a thick solid line is called an object line and represents the outline of a part on a drawing. A dash line represents an edge that is not visible in a particular view, hence it is called a hidden line.
Other common lines used in drafting include dimension lines, extension lines, construction lines, border lines, center lines among many others depending on the type of drawing.
Symbolic Lines are meant for symbolic purposes only. For example, you might sketch symbolic lines in an elevation view to represent a door swing. Symbolic lines are not part of the actual geometry of the family. Symbolic lines are visible parallel to the view in which you sketch them. Symbolic lines are mostly used in 2D drawing preparations.
Comparing Model Lines & Symbolic Lines
Model lines are always visible in three-dimensional views, they show throughout the whole model while symbolic lines show only on the plane in which you placed them. Take for an example a kitchen cabinet which in a 3d view or elevation is a 3d model with hardware and materials applied to but in plan view all you want to see is lines representing the cabinet extents only then this is where you would want to use symbolic lines.
The main thing to remember about model lines vs. symbolic lines is that symbolic lines are 'view specific' while model lines show up in all views by default.
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Amhara National Regional StateTraining, Teaching and Learning MaterialsModel lines. By default, model lines are also visible in floor plan and RCP views. To control their visibility in plan and elevation views
With the Symbolic Lines command, you can sketch lines that are meant for symbolic purposes only. For example, you might sketch symbolic lines in an elevation view to represent a door swing. Symbolic lines are not part of the actual geometry of the family. Symbolic lines are visible parallel to the view in which you sketch them.
An example of symbolic lines, phantom line to show the object is swing type, center lines to represent and show the centers, and hidden lines to show the hidden portion of the object. Symbolic lines are used in the drawing to meant for symbolic purposes
An example of model lines, to show the object in 3D. Note that in model lines symbolic lines are no longer visible. The 3D detail shows the specifications in text form using a leader.
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Self-Check 1 Symbolic Lines
Name: _________________________ Date: _______________
Test I: Short Answer Questions
Directions: Answer all the questions listed below. Examples may be necessary to aid some explanations/answers.
1. What do you mean by symbolic lines? (2points)
2. When is symbolic lines mostly used? Sight an example. (2 points)
3. What do you mean by model lines? (2 points)
4. Compare symbolic lines from model lines. (2 points)
5. Give a comparative example about the usage of model lines and symbolic lines. (4 points)
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Answer Key:
1. Is called Alphabet of Lines
2. It is used in drafting, examples; the border lines, center lines etc.
3. A model lines are lines that is not visible in drawings
4. The comparison between model lines and symbolic lines; symbolic lines are lines used in drawings like border lines, center lines and etc. but model lines are lines that is not visible it is used as reference in symbolic lines.
5. Example of model lines is in sketching projections in two-dimensional drawings.
Information Sheet-2 Line Type and Line Weight
Line Weight
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Amhara National Regional StateTraining, Teaching and Learning MaterialsLine weight and line quality are extremely important to a successful set of design drawings. Usually a set of design drawings will go to many different people including the client, other designers or architects, manufacturers, builders, and others within the profession. The lines used for design drawings must be crisp and dark so that they are easy to reproduce and clear copies can be made from them.
The line weight is the light or darkness and width of a line. Manual pencil drafting, drafting in ink and computer-aided drafting documents must have a variety of line weights. Varied drawing line weights, typically three, should be used on every drawing. These include light, medium, and bold lines. Guidelines are used for page layout and borderlines are used for framing the page. These different weights technically help to create an easy to understand document and artistically add visual interest to the document. These documents must also have consistent quality, which is uniformity of lines throughout a drawing. These two elements give a sense of professionalism to the documents, provide visual interest, create a clear and easy to read document, and demonstrate the drafting skills and abilities of the designer.
Keep in mind that the hardness/softness and the diameter of the pencil lead only help control the line weight. You should need to use a consistent amount of pressure on the pencil as you draft to keep each weight of line uniform. If the line seems either too light or too dark try varying the amount of pressure you place on the pencil as you draft. Remember, these drawings are meant to be copied and distributed to a variety of design professionals so the lines need to be crisp and readable.
Line Types
There are standards for different types of lines along with line weight and quality called line type. Each has a definite meaning and is recognized as a typical symbol or object within the building trades industry. Listed below are the standard types of lines that will typically be used in design drawings.
Solid Lines or object lines – are used to indicate visible objects that can be seen in plan, elevation or 3D
Cutting Plane Lines – are heavy dash line followed by two shorter dashes. Each end has a short line at right angle to cutting plane line, with arrowheads pointing in direction from which cut surface is viewed. It is usually labelled with a letter at either end to identify cut surface drawing called a “section”.
Dashed Lines – are used for hidden objects or edges . These are used to show hidden parts of an object or objects below or behind another object. Dashed are also used to indicate shelving or cabinets above a counter. These lines should be in contact at corners and when perpendicular to another line.
Movement, Ghost or Phantom Line – are thin lines and used to indicate alternate positions of parts or an object. It also shows repeated details or location of absent parts. It is drawn as one (1) long and two (2) evenly-spaced short dashes with the long dash at each end. These lines are a series of dashes and very short dashes and are used to show movement or imply direction. These typically are used instead of a dashed line to show an alternate position of an object that can be moved. One object would be drawn with a solid line and its alternate position would be dashed or phantom line. This can include bi-swing doors, the space needed for drawer and cabinet door openings, sliding door opening direction, hinge points for doors and windows in elevation.
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Leader Line – are used to connect notes or references to objects or lines in a drawing. Leader lines start as a solid line and end in an arrow. Leader lines may be drawn at an angle or curved.
Break lines – are used when extents of a drawing cannot fit on the size of paper being used for the drawing. It can also be used when you only need to illustrate a portion of a design or partial view.
Center Lines – are used to indicate the center of a plan, object, circle, arc, or any symmetrical object. Use a series of very long and short dashes to create a center line. If two center lines intersect use short dashes at the intersection.
Section Line – is used to show a cutaway view of a floor plan. A section cutting all the way through a floor plan is referred to as a full section. The direction of the arrows shows the direction of the section view. The symbols on the end of the section line indicate the drawing number on top and the page number the section will be located on the bottom.
Dimension Line – is used to show measurement of an object. It can be used to indicate length, width, diameter, etc. The dimension are listed in feet and inches (imperial) or meter and mm (SI) on floor plans and elevations. Detailed drawings of cabinetry or other custom pieces are dimensioned either in Imperial or SI.
The Following Figures shows the standard line conventions and samples on drawing applications :
Standard line types and line weights A
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Standard line types and line weights B
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Example on how to apply line convention to a drawing
Using phantom lines, center lines, hidden line and dimension leader in a drawing
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Using break lines in a drawing
Using phantom lines in a repeated detail indicating the alternate position of parts of the item delineated.
Using section lines in a drawing
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Amhara National Regional StateTraining, Teaching and Learning MaterialsPhantom lines shall be used to indicate the alternate position of parts of the item delineated, repeated detail, or the relative position of an absent part and shall be composed of alternating one long and two short dashes, evenly spaced, with a long dash at each end.
Application of Line types and Line weights to engineering drawing:
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Standard line types and line weights C
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Shown in the figure is the application of the alphabet of lines
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Self-Check 2 Line Type & Line Weight
Name: _________________________ Date: _________
A. Matching Type : Below are two columns A & B. Match column A with column B. Write only the corresponding letter of your choice in the space provided before the number in column A. (2points each x 9 = 18 points)
A
_____ 1. Object line
_____ 2. Hidden line
_____ 3. Center line
_____ 4. Phantom line
_____ 5. Break line
_____ 6. Extension line
_____ 7. Cutting plane line
_____ 8. Section line
_____ 9. Dimension line
B
A. Used when it is necessary to show all of a part.B. The lines which shows the visible parts in a viewC. It is used in combination with a cutting plane line to depict
the inner structure of an object.D. Used to show the location of a cut for a sectional view or
the direction from which a view is taken.E. Shows the course through which center travels.F. A thin line that extends from the part or feature being
dimensioned.G. It is used to indicate edges, intersections, etc., that are
behind other features of the part.H. It is use in conjunction with the extension lines to indicate a
linear distance.I. It shows alternate positions of parts and also the location of
parts that are not integral parts of the item depicted.J. It is the gap from the object to the start of the dimension.
B. Drawing : Draw the following Alphabet of lines for the following nine (9) items below. (2points each x 9 = 18 points)
_____ 1. Object line
_____ 2. Cutting plane line
_____ 3. Short break line
_____ 4. Extension and
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dimension line
_____ 5. Hidden lines
_____ 6. Section line
_____ 7. Center line
_____ 8. Long break line
_____ 9. Phantom line
C. Identification : Identify the ten (10) lines found in the drawing below by writing the correct name of each line on the space provided. (2points each x 10 = 20 points)
1. _________________________
2. _________________________
3. _________________________
4. _________________________
5. _________________________
6. _________________________
7. _________________________
8. _________________________
9.
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10. _________________________
Information Sheet-3 Line Quality
Line Quality
Pencil lines should be solid, uniform in width, and consistent in darkness throughout their length. If a line in a drawing needs to be changed, make sure to erase it clearly and recreate the line in appropriate line and quality. If only a part of the line needs to be modified, erase using the erasing shield and make sure the new segment and the existing segment match perfectly in width and
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Amhara National Regional StateTraining, Teaching and Learning Materialsdarkness. Being consistent also applies to pen and ink drawings and CAD drawings. A pen and ink drawing is usually made first with a very light guidelines. When using ink technical or drafting pens, typically the light, medium, and dark weights are created in proportion to one another. For instance, if light is a width of 0.05, then medium is 0.10 and dark is 0.20. The actual width of each line type should also be related to the size and scale of the drawing. A drawing in ¼” scale, like floor plan, ma need smaller pen widths than a drawing in 1 – ½” scale, like a kitchen cabinet drawer detail. The best way to create consistent line weights and line quality is to keep your pencil or pen perpendicular to the drawing surface and drawing media. This keeps the width of the line consistent. Also, keep a constant pressure as you draw a line type from its start to finish. This takes a practice and can be mastered if you focus on creating the line constantly and do not try to rush a drafted document.
A proper choice of lead pencils for particular drafting purpose should be selected. The grade of pencil to be used for various purposes depends on type of the line desired, the kind of paper employed, and the humidity, which affects the surface of the paper. Standards for line quality will govern the selection for instance :
6H is used for light construction line 4H is used for re-pencilling light finished lines (dimension lines, center lines, and visible
lines) 2H is used for visible object lines F and H are used for all lettering and freehand work
Guidelines or Construction lines ( 4H to 6H pencil lead in a 0.3mm mechanical pencil)
Construction lines are very light, gray lines used to lay out all work. They should be light enough on a drawing so they will not reproduce when making a print. The initial lines that you draw on your paper are guidelines or what some refer to as construction lines. These lines are temporary and used to lay out the page, create the initial shapes, and provide a guide for lettering heights. The line weight for guidelines is to be very light as they should be almost invisible on the finished drawing. They must be dark enough for you to see, light enough to erase lines easily, and barely visible when copies or other form of reproduction are made from the drawing. Using a harder 4H to 6H pencil lead in a 0.30mm mechanical pencil creates the best guidelines. You can also use a blue lead guidelines as it will not photocopy.
Bold Lines (soft B to 2B pencil lead in a 0.50mm or 0.7mm mechanical pencil)
The primary objects in a drawing should be created using a bold line. Bold lines are very dark and have a thick width. These are created with a 0.50mm or 0.70mm mechanical pencil and a soft B to 2B pencil lead. Walls in plan view and the outline around the perimeter of an elevation or three-dimensional object are examples where bold lines should be used.
Medium Lines (HB pencil lead in a 0.50mm mechanical pencil)
Secondary objects such as doors, furnishings, counters, and cabinets should be in a medium line weight. In elevation and 3D views, the perimeter of an object may be drawn in a bold line weight, however the information inside the object should be drawn in a medium weight. Medium line weights are best are best created using a 0.50mm width pencil with HB pencil lead.
Light Lines (H to 2H pencil lead in a 0.30mm or 0.50mm)
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Action lines, information lines, and fill patterns should be drawn with light lines. Action lines show potential movement of an object include door swings in plan view and hinge direction in elevation view. Information lines convey information about a drawing and include dimension lines, center lines, leader lines, section lines and so on. Fill patterns are specific symbols used to indicate a type of material being used. The light lines can be created with a 0.50mm pencil or with a 0.30mm pencil and H to 2H pencil leads. It is very important that all of these lines are visible, so do not confuse the term “light” with “hard to see”.
Border Lines (2B to 4B pencil lead in 0.7mm or 0.9mm pencil with a 2B to 4B lead works well for creating borderlines. These lines are the heaviest of all the lines in the drawing
Examples of Construction Lines for different purpose in engineering drawing
Using construction lines in perspective drawing
Construction lines used in projecting the 2D view of a 3D object
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Construction line/s used as temporary lines or layout of 3D object
Guidelines are also used in lettering or textual part of the drawing. Extremely light horizontal guidelines are necessary to regulate the height of letters. In addition, light vertical or inclined guidelines are needed to keep the letters uniformly vertical or inclined. Guidelines are essential for good lettering, and should be regarded as a welcome aid, not as an unnecessary requirement.
Examples of Guideline use in lettering:
A.) Guidelines for lettering
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B.) Guidelines for Vertical letters
C.) Guidelines for Inclined letters
Border lines are most commonly used in drawing templates. It enclosed the boundaries of the drawing area and the title block. It has the heaviest line weight.
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Note : Title block – contains borders, contents, sheet info, and sheet numbering
Self-Check 3 Line Quality
Name: _________________________ Date: _______
Test I: Short Answer Questions
Directions: Answer all the questions listed below. Examples may be necessary to aid some explanations/answers.
1. What do you mean by line quality? (2points)
2. What lead pencil type are you going to used for dimension lines, center lines, and visible lines?. (2 points)
3. What is the range of standard thickness of border lines? (2 points)
4. Why do we use guidelines and construction lines in engineering drafting? (2 points)
5. Give three examples of lead pencil that your know being used in engineering drawing ( one (1) each for soft, medium and hard). (3 points)
Test II:Multiple Choice : Read each item carefully and choose the correct answers from the available four choices. Write only the corresponding letter of your choice in the space or answer sheet provided. (2 points each x 5 = 10 points)
1. Action lines, information lines, and fill patterns should be drawn with
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a. dark lines b. medium dark lines c. soft lines d light lines
2. The thickest line of all the lines is
a. center line b. phantom line c. border line d dimension lines
3. Which of the lead pencils below does not to belong to the group?
a. 3H b. 2B c. HB d. F
4. Medium line weights are best are best created using a
a. 0.30mm width pencil with HB pencil lead c. 0.60mm width pencil with HB pencil lead
b. 0.50mm width pencil with HB pencil lead d. 0.70mm width pencil with HB pencil lead
5. A quality pencil line is something that is
a. solid b. consistent in darkness
b. uniform in width d. all of the above
Test III : Matching Type : Below are two columns A & B. Match column A with column B. Write only the corresponding letter of your choice in the space provided before the number in column A. (2points each x 5 = 10 points)
A
_____ 1. H to 2H pencil lead
_____ 2. B to 2B pencil lead
_____ 3. 4H to 6H pencil lead
_____ 4. HB pencil lead
_____ 5. 2B to 4B pencil lead
B
A. Border linesB. The lines which shows the visible parts in a viewC. Construction linesD. Bold linesE. Medium linesF. Light linesG. Dark lines
Information Sheet-4 Dimensioning
Dimensions
A drawing without dimensions is meaningless. Dimensions are necessary to show the exact size of an object. Dimensioning refers to the act of giving dimensions, i.e., length, width, height, diameter, etc., of the object. This information is provided by giving numeric values to various features of the object on the drawing. A feature is an individual characteristic such as a flat or cylindrical surface, a slot or a groove, a taper, a shoulder, a screw thread, etc.
Dimension is a numerical value expressed in appropriate units of measurement and indicated graphically on technical drawings with lines, symbols and notes. The important aspects of dimensioning are as follows :
Units of Measurement : on technical drawing we need to show lengths and angles. The most convenient unit for length is millimetre. In civil engineering and
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architectural drawing, inch or foot is often used as a unit of length. Angles are shown in degrees.
Symbols : Symbols are incorporated to indicate specific geometry whenever necessary.
Notes : Notes are provided to give specification of a particular feature or to give specific information necessary during the manufacturing of the object.
Elements of dimensioning
A line on the drawing whose length is to be shown is called and object line. The object line is essentially an outline representing the feature(s) of the object. While showing an angle, the two lines forming the angle will be the object lines.
Dimensioning is often done by a set of elements, which includes extension lines, dimension lines, leader lines, arrowheads and dimensions.
Extension line – is a short line drawn perpendicular to an object line. These line start immediately or a few millimetres from the ends of object lines and extend a few millimetres beyond a dimension line. Extension lines may be used to show an angle due to space constraint. In such case, extension lines are drawn parallel to and at the ends of object lines.
Dimension line – is drawn between two extension lines parallel to the object line. As a rule, there must be one and only one dimension line between any two extension lines. One dimension line represents one dimension. While dimensioning an angle, a curved dimension line is drawn by drawing a suitable are having its center at the vertex of the angle.
Leader line – is a line which connects a note or a dimension with the feature to which it applies. Leaders are drawn at suitable angles, preferably 30º, 45º or 60º, and is never drawn horizontal or vertical. One end of the leader carries an arrowhead which connects it to the outline of the object. A dot is used instead of an arrowhead, if the leader ends inside the object, figure 3.2(b). The other end of the leader is made horizontal. A note or dimension is placed above the horizontal portion of the leader. Leaders are frequently used to indicate the diameter or radius of a circular feature.
Arrowheads – an arrowhead is drawn at each end of a dimension line. The tip of an arrowhead touches the extension line. An arrowhead is also drawn at the end of a leader, which points out the feature of an object. The various styles of drawing an arrowhead are shown in the figure below. The arrowheads may be open, closed, or closed and filled. The angle formed the barbs of the arrowhead usually varies from 15º to 90º. Sometimes, an oblique stroke drawn at 45º to the extension line is used instead of an arrowhead
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The closed and filled arrowhead is most commonly adopted. It is the form of an isosceles triangle having a height three (3) times of its base. The space inside the triangle is uniformly filled in. The size of an arrowhead should be proportionate to the length of the dimension line. Too small or too large arrowheads should be avoided.
Dimension – is a numeric value of length or angle expressed in a specified unit of measurement. Dimensions are placed near the middle and above dimension lines or at the center of dimension lines by breaking them. Since all dimensions of a drawing are expressed in the same unit (i.e., mm cm or in), the unit is not written after the dimension figure. Instead, a note “ALL DIMENSIONS IN MM” is written at a prominent place (preferably on the left hand side of the title block) on the drawing sheet. The dimension text should be same for all the dimensions on a drawing and should have a suitable size.
Figure A
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Figure B
Elements of dimensioningFor placing the dimensions on a drawing, of the two systems is adopted.
Aligned system – dimensions are placed perpendicular to the dimension line so that they may be read from the bottom or right-hand side of the drawing sheet. All horizontal and inclined dimensions can be read from the bottom, whereas vertical dimensions can be read from the right-hand side of the drawing sheet. Dimensions are place at the middle and on top of the dimension lines.
Unidirectional system – dimensions are placed in such a way that they can be read from the bottom edge of the drawing sheet. All horizontal dimensions are placed at the middle and on the top of the dimension lines while vertical and inclined dimensions are inserted by breaking the dimension lines at the middle.
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It should be noted that dimensioning leader for both system is the same.
Rules for dimensioningThe following rules for dimensioning must be adopted to achieve the good dimensioning characteristics like clearness, completeness, readability and accuracy.
1. Between any two extension lines, there must be one and only one dimension line bearing one dimension.
2. As far as possible, all dimensions should be placed outside the views. Inside dimensions are preferred only if they are clearer and more easily readable.
3. All dimensions on a drawing must be shown using either aligned system or unidirectional system. In no case should, the two systems be mixed on the same drawing.
4. The same unit of length should be used for all the dimensions on a drawing. The unit should not be written after each dimension, but a note mentioning the unit should be placed below the drawing.
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5. Dimensions lines should not cross each other, Dimension lines should also not cross any other lines of the object. However, extension lines may cross each other or outlines of the object.
6. All dimensions must be given. As far as possible, there should not be need for calculation, assumption or direct measurement for any dimension.
7. Each dimension should be given only once. No dimension should be redundant, i.e., no dimension should be repeated directly or indirectly. If a particular dimension is mentioned, directly or indirectly, in one view, it should not be repeated in other views.
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8. Do not use an outline or a centreline as a dimension line. A centreline may be extended serve as an extension line
9. When it is necessary to place a dimension within a sectioned area, leave a blank space for the dimension.
10. Avoid dimensioning hidden lines.
11. Keep dimensions 6 – 8 mm away from the object line and also from each other.
12. If the space between two extension lines is too narrow to mark arrowheads and the dimension then one of the following ways, depending on space availability, should be adopted.
(i) Draw arrowheads touching the outsides of the extension lines and pointing toward each other. Place the dimension above the dimension line.
(ii) Draw arrowheads as in (i) above and place the dimension at one end of the dimension line outside of the extension line.
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(iii) Draw arrowheads as in (i) above and place the dimension at the end of the leader which terminates on the dimension line.
(iv) For two consecutive dimensions, replace two intermediate arrowheads by a dot and place the dimensions as in (i) or (iii) above, depending on the space availability.
13. For dimensions in series, adopt any one of the following ways :
(i) Chain dimensioning (continuous dimensioning) : All the dimensions are aligned in such a way that an arrowhead of one dimension touches tip-to-tip the arrowhead of the adjacent dimension. The overall dimension is placed outside the other smaller dimensions.
(ii) Parallel dimensioning (progressive dimensioning) : All the dimensions are shown form a common reference line. Obviously, all these dimensions share a common extension line. This method is adopted when dimensions have to be established from a particular datum surface.
(iii) Combined dimensioning : When both the methods, i.e., chain dimensioning and parallel dimensioning are used on the same drawing, the method of dimensioning is called combined dimensioning.
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14. Smaller dimensions should always be placed nearer the view. The next dimension should be placed next and so on The overall dimension should always be away from the view. This will avoid crossing of the extension lines and dimension lines.
15. All notes should be written horizontally.
Below are samples figures on how to place dimensions in objects :
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Self-Check 4 Dimensioning
Name: _________________________ Date: _______________
Test I: Short Answer Questions
Directions: Answer all the questions listed below. Examples may be necessary to aid some explanations/answers. (total points = 15 points)
1. What are the five (5) elements of dimensioning? (5points)
2. Give the four (4) characteristics of good dimensioning. (4 points)
3. Give at least two (2) rules of dimensioning that you know? (2 points)
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Amhara National Regional StateTraining, Teaching and Learning Materials4. What do you mean by “chain dimensioning”? (2 points)
5. What area the two (2) elements of dimensioning. (2 points)
Test II:Multiple Choice : Read each item carefully and choose the correct answers from the available four choices. Write only the corresponding letter of your choice in the space or answer sheet provided. (2 points each x 2 = 10 points)
Start here:
1. What is the labeled line in the drawing below called?
A. extension line C. hidden line
B. dimension line D. focus line
2. What does this symbol Ø indicate in the drawing?
A. diameter C. number
B. hole center D. radius
3. What is the labelled line in the drawing called?
C. hidden line C. extension line
D. focus line D. dimension line
4. If the diameter of a circle is 300mm, what is its radius?
E. 75mm C. 30mm
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F. 60mm D. 150mm
5. A line which connects a note or a dimension with the feature to which it applies?
G. arrowheads C. dimension line
H. extension line D. leader
Test III: Identification : Study and look at the drawing below carefully. The drawing is labelled by numbers 1 to 5. Identify correctly the labelled parts of the drawing and write your answer in the space or answer sheet provided. (2 points each x 5 = 10 points)
Answer Sheet I
Name: _________________________ Date: _______________
Test I. Short Answer Questions
1. The five elements of dimensioning are, extension lines, dimension lines, leader lines, arrowheads and dimensions.
2. The four characteristics of dimensioning are; clearness, completeness, readability and accuracy.
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Score = ___________
Rating: ____________
Amhara National Regional StateTraining, Teaching and Learning Materials
3. The two rules of dimensioning are; a.) Between any two extension lines, there must be one and only one dimension line bearing one dimension.
b.) As far as possible, all dimensions should be placed outside the views. Inside dimensions are preferred only if they are clearer and more easily readable.
4. Chain dimensioning are the dimensions are aligned in such a way that an arrowhead of one dimension touches tip-to-tip the arrowhead of the adjacent dimension. The overall dimension is placed outside the other smaller dimensions.
5. Aligned system – dimensions are placed perpendicular to the dimension line so that they may be read from the bottom or right-hand side of the drawing sheet. All horizontal and inclined dimensions can be read from the bottom, whereas vertical dimensions can be read from the right-hand side of the drawing sheet. Dimensions are place at the middle and on top of the dimension lines, and Unidirectional system – dimensions are placed in such a way that they can be read from the bottom edge of the drawing sheet. All horizontal dimensions are placed at the middle and on the top of the dimension lines while vertical and inclined dimensions are inserted by breaking the dimension lines at the middle.
Answer Sheet II
Name: _________________________ Date: _______________
A. Matching Type
1. B
2. A
3. D.
4. D.
5. G.
6.
7. _______
8. _______
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Score = ___________
Rating: ____________
Amhara National Regional StateTraining, Teaching and Learning MaterialsB. Drawing
1.
2.
3.
4.
5.
6.
7.
8.
9.
C. Identification
1. _______
2. _______
3. _______
4. _______
5. _______
6. _______
7. _______
8. _______
9. _______
10. _______
Answer Sheet III
Name: _________________________ Date: _______________
Test I. Short Answer Questions
1. __________________________________________________________________
__________________________________________________________________
__________________________________________________________________
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Score = ___________
Rating: ____________
Amhara National Regional StateTraining, Teaching and Learning Materials2. __________________________________________________________________
__________________________________________________________________
3. __________________________________________________________________
__________________________________________________________________
4. __________________________________________________________________
__________________________________________________________________
__________________________________________________________________
5. __________________________________________________________________
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
II. Multiple Choice
1. _______
2. _______
3. _______
4. _______
5. _______
III. Matching Type
1.
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2.
3.
4.
5.
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Answer Sheet IV
Name: _________________________ Date: _______________
Test I. Short Answer Questions
1. __________________________________________________________________
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
2. __________________________________________________________________
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
3. __________________________________________________________________
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
4. __________________________________________________________________
__________________________________________________________________
__________________________________________________________________
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Score = ___________
Rating: ____________
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5. __________________________________________________________________
__________________________________________________________________
__________________________________________________________________
Test II : Multiple Choice
1. _______
2. _______
3. _______
4. _______
5. _______
C. Identification
1. _______
2. _______
3. _______
4. _______
5. _______
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Operation Sheet Lines
Operation Title: Freehand sketching of Alphabet of Lines
Purpose : Using repetitive freehand sketching exercise of the alphabet of lines will condition the reflexes of the hand. This activity will condition the hand in doing freehand sketching works.
Conditions or Situations for The Operation : A template for this activity is given with a sample. The drawing area in the paper is divided into nine (9) equal boxes where the student will repetitively draw the sample alphabet of lines inside the box until it is filled using freehand sketching.
Equipment, Tools and Materials :
HB drawing pencil lead
4H drawing pencil lead
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45º x 90º triangle
30º x 60º triangle
Eraser
T-square
Drawing table
Drawing papers
Procedure:1. Set up the oslo drawing paper on top of the drawing board.2. Check to see that the paper edges are parallel to the left and bottom edges of the board
respectively.3. Properly secure the paper on top of the table by using masking tape or tacks or the likes.4. Using the set of triangles and t-square, draw the border line around the drawing paper,
leaving area for the title block at the bottom part.5. Divide the effective drawing area into nine (9) equal parts as shown in the figure
template below.6. Be sure to check the sharpness of your pencil lead. Use standard sharpening for good
aesthetic result of your work.7. For normal drafting or lettering use the soft lead pencil (HB) for final results. Use the
harder lead pencil (4H) for guidelines drawing only.8. Fill the each box with alphabet of lines according to each respectively examples.
Observe approximately uniform spacing of your work.9. This is not a work of speed but a work of accuracy and aesthetics, so do your work with
quality.10. You may submit your finish work once you are true but should be within the time
specified for submission.
Precautions : 1. Some of the instruments are pointed objects, observe standard safety of works. 2. Place the drawing instruments in a safe location when in idle.3. Observe proper posture of body in drafting works to avoid if not minimize body
stress.
Quality Criteria :1. Guidelines to be should be almost invisible. Do not erase the guidelines as it adds
aesthetic looks to the drafting works.2. Uniform line weight and intensity or darkness of pencil lead.3. Observe neatness of workmanship.
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LAP Test Alphabet of Lines
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Name: _____________________________ Date: ________________
Time started: ________________________ Time finished: ________________
Instructions:
1. Using freehand sketching, you are required to do the following :
Request from your teacher the following materials.
HB drawing pencil lead
4H drawing pencil lead
45º x 90º triangle
30º x 60º triangle
Eraser
T-square
Drawing table
Drawing papers
2. Draw and fill each box with the respective given sample alphabet of lines. See Figure 1 below.
3. Label each line type in the drawing below (Figure 2) within the guidelines.
4. You are given 2 hours to accomplish the task
5. Ask your teacher for an evaluation and feedback
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Figure 1
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