Practical and graphic work on drawing. Practical and graphic work on drawing Graphic work 4 on drawing

2.1. The concept of ESKD standards. If every engineer or draftsman performed and designed the drawings in his own way, without observing uniform rules, then such drawings would not be understandable to others. To avoid this, the state standards of the Unified System for Design Documentation (ESKD) have been adopted and are in force in the USSR.

ESKD standards are regulatory documents that establish uniform rules for the implementation and execution of design documents in all industries. Design documents include drawings of parts, assembly drawings, diagrams, some text documents, etc.

Standards are set not only for design documents, but also for certain types of products manufactured by our enterprises. State standards (GOST) are mandatory for all enterprises and individuals.

Each standard is assigned its own number with the simultaneous indication of the year of its registration.

The standards are revised from time to time. Changes in standards are associated with the development of industry and the improvement of engineering graphics.

For the first time in our country, standards for drawings were introduced in 1928 under the name "Drawings for all types of mechanical engineering." Later they were replaced by new ones.

2.2. Formats. The main text of the drawing. Drawings and other design documents for industry and construction are performed on sheets of certain sizes.

For economical use of paper, ease of storing drawings and using them, the standard establishes certain sheet formats that are outlined with a thin line. At school, you will use a format whose sides are 297X210 mm. It is designated A4.

Each drawing must have a frame that limits its field (Fig. 18). The frame lines are solid thick main lines. They are carried out from above, to the right and from below at a distance of 5 mm from the outer frame, performed by a solid thin line along which the sheets are cut. On the left side - at a distance of 20 mm from it. This strip is left for filing drawings.

Rice. 18. Making an A4 sheet

In the drawings, the main inscription is placed in the lower right corner (see Fig. 18). Its form, dimensions and content are established by the standard. On educational school drawings, you will perform the main inscription in the form of a rectangle with sides of 22X145 mm (Fig. 19, a). A sample of the completed title block is shown in Figure 19, b.

Rice. 19. The main inscription of the training drawing

Production drawings, performed on A4 sheets, are placed only vertically, and the main inscription on them is only along the short side. In drawings of other formats, the title block can be placed along both the long and short sides.

As an exception, on A4 training drawings, the main inscription is allowed to be placed both along the long and along the short side of the sheet.

Before starting the drawing, the sheet is applied to the drawing board. To do this, attach it with one button, for example, in the upper left corner. Then a T-square is placed on the board and the upper edge of the sheet is placed parallel to its edge, as shown in Figure 20. Pressing a sheet of paper to the board, attach it with buttons, first in the lower right corner, and then in the other corners.

Rice. 20. Preparing the sheet for work

The frame and columns of the main inscription are made with a solid thick line.

What are the dimensions of an A4 sheet? At what distance from the outer frame should the drawing frame lines be drawn? Where is the title block placed on the drawing? Name its dimensions. Consider Figure 19 and list what information is indicated in it.

2.3. Lines. When making drawings, lines of various thicknesses and styles are used. Each of them has its own purpose.

Rice. 21. Drawing lines

Figure 21 shows an image of a part called a roller. As you can see, the detail drawing contains different lines. In order for the image to be clear to everyone, the state standard establishes the style of lines and indicates their main purpose for all drawings of industry and construction. In the lessons of technical and service labor, you have already used various lines. Let's remember them.

In conclusion, it should be noted that the thickness of lines of the same type should be the same for all images in a given drawing.

Information about the lines of the drawing is given on the first flyleaf.

What is the purpose of a solid thick main line?
What is a dashed line? Where is it used? What is the thickness of this line?
Where is a dash-dot thin line used in a drawing? What is its thickness?
In what cases is a solid thin line used in a drawing? How thick should it be?
Which line shows the fold line on the scan?

In Figure 23 you see a picture of the part. Various lines are marked on it with the numbers 1,2, etc. Make a table in your workbook according to this sample and fill it out.

Rice. 23. Task for exercises

Graphic Work No. 1

Prepare an A4 sheet of drawing paper. Draw the frame and columns of the title block according to the dimensions indicated in Figure 19. Draw different lines, as shown in Figure 24. You can also choose a different arrangement of line groups on the sheet.

Rice. 24. Task for graphic work No. 1

The main inscription can be placed both along the short and along the long side of the sheet.

2.4. Drawing fonts. Sizes of letters and numbers of the drawing font. All inscriptions on the drawings must be made in drawing font (Fig. 25). The style of letters and numbers of the drawing font is established by the standard. The standard defines the height and width of letters and numbers, the thickness of stroke lines, the spacing between letters, words, and lines.

Rice. 25. Inscriptions on drawings

An example of building one of the letters in the auxiliary grid is shown in Figure 26.

Rice. 26. An example of building a letter

The font can be both slanted (about 75°) and non-slanted.

The standard specifies the following font sizes: 1.8 (not recommended, but allowed); 2.5; 3.5; 5; 7; ten; fourteen; twenty; 28; 40. The size (h) of the font is taken as the value determined by the height of uppercase (capital) letters in millimeters. The height of the letter is measured perpendicular to the base of the line. The lower elements of the letters D, C, U and the upper element of the letter Y are performed due to the spaces between the lines.

The thickness (d) of the font line is determined depending on the height of the font. It is equal to 0.1h;. The width (g) of the letter is chosen to be 0.6h or 6d. The width of the letters A, D, Zh, M, F, X, C, SH, W, b, Y, Yu is 1 or 2d more than this value (including the lower and upper elements), and the width of the letters Г, 3, С is less than d.

The height of the lowercase letters roughly matches the height of the next smaller font size. Thus, the height of lowercase letters of size 10 is 7, of size 7 is 5, and so on. The width of most lowercase letters is 5d. The width of the letters a, m, c, b is 6d, the width of the letters w, t, f, w, u, s, u is 7d, and the letters h, c are 4d.

The distance between letters and numbers in words is taken equal to 0.2h or 2d, between words and numbers -0.6h or 6d. The distance between the lower lines of the lines is taken equal to 1.7h or 17d.

The standard also establishes another type of font - type A, narrower than just considered.

The height of letters and numbers in pencil drawings must be at least 3.5 mm.

The outline of the Latin alphabet according to GOST is shown in Figure 27.

Rice. 27. Latin script

How to write in cursive font. It is necessary to draw up drawings with inscriptions carefully. Indistinctly made inscriptions or carelessly applied figures of different numbers can be misunderstood when reading the drawing.

To learn how to write beautifully in a drawing font, first a grid is drawn for each letter (Fig. 28). After mastering the skills of writing letters and numbers, you can only draw the top and bottom lines of the line.

Rice. 28. Examples of inscriptions in drawing font

The contours of the letters are outlined with thin lines. After making sure that the letters are written correctly, circle them with a soft pencil.

For the letters G, D, I, I, L, M, P, T, X, C, W, W, only two auxiliary lines can be drawn at a distance equal to their height A.

For letters B, C, E, N. R, U, H, b, Y, b. Between two horizontal lines, one more should be added in the middle, but with which their middle elements perform. And for the letters 3, O, F, Yu, four lines are drawn, where the middle lines indicate the boundaries of the fillets.

To quickly make inscriptions in a drawing font, various stencils are sometimes used. You will fill in the main inscription in font 3.5, the name of the drawing in font 7 or 5.

What is the font size?
What is the width of the capital letters?
What is the height of lowercase letters of size 14? What is their width?

Complete a few inscriptions in the workbook for the teacher's assignment. You can, for example, write your last name, first name, home address.
Fill in the main inscription on the sheet of graphic work No. 1 with the following text: drew (surname), checked (name of the teacher), school, class, drawing No. 1, the name of the work "Lines".

2.5. How to measure. To determine the size of the depicted product or any part of it, dimensions are applied to the drawing. Dimensions are divided into linear and angular. Linear dimensions characterize the length, width, thickness, height, diameter or radius of the measured part of the product. The angular dimension characterizes the magnitude of the angle.

The linear dimensions in the drawings are indicated in millimeters, but the designation of the unit of measure is not applied. Angular dimensions are indicated in degrees, minutes and seconds with the designation of the unit of measurement.

The total number of dimensions in the drawing should be the smallest, but sufficient for the manufacture and control of the product.

The rules for sizing are set by the standard. Some of them you already know. Let's remind them.

1. Dimensions in the drawings are indicated by dimensional numbers and dimension lines. To do this, first draw extension lines perpendicular to the segment, the size of which is indicated (Fig. 29, a). Then, at a distance of at least 10 mm from the contour of the part, a dimension line parallel to it is drawn. The dimension line is limited on both sides by arrows. What should be the arrow is shown in Figure 29, b. The extension lines extend beyond the ends of the arrows of the dimension line by 1...5 mm. Extension and dimension lines are drawn with a solid thin line. Above the dimension line, closer to its middle, a dimension number is applied.

Rice. 29. Drawing linear dimensions

2. If there are several dimension lines parallel to each other in the drawing, then a smaller size is applied closer to the image. So, in Figure 29, first the size 5 is applied, and then 26, so that the extension and dimension lines in the drawing do not intersect. The distance between parallel dimension lines must be at least 7 mm.

3. To indicate the diameter, a special sign is applied in front of the dimension number - a circle crossed out with a line (Fig. 30). If the dimension number does not fit inside the circle, it is taken out of the circle, as shown in Figure 30, c and d. The same is done when applying the size of a straight segment (see Fig. 29, c).

Rice. 30. Applying the size of circles

4. To designate the radius, a capital Latin letter R is written in front of the dimension number (Fig. 31, a). The dimension line to indicate the radius is drawn, as a rule, from the center of the arc and ends with an arrow on one side, resting on the point of the circular arc.

Rice. 31. Dimensioning Arcs and Angle

5. When specifying the size of the corner, the dimension line is drawn in the form of an arc of a circle with the center at the apex of the corner (Fig. 31, b).

6. Before the dimension number indicating the side of the square element, a "square" sign is applied (Fig. 32). In this case, the height of the sign is equal to the height of the digits.

Rice. 32. Drawing the size of the square

7. If the dimension line is located vertically or obliquely, then the dimension numbers are arranged as shown in Figures 29, c; thirty; 31.

8. If the part has several identical elements, then it is recommended to put the size of only one of them on the drawing, indicating the quantity. For example, the entry in the drawing “3 holes. 0 10" means that the part has three identical holes with a diameter of 10 mm.

9. When depicting flat parts in one projection, the thickness of the part is indicated, as shown in Figure 29, c. Please note that in front of the dimension number indicating the thickness of the part, there is a small Latin letter 5.

10. It is allowed to indicate the length of the part in a similar way (Fig. 33), but in this case they write a Latin letter before the size number l.

Rice. 33. Drawing the size of the length of the part

In what units are linear dimensions expressed on engineering drawings?
How thick should extension and dimension lines be?
What distance is left between the image outline and the dimension lines? between dimension lines?
How are dimensional numbers applied on inclined dimension lines?
What signs and letters are applied before the size number when indicating the size of diameters and radii?

Rice. 34. Task for exercises

Redraw in a workbook, maintaining proportions, the image of the part given in Figure 34, increasing it by 2 times. Apply the required dimensions, indicate the thickness of the part (it is 4 mm).
Draw circles in the workbook with diameters of 40, 30, 20 and 10 mm. Enter their dimensions. Draw circular arcs with radii of 40, 30, 20 and 10 mm and dimension.

2.6. Scales. In practice, you have to make images of very large parts, for example, parts of an aircraft, a ship, a car, and very small ones - parts of a clockwork, some instruments, etc. Images of large parts may not fit on sheets of a standard format. Small details that are barely visible to the naked eye cannot be drawn in full size with the available drawing tools. Therefore, when drawing large parts, their image is reduced, and small ones are increased compared to the actual dimensions.

Scale is the ratio of the linear dimensions of the image of an object to the actual. The scale of the images and their designation in the drawings sets the standard.

Reduction scale-1:2; 1:2.5; 1:4; 1:5; 1:10 etc.
Natural size-1:1.
Magnification scale-2:1; 2.5:1; 4:1; 5:1; 10:1 etc.

The most desirable scale is 1:1. In this case, you do not need to recalculate the dimensions when rendering the image.

Scales are written as follows: M1:1; M1:2; M5:1, etc. If the scale is indicated on the drawing in the main inscription specially designed for this, then the letter M is not written before the scale designation.

It should be remembered that, no matter what scale the image is made, the dimensions in the drawing are applied to the actual ones, that is, those that the part should have in kind (Fig. 35).

The angular dimensions do not change when the image is reduced or enlarged.

What is the scale for?
What is called scale?
What scales of increase are known to you, established by the standard? What scale of reduction do you know?
What do the entries mean: М1:5; M1:1; M10:1?

Rice. 35. Drawing gasket, made in different scales

Graphic Work No. 2
Drawing "flat part"

Make drawings of the “Gasket” parts according to the existing halves of the images separated by the axis of symmetry (Fig. 36). Apply dimensions, indicate the thickness of the part (5 mm).

Do the work on an A4 sheet. Image scale 2:1.

Instructions for work. Figure 36 shows only half of the part image. You need to imagine how the part will look like in full, keeping in mind the symmetry, sketch its image on a separate sheet. Then you should proceed to the execution of the drawing.

A frame is drawn on an A4 sheet and space is allocated for the main inscription (22X145 mm). The center of the working field of the drawing is determined and the image is built from it.

First, axes of symmetry are drawn, a rectangle is built with thin lines, corresponding to the general shape of the part. After that, images of rectangular elements of the part are marked.

Rice. 36. Tasks for graphic work No. 2

Having determined the position of the centers of the circle and the semicircle, they are carried out. Apply the dimensions of the elements and overall, i.e., the largest in length and height, the dimensions of the part, indicate its thickness.

Outline the drawing with lines established by the standard: first - circles, then - horizontal and vertical lines. Fill in the main inscription and check the drawing.

The course discusses the sequence of performing some exercises from the textbook "Drafting" edited by A.D. Botvinnikov.

Stages of performing graphic work No. 4 of the first and second tasks Fig. 98 and 99.

These types of exercises contribute to the development of spatial thinking. Graphic work No. 4 is a summing up, generalization and consolidation of the skills acquired in the process of studying the topics "Vertices, edges and faces of an object", "Analysis of the geometric shape of an object". Quality control of knowledge, skills and abilities obtained during the implementation of practical exercises to determine the projections of a point on the surface of an object shown in the drawing and visual image.

This type of activity can be used both in the lessons of technology and drawing. Such tasks can be given at home as independent work.

Requirements for the trainee

This course is designed for students of the 7th grade of a comprehensive school, it can also be useful for students of technical specialties, for the simple reason that it contains elements of descriptive geometry. It also trains spatial imagination.

Necessary requirements for students: knowledge of the rules of orthogonal projection; oblique parallel projection.

The student should be able to: analyze the geometric shapes of the object; determine the projections of edges, faces, vertices of the object; determine the projections of points on the surface of the object; build an image along the axes of isometric and frontal dimetric projections of edges, faces, ovals.

a) Construction of the third type according to two given ones.

Build a third view of the part according to two data, set dimensions, and make a visual representation of the part in axonometric projection. Take the task from table 6. A sample of the task (Fig. 5.19).

Methodical instructions.

1. The execution of the drawing begins with the construction of the axes of symmetry of the views. The distance between the views, as well as the distance between the views and the frame of the drawing is taken: 30-40 mm. The main view and the top view are built. The two constructed views are used to draw the third view - the left view. This view is drawn according to the rules for constructing the third projections of points for which two other projections are given (see Fig. 5.4 point A). When projecting a part of a complex shape, it is necessary to simultaneously build all three images. When constructing the third view in this task, as well as in subsequent ones, you can not plot the projection axes, but use the "axleless" projection system. For the coordinate plane, you can take one of the faces (Fig. 5.5, plane P), from which the coordinates are measured. For example, having measured the segment on the horizontal projection for point A, expressing the Y coordinate, we transfer it to the profile projection, we get the profile projection A 3 . As a coordinate plane, one can also take the plane R of symmetry, the traces of which coincide with the axial line of the horizontal and profile projections, and count the coordinates Y C, Y A from it, as shown in Fig. 5.5, for points A and C.

Rice. 5.4 Fig. 5.5

2. Each detail, no matter how complex it may be, can always be divided into a number of geometric bodies: a prism, a pyramid, a cylinder, a cone, a sphere, etc. The projection of the part is reduced to the projection of these geometric bodies.

3. Dimensions of objects should be applied only after constructing the view on the left, since in many cases it is on this view that it is advisable to apply part of the dimensions.

4. For a visual representation of products or their components in technology, axonometric projections are used. It is recommended that you first study the chapter "Axonometric projections" in the course of descriptive geometry.

For a rectangular axonometric projection, the sum of the squares of the coefficients (indicators) of the distortion is equal to 2, i.e.

k 2 + m 2 + n 2 \u003d 2,

where k, m, n are the coefficients (indicators) of distortion along the axes. In isometric

projections, all three distortion coefficients are equal to each other, i.e.

k=m=n=0.82

In practice, for simplicity of constructing an isometric projection, the distortion factor (indicator) equal to 0.82 is replaced by the reduced distortion factor equal to 1, i.e. build an image of the object, enlarged 1/0.82 = 1.22 times. The X, Y, Z axes in the isometric projection make angles of 120° between themselves, while the Z axis is directed perpendicular to the horizontal line (Fig. 5.6).

In a dimetric projection, two distortion coefficients are equal to each other, and the third in a particular case is taken equal to 1/2 of them, i.e.,

k=n=0.94; and m \u003d 1/2 k \u003d 0.47

In practice, for simplicity of constructing a dimetric projection, the distortion coefficients (indicators) equal to 0.94 and 0.47 are replaced by the reduced distortion coefficient equal to 1 and 0.5, i.e. build an image of the object, enlarged 1/0.94 = 1.06 times. The Z-axis in rectangular dimetry is directed perpendicular to the horizontal line, the X-axis is at an angle of 7°10", the Y-axis is at an angle of 41°25". Since tg 7°10" ≈ 1/8, and tg 41°25" ≈ 7/8, these angles can be constructed without a protractor, as shown in Fig. 5.7. In rectangular dimetry, natural dimensions are laid along the X and Z axes, and along the Y axis with a reduction factor of 0.5.

The axonometric projection of a circle is generally an ellipse. If the circle lies in a plane parallel to one of the projection planes, then the minor axis of the ellipse is always parallel to the axonometric rectangular projection of the axis that is perpendicular to the plane of the depicted circle, while the major axis of the ellipse is always perpendicular to the minor one.

In this task, a visual representation of the part is recommended to be performed in isometric projection.

b) Simple cuts.

Build a third view of the part according to two data, make simple cuts (horizontal and vertical planes), set dimensions, make a visual image of the part in axonometric projection with a 1/4 part cutout. Take the task from table 7. A sample of the task (Fig. 5.20).

Perform graphic work on a sheet of A3 drawing paper.

Methodical instructions.

1. When completing the task, pay attention to the fact that if the part is symmetrical, then it is necessary to combine half of the view and half of the section in one image. At the same time, in view don't show lines of an invisible contour. The boundary between the appearance and the section is the dash-dotted axis of symmetry. Cut image details located from the vertical axis of symmetry to the right(Fig. 5.8), and from the horizontal axis of symmetry - from below(Fig. 5.9, 5.10), regardless of which projection plane it is depicted on.

Rice. 5.9 Fig. 5.10

If the projection of the edge belonging to the external outline of the object falls on the axis of symmetry, then the cut is performed, as shown in Fig. 5.11, and if an edge belonging to the internal outline of the object falls on the axis of symmetry, then the cut is performed, as shown in fig. 5.12 i.e. in both cases, the projection of the edge is preserved. The boundary between section and view is shown as a solid wavy line.

Rice. 5.11 Fig. 5.12

2. In the images of symmetrical parts, in order to show the internal structure in an axonometric projection, cut out 1/4 of the part (the most illuminated and closest to the observer, Fig. 5.8). This cut is not associated with a cut in orthogonal projections. So, for example, on a horizontal projection (Fig. 5.8), the axes of symmetry (vertical and horizontal) divide the image into four quarters. When making a cut on the frontal projection, the lower right quarter of the horizontal projection is removed, and on the axonometric image, the lower left quarter of the model is removed. The stiffeners (Fig. 5.8), which fell into the longitudinal section on orthogonal projections, are not shaded, but shaded in axonometry.

3. Building a model in axonometry with a cutout of one quarter is shown in fig. 5.13. The model built in thin lines is mentally cut by the frontal and profile planes passing through the Ox and Oy axes. The quarter of the model enclosed between them is removed, the internal structure of the model becomes visible. Cutting the model, the planes leave a trace on its surface. One such trace lies in the frontal, the other in the profile plane of the section. Each of these traces is a closed broken line consisting of segments along which the cut plane intersects with the faces of the model and the surface of the cylindrical hole. The figures lying in the plane of the section are shaded in axonometric projections. On fig. 5.6 shows the direction of hatching lines in isometric projection, and in fig. 5.7 - in dimetric projection. The hatching lines are applied parallel to the segments that cut off the same segments on the axonometric axes Ox, Oy and Oz from the point O in the isometric projection, and in the dimetric projection on the Ox and Oz axes - the same segments and on the Oy axis - a segment equal to 0.5 segments on the axis Ox or Oz.

4. In this task, a visual representation of the part is recommended to be performed in a dimetric projection.

5. When determining the true type of section, one of the methods of descriptive geometry must be used: rotation, alignment, plane-parallel movement (rotation without specifying the position of the axes) or changing projection planes.

On fig. 5.14 gives the construction of projections and the true view of the section of the front-projecting plane Г of a quadrangular prism by changing the projection planes. The frontal projection of the section will be a line coinciding with the trace of the plane. To find the horizontal projection of the section, we find the points of intersection of the edges of the prism with the plane (points A, B, C, D), connecting them, we get a flat figure, the horizontal projection of which will be A 1, B 1, C 1, D 1.

symmetry, parallel to the axis x 12, will also be parallel to the new axis and be at a distance from it equal to b 1.In the new system of projection planes, the distances of points to the axis of symmetry are kept the same, as in the previous system, therefore, to find them, distances can be set aside ( b 2) from the axis of symmetry. Connecting the obtained points A 4 B 4 C 4 D 4 , we obtain the true view of the section by the plane G of a given body.

On fig. 5.16 the construction of the true view of the section of a truncated cone is given. The major axis of the ellipse is determined by points 1 and 2, the minor axis of the ellipse is perpendicular to the major axis and passes through its middle, i.e. point O. The minor axis lies in the horizontal plane of the base of the cone and is equal to the chord of the circle of the base of the cone passing through the point O.

The ellipse is limited by a straight line of intersection of the secant plane with the base of the cone, i.e. a straight line passing through points 5 and 6. Intermediate points 3 and 4 are constructed using the horizontal plane G. In fig. 5.17 gives the construction of a section of a part consisting of geometric bodies: a cone, a cylinder, a prism.

Rice. 5.16

Rice. 5.17

c) Complex cuts (complex stepped cut).

Build a third view of the part according to two data, make the indicated complex cuts, build an oblique section with the plane specified in the drawing, set dimensions, and make a visual representation of the part in axonometric projection (rectangular isometry or dimetry). Take the task from table 8. A sample of the task (Fig. 5.21). Perform graphic work on two sheets of A3 drawing paper.

Methodical instructions.

1. When performing graphic work, one should pay attention to the fact that a complex stepped section is depicted according to the following rule: the secant planes, as it were, are combined into one plane. The boundaries between the cutting planes are not indicated, and this section is drawn up in the same way as a simple section made not along the axis of symmetry.

2. Due to the absence of a third image, some of the dimensions in the task are not placed sufficiently appropriately, therefore, the dimensions must be applied in accordance with the instructions given in the “Dimensioning” section, and not copied from the task.

3. In fig. 5.21. shows an example of the execution of the image of a part in a rectangular isometry with a complex cutout.

d) Complex cuts (complex broken cut).

Build a third view of the part according to two data, perform the indicated complex broken cut, and set dimensions. The task is taken from table 9. A sample of the task (Fig. 5.22).

Perform graphic work on a sheet of A4 drawing paper.

Methodical instructions.

On fig. 5.18 shows an image of a complex broken section obtained by two intersecting profile-projecting planes. To obtain a cut in an undistorted form when an object is cut by inclined planes, these planes, together with the section figures belonging to them, are rotated around the line of intersection of the planes to a position parallel to the projection plane (in Fig. 5.18 - to a position parallel to the front projection plane). The construction of a complex broken section is based on the method of rotation around the projecting line (see the course of descriptive geometry). The presence of breaks in the section line does not affect the graphic design of a complex section - it is drawn as a simple section.

Variants of individual tasks. Table 6 (Construction of the third view).

Task completion examples.

Rice. 5.22

Rice. 99. Tasks for graphic work No. 4

3) Are there holes in the part? If so, what is the geometry of the hole?

4) Find on each of the views all flat surfaces perpendicular to the frontal, and then to the horizontal projection planes.

2. Based on a visual representation of the details (Fig. 99), draw a drawing in the required number of views. Apply to all views and mark points A, B and C.

13. The order of construction of images in the drawings

13.1. A method for constructing images based on the analysis of the shape of an object. As you already know, most objects can be represented as a combination of geometric bodies. Therefore, in order to read and execute drawings, you need to know how these geometric bodies are depicted.

Now that you know how such geometric bodies are depicted in the drawing, and have learned how vertices, edges and faces are projected, it will be easier for you to read the drawings of objects.

Figure 100 shows a part of the machine - a counterweight. Let's analyze its shape. What geometric bodies known to you can be divided into? To answer this question, let us recall the characteristic features inherent in the images of these geometric bodies.

In Figure 101, and one of them is highlighted in conditional brown. What geometric body has such projections?

Projections in the form of rectangles are characteristic of a parallelepiped. Three projections and a visual representation of the parallelepiped, highlighted in Figure 101, and in brown, are given in Figure 101, 6.

In Figure 101, in gray conditionally, another geometric body is highlighted. What geometric body has such projections?

You met with such projections when considering images of a triangular