Technical drawing detail drawing. Drawing

Theme: Technical drawing

Target: learn to visually perform this or that figure by hand, observing the proportionality of the individual parts of the figure.

As a result of studying the discipline, the student must:

Educational (didactic):

have an idea:

about the role and place of technical drawing in the engineering activities of the future specialist;

know:

Basic concepts, principles and methods for constructing a technical drawing;

Rules for applying axonometric projections in a drawing

be able to:

Build drawings of flat figures, geometric bodies;

Perform drawings of parts and assembly units from nature and according to the drawing;

Determine the best ways to complete the task;

master the skill:

Building drawings in perspective;

Definitions of the method of solving the construction of shadows;

Basics of technical drawing according to the rules of axonometric projections;

The ability to construct images of geometric shapes on a plane.

Developing:

develop logical and analytical,spatialthinking, reasoning,the ability to work with a pencil without drawing tools,cognitive interest, development of attention and observation.

Educational:

to cultivate the accuracy of construction, accuracy, attentiveness and perseverance; formation of the need for intellectual development and self-organization for solving applied problems, the formation of independent work skills.

Relevance of the topic (motivation): In production conditions, it is sometimes necessary to explain the technical idea or the design of the part directly at the workplace with a drawing. This means that a craftsman, technologist, designer must be able to express his idea with a technical drawing with a pencil and pen on paper or with chalk on plywood, board and sheet metal. Making a technical drawing makes it easier and easier to make preliminary sketches, technical drawings or perspective drawings.

Educational technologies. Technology explanatory-illustrated learning, collective learning. used group teaching method and health-saving technologies. As a result of the application of the presented technologies, each student has emotional and meaningful support and works productively during the entire lesson, while maintaining concentration, the ability to perceive and retain information.Responsibility is increasing not only for one's own successes, but also for the results of collective work; in the process of mutual communication, memory is turned on, the mobilization and actualization of previous experience and knowledge takes place.AppliedICT technology to simplify the perception of the material being presented, which generally improves the quality of education.

Elements of teaching methodology.

Verbal methods - for the formation of theoretical and factual knowledge.

Visual methods - for the development of observation and increasing attention to the issues being studied.

Practical skills - for the development of practical skills and abilities.

Methodological support: Samples of graphic works, blackboard,computer, interactive whiteboard, electronic curriculum.

Handout: Task options.

Materials and accessories.

Drawing board, buttons. A3 drawing paper, soft graphite pencils (3M, 2M) and medium hard pencils (TM and M), fine eraser.

Literature: Kulikov V.P. Engineering graphics (2013),

Tomilina S.V. Engineering graphics (2012)

The sequence of the training session

1 organizational moment.

3 Checking homework.

4 Learning new material

5 Physical education minute

6 Learning new material

7 Consolidation of the studied material

8 Homework

Lesson progress:

1 organizational moment.

Greeting, psychological attitude, identifying absentees, checking preparedness for the lesson.

2 Familiarization with the topic of the lesson, setting its goals. Motivation.

Form: story-speech.

People have been using technical drawing for a long time and in its most diverse forms: design engineers most often used a realistic drawing (perspective), an example is the numerous drawings of Leonardo da Vinci. Designers of men's and women's clothing use a conditional pattern. Applied artists use their own special techniques. Even in everyday life, we often resort to the help of a technical drawing, explaining to friends our address and the location of houses.

Therefore, revealing the concept of the term "technical drawing", one cannot narrowly and one-sidedly interpret its content and purpose.

Most often, technical drawing is used when creating new objects. A new idea that is born in a person’s mind, a new image of an object that has suddenly arisen, require immediate fixing, and the simplest, most convenient and fastest form of fixing a creative thought is a drawing. Noting this quality of technical drawing, General Aircraft Designer A.S. Yakovlev wrote: “The ability to draw helped me a lot in my future work. After all, when a design engineer conceives some kind of machine, he must mentally imagine his creation in all details and be able to draw it with a pencil on paper.

The active creative activity of an inventor, architect, engineer, designer always begins with a technical drawing.

The technical drawing allows you to immediately see the benefits of new design improvements and gives you the basis to start refitting or replacing individual parts of the machine. But the main advantage of a technical drawing is that it forces the author to go further, make additions and corrections to his drawing, activate and improve his creative thought. And this, in turn, forces the designer to move on to new drawings until the author approaches the ideal.

3 Checking homework

The technology of level differentiation was applied to identify the residual knowledge of students, taking into account their capabilities.

Students choose an accessible question and formulate an answer. The result is the identification of positive dynamics and the creation of a situation of "success".

Issues to be discussed when updating knowledge:

1 What projection methods do you know?

2 Name the types of axonometric projections.

3 What is the distortion factor in dimetry?

Answer 1: The central projection of the object is obtained as follows: from the vanishing point of the rays, called the center of projections, a series of projecting rays is drawn through all the most characteristic points of the object until they intersect with the projection plane.

An axonometric projection of an object is obtained if the vanishing point of the rays (the center of projection) is mentally transferred to infinity (move away from the projection plane infinitely far). Axonometric projections give visual, but distorted images of an object: right angles are transformed into obtuse and acute ones, circles into ellipses, etc.

Rectangular (orthogonal) projections. Here, the projection center is infinitely far from the projection plane, the projecting rays are parallel and form a right angle with the projection plane (hence the name - rectangular projections).

Answer 2: Types of axonometric projections.

Rectangular Isometric View

Rectangular dimetric projection

oblique frontal isometric view

Oblique frontal dimetric projection

oblique horizontal isometric view

Answer 3: Distortion factor in dimetry:

Axis X-1; axis Y-0.5; axisZ-1.

4 Learning new material

technical drawing – this is a visual graphic representation of an object, made by hand on an eye scale, in which the technical idea of ​​the object is clearly disclosed, its constructive form is correctly conveyed, and proportional relationships are correctly found.

Before proceeding with the technical drawing, it is useful to do a number of exercises, which include: 1) drawing lines, 2) dividing line segments into equal parts, 3) drawing corners, 4) dividing corners into equal parts. It must be remembered that all constructions are carried out in pencil, without the use of drawing tools. In addition, it is necessary to be able to correctly determine the dimensions and ratios of parts by eye, to divide the lines and plane of the sheet into equal parts.

line drawing

Lines are straight, broken and curved. In the practice of drawing, horizontal and vertical lines are most often used.

Horizontal the line is drawn as follows. Let's outline several points spaced at an equal distance from the top edge of the sheet, and

let's make a movement of the right hand from left to right through the air, as if connecting the marked points. This exercise is repeated several times, after which a straight line is drawn with long thin strokes. The resulting curvature must be corrected by drawing a brighter line with a pencil.

The eraser is used after correcting the drawing

vertical a straight line is drawn by moving the hand from top to bottom along the same rules as horizontal

oblique A straight line is drawn by moving the hand from left to right. Depending on the angle of inclination, the straight line will move from top to bottom or from bottom to top.

Next, you should practice dividing the drawn line segments into equal parts: first - into two, four, eight, then - into three, six, five, seven. Developing the eye, you should check with a compass - a meter, whether the parts into which the straight line segment was divided are equal.

Building corners.

To divide an angle into equal parts, you must first draw an auxiliary arc and divide it by eye into the required number of equal parts. Then draw straight lines through the resulting serifs and the top of the corner. The figure shows an approximate sequence of exercises.

Preparation for drawing flat figures.

To acquire skills in drawing lines without taking the pencil off the paper, it is useful to perform the following exercises:

Drawing flat figures.

The acquired skill in the previous exercises should be used to draw some flat figures: a rectangle, a regular triangle and a hexagon, a circle and an ellipse.

5 Physical education minute

6 Learning new material

Drawing flat figures located in axonometric coordination planes.

The ability to correctly draw flat figures by hand will help you quickly build them in axonometric coordinate planes.

When constructing an oval, it is necessary to take into account the distortion coefficients along the axes

The ability to draw geometric bodies from nature, as well as from an axonometric representation, allows you to move on to drawing according to an orthogonal drawing, which is often found in design practice.

Building a drawing begins with the construction of a general form according to the proportions of the given drawings. Then the geometric body is divided into parts. And finally, they reveal the volume of the object, remove unnecessary lines and finish the drawing by applying hatching.

7 Fixing the material

Answer the questions

What is the difference between a technical drawing and an axonometric projection?

What should be the sequence of execution of a technical drawing?

What rules are used when making a technical drawing?

Complete several tasks shown in the picture.

Using two given projections of the model, clearly imagine its shape.

The general shape of the object, its individual parts, as well as the proportions are determined according to the drawing. The process of reading a drawing is carried out in two stages:

preliminary acquaintance;

Trial analysis-synthesis.

Preliminary acquaintance consists in finding out general data - the name of the part, scale, material, mass, etc. detailed analysis - synthesis is the reading of the drawing, which primarily consists in mentally recreating the spatial image of the part according to a flat drawing. At the same time, analyzing the shape of the object, they mentally divide it into composite geometric shapes, elements and consider each part in the images of the drawing. This order creates conditions for studying the overall size and dimensions of individual elements, their relationship to overall dimensions. Reading the symbols, designations and technical requirements completes the picture of the presentation and makes it possible to mentally combine (synthesize) all the drawing data.

Apply for drawingisometric rectangular projection.

The simplicity and clarity of the image are necessary conditions for simplifying and facilitating the implementation of graphic work. When drawing, it is not required to maintain dimensions, but it is imperative to maintain their proportionality, respectively, to a given subject, detail. The overall dimensions of the drawing should be chosen so as to successfully fill the field of the drawing. The layout of the drawing on the sheet, i.e. its location in proportion to the format of the sheet is of great importance for the construction of a holistic work. The position of the sheet can be horizontal or vertical with respect to the drawing and depends on the shape of the depicted object.

The image of the subject should occupy approximately ¾ of the useful area of ​​the sheet on the sheet. It should not be too small or too large in relation to the format. An image of an object that will go beyond the format is not allowed.

In order to arrange the drawing correctly compositionally, it is necessary to slightly outline the general shape and the relative position of its main parts with lines.

When drawing, it is not required to maintain dimensions, but it is necessary to take into account not only the design (structure, relative position of the parts of the object), but also the proportions - the dimensional ratios of height to width, one part to another and to the shape of the object as a whole. Violation of the proportion distorts the correctness of the drawing - the similarity of the image with nature. All constructions are carried out without drawing tools. To give the picture clarity, apply chiaroscuro.

8 Homework: repeat the material on the topic studied, perform graphic work « technical drawing of the model»

Graphic work "Technical drawing of the model".

Subject: "Technical drawing".

Content: On the A3 format, according to the given complex drawing, make a technical drawing of the model.

Target: Reading the spatial form of bodies according to a complex drawing, the development of spatial thinking, mastering the technique of manual graphics.

Work progress.

1. Using two given projections, present the shape of the model.

2. Determine the main proportions of the whole and parts of the model.

3. Analyze the design of the model, connections and dependencies between the individual parts.

4. Determine the position of the model relative to the projection axes.

5. Perform axonometric axes (for drawing, apply an isometric rectangular projection, correctly depicting the inclination of the axes).

6. Make a drawing without the use of drawing tools (image in the technique of "hand graphics") The construction must begin from the lower base of the model, gradually building up its other elements on it.

7. Check the correctness of the constructions, the correspondence of proportions and the relationship of all elements of the model.

8. Outline the drawing.

9. For clarity of the picture, apply chiaroscuro (dashed or cut). Assume that the light falls on a horizontal surface at an angle of 45°, due to the left shoulder.

Task report:

Technical drawing of the model, made on A3 format using the "hand graphics" technique.

A sketch is a design document made by hand, without the use of drawing tools, without exact scale, but with the obligatory observance of the proportions of the elements of the parts. The sketch is a temporary drawing and is intended for one-time use.

The sketch must be drawn up carefully in compliance with the projection connections and all the rules and conventions established by the ESKD standards.

A sketch can serve as a document for manufacturing a part or for making its working drawing. In this regard, the sketch of the part must contain all the information about its shape, dimensions, surface roughness, material. Other information is also placed on the sketch, drawn up in the form of graphic or textual material (technical requirements, etc.).

Sketching (sketching) is carried out on sheets of any paper of a standard size. In training conditions, it is recommended to use writing paper in a cage.

The sketching process can be conditionally divided into separate stages, which are closely related to each other. On fig. 367 shows a step-by-step sketching of the “support” part.

I. Introduction to the part

When familiarized, the shape of the part is determined (Fig. 368, a and b) and its main elements (Fig. 368, c), into which the part can be mentally divided. If possible, the purpose of the part is clarified and a general idea is made of the material, processing and roughness of individual surfaces, the manufacturing technology of the part, its coatings, etc.

II. Selecting the main view and other necessary images

The main view should be chosen so that it gives the most complete idea of ​​the shape and dimensions of the part, and also facilitates the use of the sketch in its manufacture.

There are a significant number of parts limited by surfaces of rotation: shafts, bushings, sleeves, wheels, disks, flanges, etc. In the manufacture of such parts (or blanks), machining is mainly used on lathes or similar machines (carousel, grinding).

The images of these parts in the drawings are arranged so that in the main view the axis of the part is parallel to the main inscription. Such an arrangement of the main view will facilitate the use of the drawing in the manufacture of parts from it.

If possible, you should limit the number of invisible contour lines that reduce the visibility of images. Therefore, special attention should be paid to the use of cuts and sections.

The necessary images should be selected and performed in accordance with the rules and recommendations of GOST 2.305-68.

On fig. 368, a and b, the options for the location of the part are given and the arrows show the direction of projection, as a result of which the main view can be obtained. Preference should be given to the position of the part in Fig. 368b. In this case, the contours of most elements of the part will be visible in the left view, and the main view itself will give the clearest idea of ​​its shape.

In this case, three images are sufficient to represent the shape of the part: main view, top view, and left view. A frontal incision should be made in place of the main view.

III. Selecting the paper size

The sheet format is selected according to GOST 2.301-68, depending on what size the images selected during stage II should have. The size and scale of the images should clearly reflect all the elements and apply the necessary dimensions and symbols.

IV. Sheet preparation

First, you should limit the selected sheet with an outer frame and draw a drawing frame of a given format inside it. The distance between these frames should be 5 mm, and a 20 mm wide margin is left on the left for filing the sheet. Then the contour of the frame of the main inscription is applied.

V. Layout of images on a sheet

Having chosen the visual scale of the images, the ratio of the overall dimensions of the part is set by eye. In this case, if the height of the part is taken as A y, then the width of the part is B ^ A, and its length is C "2L (see Fig. 367, a and 368, b). After that, rectangles with the overall dimensions of the part are applied on the sketch with thin lines (see Fig. 367, a). The rectangles are arranged so that the distances between them and the edges of the frame are sufficient for drawing dimension lines and symbols, as well as for placing technical requirements.

The implementation of the layout of images can be facilitated by the use of rectangles cut out of paper or cardboard and having sides corresponding to the overall dimensions of the part. By moving these rectangles across the drawing field, the most appropriate arrangement of images is chosen.

VI. Application of images of detail elements

Inside the resulting rectangles, images of the elements of the part are applied with thin lines (see Fig. 367, b). At the same time, it is necessary to observe the proportions of their

sizes and ensure the projection connection of all images by drawing the appropriate axial and center lines.

VII. Registration of views, cuts and sections

Further, in all views (see Fig. 367, c), details are specified that were not taken into account when performing stage VI (for example, fillets, chamfers), and auxiliary construction lines are removed. In accordance with GOST 2.305-68, cuts and sections are drawn up, then a graphic designation of the material is applied (shading of sections) in accordance with GOST 2.306-68 and the images are stroked with the corresponding lines in accordance with GOST 2.303-68.

VIII. Drawing dimension lines and symbols

Dimension lines and symbols that determine the nature of the surface (diameter, radius, square, taper, slope, thread type, etc.) are applied in accordance with GOST 2.307-68 (see Fig. 367, c). At the same time, the roughness of the individual surfaces of the part is outlined and conventional signs are applied that determine the roughness.

IX. Application of dimensional numbers

Using measuring tools, determine the dimensions of the elements and put the dimensional numbers on the sketch. If the part has a thread, then it is necessary to determine its parameters and indicate the corresponding thread designation on the sketch (see Fig. 367, d).

X. Finishing the sketch

At the final design, the main inscription is filled in. If necessary, information is provided on the maximum deviations of the dimensions, shape and location of surfaces; technical requirements are drawn up and explanatory inscriptions are made (see Fig. 368, d). Then the final check of the completed sketch is made and the necessary clarifications and corrections are made.

When sketching a part from nature, one should be critical of the shape and arrangement of its individual elements. So, for example, casting defects (uneven wall thicknesses, displacement of hole centers, uneven edges, asymmetry of part parts, unreasonable tides, etc.) should not be reflected in the sketch. Standardized elements of the part (grooves, chamfers, drilling depth for threading, fillets, etc.) must have the design and dimensions provided for by the relevant standards.

How are ideas for new models born? Everyone is different. Someone is inspired by their favorite films, someone is glossy magazines, someone is fascinated by the colors of nature. But no matter what inspired fashion designers, all their ideas that are born in the process of creativity find their expression in artistic sketches of new models.

This is natural, because in order to start the process of modeling patterns, it is necessary to think over each new model to the smallest detail - the silhouette, design solution, color and texture of the fabric, finish - everything affects how the finished product will look like. At the stage of creating an artistic sketch, you can make any changes to the product, experiment with color, length, show your imagination, give freedom to creativity, imagination and create a real masterpiece!

Advice! Keep a separate album for your artistic sketches and sketch all new ideas into it.

Keep a separate album for your artistic sketches and sketch all new ideas into it. Even if some of them do not find an instant embodiment, none of the sketches should be thrown away, because they may be useful to you in the future. Adding new models to the album, sometimes return to previous, unrealized ideas. Perhaps, after some time, you will look at them in a new way, and bring them to life.
And now a few words about what an artistic sketch should be.

What is an artistic sketch of a model?

First, you can do a fore-sketch or sketch to capture your idea on paper. It can be fuzzy, disproportionate, not having accurate drawings. These are the sprouts of an idea, the initial stage when you can depict a flight of fancy in the way you consider necessary, understandable only to you. Experiment at this stage without limiting yourself in anything.

Rice. 1. Fore-sketch of the dress

This is followed by the creation of an artistic sketch of the model.
An artistic sketch of a model is a drawing made in any drawing technique. You can use gouache, watercolor, colored or monochrome pencils, felt-tip pens and whatever is at hand for drawing. An artistic sketch is performed on a figure in an arbitrary pose. The main thing is that the model you draw should betray the mood, match the image that you have in mind, be aesthetically pleasing and comfortable to wear. All this must be considered at the stage of creating an artistic sketch.

Rice. 2. Artistic sketch of the model - watercolor, ink

Rice. 3. Artistic sketch of the model - graphics

After completing the artistic sketch, it must be translated into a technical sketch, according to which it will be necessary to model the patterns.

Technical sketch of the model

The technical sketch of the model is a drawing of the product on a conditionally typical figure, with a clear definition of all the design features of the model, using a grid of base lines - the base of the neck, chest, waist, hips, and the central axis. This will allow you to make a more accurate calculation of the location of structural seams, parts, pockets, etc.

Rice. 4. Technical sketch of the model - front and back

Make a rule for yourself: always accompany the technical sketch of the model with a detailed description and calculation of the required amount of fabrics and applied materials for its tailoring. This will greatly simplify your work and allow you to more accurately estimate the cost of the finished product, make it possible to optimize the process of modeling and cutting and get a more accurate result. And that's exactly what we're aiming for!

In the description of the technical drawing of the product, be sure to specify the following parameters:

1. A brief description of the product in free form.
2. Silhouette, product design features, size.
3. Calculation and description of the required amount of fabrics for the product.
4. Description and calculation of the required amount of additional materials for the product (gaskets, fittings, threads, etc.).
5. Features of the model.

Rice. 5. Description of the technical drawing

If artistic sketches, as mentioned above, are best sketched on landscape paper, a checkered notebook is ideal for technical drawing. You can easily enter a technical sketch into it and fill out a table with a description of the model.
After you have done all the preparatory work and created a technical drawing, it will be much easier for you to build a basic pattern for a product and develop patterns.

Ready-made templates for your sketches

Rice. Template for artistic sketch

And now - the most interesting! We have prepared for you a template with silhouettes of female figures for artistic sketches on A4 format. Just download the pdf file, print it on a black and white printer and draw your sketches directly on the silhouettes.

So you don't have to waste time drawing figures - after all, we have already drawn them for you! By the way, it is very convenient to store ready-made sketches in a binder folder.

Limitless creativity!

The technical drawing in design practice is of great importance, being the primary form of the image. An engineer or designer, starting to create a project, most often begins his activity with the construction of a technical drawing, because it is carried out much faster than a drawing, and is more visual, i.e., from such a drawing that has a high technique of execution and helps to draw up a drawing , make a project.

A technical drawing is a drawing made by eye, by hand, without the use of measuring and drawing tools. Technical drawing is performed according to the laws of axonometric projections of descriptive geometry. A technical drawing is designed to quickly create a visual representation of a part or structure.

Depending on the nature of the object and the task set in a particular project, a technical drawing can be made either in the central projection (in perspective) or according to the rules of parallel projections (in axonometry).

A technical drawing can be linear (without chiaroscuro) and three-dimensional with the transmission of chiaroscuro and color.

To give the drawing greater clarity and expressiveness in technical drawing, conditional means of conveying volume with

using shading - chiaroscuro. Chiaroscuro called the distribution of light on the surfaces of an object. Chiaroscuro plays a major role in the perception of the volume of an object. The illumination of an object depends on the angle of inclination of the light rays. When light rays fall on an object perpendicularly, the illumination reaches its greatest strength, so that part of the surface that is closer to the light source will be lighter, and that farther away will be darker.

In technical drawing, it is conventionally assumed that the light source is on the top left and behind the painter.

Chiaroscuro consists of the following elements: own shadow, drop shadow, reflex, midtone, light and glare.

own shadow - a shadow that is on an unlit part of an object.

drop shadow A shadow cast by an object on a surface. Since the technical drawing is mostly conditional, applied in nature, falling shadows are not shown on it.

Reflex - reflected light on the surface of an object in its unlit part. It is slightly lighter in tone than the shadow. With the help of a reflex, the effect of bulge, stereoscopicity of the picture is created.

Semitone - dimly lit place on the surfaces of the object. Halftones make a gradual, smooth transition from shadow to light, so that the picture does not turn out to be too contrasting. A semitone "sculpts" the three-dimensional shape of the object.

Light - the illuminated part of the surface of the object.

glare - the lightest spot on the subject. In technical drawing, highlights are shown mainly on surfaces of revolution.

Shadows in a technical drawing are depicted using shading, hatching or scratching (cross hatching)

ALGORITHM FOR CONSTRUCTING A TECHNICAL DRAWING OF A PART

When starting to perform a technical drawing, it is necessary to first study the depicted object and mentally divide it into constituent elementary geometric bodies. Next, you should determine the main proportions of the object: the ratio of height, width and length, as well as the proportions of its individual parts. Then the appropriate type of axonometry is selected and axonometric axes are built.

Technical drawing begins with the general contours of the object, and then proceeds to the image of its individual parts. Dimensions are not set on the technical drawing, since, as a rule, parts are not manufactured according to the drawings.

Lines of an invisible contour in a technical drawing are usually not drawn; hatching in a technical drawing, unlike a drawing, is done with straight or curved lines, solid or intermittent, of the same or different thicknesses, as well as applying shadows.

Technical drawing.pptx

The construction of a technical drawing of a geometric body, like any object, begins from the base. For this purpose, the axes of the flat figures lying at the base of these bodies are first drawn.

The axes are built using the following graphic technique. Randomly choose a vertical line, set any point on it and draw two intersecting lines through it at angles of 60 ° to the vertical line (Fig. 82, a). These straight lines will be the axes of the figures, the technical drawings of which must be completed.

Let's look at some examples. Let it be necessary to perform a technical drawing of a cube. The base of a cube is a square with a side equal to a. We draw the lines of the sides of the square parallel to the constructed axes (Fig. 82, b and c), choosing their value approximately equal to a. We draw vertical lines from the vertices of the base and draw segments on them that are approximately equal to the height of the polyhedron (for a cube, it is equal to a). Then we connect the vertices, completing the construction of the cube (Fig. 82, d). Similarly, drawings of other objects are built.

Rice. 82

It is convenient to build technical circle drawings by fitting them into a square drawing (Fig. 83). The drawing of a square can be conditionally taken as a rhombus, and the image of a circle as an oval. An oval is a figure consisting of circular arcs, but in technical drawing it is performed not with a compass, but by hand. The side of the rhombus is approximately equal to the diameter of the depicted circle d (Fig. 83, a).

Rice. 83

In order to fit an oval into a rhombus, arcs are first drawn between points 1-2 and 3-4 (Fig. 83, b). Their radius is approximately equal to the distance A3 (A4) and B1 (B2). Then arcs 1-3 and 2-4 are drawn (Fig. 83, c), completing the construction of the technical drawing of the circle.

To depict a cylinder, it is necessary to build drawings of its lower and upper bases, placing them along the axis of rotation at a distance approximately equal to the height of the cylinder (Fig. 83, d).

To build the axes of figures located not in the horizontal plane of projections, as given in Figure 83, but in vertical planes, it is enough to draw one straight line through an arbitrarily chosen point on a taken vertical line, directing it down to the left for figures parallel to the frontal projection plane, or down to the right - for figures parallel to the profile plane of projections (Fig. 84, a and b).

Rice. 84

The placement of ovals when performing technical drawings of circles located in different coordinate planes is given in Figure 85, where 1 is the horizontal plane, 2 is the frontal and 3 is the profile.

Rice. 85

It is convenient to perform technical drawings on checkered paper (Fig. 86).

Rice. 86

To make the technical drawing more clear, various methods of conveying the volume of an object are used. They can be linear hatching (Fig. 87, a), scratching (hatching with a “cell” - Fig. 87, b), dot shading (Fig. 87, c), etc. (see also Fig. 88). It is assumed that light is incident on the surface from the top left. Illuminated surfaces are left light, and shaded surfaces are covered with strokes that are thicker where one or another part of the surface of the object is darker.

Rice. 87

Rice. 88

Figure 89 shows technical drawings of more complex parts using hatching, scratching, and spot shading.

Rice. 89 1. What drawing is called technical? 2. What methods of conveying the volume of objects are used in technical drawing?

Option 1. Technical drawing of the part

According to the drawing in rectangular projections, perform a technical drawing of one of the parts (Fig. 90).

Rice. 90

Requirements for the design of practical work

When drawing models, approximate methods of their construction are used.

Think about the layout of the drawing. Perform a technical drawing of models on A 4 (A3) format, by hand from nature (or according to complex drawings), without the use of a drawing tool, apply (hatching) scribing and a quarter cut. Save construction lines.