Sketch – A quickly executed free-form drawing, not intended to be a final work, often consisting of many overlapping lines. Can be made using various techniques.
Sketching is inexpensive and allows the artist to sketch and try out other ideas before turning them into painting. Pencil or pastel are preferred for sketching due to time constraints, but a quick sketch in watercolor or even a quickly modeled model in clay or soft wax can also be considered a sketch in more detail. broad meaning words. Graphite pencils are a relatively new invention; Renaissance artists made sketches using a silver pen on specially prepared paper.
When working on a sketch, you can use an eraser, which is used to remove construction lines or soften too sharp lines.
Sometimes a sketch is called a sketch (not to be confused with a skit - a one-act play with comedic content). “Sketch” (from the English “sketch” - outline, sketch) is a drawing quickly done by hand, usually not considered a completed work. Sketch can serve for various purposes- it will help you quickly capture what the artist sees. Write down or develop an idea for further use, or serve convenient form a graphic demonstration of a picture, idea, or principle.
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Before you start making different items, you need to complete certain preparatory work. They usually begin with sketches and drawings, called graphic documentation. Items that need to be manufactured are called products, and their individual parts are called parts.
Definition
Sketch- this is a conventional image of a product, drawn by hand, without the use of drawing tools, but with necessarily maintained “by eye” proportions between it in separate parts, i.e. This is a preliminary, rough sketch of the product.
Drawing- this is a conventional image of a separate part or product, made using drawing tools. The drawing is considered the main graphic document. If you know how to read drawings correctly, then from them you can find out what the dimensions of the product depicted on them are, what material it should be made of, what its appearance and shape. In the drawing, all dimensions of products and parts are indicated in millimeters.
Comparison
A sketch is an inaccurate, very preliminary sketch of a part or product. A sketch is performed when you need to quickly depict on paper the idea of a new product. It is most convenient to apply it to checkered paper. And it is intended for one-time use. Subsequently, working drawings are developed based on the sketches, and sometimes even parts are manufactured.
A working drawing of a part, in contrast to a sketch, is made using drawing tools or using a drawing computer program (for example, AutoCAD, Compass, etc.) in standard formats, on a standard scale with strict adherence to the types and thickness of lines. Both the sketch and the drawing of the product must contain all the necessary information, i.e. the shape of the product and its dimensions are conveyed, and the permissible errors of the nominal dimensions are also indicated.
Drawing of a machine for rolling out arches
Often drawings and sketches are made in a reduced or enlarged form compared to the part to be manufactured. For drawings, a clearly defined scale is used (1:2; 1:4, etc.) For sketches, such strict requirements do not exist.
Conclusions website
- A sketch is an inaccurate, approximate sketch of a part or product, made by hand.
- A sketch is usually performed when developing a structurally new part, when finalizing a design in a pilot version, or in the event of a part failure during operation.
- In the sketch, all the proportions between the individual parts of the part must be maintained “by eye”.
- The drawing is the main graphic document from which the part is manufactured.
- A drawing is a conventional image of a part or product made using drawing tools.
- In the drawing, all part dimensions are presented in millimeters.
A, m. 1. Preliminary sketch of a drawing, painting or part of it. I showed Kuindzhi a large sketch of the planned painting. The sketch depicted the figure of a contemplator in the evening in a field. Rylov, Memoirs. Small academic dictionary
A sketch is a design document made by hand, without the use of drawing tools, without exact adherence to scale, but with mandatory 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 projection connections and all the rules and conventions established by the ESKD standards.
A sketch can serve as a document for the manufacture of a part or for the execution of its working drawing. In this regard, the sketch of the part must contain all the information about its shape, size, surface roughness, and material. The sketch also contains other information, presented in the form of graphic or text material ( technical requirements and so on.).
Sketching (sketching) is done on sheets of any standard size paper. In educational settings, it is recommended to use checkered writing paper.
The sketching process can be divided into separate stages, which are closely related to each other. In Fig. 367 shows a step-by-step sketch of the “support” part.
I. Familiarization with the part
Upon familiarization, 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 about the material, processing and roughness of individual surfaces, about the manufacturing technology of the part, about its coatings, etc.
II. Selecting the main view and other required 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 during 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 workpieces), processing is mainly used on lathes or similar machines (rotary, grinding).
The images of these parts in the drawings are positioned so that in the main view the axis of the part is parallel to the main inscription. This arrangement of the main view will make it easier to use the drawing when manufacturing parts based on it.
If possible, you should limit the number of invisible contour lines that reduce the clarity of images. Therefore, attention should be paid Special attention the use of cuts and sections.
The required images should be selected and performed in accordance with the rules and recommendations of GOST 2.305-68.
In Fig. 368, a and b, options for the location of the part are given and the arrows show the direction of projection, as a result of which it can be obtained main view. Preference should be given to the position of the part in Fig. 368, b. In this case, the view on the left will show the outlines of most of the elements of the part, and the main view itself will give the clearest idea of its shape.
IN in this case Three images are enough to represent the shape of the part: main view, top view and left view. A frontal incision should be made at the site of the main view.
III. Selecting a Sheet Size
The sheet format is selected according to GOST 2.301-68 depending on the size of the images selected during stage II. The size and scale of the images must allow all elements to be clearly reflected and the necessary dimensions and symbols to be applied.
IV. Sheet preparation
First, you should limit the selected sheet to 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 outline of the frame of the main inscription is applied.
V. Arrangement of images on a sheet
Having chosen the visual scale of the images, the ratio of the overall dimensions of the part is established 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 this, rectangles with the overall dimensions of the part are drawn in thin lines on the sketch (see Fig. 367, a). The rectangles are positioned so that the distances between them and the edges of the frame are sufficient for applying dimension lines and symbols, as well as for placing technical requirements.
The layout of images can be facilitated by using rectangles cut from paper or cardboard and having sides corresponding to the overall dimensions of the part. By moving these rectangles around the drawing field, the most suitable location of the images is selected.
VI. Drawing images of part elements
Inside the resulting rectangles, images of the elements of the part are drawn with thin lines (see Fig. 367, b). In this case, it is necessary to maintain their proportions
sizes and ensure projection connection of all images by drawing appropriate axial and center lines.
VII. Design of views, sections and sections
Next, in all views (see Fig. 367, c), details not taken into account when performing stage VI (for example, roundings, chamfers) are clarified 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 (hatching of sections) in accordance with GOST 2.306-68 and the images are outlined with the corresponding lines in accordance with GOST 2.303-68.
VIII. Drawing dimension lines and symbols
Dimensional lines and conventional signs, which determine the nature of the surface (diameter, radius, square, taper, slope, type of thread, etc.), are applied according to GOST 2.307-68 (see Fig. 367, c). At the same time, the roughness of individual surfaces of the part is marked and symbols are applied to determine the roughness.
IX. Applying dimensional numbers
Using measuring tools, determine the dimensions of the elements and apply 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. Final design of the sketch
When finalized, 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 notes are made (see Fig. 368, d). Then a final check of the completed sketch is made and the necessary clarifications and corrections are made.
When sketching a part from life, you should be critical of the shape and arrangement of its individual elements. For example, casting defects (uneven wall thicknesses, displacement of hole centers, uneven edges, asymmetry of parts of a part, unreasonable tides, etc.) should not be reflected in the sketch. Standardized elements of the part (grooves, chamfers, drilling depth for threads, roundings, etc.) must have the design and dimensions provided for by the relevant standards.
Sketches are intended for one-time use. Working drawings are made from the sketches, and in some cases parts are manufactured.
Sketches are usually made with a soft pencil on checkered paper. Lines, inscriptions and numbers must be clear. All constructions should be done by hand. In the sketch, it is necessary to observe the proportionality of the linear dimensions of the elements of the parts and the projection relationship.
A working drawing of a part differs from a sketch in that it is performed using drawing tools or using a drawing program on a computer (for example, AutoCAD, Compass, etc.) in a standard scale, in standard formats, with strict adherence to line types and their thickness. The working drawing, as well as the sketch of the part, must contain all the information necessary for the manufacture of the part, i.e. The shape of the part and its dimensions must be conveyed, and permissible deviations from the nominal dimensions must be indicated.
Sketches and drawings made by students in the “Mechanical Engineering Drawing” course can be considered as a design document compiled for a specific educational task. Each drawing must have a title block, which is located in the lower right corner of the drawing. The form of the title block for mechanical engineering drawings must comply with GOST 2.104-68.
Applying dimensions on sketches and drawings
Before applying dimensions, we recommend that you carefully study GOST 2.307-68 on applying dimensions and maximum deviations in drawings. When putting down dimensions, you should take into account the design requirements, part processing technology and the possibility of control. Therefore, before setting dimensions, you should select the surfaces or lines of the part from which the part will be measured when it is processed on mills. These surfaces are called bases. The bases can be design and technological. The relative position of different surfaces of a part is specified by linear or angular dimensions. The points and lines of the drawing of a part, in relation to which the designer orients other parts, are called design bases. The surface from which it is best to measure during the manufacturing process of a part is called the technological base.
Setting dimensions so that the requirements of design and technology are taken into account is a very difficult task, since often dimensioning from structural bases does not coincide with dimensioning from technological bases. The dimensions should be set in such a way that they can be conveniently controlled with a specific measuring tool, so that when manufacturing a part according to the drawing, the worker does not make any calculations and uses only those dimensions that are marked on the drawing.
Shown is the application of dimensions from one base (surface of the part) of holes located on the same axis. In the figure, the axis is taken as the base, since the holes are located around the circle.
In practice, three methods of applying dimensions are used: chain, coordinate (from one base) and combined. When applying dimensions in a chain, one of them is not indicated, since it is determined by the overall size of the part. The main disadvantage of this method is the accumulation of errors that may appear during the manufacturing process of the part. With the coordinate method, dimensions are applied from the selected base. With this method, any size does not depend on other dimensions of the part. The combined method combines the features of the chain and coordinate methods. This method is the most common.
The total number of dimensions in the drawing should be minimal, but sufficient for the manufacture of the part. It is not allowed to repeat the dimensions of the same element in different images. The dimensions of several identical elements can be applied once, with the number of these elements indicated on the callout.
Each size corresponds to a specific technological operation. Recommended sizes related to inner surface, apply from the sides of the cut, and the external dimensions - from the side of the view.
When making sketches of parts from nature, as well as when making working drawings of parts, you should use the normal linear dimensions established by GOST 6636-69.
The requirement to use normal dimensions applies to those surfaces that are manufactured according to a tolerance system. It is recommended to round normal dimensions, if possible, giving preference first to numbers ending in zero, then zero and five, and finally 2 and 8. The use of normal linear and angular dimensions in the manufacture of machine parts significantly reduces the number of required measuring gauges and the cost of products.