How to enlarge a drawing at home. Enlarging the picture by cell. Why is such a function needed?

During the learning process, the problem of accurate transferring a drawing from a sketch to a large sheet. In this article we will analyze the most practical and convenient method.

If the sketch is for great job is too complex and full of small details, and it is necessary to accurately, quickly and cleanly transfer it to a large format, then there is only one normal and easy affordable way do it. This method is called Grid or cells.

For greater clarity, we will illustrate this method using our task. In that preliminary assignment great importance has a balanced composition and effective intersection of objects, so much attention is paid to the sketch, and it must be accurately transferred to a large sheet.

What is the grid method?

The original image (sketch, sketch) is divided into a certain number of equal parts using vertical and horizontal lines, thus forming a grid. The number and size of cells (cells) may be different, the more small parts in the sketch, the smaller the size of the cells should become.

After the grid is marked on the sketch, it must be transferred to a large format. In our case, the sketch was made on A4 format and should be transferred to an A2 sheet. The most reliable way to transfer the grid while maintaining scale is to mark from the center.
When marking a sketch, you need to start by finding the center and draw a vertical and horizontal line through it. Next, the resulting half of the horizontal line is divided into an equal number of parts, or divided again in half, and then again, if necessary. The final size of the cell is formed; it needs to be transferred to a vertical line, and then the entire grid can be drawn without any problems.

After this, the middle is located on a large sheet, a vertical and horizontal line are drawn through it. The horizontal line is divided in a similar way as in the sketch, the resulting size is used to construct the entire mesh.

The resulting intersections of lines are the most important guideline for transferring the drawing; starting from them, you can begin to transfer the drawing. There may be some slight discrepancies in the process, but in general, the drawing will be transferred accurately, since the grid provides an error-free reference.

By practicing, getting your hand on, you will be more free to approach the transfer of the drawing. Marking will remain necessary in certain cases, such as: a large scale of the final work (for example, a drawing on the wall) or too complex composition with moving lines and proportions. The transfer technique itself can be reduced to finding the center and dividing into just a few parts, in any case, this is a very useful method that should be in the arsenal of every professional artist.

Quite often it is necessary to enlarge (or reduce) some drawing, drawing or diagram several times. For example, you liked the burning patterns in the magazine. But in the magazine they are usually given in a reduced form, so you have to enlarge them to the required size yourself, either manually using the “cell method”, or using devices: an epidiascope, or a pantograph (copier).

Pantograph (the name comes from two Greek words (pantos) - everything and qrapho - I write) is a device in the form of a sliding articulated parallelogram for redrawing pictures, drawings, diagrams in a different (increased or reduced scale). The main advantages of this device are the simplicity of the design and the fairly high “accuracy” of the copied image. Unfortunately, the pantograph has not yet found due recognition among amateur artists and other handy admirers of decorative and applied arts.

You can find pantographs (copiers) on sale now industrial production very hard. In addition, the range of such pantographs is relatively small, and they are made of metal, which does not make the device convenient enough. So God himself ordered to make for himself a pantograph (copier) with long wooden rulers.
Anyone can make a sufficiently high-quality pantograph with their own hands, provided that the exact dimensions of all parts are observed.
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The design of a homemade pantograph (copier), which we would like to bring to your attention, consists of four lever-rulers (three long and one short), in which holes are drilled in a certain order to secure the axes. Brass bushings are inserted into the holes of the rulers.
The axes of the pantograph mechanism are of different designs; the two central axes are a pin with a cap. The axes for attaching the lead (copier) and the tracking rod are made like a device for clamping the lead in the leg of the compass. It is advisable to use a plastic tip as a tracking rod. This tip does not spoil the original and provides good glide. One axis (extreme) with a heel on which the pantograph mechanism rests, and, finally, an axis that secures the entire mechanism to the base boss.
All axes have an annular groove in the upper part, which serves to secure a wire pin-clamp.
The boss is metal. Three stings (gramophone needles) are embedded into the boss from below, making it easy to fix the base on the drawing board.
Rulers are best made of plastic, for example, plexiglass (plexiglass), 5 mm thick. The most important operation is marking and drilling holes in the rulers, so it must be treated with special attention. To ensure high accuracy and alignment of the holes, it is enough to make markings on one ruler, put all the rulers in a bag and drill holes in all the rulers along the marked ruler in one step. Try to make the diameter of the holes such that the bushings fit into them tightly, with a slight interference fit.
The bushings are machined from brass according to the dimensions given in Fig. 2. Axles - steel. The length of the axles is directly dependent on the length of the bushing. Bend wire pins-clamps from steel wire with a diameter of 1.2-1.5 mm.
The base boss can be made from an aluminum block 39 mm thick. In the lower part of the boss, punch three needles into the blind holes (you can use a gramophone), so that their points protrude 2-3 mm.

Specification of parts for a homemade pantograph

When all the parts are ready, assemble the pantograph mechanism. When assembling and adjusting parts, try to ensure ease of movement of all links of the mechanism, for which their rubbing surfaces can be slightly lubricated.
The final step in making a homemade pantograph with your own hands is to mark the holes on a ruler, according to which it will be easy to select the scale of enlargement (reduction) of the copy.
Be sure to check the correspondence of the markings with the resulting dimensions experimentally.

How do they work with a pantograph (copier)?

First of all, the pole (needle) of the pantograph is attached to a certain point on the table. The drawing from which a copy needs to be made is placed where the spire is located, and Blank sheet paper - under the pencil. Next, we draw the pin along all the lines of the drawing, while the pencil automatically draws an enlarged drawing on the paper. And if you need to depict the drawing in a reduced form, you will have to use a pin and a pencil in places, which is not at all difficult if you have sleeves.
Usually, when working with a pantograph, the hand of the artist guides the pin along the lines of the pattern. In this case, you will have to attach a weight (nut, lead plate) to the ruler next to the pencil so that the pencil is pressed against the paper. But you can copy in another way. Namely, move your hand not with a pin, but with a pencil, while ensuring that the marker moves correctly along the lines of the pattern. In this case, the weight on the ruler, of course, is not needed.

And a few more practical tips.
If the original from which the copy is made has too much big sizes and it is not possible to go through all its lines with a pin at one time, just move the needle to a new place and continue working.
When you enlarge (or reduce) a drawing or drawing, straight lines and circles usually turn out to be of poor quality. Therefore, you will have to correct such a defect using a ruler and compass.
It is known that fairly good accuracy of a copy is ensured by enlarging the original no more than 2...3 times. Therefore, if you need to enlarge the drawing 4 times, it is better to first enlarge the original by 2 times, and then enlarge the resulting copy again by 2 times.
It is not forbidden to change the dimensions of the pantograph rulers, making them smaller, for example. In this case, the method for calculating the locations of holes on the rulers remains the same, that is, the length of the working part of the ruler will have to be divided by the magnification factor.

You don't know how to increase the size of a picture? This is very simple task, since everything you need is already installed on your computer. Read this tutorial and you'll learn how to resize a photo using 5 simple tools.

Method 1: How to Resize an Image in Microsoft Paint

1. Find and launch MS Paint. It comes pre-installed on all versions operating system Windows. Start> All Programs> Accessories> Paint:

1. Drag the image into the Paint window or use Menu > Open (Ctrl + O).
2. In the main menu of the program, find the item “ Resize" and select it:

1. The panel for changing image sizes and proportions will open. You can specify the value in pixels. Don't forget to check the " Maintain proportions" Otherwise the image will be deformed:

1. To increase the size of the picture, click the "OK" button and save the photo.

Adviсe:

• If you can't size your photo without stretching it, you can use the Crop tool to remove unwanted edges. How to do this is described in paragraph 3;
• To open a photo faster, right-click on it and select “ Open with Paint»;
• It is best to save the image in the same format as the original.

Method 2. How to resize an image in MS Photo Gallery

1. If Microsoft Photo Gallery is not installed on your computer ( Start > Photo Gallery), you need to download and install it as part of Windows Essentials 2012;
2. Launch MS Photo Gallery and find your graphic file;
3. Right-click on it and select “Resize...”:

1. Select a ready-made preset: " Small 640 pixels", "Medium 1024", "Large 1280", etc.

1. Click " Resize and save" After you increase the size of the picture, the image will be placed in the same folder, and the original will also remain in it.

Adviсe:

• If you need to set the exact image size, select " Custom" and set the size to the larger side of the photo;
• To resize multiple photos at once, select them while holding down the Ctrl key.

Method 3: How to Resize an Image in Photoscape

You can increase the size of the picture in Photoshop. Or use Photoscape for this.

1. Download Photoscape and install it. Launch the program;
2. Go to the "Editor" tab and find the photo you want to edit:

1. At the bottom of the image there is a button “Resize”, click on it.
2. Set new size photographs. Make sure the option " Maintain aspect ratio" is enabled and press the "OK" button:

1. Save the edited image.

Adviсe:

• If you need to resize multiple images, use the " Batch editor" Add a folder and resize all the photos in it;
• If you don't know the exact size, you can set the "Percentage" of the original size.

Method 4. How to resize an image in IrfanView

1. Install IrfanView - a great tool for viewing and enlarging pictures;
2. Add a photo by dragging it into the program window, or by clicking the first button in the toolbar:

1. Go to the "Image" tab, select " Change size/proportions» ( Ctrl+R);
2. Set the new size in pixels, centimeters, inches, or as a percentage of the original image:

1. Save the image.

Adviсe:

• you can use standard sizes: 640 by 480 pixels, 800 by 600 pixels, 1024 by 768 pixels, etc.;
• To maintain high quality photos, make sure your DPI is set to at least 300.

Method 5. How to resize an image online

1. To resize a picture online, go to PicResize.
2. Click the button Browse" to select a photo. Click " Continue»:

1. Select a percentage of the original image, such as 50% smaller. The tool will display the output image size. Alternatively, you can enter your exact size by selecting " Custom Size»:

Drawing is the language of technology. Based on the drawings, an engineer, technician, or skilled worker understands the structure of any mechanism; Simple and complex parts of each machine are manufactured according to drawings. Members of the circle " Skillful hands“They don’t study drawing at school yet. They will begin to draw only in the 6th grade during geometry lessons, and will become familiar with technical drawing later - starting in the 7th grade. However, in the circle they will often have to use simplified drawings and technical drawings (sketches) of various products. Many such drawings and drawings are printed in this book. That is why members of the circle need to learn to read simplified drawings and understand symbols on them.

How to read blueprints

In any drawing, bold, contour lines indicate the contours of an object. Sometimes there are broken lines in the drawing - dotted, consisting of individual dashes. Such lines indicate the contours of an object that are not visible when looking at it from the outside or from any one side, since they are hidden inside the object or hidden from view, for example, by its front wall.

The thinnest lines in the drawing are called dimensional: They show the dimensions of an object. There are arrows at the ends of such a line. They are connected by dotted lines with the outline of the object. The dimension line is usually broken in the middle, and a number is placed in the gap. According to drawing rules, all dimensions in the drawings are indicated in millimeters, so next to the numbers letter designations no measures are given. The number on the dimension line shows how many millimeters from the tip of one arrow to the tip of the other.

Very small distances are indicated without a dimension line, and sometimes with two arrows with a number between them. Next to the designation of the diameter (thickness) of a round rod or hole, an icon similar to the letter “F” is often placed: a circle crossed out by an oblique line. This icon indicates that the drawing depicts a round object.

Sometimes, especially for products made of paper and cardboard, instead of a drawing of the finished item, a development of it is given. Such a development according to the specified dimensions is drawn on paper or cardboard, then cut out and folded. The places of folds on the development are also shown with dotted lines - the same as the invisible contours of objects in the drawings.

Near general view An object in a drawing or picture is often depicted with its individual parts (details) in an enlarged form. Where are these parts located? general drawing, indicated in two ways: arrows and identical letters or numbers.

Letters (alphabetically) or serial numbers sometimes indicate the order in which a product should be assembled from individual parts or a part should be processed. In order not to confuse these numbers with size designations, they are usually marked in circles.

Very long parts that cannot be placed on a drawing or drawing to scale are drawn torn at one end or torn in the middle. The dimensions are given in full.

Dimensions are not always indicated in product pictures; they are often given only in the description text. In this case, abbreviated size designations are used. For example, the designation 40x15 mm means that the part is 40 mm long and 15 mm wide. The designation 40x15x10 mm indicates that three dimensions are given: length, width and height (thickness). If they want to indicate the width and thickness of the slats (that is, its cross-sectional dimensions), they write, for example, like this: slats with a cross-section of 8×5 mm.

The abbreviated names of measures used in product descriptions are the same as in school textbooks: m - meter, dsm - decimeter, cm - centimeter, mm - millimeter, kg - kilogram, g - gram.

Enlargement of drawings and drawings

In books, drawings and drawings are printed in small sizes. Often they have to be redrawn to full (natural) size. Straight lines the right size to the young technician It's easy to draw with a ruler. It is much more difficult to accurately depict complex, sinuous contours when enlarged. In these cases, the drawings are given on a grid.

To enlarge the drawing, you need to draw as many large squares on a sheet of paper as there are small ones in the drawing. The required square sizes are indicated in the description text. A drawing is drawn on these squares. The grid breaks it up into short lines, which are much easier to draw correctly by referring to the drawing.

You can also enlarge drawings and pictures using epidiascope. A homemade epidiascope, described in this book on the page, is quite suitable for this. The drawing or drawing that needs to be enlarged is placed in an epidiascope and projected onto a sheet of clean paper, secured with pins on a board or on a sheet of plywood. The screen and epidiascope are installed so that the desired magnification is obtained and the image is clear.

The contours of the image are traced on paper with a pencil - an enlarged drawing is obtained in which all the details are accurately conveyed.

Finally, you can enlarge or reduce drawings and drawings in another way - using a special device called a pantograph.

Homemade pantograph

For the pantograph, four strips 610 millimeters long and 12 millimeters wide are cut out of plywood. The width of the planks can be increased or decreased; their thickness does not matter. But the narrower and thinner the strips are made, the more convenient it is to use the pantograph. On each plank, 11 holes are drilled at the same distance from each other as indicated in Figure 64. All holes should be the same diameter - approximately 4 millimeters. The holes, except the two outer ones, are marked with numbers: 1.5; 2; 3; 4; 5; 6; 7; 8; 10. These numbers indicate how many times the drawing is enlarged or reduced. Let's agree that the end of the bar, where the number 10 is, will be considered the bottom, and the opposite end - the top. The distance between the extreme holes is 600 millimeters.

Using a knife, five pins are cut from a wooden strip or a suitable stick of such a size that they fit into the holes of the planks and can fasten two planks superimposed on each other. Three pins are made with semicircular ends, the fourth has pointed ends, and a gramophone needle is inserted into the end of the fifth, point down.

A square is assembled from two planks. A pin with a gramophone needle is inserted into the lower end of the first bar, and a piece of pencil with a pointed soft lead is inserted into the upper end of the second bar. The free ends of both strips are placed on top of each other and connected with a pin with a semicircular end. To make the pencil press better to the paper, the end of the rod near it is made heavier: a metal (preferably lead) plate is attached here.

From the other two strips, a second square is assembled by connecting the lower end of one strip with the upper end of the other with a pointed pin. The opposite ends of these strips remain free.

The remaining pins connect both squares together. This is done before using the pantograph for work. Let's say you want to enlarge a drawing four times. Having spread the free ends of the squares, they are placed on top of each other so that the slats intersect in those places where the holes with the number “4” are located. The pins are inserted into these holes. If the drawing needs to be doubled, then the squares are connected with pins inserted into holes “2”, etc.

All pins are cleaned well and made smooth. They should fit tightly into the hole, but not too tight so that the pantograph bars can rotate freely around the pin. The pantograph is easy to use.

Rice. 64. Pantograph.

Place the drawing you want to enlarge on a piece of plywood or a smooth board, and next to it a sheet of blank paper. A pantograph is placed on top. To secure it, the needle of one of the pins is stuck into the board. A pointed pin is placed in the drawing, and a pencil is placed on a sheet of clean paper. A sharp pin is driven along the contours of the picture or drawing. The pantograph bars move, and the pencil draws the same contours on paper, but enlarged. The staff with the pencil is lightly held with the left hand, without interfering with its movement.

Using a pantograph, on the contrary, you can reduce large drawing. To do this, you need to swap places with a sharp pin and a pencil. How are the holes on the planks marked?

The length of the strip between the two outer holes for the pins is 600 millimeters (the remaining 10 millimeters at the ends of the strip are not taken into account). Dividing 600 millimeters by the number indicating the degree of magnification, the distance of the corresponding hole from the lower end of the bar is obtained in millimeters. For example, to increase the magnification by three times, the hole must be located at a distance of 200 millimeters from the extreme hole of the lower end (600: 3 = 200) or at a distance of 400 millimeters from the upper end.

Using this simple calculation, the same pantograph can be adapted for other magnifications. For example, to increase two and a half times, you need to drill an additional hole at a distance of 240 millimeters from the extreme hole of the lower end of the bar (600: 2.5 = 240), and to increase nine times - at a distance of 66.5 millimeters (600 : 9 = approximately 66.5).

The manufacture of a pantograph will be simplified if it is adapted for a few magnifications: for example, only two and a half and ten times. In this case, you will have to drill fewer holes.

A pantograph is convenient when, for example, you have to enlarge patterns for sawing.

The simplest measurements

When making various things, members of the circle must firmly grasp the basic rule that ensures accurate and accurate execution of the work: do not do anything by eye. Before cutting out any part of a product from any material - be it paper, cardboard, plywood or tin, it is necessary to mark this part on it according to a drawing, drawing or description. Be sure to check the cut part to see if it exactly matches the required dimensions. One piece of the wrong shape or the wrong size can ruin the entire product.

And in order to correctly mark the material and check the dimensions of parts, you need to learn how to use the simplest measuring tools. Members of the circle have already met some of them during lessons at school.

Familiar to all pioneers scale bar with divisions into centimeters and millimeters. To measure, for example, 10 centimeters using a ruler on a sheet of paper or on a board, you need to make two marks: against the “0” division and against the “10” division. The distance between these two marks will be equal to 10 centimeters. Guys sometimes measure differently: from division “1” to “10”. The result, of course, is incorrect. Sometimes guys make other mistakes: when measuring, for example, the width of a board, the ruler is not placed perpendicular to its edge (that is, exactly across the board), but obliquely. As a result, the measured width is larger than the actual width. Sometimes they look at the divisions of the ruler incorrectly, directing their gaze not at a right angle, but from the side. And in this case the result is distorted.

The most accurate measurement is obtained when the scale ruler is not placed on a board or sheet of paper, but placed edge-on, with divisions down. With this position of the ruler it is easy to make a mark exactly along the division.

A new measuring tool for many children will be pocket roulette with a 1 meter measuring tape. The divisions on the tape measure are the same as on the scale ruler, so the kids will learn how to use it quickly. A tape measure is needed if you need to measure a length of up to one meter, because a regular ruler is designed for only 35-40 centimeters. The tape measure can be replaced with a folding meter or the so-called centimeter - a measuring tape used for sewing work.

Members of the circle should learn to use compass not only for drawing circles, but also for measurements. A compass is convenient in cases where for some reason a ruler cannot be used: for example, it does not fit inside a homemade product. The legs of the compass are installed on two points, the distance between which they want to measure, then, without changing the solution of the compass, they apply the legs to the scale ruler and find out the distance. It is also convenient to use a compass to check the size of several parts that should be the same.

Members of the circle will not yet use special tools for measuring the diameters of round rods or holes - calipers, bore gauges, calipers, micrometers. It will be enough for them to measure diameters with a ruler or compass. Coins can also be used as auxiliary measuring instruments when measuring round holes:

The diameter of a 20-kopeck coin is 22 millimeters, the diameter of a 15-kopeck coin is 20 millimeters, the diameter of a 10-kopeck coin is 17.5 millimeters, and the diameter of a 5-kopeck coin is 25.5 millimeters.

It is also useful for members of the circle to remember that the diameter of an ordinary pencil is 7 or 8 millimeters.

Sometimes product descriptions indicate what diameter the wire should be taken. The diameter of a thin wire is calculated as follows: wrap a piece of wire tightly around a round pencil, turn to turn; Use a ruler to measure the length of the resulting spiral and divide it by the number of turns. For example, if 40 turns of wire are laid at a distance of 2 centimeters, then its diameter is 0.5 millimeters (20 mm: 40 = 0.5 mm).

The length of any circle can be easily measured with a lace or thread. Then the lace or thread is stretched along the divisions of the scale ruler and the circumference in centimeters is found out.

To prepare paste and glue, as well as in other cases, you will sometimes need to measure out a certain amount of water in a mug and weigh out some shares of dry glue, flour, etc. In this case, great measurement accuracy is not needed, so you can get by with the simplest means.

The amount and weight of water is measured with a beaker (1 cubic centimeter of water weighs 1 gram) or with existing utensils. A faceted tea glass holds 200 grams (or cubic centimeters) of water, a smooth thin-walled glass holds 250 grams, a tablespoon holds 12 to 15 grams, and a teaspoon holds 3 to 4 grams.

A small amount of dry substances can be weighed on homemade scales (see their description on page 149), and coins can be used as weights:

A 5-kopeck coin weighs 5 grams,

A 3-kopeck coin weighs 3 grams,

A 2-kopeck coin weighs 2 grams,

a penny coin weighs 1 gram.

For accurate weighing, if necessary, with the permission of the teacher, you can use the scales available in the physics and chemistry classrooms of the school.

Material marking

The material is marked in all cases when they want to cut out some part from it according to the drawing or at least separate (cut, saw off) a piece of the required size. For members of the Skillful Hands circle who do not yet have sufficient experience in working with tools, it is especially important to learn how to saw and cut material exactly along the drawn lines.

Paper, cardboard, plywood, bars and boards are marked with a soft black pencil. Suitable for this purpose, for example, school pencil"Pioneer" or even softer. A hard graphite pencil will leave an indented mark on the material, which is sometimes undesirable. The trace of a chemical pencil is difficult to remove; it dissolves in liquids and stains the material. Therefore, a chemical pencil is never used for marking. Colored pencils are also inconvenient: they have thick leads that leave wide lines.

When transferring drawings for sawing onto plywood, on the contrary, it is better to use a hard pencil. It is easier to sharpen it, it is more convenient for them to trace thin lines of a drawing, a trace from hard pencil It comes out clear on carbon paper.

When marking a wooden block or board (but not plywood), you can use an awl instead of a pencil.

Tin and other metals in sheets are marked with a metal scriber, which can easily be replaced with a sharp nail, an awl, a piece of a knitting needle or another sharpened rod. Any scriber leaves a clear mark on the surface of the tin.

Straight lines are marked using a ruler. First, the ruler is placed edge-on on the material and the extreme points are marked with a pencil. Then lay the ruler flat and draw a line along it between the intended points. The pencil is pressed against the edge of the ruler and held almost perpendicular, with a very slight tilt. They also work with a scriber.

A straight line on a long board can be marked in the same way as carpenters. A thin cord is rubbed with chalk. One end of it is fixed to the board, for example, with an awl. The second end, pulled tightly, is held by hand. Using the fingers of the other hand of the cast, they pull the lace upward and immediately release it. He hits the board and leaves a clear chalk line on it. It is more convenient to make such markings together, holding both ends of the cord in their hands. Instead of chalk, you can rub it with a piece of charcoal.

When drawing a marking line along a board, sheet of paper or plywood, you must ensure that the line does not run obliquely, but strictly parallel or perpendicular to one of the edges of the board or sheet. You can check whether the line is correctly laid by measuring the distance to the parallel edge at both ends of the line.

If you need to cut a rectangle out of some material, then first draw one of its sides along a ruler - a vertical or horizontal line. Then, attaching a triangle to this line with one of the legs, draw along the second leg perpendicular line. All right angles of the marking must be checked with a square. This is especially important when marking the unfolding of a cardboard box or geometric figure. The slightest mistake will lead to the box being skewed.

Acute and obtuse angles are marked according to transporter.

Draw a straight line along the ruler and mark on it the point from where you want to draw an oblique line to form an angle. The protractor is placed so that the middle of its lower edge lies on the intended point. A second point is placed at the upper arc of the protractor - at the division corresponding to the marked angle. After this, the protractor is removed, and a straight line is drawn between the marked points, extending it to the required length.

In a picture or drawing, the angle value is sometimes not indicated by numbers. You can measure it with the same protractor.

Curved lines are drawn along curved slats. A thin strip is bent according to the drawing and in this form is lightly secured with two or three nails or pins on the material to be marked. Draw a line along the rail with a pencil.

You can mark curved lines differently: draw on a grid on paper in life size drawing and transfer it through carbon paper onto wood - in the same way as drawings for sawing are transferred. The finished parts are then applied to the same drawing for verification.

Circles are drawn with a compass. If you need to draw a large circle and the size of the compass is not enough, use a homemade circle cutter, described on the page. In this case, instead of a knife, insert the tip of a pencil or an awl into the hole of the circle cutter. There is an even simpler way to mark large circles on plywood: hammer a nail in the center, tie a thread to it (do not tighten it tightly), and a pencil to the other end. The length of the thread is taken equal to the radius of the circle. The thread is pulled and a circle is drawn.

We need to teach the kids how to use compasses in other cases as well. For example, using a compass it is easy to divide a straight line in half, exactly in the middle. For this purpose it is enough extreme points draw two arcs of the same radius - more than half a line. The intersection points of the arcs are connected along a ruler by a straight vertical line. It will run perpendicular to the horizontal line and divide it into two equal parts.

Sometimes you need to cut out several identical shapes from cardboard, plywood or tin. The best way to do this is to cut out a pattern - a template - of such a shape from cardboard, and then apply it to the material and trace it with a pencil. All figures will be the same.

Any material must be marked sparingly so that there is as little waste as possible and the work is made easier. For example, cutting a small rectangle from a sheet of cardboard or plywood should be done in the corner of this sheet, where it is enough to make two cuts, and not in the middle, where three or four cuts will be required and unnecessary strips of cardboard may remain.

Each manufactured part must be checked: does it correspond to the drawing in shape and size, are its corners cut correctly, does it fit tightly to other parts, etc. To check, use the same measuring and marking tools: ruler, squares, compass.

Only after careful checking of all the details are they put together to form the intended thing.