Topic: measuring instruments for straightness, flatness, horizontal and surface roughness. Topic: tools for measuring straightness, flatness, horizontalness and surface roughness Checking large planes using

Based on the review of methods and devices for flatness control, conclusions can be drawn.

The methods and devices currently used for high-precision flatness control are based on mechanical and optical principles. However, only optical instruments and methods can provide high precision control of the plane and surfaces of large extent.

Mechanical methods are mainly used in mechanical engineering and machine tool construction.

When checking flatness with surface plates, the measurement error has a large variation. It is caused not only by the deviation of the shape of the controlled surface, but also by the state of the surface of the surface plate.

When controlling flatness using a level, the main disadvantage of the method is its high sensitivity to temperature fluctuations.

Optical methods for measuring flatness are widespread and are distinguished by their versatility and reliability of control.

Optical methods of flatness control can be divided into optomechanical and optoelectronic methods.

Optical and mechanical measurements include measurement of deviations from flatness by collimation and autocollimation methods, sighting method.

Optoelectronic methods are carried out using visual and photoelectronic autocollimators. Optical-electronic devices are called devices that allow obtaining information about the geometric parameters, spatial position and energy state of an emitting object using radiation energy converted into an electrical signal, followed by its processing and registration. Information about the objects under study is transferred by optical radiation, and the primary processing is accompanied by the conversion of optical radiation energy into electrical energy using an optical radiation receiver.

Optoelectronic devices and methods are currently the most promising.

Thus, based on the review of testing methods and instruments, an optoelectronic device was developed for measuring the control of surface flatness. A flat meter was chosen as the basis of the device, since this device high accuracy measurements, a large length of the tested surfaces, reliability in operation and ease of use. Measurement of deviations from flatness of the developed device is carried out by a step-by-step control method. The essence of the step-by-step method lies in the sequential measurement of the displacement of individual points of the tested surface relative to the previous point.

With the step-by-step method of control, the choice of the base depends on the design of the device. When using a stepping bridge with a probe, a horizontal plane passing through the origin located at point A is taken as the base (Fig. 18).

The X and Y axes lie in this plane, and Z is perpendicular to it. The tested surface of the product is set roughly in a horizontal position.

The step bridge moves along straight lines AD and DC (with the end of the measurement at point C), and then along straight lines AB and BC (the same with the end at point C).

The values ​​of all points of the step measurement are calculated by the formula (1)

Pi- current readings of the measuring device during step measurement;

i - any of the points (on which the legs of the stepping bridge rest).

After finding all the points of the grid of the controlled surface, they are entered into the table and proceed to the construction of graphs in three coordinates, and then to the construction of the adjacent plane.

When conducting renovation works a very important procedure is to check the evenness of the wall surface. Especially in old buildings, in Stalin and Khrushchev buildings, this factor is very relevant, since at the time of construction this issue was not given due attention. The presence of curved walls, the presence of dents and bumps on them and other flaws can completely spoil the impression even with the most luxurious renovation. In this article, we will look at how to check the evenness of the walls.

What is a level?

The laser level, or the so-called level, is a device thanks to which it is possible to construct high-quality horizontal and vertical stripes. Moreover, it is irreplaceable assistant during the construction of structures and during interior finishing work.

The level contains LEDs and prisms, which are characterized by visible vertical and horizontal lines. Thanks to the laser level, there is the possibility of erecting smooth walls, leveling lighthouses, leveling the floor, ceiling and other surfaces, quickly and evenly laying tiles, laminate and other work.

Estimating the curvature of a rough wall

Estimating the curvature of the rough wall helps to determine the amount of work and to draw up an approximate list of future material consumption. The level works by building a virtual plane that is parallel to the wall surface and measuring the distance from the vertical plane to the previously marked points.

How to check the evenness of the wall with a laser level:

1. We select a mode at the laser level that helps to build a vertical plane, since the wall surface is located vertically. In the case of such work, a horizontal plane is displayed on the floor.
2. We move the level as close to the wall as possible, while the plane should be parallel to the wall, the beam should not touch it anywhere.
3. We prepare a ruler (a tape measure is not suitable), which we apply to the wall at different points. The resulting trace from the laser level determines the distance from the wall surface to the virtual plane.
4. At different levels, every 40-50 cm, we take measurements, which we enter into the table.

Thus, you can determine the point that corresponds to the most convex and most concave lines, find the general unevenness in comparison with the base vertical and determine the volume plastering works.

Evaluating wall flatness using a rule

Without applying laser level, check the flatness of the wall surface after finishing you can use the rule.

How to check walls for evenness after plastering using the rule:

1. We apply the device to the wall surface, determine if there is a gap between the wall and the rule.
2. Using a ruler, we measure the amount of clearance. Mostly unevenness finished wall corresponds to several millimeters, so it is very difficult to determine the value with a ruler.
3. We use a laser level, thanks to which we can make a more accurate measurement.
4. When determining vertical evenness, turn on the vertical axis construction mode. If it is necessary to determine horizontal evenness, then we use the horizontal axis.
5. For convenience, draw the corresponding line on the wall surface.
6. Place the level at an angle of 45 degrees to the wall surface.
7. The resulting laser line looks straight only if the wall surface is perfectly flat:
   • If there is a bubble on the wall, then in this area the line will deviate in the direction towards the level.
   • If concavity is present, then in this place the beam deviates from the vertical line away from the device.
8. Placing the tool at a 45 degree angle determines the size of the bump, which corresponds to the distance from the drawn ray to the bent line.

Important! Also, the level can be used to determine the evenness of corners. In this case, we direct the beam to the junction of the walls and thus check its verticality. If there is an even angle, then the beam will be strictly located. Otherwise, the unevenness of the corner is immediately visible when it is piled in one direction.

Currently, the level is very handy tool... In the old days, they used old-fashioned methods and somehow managed without this device, but now the use of the level saves time and effort in many ways, facilitates the repair process, so it is worth using Newest technologies and do not give up modern developments.

Checking flatness over a large wall area

This technique is convenient to use when determining the volume of plastering work, but it can also be used at the end of painting and plastering work in order to assess the quality of the completed process. Basically, before plastering, you can visually determine the differences on the wall, which are already noticeable.

How to check the evenness of the wall after plastering over a large area:

• We prepare a laser linear level (plane builder) and turn on the vertical plane.
• We set the laser level near the edge of the wall, while the vertical laser plane should be parallel to the wall surface.
• On the floor along the entire wall, we make marks that should be at the same distance from the wall surface A and B.

Important! The builder builds a plane that is parallel to the planned surface of the stucco wall (not the plastered surface itself, but a plane that is parallel to it).

• We evaluate the work. If a fragment of the wall that does not have a laser beam appears on the wall opposite to the level, this indicates that the beam is interrupted due to the presence of a bulge on the wall.
• Move the laser level away from the wall surface and mark new points A and B.
• So that on one vertical section(from the floor surface to the ceiling) check the differences on the wall surface, take a wooden or steel meter with a millimeter scale. There should be no moving parts on the tool.

Important! Almost every tape measure is equipped with a movable hook, so the tape does not fit.

• On the selected vertical section of 1-2 cm, set the meter parallel to the wall surface. In this case, the free end of the meter should rest against the wall at right angles to the wall surface, and the laser line should appear on the plane of the meter. Thus, the first value is found, corresponding to the distance from the reference laser plane to the wall surface.
• Then, on the same vertical segment, we rearrange the meter a little lower, define a new value.
• We measure as many times as necessary.
• Now the obtained dimensions along the vertical line are compared with the data on the vertical segment of the wall surface after 40-50 cm, thus the curvature of the wall relative to the base vertical is found.

Checking evenness in a small area

After finishing the plastering work and preparing the wall surface for painting or wallpapering, as a rule, there are irregularities on the wall of 1-3 mm, which are inconvenient to find with a ruler. Defects appear especially clearly on walls prepared for painting and painted in dark colors on which straight lines fall at an angle Sun rays... There is a simple technique that is used to determine the evenness of the wall after final finishing until the moment of wallpapering or painting.

How to check the verticality of a wall in a small area:

1. At the beginning of the wall to be measured, on the floor surface, we visually mark a square, which can be marked with any objects or drawn with chalk. Such a figure is needed in order to subsequently put the builder at such an angle to the wall that you need.
2. We make marks: point A corresponds to the laser plane perpendicular to the wall, point B defines the laser plane at an angle of 45 ° to the wall surface.
3. Then we find the points C, D, E, which are determined by dividing the corresponding segment between the wall and the previously selected mark. As a result, the angles are obtained: 45/2 = 22.5, 22.5 / 2 = 11.25, 11.25 / 2 = 5.62.
4. At the moment the plane falls on the wall, it is flat at any angle of inclination only if the wall is characterized by an ideal flat surface... The presence of unevenness bends the beam, and the sharper the angle, the greater the curvature.
5. In the areas of irregularities, the beam will bend relative to the central point of the measured fragment:
   • If the beam is bent away from the builder, that is, point A1, there is a hole in this place on the wall.
   • If the beam is bent in the direction of the builder, which corresponds to point A2, then the wall is characterized by a bulge.
6. When the horizontal beam is tilted at an angle to the wall (in this case, the builder must be tilted relative to the horizontal plane), then an unevenness from left to right is determined on the wall, which corresponds to horizontal curvature, and not from top to bottom, which is observed with vertical curvature.

Important! The dip or bulge can be calculated in millimeters. To do this, you will have to remember the trigonometric formula from the course high school... We will use the cotangent, which is defined as the ratio of the leg adjacent to the angle (which corresponds to the distance A1) to the opposite leg (which is the desired value, that is, the roughness X).

By changing the angle of incidence of the beam on the wall surface, the ratio of A1 to the desired value of X changes. The smaller the angle of incidence, the greater the value of A1 or A2, which means that the coefficient will be larger: A1 / ctg “angle of incidence of the beam on the wall” = X.

Plastering with beacons and leveling

This method is one of the most accurate and fastest modern methods, in which a perfectly flat surface is formed in a short time.

How to get the job done with a level and beacons:

• We pre-prepare and treat the surface with a primer.
• We mark the vertical lines on which the beacons will be located, departing from the corner of 10 cm so that the distance between the adjacent ones corresponds to 15-20 cm less than the length of the rule.
• On the laser level, turn on the mode, thanks to which we form the vertical plane.
• On adjacent walls that adjoin the wall surface to be repaired, mark points at a distance of 5 cm from the corners.
• Set the level plane using the marks.
• At a distance of 4 cm from the edge, we make marks on the rule.
• Using the level, we set the rule vertically according to the marks, as a result, a gap is obtained between it and the wall, which, depending on the unevenness, corresponds to plus or minus 1 cm.
• We install beacons in the resulting gap and make sure that they will pass at any point of the installation, even if it is necessary to move the laser vertical plane.
• After the final marking and control over the performed actions, we prepare the plaster and process the wall surface with a small amount, while observing the markings every half meter.
• We attach the lighthouse to the wall surface and process it with plaster.
• We attach the rule to the lighthouse, correct it in the necessary places, tamp it so that the marks on the rule are aligned with the laser beam. If this procedure is performed with your hands, and not with the rule, then you can bend the beacons.
• Remove excess plaster from the lighthouse and the rules.
• Once again, we control the verticality of the lighthouse and leave it for a while so that the lighthouse can freeze.

Important! Drying time is influenced by the amount of plaster and the surface material.

• Moving on to the next lighthouse.
• After all the lighthouses have dried, we prepare plaster mix, which we apply between two beacons.
• With slow movements from bottom to top, we press the rule to the beacons and, shaking the tool left and right, smooth the plaster.
• Remove the excess mixture from the rule.
• Using a trowel or spatula, fill in the cracks in the wall surface.
• Using the rule, we make the finish pass.
• Moving on to the next two beacons.
• As a result of the work performed, an almost perfectly flat surface is observed, which is ready for finishing.

In addition, the level is used when building right angle in the bathroom or kitchen, as well as for the installation of large furniture. In this case, you need a tool that allows you to build vertical perpendicular planes. Nowadays, almost every model has a similar regime. How to check the evenness of the walls and draw the necessary perpendicular planes:

1. Using the marks that were marked when leveling the wall, set the level relative to the prepared wall surface. You can also mark new marks, then check that the laser plane is perfectly parallel to the wall surface and mark a right angle.
2. After that we mark the adjacent wall.
3. Following the above instructions, we beat off and expose the beacons.
4. We process the wall surface with plaster.

In this article, we have analyzed many stages of construction and repair work, during which it is appropriate to apply a rule and a laser level to check the evenness of the walls. Do not ignore all of the above points so that the quality of your new home design meets your expectations.

Checking large planes with a ruler and indicator.

A common way to control the straightness of planes is to check them using control rulers. This check can be carried out “for paint” or using gauge blocks and an indicator. Checking "for paint" is usually carried out with the rulers of the "Caliber" I-section. However, for large surfaces such a check cannot be recommended due to the deflection of the long rulers due to their own weight. This method can be successfully applied to check planes up to 2500 mm long, with a straightness tolerance of up to 0.1 mm per 1 m length. With tighter tolerances, for example 0.03 mm per 1 m, the length of the tested plane should not exceed 1500 mm.

More objective is the way to check large planes using a ruler and indicator. In this case, a control ruler with a length of 3-5 m is installed on the checked plane on two identical supports (for example, on two end measures) located from the ends of the ruler at a distance p equal to 0.22 of its total length. Surface deviations are measured according to the indications of an indicator sliding with a measuring tip along the top of the ruler and fixed on a stand that moves along the surface to be tested. Sometimes deviations of the surface from straightness with this method of verification are measured with end measures, measuring the distance from the bottom plane of the ruler to the surface of the product.

Using control rulers and others measuring instruments large sizes are associated with the need to take special measures to eliminate their significant deflection from their own weight. So, for example, the deflection from its own weight of a control ruler of an I-section, having a length of 3000 mm, when the supports are located at the ends, can reach 0.3 mm, and for rulers with a length of 6000 mm - up to 1.5 mm.

When checking, for example, machine bed guides that have a concavity in the middle, a ruler installed directly on the plane, due to deflection, will significantly distort the test results. To obtain the smallest deviation from the straightness of the control rulers under the influence of its own weight, it is necessary to locate the points of support of the ruler from its ends at distances equal to 0.2232 of the total length of the ruler, or with sufficient approximation at distances of 0.22 of the ruler length.

The deflection arrow due to its own weight of a ruler lying on two supports located at its ends is expressed by the formula

where P is the weight of one linear centimeter of the ruler in kg / cm; l is the length of the ruler in cm; E is the modulus of elasticity in kg / cm 2; I - moment of inertia in cm 4. If this ruler is put on two supports located from its ends at a distance of 0.2232 of the ruler length, then the deflection arrow will be expressed by the formula

Comparing the values ​​f1 and f2, we obtain

Consequently, the specified optimal position of the supports reduces the effect of deflection in comparison with the position of the supports at the ends of the ruler by approximately 48 times and, for the above case, can reduce the deflection of a 6000 mm ruler to 0.03 mm, and a 3000 mm ruler to 0.006 mm. A plane-parallel end block with a length of 1000 mm and a section of 9X35 mm, supported in this way, decreases in length with a deflection from its own weight by only 0.2 microns. By the way, its decrease from its own weight in an upright position is also 0.2 microns. The same terminal block with a length of 3000 mm with an optimal position of the supports is reduced due to the deflection by only 2 microns. This magnitude of measurement errors is of no practical importance and can be disregarded. The limit of application of long rulers is limited by their deflection from their own weight; usually in machine-building plants, control rulers are used only up to 5000 mm in length.

To control the perpendicularity of the machined surfaces to the base surface, in some cases on large parts, a boring machine spindle equipped with an indicator is used (see Fig. 219). However, with a significant extension of the spindle, its deflection from its own weight affects the accuracy of measurements, therefore, in this case, use exact levels bearing in mind that the base and the controlled surfaces are pre-checked and straight. If the base surface is separate, small in size and distant from each other areas (constructive or technological), then its horizontalness is checked by an optical method using a telescope and target signs, or by a hydrostatic device — the method of communicating vessels. The latter method is used to check the straightness and horizontalness of surfaces.

FIG. 221. Checking with a hydrostatic device.

So, for example, a hydrostatic device is used for alignment on the machine and for further monitoring of large beds on base sites in the horizontal plane. On the base platforms 1, 5 and 7 of the bed of the working stand of the rolling mill (Fig. 221), located in the same plane and processed in one installation, three communicating measuring vessels 2, 4 and 8 are installed. In each vessel (unit M) a micrometer head is fixed 11 with pointed measuring tip. The heads in all three vessels are zeroed from their scraped support surfaces. The vessels are connected by flexible hoses to the receiver 3; When installing the receiver on the support 9, which is located on the cage frame on the beam between the base platforms, water fills the hoses and measuring vessels. The moment of contact of the measuring tip with the surface of the water in the vessel is determined visually.

When the measuring tips touch the surface of the water in the vessels, the difference in the readings of all three micrometer heads is used to judge the correct location of the base pads in the same horizontal plane. After checking the horizontalness of the reference plane, you can check the perpendicularity of the supporting surfaces 6 of the legs of the bed and the guide surfaces 10 to the reference plane using a frame level or a machine spindle.

The accuracy of the instrument, not exceeding 0.02 mm, is quite sufficient. When working, it is necessary to avoid the appearance of air bubbles in the hoses, which can lead to gross errors. All three micrometer heads should be read directly one after the other to avoid increasing errors.

Straightness of planes during assembly and installation works verified by methods that directly measure linear or angular deviations. Linear methods include checking with a water mirror, a string method, checking with a telescope and target signs, etc. Using a level, a telescope and a collimator, angular deviations from straightness are determined.

The results of measuring the angles of the passing cutter

LABORATORY WORK No. 6

1. Purpose of work:

To study the devices and rules for the use of instruments for measuring straightness, flatness, horizontality and surface roughness.

2. Work schedule: 1 hour 20 minutes.

3. Workplace equipment:

3.1 Methodical instructions for this work

3.2 Posters

3.3 Rulers, levels, plates, block head, sleeves, fingers, paint, brush, samples.

4. Theoretical part:

The accuracy of the geometric parameters of parts is characterized by the accuracy not only of the dimensions of its elements, but also the accuracy of the shape and the relative position of surfaces. Deviations (errors) in the shape and location of surfaces occur during the processing of parts due to inaccuracy and deformation of the machine, tool and fixture; deformation of the workpiece; uneven machining allowance, etc.

The shape of flat surfaces is characterized by straightness and flatness.

of the peaceable site (Fig. 6.1. c.). Particular types of deviations from straightness and flatness are convexity (Fig. 6.1. A.), In which the deviations decrease from the edges to the middle and concavity (Fig. 6.1 b.) - the nature of the deviations is the opposite.

Surface roughness is a set of irregularities with relatively small steps that form the surface relief of a part and are considered within the base length.

Horizontalness is understood as the position of the checked plane relative to the horizon.

By the value of deviations, flat surfaces are divided into 16 degrees of accuracy in accordance with the established tolerances of flatness and straightness within the normalized area. As the degree of accuracy increases, the size of the tolerance increases.

1) Curve rulers are four types: with one-sided bevel from 75 to 125 mm long, with double-sided bevel from 175 to 225 mm, triangular 300 and 400 mm long and tetrahedral 500 mm long. Linear lines

Ki are divided into two classes 0 and 1.

2) Rulers with a wide working surface are divided into four types: steel rectangular section from 500 to 2000 mm and cast iron bridges from 500x4 to 4000x100 mm.

In the repair industry, rulers with a size of not more than 1000 mm are common. rulers are divided into three classes: 1, 2 and 3.

Corner rulers are used to simultaneously control the flatness and angle between two intersecting surfaces (for example, when checking the "dovetail"). These rulers from 250 to 1000 mm are used for the paint test.

Corner rulers have a triangular cross-section and two scraped planes that form a working angle.

Slabs... The surface plate is the main tool for checking the flatness of the surface "for paint". Plates are made of cast iron with dimensions from 100x200 to 1000x1500 mm of four classes: 0, 1, 2 and 3. 0, 1, 2 classes refer to surface plates, and 3 classes - to marking plates. The working surface of the surface plates intended for testing "for paint" must be scraped or cleanly sanded, and the marking surface must be planed. Plates are also checked for paint. Classes 0 and 1 include slabs in which the number of spots with a side of 25 mm is at least 25, for slabs of class 2 - at least 20, and for slabs of class 3 - at least 12. Plates on their surface must not have corrosion spots or shells. Surface plates are used as a base for various control operations using universal remedies measurements (thickness guides, indicator racks, etc.).

Levels are used to control the horizontal and vertical position of the planes of various parts, as well as to check the straightness and flatness of long surfaces. They are also used for the installation of equipment and for checking the accuracy of machine tools.

In the practice of measurements, the most common levels are bar (locksmith) and frame GOST 9392-60 (Figure 6.3 a, b). Bar and frame levels have a housing 1 with measuring surfaces 4, a main ampoule 2 and a setting ampoule 3. The level is set on the surface to be checked using an ampoule 3 so that the ampoule 2 is in the horizontal plane. Ampoule 2 measures the deviation of the surface from horizontal and vertical (only frame level). The ampoule of levels (Fig. 6.4) is a cylindrical tube filled with ether so that an air bubble remains inside the tube, steamy ether. Inner surface the ampoule has a barrel-shaped shape, therefore, when the level is horizontal, the bubble takes the upper position.

On the outer surface of the ampoule, there is a scale with a division interval of 2 mm. when tilted, the bubble moves relative to the neutral position (pulp point) proportional to the tilt angle. On the scales of the ampoule,

The slope of the level in millimeters is measured, referred to the length equal to 1 m. The division of the level ampoules is 0.02; 0.05; 0.10 and 0.15 mm-m and the error should not exceed ± 0.004, respectively; 0.0075; 0.015 and 0.02 mmm. The slope of the level surface by 0.01 mm corresponds to an angle of 2 degrees.

You can use the formula: Eº = 200 Ƭ · n, where Ƭ is the division value in (mm-m), and n is the number of divisions by which the bubble will move.

The maximum permissible error of frame and bar levels when installed with their base on a horizontal plane or on a horizontally located cylinder, as well as when installing a frame level (any of its vertical working surfaces along a vertical plane or a vertical cylinder) is equal to the deviation of the main ampoule from the average (zero) position 1-4 divisions.

When the frame level is installed with the upper side of the body on a horizontal surface or a horizontal cylinder, the limit of permissible error is ½ of the ampoule division. The levels for the price of the main ampoule are classified (according to GOST 9392-60) as follows:

Optical quadrants are devices in which a protractor is connected to a level. They are designed to measure the angles of inclination of flat and cylindrical surfaces of various products.

Surface roughness is a set of surface irregularities with relatively small steps forming the surface relief of the part, highlighted at the base length ℓ.

The roughness of the surface of the product is assessed by comparing it with roughness samples.

For this purpose, samples of flat or cylindrical

working surface. They are made from steel, cast iron, brass and other materials, processing with different surface roughness. Samples from the same material and the same type of processing are mounted in a special metal frame. The frames are assembled into a set, and for each material and type of processing, samples of different accuracy classes are selected, which can be obtained with this type of processing.

Comparison of the surfaces of the product and the samples is usually done by inspection or by touching the fingernail across the marks of processing. Touch control has some advantage over eye control. Both methods are able to provide a reliable assessment within the 3-5 roughness grades. The comparison accuracy can be increased up to grade 8 roughness using a magnifier of 4-6 times magnification.

Contact measurements of roughness are performed by continuous palpation of the product surface - using a profilometer (by moving the diamond needle).

5. The order of the work.

5.1 Checking the straightness by the light slit method (transmission) or by the trace method.

To improve the accuracy of observations, it is necessary to create a sufficiently bright and uniform illumination of the slit on the other side of the ruler. The lumen sample is made from a micron set of gauge blocks, a flattened bar with a wide working surface and a curved ruler. Two identical measures (along the edges) are installed on the bar, and end measures of such dimensions are placed between them so that a gap is created with an increase in the clearance 1, 2, 3, etc. microns to the required maximum lumen. Measurement error at

approximately 1-3 microns.

When checking by the trace method, the working edge of the ruler is drawn along the clean finished surface of the product. After that, a thin light trail remains on the surface of the tested product. If the surface is non-flat, then the track will be discontinuous. When checking the plane, it is necessary to set the straight edge sequentially in several positions and determine deviations from straightness in each direction.

5.2 When measuring by the method of linear deviations, the ruler is placed on two identical supports located on the surface to be tested and the distances from the ruler to the surface are determined using gauge blocks or special device with a measuring head. The supports are placed at a distance of 0.21 of the length of the ruler from its ends.

When measured by the "paint" method work surface the rulers are covered with a thin layer of paint. Then the ruler is placed on the surface to be tested. Longitudinal movement is reported to the ruler and flatness is determined by the location of the spots. Since the surface to be inspected consists practically of hills and depressions, paint remains on the hills as well. With good flatness of the product, the spots are evenly distributed over the entire surface. Consequently, the number of spots in a given area will accurately characterize flatness. A square with a side of 25 mm is taken as the calculated area on which the nature of the distribution of spots is considered.

For metal-working machines, at least 9 spots are allowed on the indicated square, for plates and fixtures - 16, for control plates and precision machines - 25, for measuring instruments - 30 spots.

Number of spots for different surfaces are given in Table 6.1.

Cylinder head repair, as you understand, is a long tedious work that requires special care. If you think that this is like pissing two fingers, you are very mistaken. I'll tell you why. First you need to remove the head, on some cars it is easier to remove the entire engine than to remove only the head. The removed head must be thoroughly washed with diesel fuel or better with gasoline, but it would be very good to put it in a bath with caustic soda.

Further visual inspection and diagnostics. Aluminum heads have such a feature or property - after overheating, the plane of the cylinder head bends slightly, after which the cylinder head gasket (cylinder head) begins to let oil and water in small or large quantities. Oil and coolant can seep both outside (as a result, the engine becomes dirty and with all its appearance shows that it needs repair), and inside the engine, where the coolant will enter the oil pan and mix with engine oil, turning into motor poison. which will stagger your car engine very quickly.

It is necessary to check the plane, for this I have a special perfectly flat ruler, made at the ultra-precise instrument factory specifically for measuring the unevenness of flat surfaces. I don't even know how a person who does not have such a device can measure the plane of the cylinder head ... But if you still find something suitable with a perfectly flat surface, then do the following: 1. Clean the plane of the head from carbon deposits, scale and remnants of the old cylinder head gasket. 2. Put your " measuring device"along the length of the head and see the gap between the device and the plane of the cylinder head, move the device along the entire plane, set it diagonally and look for the gap again. If there is no gap, then the plane of the cylinder head is in order; if there is a gap of 0.5-1mm, then it is better to cut the head or if allow finances to put a new one.If the gap is more than 2mm, then the head needs to be restored, that is, it must be trimmed. When trimming the cylinder head, the curved layer of the plane is removed, after which the cylinder head can be used again. that the oil has become twice as much, and the half-empty radiator will simply pour more antifreeze into the radiator and go further, in a few days it will get for repairs and spare parts.

yamotorist.ru

How to check the cylinder head on a VAZ 2114 - Repair 2114

To perform the work of checking the cylinder head, you will need:

• set of flat probes
• special template or wide locksmith's ruler

Related videos:

Remont2114.ru

Checking the cylinder head

carmanz.com

How to check the cylinder head after grinding?

Checking the cylinder head is, in principle, not so difficult.

Clean the cylinder head from dirt, oil, shavings. Carefully inspect the head from all sides to ensure that there are no cavities and cracks.

In specialized workshops, the plane of the block head is checked with a special template.

At home, when this template is not available, you can check the flatness with a metal wide long ruler. It must be applied to the plane of the head with an edge, the figure shows in which places to apply

And check the gaps with a feeler gauge. The gap is checked around the entire perimeter. Ideally, there should be no gaps. But if the gap is not more than 0.01 mm, then this is allowed.

I will emphasize and highlight: a new or polished cylinder head, the clearance is NOT MORE THAN 0.01 mm.

Because with the left gaps of 0.1 mm (in some repair instructions this typo was made), there will be a high probability of breaking the block head gasket. And this is again the analysis and repair of the cylinder head, or even the entire engine, up to its replacement.

The cylinder head must also be checked for leaks. This can be done, for example, by pouring kerosene into the cooling cavity by plugging the liquid supply hole. Pressure testing is also done with compressed air at about 1.5 - 2 atmospheres, but of course you need a compressor, a bath, that is, certain conditions.

When the head is checked, ground, and again checked for flatness, for tightness, then you can install the valves, having previously rubbed them, and after assembly, also check them for kerosene leakage. If the kerosene does not flow for about half an hour, then this already well means the valves are lapped.

Clearly, the cylinder block must also be cleaned of carbon deposits, rinsed from dirt, cleaned and blown through all channels. Wash the crankcase, the oil pump intake screen, make sure that the oil pump itself is working. Well, you can start final assembly motor.