How to use a caliper: step by step instructions. How to choose a caliper for the work of a home master Components of a caliper
The caliper got its name due to the main element of its body - the rod, but the compass we are used to is a little far from this tool with its device. To understand a subject full of mysteries, we will try with the help of this article, consider its structure and principle of operation.
Caliper device - the main components and their purpose
The device of the caliper does not look complicated on the surface, but its parts are so compact and optimally composed that they make this device easy and convenient to use. And it can do a lot, and the measurements that are performed with its help are very important in many areas of industry and construction. When using a caliper, we get the linear dimensions of objects, both external and internal. And the accuracy, which in some models reaches an enviable level, makes this simple tool more and more in demand.
The purpose of the caliper is to measure the length, diameters, depth, but what provides this opportunity, we will analyze using the example of the simple form this fixture. The main node is the ruler, which is called the bar, giving part of the name to the tool. The divisions on it are usually 1 mm, and the total length is usually 15 cm, but individual models may be longer. The ruler determines the maximum size that this tool can measure.. Which means maximum length or the diameter of the object must be no more than 15 cm.
At the end of the ruler are sponges, or rather their halves, and the second halves are located on a movable frame that moves along the ruler, measuring the size of the object being examined. Sponges are internal and external, in the first incisors look outward, in the second - at each other. Consequently, the first ones are inserted into the object and move apart to fix the internal geometric parameter, and the second ones are moved apart widely, and then come closer to fix the object under study among themselves. To accurately measure or transfer it to another surface, the movable frame can be fixed with a special screw located on it.
On the main ruler, we can see the integer value of the desired size, but the vernier scale, which is applied to the bottom of the frame, to be exactly under the main ruler markup, will help clarify the result. The vernier has ten divisions, each of which measures 1.9 mm, the entire scale is 1.9 cm long. These are the parameters of a conventional household caliper, on other models this ratio changes. Having found the vernier division, which coincides with any division of the main scale, you can refine the desired value to tenths of a millimeter. The use of a caliper is not limited to internal and external dimensions, you can also mark the depth of the holes, for this there is a tail that extends from the ruler. This is the depth gauge.
Caliper - classification and marking
The measuring tool caliper can be of 3 types and about 8 sizes, in any case, according to domestic regulatory documents. Moreover, when buying any precision instrument, it is important to focus on the standards by which it is made and calibrated. It is divided into types depending on the indicator of the measured value, from which we take the desired numbers. it can be vernier (ShTs), dial (ShTsK) and digital (ShTsTs) calipers. In the first case, we will have to go over both scales ourselves with our eyes, count the divisions and report the result. In the second case, we will see the numbers on a mechanical scale with a moving arrow, but in the third case, we will be shown the finished result on the display.
Within these species, subspecies can also be divided depending on the design and length of the main ruler. For example, you can divide tools by the type of material from which they are made. ShTsT-I can serve as an example of a hard alloy tool. There are differences in the device of sponges or accessories. So, ShTs-I and ShTs-III differ in the location of the jaws, in the first case it is two-sided, and in the second - one-sided. But in ShTs-II there is a micrometric feed frame, which will make marking easier if you need to transfer your measurements to another plane. It makes no sense to discuss the differences in standard sizes for a long time, one has only to say that the larger the ruler, the greater the error in the values obtained.
How to measure with a caliper - instructions for beginners
Most technically developed people it is intuitively clear how to use a caliper, so we briefly recall the main points.
How to measure with a caliper - step by step diagram
Step 1: Fixing the Part
First check the tool for serviceability, to do this, reduce the sponges without a part to zero, look at the clearance, how correctly they are connected, and also look at the scale to see if the zeros on the two scales coincide. After a positive result, you can start working with the part. It is most convenient to work when the tool is in your right hand, and the part to be measured is in your left, or it is completely fixed somewhere. If you are left-handed, then the ratio is, of course, the opposite. For measuring outer dimension open the jaws of the caliper, place an object between them and connect them. They should rest against the edges of the part being examined. If it is hard, you can lightly squeeze the lips for a firm touch. If the part is soft, do not do this, the results will be distorted.
Effort is controlled simply, if you try to move the lips relative to the object, then they should do it reluctantly, but if you also need effort for this, then you obviously squeezed it.
Move the frame more conveniently with your thumb right hand, while holding the barbell with the rest. Check the position of the caliper relative to the object, if there are any distortions (the sponges should be at the same distance from the edge of the object on both sides), it is better to raise the structure to eye level. To see more clearly, it is better to hold the object in the plane behind the instrument with the left hand, and not in front. Now you should carefully tighten the mounting screw, index and thumb, while the rest should continue to hold the bar. When the value is fixed, the part can be put aside and proceed to the study of the next step, how to measure the resulting number with a caliper.
Step 2: Remove value
It is best to read the readings also at eye level. First of all, we write down the value of the main scale, i.e. integer. To do this, we are looking for a stroke on the main rod, which is closest to the zero value of the vernier, this is an integer number of millimeters. You can remember, or you can mark it somewhere on a draft. Now we are looking for a stroke on the vernier that is closest to its zero, but also exactly coincides with some division on the bar. Its serial number should be multiplied by the division value of the vernier used (usually 0.1 mm). If you are not sure that you know this value, look in the passport of this caliper.
Now the matter is small, you just need to sum up these numbers, and the result is ready. For example, on the bar you had a value of 35 mm, and on the vernier you counted 4 more divisions, then general meaning equals 35.4 mm (3.54 cm). After work, the tool is wiped (degreased), the sponges are slightly pushed apart (by a couple of mm), the clamp is loosened and placed in a case. If storage is planned for a long time, then you can lubricate it against corrosion.
As you will see from this article, modifying an electronic digital caliper is a very simple procedure, but it must be done carefully so as not to damage the tool. The design of the electronic caliper provides 4 special contacts. These contacts, for example, can be used to connect an external power supply, control functions, etc.
The pin assignments are (from left to right): negative terminal, data, clock, and positive terminal.
To activate the hidden options of the electronic digital caliper, pins 2 and 4 must be connected together.
Perhaps different electronic calipers have some differences, but in general, their modification is carried out in the same way.
The first step in finalization is to find the screws holding the case together. On our caliper, they are located under a plastic sticker. Their location can be seen in the photo.
After opening plastic case containing a circuit board, a display, and a few metal elements, you need to unscrew a few screws to remove printed circuit board.
Special care must be taken when handling printed circuit board and display.
The display is connected to the printed circuit board by means of a conductive rubber gasket. Be careful not to detach the display from the board, as this will make it difficult to align the connections during reassembly. And if the location is incorrect, the display may turn off spontaneously and strange characters appear on it.
After removing the printed circuit board of the electronic caliper, we get access to the necessary contacts.
Now you can solder 2 thin wires (the thinner the better). Solder one to pin number 2 and the other to pin number 4.
To close these terminals, it is best to use a micro button, for example, from an old computer mouse. The pins of the button need to be bent at a 90º angle (as in the picture) so that it fits snugly into the slot and therefore is held firmly in place.
After soldering the wires, the assembly of the electronic digital caliper is carried out in the reverse order. After assembly, soldered wires should stick out of the socket.
After that, solder the button and place it in the slot.
Because the button legs have been pre-bent, they spring the button and hold it firmly in place. Here's what it looks like.
By pressing a new button, we get access to some modes that were previously not available.
When the button is pressed for the first time, electronic caliper enters the fast reading (FT) mode, by pressing the "ZERO" button, we can freeze the measured value (H).
When the button is pressed again, the electronic caliper will enter the mode minimum value(MIN). In this mode, the display shows the smallest measured value.
If you press the "ZERO" button again, we will again switch to the mode of fixing the measured value (H).
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Expansion of the technical capabilities of the caliper.
Caliper - universal tool, designed for high-precision measurements of outdoor and internal dimensions, as well as hole depths.
I offer my homemade product, which expands the capabilities of this wonderful tool, namely: drawing circles up to 28 centimeters in diameter. Agree, it is very convenient to have two tools in one! Refinement will require a minimum of time and cost.
We need: a circuit breaker, a pencil, a paper clip, a terminal block, a dowel, a couple of bolts.
To begin with, we drill a caliper in three places: two holes on the bar and one on the vernier. The holes are 4 mm.
We remove the contact clamp from the unnecessary circuit breaker, and the inner metal part from the terminal block.
We assemble our design: we fasten the block on the bar, and the clip with the pencil inserted into it on the nonius, for fixing we insert part of the paper clip.
The distance between the tip of the dowel and the pencil lead I got exactly one centimeter. In the future, we will add this centimeter to the radius of the circle we need, which we want to draw. For example, we need to draw a circle with a radius of 10 cm. We set 9 cm on the caliper scale and mentally add one more centimeter.
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Help the toolmaker
Inspection and repair of caliper tools
Malfunctions of calipers and their check.
The most typical malfunctions of caliper tools, as a result of which the accuracy of readings is violated, are: wear of the measuring surfaces and blunting of the sharp ends of the jaws; wear and deformation of the working surfaces of the rods and the frame; skew of the main frame; incorrect installation of the vernier; spring weakening; wear of the thread of the screw and nut of the micrometric feed, and a number of others. n The readings of caliper tools with a reference value of 0.05 mm are checked using gauge blocks of the 2nd accuracy class (6th category), and with a reference value of 0.1 mm - end blocks of the 3rd class.
The skew of the movable jaw is relatively immobile and is also detected with the help of an end measure of length.
Having set the end measure in two extreme positions, take readings and, by their difference, judge the magnitude of the non-parallelism of the measuring surfaces caused by the skew of the movable sponge.
The wear of the measuring surfaces is determined by the magnitude of the discrepancy between the zero strokes of the rod and vernier scales with tightly shifted jaws. For caliper tools with a reading of 0.02 and 0.05 mm, the clearance between the measuring surfaces should not exceed 0.003 mm, and for caliper tools with a reading of 0.1 mm - 0.006 mm. On fig. 79.6 shows how, with the help of end measures and a curved ruler, it is possible to determine the size of the gap between the measuring surfaces by eye.
Rice. 1. Checking the calipers.
The scheme for checking the wear of the working surfaces of the sponge for internal measurements is shown in fig. 1, e. Between the jaws for external measurements, a limit measure is placed, and then, using another caliper, the distance between the jaws for internal measurements is checked. This distance must be equal to the size of the gauge block.
The wear of the rod is set with a curved ruler to the light.
Repair of calipers. The wear of the working surfaces of the caliper tools is eliminated by straightening the jaws with their subsequent fine-tuning. Straightening also eliminates defects in the measuring surfaces of the jaws and matches the zero strokes of the scales. After straightening, they begin to refine the measuring surfaces with plane-parallel laps, for which the caliper is fixed in a vice, the lap is placed between the jaws, and the frame is shifted until the jaws come into contact with the lap. In this position, the Frame is fixed with a locking screw and, moving the pri-g between the jaws with a slight effort, R finishes the surfaces from the side of both sharp and blunt jaws until flatness, parallelism and the same size of the solution on both sides are achieved.
Rice. 2. Fine-tuning of the measuring surfaces of the caliper.
The straightness of the measuring surfaces is checked with a curved ruler, and the parallelism of the jaws of the frame with the jaws of the rod and the dimensions between them are controlled by end measures, while the force with which the measure is inserted between the jaws must be the same for both sides. By inserting the end measure not from the end of the jaws, but from the side along the entire plane and at the same time slightly turning it, you can determine the degree of parallelism of the surfaces. If the tile is delayed by the ends of the jaws, freely rotating further over the entire surface, or if there is a gap in front, then the jaws are not parallel.
The outer surfaces of blunt jaws are brought to parallelism. The size of the jaws should be equal to a whole number of millimeters with tenths (for example, 9.8 mm). After finishing the sponges, the vernier is set to zero division of the rod. To do this, the jaws are shifted until the measuring planes touch and the movable frame is clamped. Then the vernier is moved until the first and last divisions coincide, while its scales must exactly match the first and corresponding divisions of the bar. In this position, the vernier is fixed.
When repairing a large number calipers, the finishing of measuring surfaces can be mechanized. The scheme of mechanized finishing is shown in fig. 2b. A complex zigzag movement during mechanical finishing is formed as a result of two movements: the horizontal reciprocating movement of the lap 1 (at i = 400 strokes / min and a stroke length of 23 mm) and the vertical translational movement of the caliper 2 (periodic feed movement 5 = 1, 5-3 m / d. stroke. lap). To ensure the quality of finishing, both movements are coordinated with each other. The caliper only receives vertical movement when the lap moves. At half the stroke of the lap at maximum speed, the caliper is also given a small amount of vertical feed. At the extreme points of the path of the lap, where its speed is zero, the vertical feed of the caliper stops. Finishing pressure should be P-2-3 kg/cm2.
When mechanically finishing the jaws of the caliper, cast-iron laps are used, cartoonized with M20 micropowder.
Repair of lightweight calipers in case of breakage of sponges is carried out in the following order. After tempering in a salt bath, the worn or broken end of the sponge is cut off. Then in the thickened part of the leg disc cutter cut a groove that is equal in width to the thickness of the sponge. A new sponge blank is inserted into the groove of the leg and two or three holes are drilled together, then both parts are riveted. Sponges are sawn to the specified dimensions and hardened. After stripping, their measuring surfaces are finished.
Rice. 3. Caliper repair.
If both jaws break, the upper leg is completely replaced with a new one. To do this, knock out the rivets and remove the broken leg from the rod. In the blank of a new leg, a rectangular window is milled and filed, equal in shape and size to the end of the rod. Then a leg is put on the rod, the perpendicularity of its position relative to the faces of the rod is verified, holes are drilled in another place and the leg is riveted. The jaws are filed so that their configuration and dimensions correspond to the shape of the frame jaws, and then they are finished.
The broken sponges of the frame are replaced with new ones, for which, having knocked out the rivets and removing the unusable sponge, a blank of a new sponge is riveted in its place, filed, hardened and brought to a finish.
The repair of broken jaws of stamped-bar calipers is somewhat more difficult, since the entire stem, together with the jaws, has the same thickness and it is impossible to insert a new jaw. Overlay riveting does not always provide sufficient bond strength. Welding can be used, but it is best to replace the entire top of the stem with a new leg.
For this purpose, after annealing and cutting off the jaws, the end of the ruler is milled or filed by hand so that shoulders are formed on the edges of the ruler, against which the leg rests. When filing the measuring planes of the jaws of the legs, it is necessary to ensure that the zero division of the vernier of the frame approximately coincides with the zero division of the scale on the ruler, since with a significant displacement of the vernier at its end, too much metal will have to be removed, which will worsen the quality of the repair.
Rod deformation can be caused by warping or uneven wear of the rod. working surface. The bending of the rod is eliminated by straightening, carried out by bending in a vice with the help of three narrow brass washers.
Uneven wear of the rod is eliminated by sawing and finishing on the lapping plate, controlling the straightness with a curved ruler or the paint method. Dents and nicks are cleaned with a velvet file, a whetstone and fine sandpaper with oil.
To eliminate the misalignment of the vernier with the scale of the ruler, it is rearranged. If the end of the vernier rests against the wall of the frame window and cannot be moved, then it is filed. At the same time, the holes for the screws are also sawn, after which, by rearranging the vernier, they fix it in the correct position.
Repair of other universal measuring tools(goniometers, calipers and calipers) is similar to the repair of calipers.
The main defects of the depth gauge can be the non-straightness of the supporting surface, the lack of perpendicularity of the ruler relative to the reference plane, and incorrect installation of the vernier.
To ensure the straightness of the supporting plane of the body and the end of the ruler, they are brought together on a plate. Having extended the ruler above the plane of the body, using a curved square, check its perpendicularity relative to the reference plane.
Repair of the vernier is done in the same way as the vernier caliper. When setting the ruler to a certain size, its end is combined with the plane of the depth gauge. In this position, the zero division of the vernier is combined with the zero division of the scale of the ruler or with the division corresponding to the height of the set of gauge blocks, after which the vernier is fixed with screws.
