Compasses from improvised means. Compasses from improvised materials

What do we know from the history of the kronzikul? The compass known to us from school serves to draw perfectly regular circles. The history of this tool has more than one thousand years, as far as one can judge from the perfectly accurate circles that archaeologists see on the surfaces of ancient structures. During excavations of the mounds of the ancient Gauls, in France, an ordinary compass made of iron was found. And during the excavations of Pompeii, scientists were surprised to find a slightly different tool, it was about the same purpose, but very, very complex.

As it turned out, it has changed little since the time of the Roman Empire, in the same form it is produced and used in the modern world, although now there is even a digital caliper. This term of foreign origin, consists of the German word "krone" - a crown and the Latin "circulus" - a circle. Belongs to the category of drawing and measuring instruments. It has two legs, most often of an arcuate shape, between which you can set the desired angle using a micrometer screw, which is also included in the design of the tool. The screw serves to be able to adjust the desired distance between the legs. There is also a simplified version.

In the photo - for measuring the outer diameters and dimensions of parts.

Today, such a device is used in production to measure the outer diameters and dimensions of parts (one category of tools), as well as to determine the dimensions of the inner diameters of parts (other fixture models). In medicine, this tool is also widely used in a variety of industries, but all of its varieties are associated with microscopic elements, for example, in dentistry or neurosurgery.

According to the method of obtaining data, mechanical and electronic models are distinguished.
This tool, as a measuring device, does not need to be verified, because it is not included in the state register. To compare the dimensions of the details of an object with exemplary dimensions, this type of caliper is used. So, having measured a part with such a specific method, the data obtained are compared with the data of the samples, from which conclusions are drawn.

The caliper is also very convenient in turning, especially among woodworkers - indeed, when turning decorative parts made of wood, exact dimensions are often not very important and a tool that allows you to quickly, on the go, evaluate the size of a part or workpiece is popular. The caliper is especially convenient when turning identical parts, and every turner faces such a task regularly. The presence of several such tools greatly speeds up the process - you can pre-set them to the main dimensions of the part and not be distracted by measurements with a ruler or caliper.

A simple caliper, like in the photo above, is not difficult to make yourself. It can be seen that the difficulty is only to choose the right material, then - a little simple plumbing work.

On the drawing, calipers with measuring diameter up to 180 mm.

What was used in the work.

Tool.
A set of ordinary plumbing tools, something for drilling holes. I used a simple grinding drum installed in a wood lathe. I used a small angle grinder with a thin cutting disc, an electric sharpener. Hallmarks with numbers came in handy. You can not do without a steel plate or anvil.

Materials.
A piece of sheet steel of suitable thickness. I used stainless steel, 1.5 mm thick. It is desirable that the workpiece be smooth, without dents. Medium coarse sandpaper. Few hardware.

So.
In the manufacture of the tool, several deviations from the drawing were made - the legs of the caliper were taken to be of the same thickness, instead of a rivet, a conventional M6 screw was used. Practice has shown that two reinforced "body" washers and a washer-stopper allow the legs to move smoothly, with little effort. The tightening torque of the nut can be adjusted.
The drawing of the caliper leg was printed on a printer on thick paper, adjusting the size to the required one. Having cut out, I received a template. The contour of the leg can be transferred to the workpiece using carbon paper.

Everything that is possible is cut off by the "Bulgarian". The difficulty is cutting the inner radius. It had to be cut out with a very small "remnant" of the cutting disc.

After rough sawing, I finished the contour on a sharpener and a magic file.

Here, again, there is a problem with the inner radius. I solved it by making a small grinding drum from a birch log with a radius slightly less than the inner radius of the caliper leg. On the block of wood, without removing it from the machine, I wound a sandpaper, fixed the ends with adhesive tape.

After complete finishing the shape of the legs, holes for the hinge were drilled.

An M6 bolt of suitable length was selected, the legs were fastened with an impromptu hinge. It turned out to be simple and quite efficient, moreover, the force with which the legs move can be adjusted.

We can recommend an alternative manufacturing option, more, hmm, classic - without dancing with angle grinders. Along the contour of the legs, a series of holes with a diameter of 4 ... 5 mm are drilled and punched. A small chisel cuts through the jumpers between the holes. Further the same.

The hardening of the working part of the legs has been omitted, and when using a tool not only for pieces of wood, it would be better to do it:
- heat the working parts of the legs to a length of 20 mm to a light cherry-red color and cool through a layer of oil in water;
- straighten the legs of the caliper after hardening and clean with abrasive sandpaper.

In the described sequence of manufacturing calipers, you can make some changes.
If the blanks for the legs are small and it is inconvenient to mark them geometrically, then two templates are made from thin sheet steel for marking them: one for drawing lines on which it will be necessary to mark the centers for the auxiliary holes, and the second (smaller) for marking the contour of the leg . Previously, a pattern is applied, which is a contour. First, auxiliary lines are applied on the workpiece according to the first template, and then the main lines are applied according to the second template of smaller sizes. The latter is set so that its contour lines are equally distant from the applied auxiliary contour lines for the centers of the auxiliary holes.

If the material for the blank of the caliper is a strip of 25X4 or 30X4 mm, then straight lines are marked on them, reproducing the shape and length of the legs in an unbent form. Then the strip is chopped off with a chisel on a plate or in a vice, stepping back 0.5-1 mm from the marking line, and filed in a rough way. After that, the leg is heated and bent by hammer blows on a round mandrel, the dimensions of which correspond to the bending radius of the legs.

The final processing of the caliper does not differ from the sequence above.
With this method of manufacturing calipers, less time is spent, since there is no need to drill auxiliary holes along the contour of the workpiece. The latter method is most often used in the manufacture of an inside gauge, since bending the ends of its legs is very simple, while bending the legs of a caliper is a rather complicated operation that requires certain skills and abilities.

Caliper test and technical requirements for it. The test of the caliper is to open and compress its legs. In this case, the movement in the hinge should be smooth, and the ends of the legs should converge tightly. The surfaces of the caliper must be clean, free of scratches, nicks and dents, and sharp edges blunted. The ends of the legs of the caliper must be hardened to a length of 20 mm to a hardness of HRC 40-50.

It remains to be said that the tool in the arsenal of a wood turner is in great demand. Practice has shown that it is better to have several pieces. Used at the same time, a maximum of four.

It was in the evening, there was something to do ...

Once I got tired of drawing circles using the well-known "compass" type "bar with two nails" ...

I decided to buy a compass - in stationery there are school "goat's legs" that cannot draw a large circle, at least 50 cm, and even so flimsy that they bend during the process of drawing a circle (as schoolchildren draw something with them) ... I realized that this is not an option.

I looked on the websites of tool stores in my city - there are no compasses (nixt compasses ...). But I found a couple of Moscow online stores where I was offered to buy a good compass for 3500-4000 rubles. :wacko: Why is this necessary?? I thought.

And I decided to make a compass with my own hands. By the way, the manufacturing process took - only one evening.

Compasses materials

For the circle I used:

• square profile pipe - 15mm;
• M8 bolts with nuts and washers;
• M6 bolts with nuts and washers;
• shaft from a printer with a diameter of 3mm (any hardened rod will do).

Do-it-yourself compass assembly

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I cut off two pieces of pipe, the length is at your discretion, but at least 1 meter each, I used 30cm. It all depends on what circles you draw ...

The edges of the profile are cut off, as shown in the photo below, to insert the needle mounting bolts. Those. 3 out of 4 sides are cut off from the profile so that a plate for drilling under the needle mounting bolts remains.

And for the upper part - 6mm, because. M6 bolts are used there.

The top bracket can be made from 1mm thick sheet steel.

A 6mm hole is drilled at the top of the bracket and an M6 bolt with two nuts is inserted there - this is a handle for convenient rotation of the compass (see photo at the bottom of the article).

On the bolts that hold the legs in the bracket, wing nuts are put on to make it convenient to fix the position of the legs of the compass.

The lower M8 bolts are clamped in a vise, on the thread, close to the bolt head, a small notch is made with a round file - it will be more convenient to drill them, then a 3mm hole is marked and drilled for inserting a needle

It is better to grind the heads of the bolts in half so that the legs of the compass can touch as closely as possible.

And also, after inserting the needle, it is better to put a washer under the nut, otherwise the nut will rotate very poorly on the needle.

For the needles, two pieces of the shaft from an old printer were used - a hardened rod with a diameter of 3mm.

As a result, for an evening of work (the other evening I took it apart and painted it), I got an excellent compass with great advantages and few disadvantages.

About the shortcomings of my compass

• the legs of the compass do not compress completely due to the heads of the bolts, the needles do not close to zero, about 1 cm remains, i.e. compasses cannot draw very small circles, less than 1cm. This can be solved by increasing the width of the upper bracket so that the legs of the compass are mounted at a greater distance from each other, but for myself I decided that I do not need circles less than 1 cm in diameter;
• the thickness of the profile pipe was not chosen very well, because it includes only an M8 bolt (when using an M10 bolt, there will already be 2.5 mm to the edges of the profile), in which a 3 mm hole has to be drilled and when the nuts are tightly tightened, the bolt breaks in a thin place. I recommend using a 20 mm profile, into which you can safely insert an M10 bolt, which will increase the strength of the needles. But in my case, the tightening force is enough to hold the bolts, one needle fastening bolt broke only when I decided to tighten it with 2 wrenches quite hard: unsure:
• this compass can only draw with needles, not with a pencil, but for marking circles on wood and sheet steel it is much more convenient to use a needle (it turns out a thin and accurate line that is clearly visible), and not a pencil. If desired, you can make devices for attaching a pencil to this compass.

Otherwise, the compass turned out wonderful and already helps me in my work. It is possible that in the future I will make a version 2.0 compass, where I will take into account all the shortcomings of the first version.

Update

On the advice of experienced people from the wonderful chipmaker.ru forum, the compass was improved - the legs were turned 90 degrees, so that the bolt heads no longer touch, and the needles can be set at an angle - this is very convenient when drawing large circles. Thanks for the advice!

In the last two photos, the compasses have already been modified.

DIY compass photo:

Quite often, a large compass is needed to work with curved workpieces made of wood and laminate. It is used when it is necessary to cut circles or semicircles of large diameter, as well as in the manufacture of arched structures. Ordinary compasses, even with the use of attachments, cannot provide such a large circle diameter, and even large carpenter's compasses do not always cope. To solve this problem, you can do it yourself with a simple device for forming circles of large diameter.

The design of such a homemade compass is very simple, and everyone can make such a device. A round wooden rod 1-1.2 meters long is used as a base. The diameter of this rod can be anything, but the best option would be a size of 20-25 mm. With a greater thickness of the rod, a home-made compass will turn out to be too heavy and it will be inconvenient for work. These round rods can be bought at woodworking stores, or you can just go to the market and buy a thin handle for gardening tools.

At one end of a wooden rod, a hole is drilled about the diameter of an ordinary pencil. Then, with a hacksaw, the rod is cut along its axis. After that, you need to drill another hole (across the cut) for fastening the pencil. A bolt with a nut is threaded into this hole (it is better to take a clamping bolt, which has a convenient lamb for twisting and unscrewing). In the case of using a simple nut to clamp the pencil, you will need to use a wrench.

Then they take a plastic pipe of a suitable diameter (you can take a piece of pipe for hot water supply or heating). Its diameter is selected for the selected wooden rod, and the length can be in the range of 10-15 centimeters. Two holes are drilled in this tube with a drill, a nail is inserted into one of which from the inside of the tube, and a clamping bolt is screwed into the second.

Now you can start assembling the compass. In the part that will describe the circle, a pencil is inserted into the intended hole, and a clamping bolt is screwed into the hole through the cut and with its help the cut is tightened.

From the second end of the rod, a plastic cylinder with an inserted nail is put on it, which will act as the axis of a homemade compass.

It is necessary to use the compass as follows: set the required radius and fix the tube together with the nail-axis with the upper bolt. With well-chosen diameters of the wooden rod and tube, when the tube is clamped, the nail head will also be tightened. It is important not to overdo it when tightening the bolt, it is enough to tighten it a little by hand.

In joinery and carpentry, sometimes it becomes necessary to draw large circles. This can happen when cutting out round pieces of furniture, such as countertops, from blockboard or sheet material. I mean cutting round blanks from chipboard, chipboard, plywood, MDF. And in the construction business, when designing, figures are also cut out of drywall. For such markings, a large carpenter's compass is required, but it may not be enough in radius.

The fact is that the radius of the classic compass is limited by the length of the legs. And if you need to mark a circle with a large radius, for example, about a meter, then the standard tool will not help. For such work, you can make a fixture using parts that are likely to be found in any home workshop.

The main part of the tool is a wooden rod, the length can be taken about 1 meter. For most works, this is enough, however, the size is chosen as needed. The rod is better suited round, with a section of 20 mm. . By the way, a thin handle for a light country tool is well suited as a blank.

When choosing a diameter, you should immediately think about another important detail. A plastic tube will be put on the rod, and it should be slightly larger in inner diameter than the outer diameter of the rod.

On one side of the rod we drill a hole, the diameter is selected according to the diameter of the pencil. After that, we saw through the part with a hacksaw from the end along with the hole. Drill another hole across the cut for the lamb clamp bolt. A working pencil will be clamped into this device.

Now cut off a piece of plastic tube 100-150 mm long. , pierce with an awl or drill a hole through the tube in the center. Then from the inside we insert a thin nail into one hole, and expand the other and screw the clamping bolt into it. By the way, it is better to choose a nail with a large flat head, so it will be more rigid.

We collect all the details of the compass together, insert a pencil into the split end of the rod and clamp it with a lamb. From the other end, we put on a tube with a central axis and tighten it with a clamping bolt. We set the desired radius of the circle, the distance between the end of the pencil and the central axis and tighten the clamping bolt on the tube. This bolt will simultaneously press the head of the nail - the axis of the compass. Just don't pull it too hard, it will break quickly.

By the way, if you need to draw a circle somewhere on a construction site, and there is no time to look for suitable details, then you can use a simplified version of the compass. We take a thin long rail, we attach a pencil to one end with tape. We measure the desired radius and nail a thin sharp nail, it should go through the slats and become the central axis. I think it is clear that the tip of the nail and the sharpened end of the pencil should be on the same side of the rail. There is one inconvenience here, for accurate marking, sometimes you have to pull out and interrupt the nail several times, but in general you can work.

Topic from the site http://ostmaster.blogspot.ru/2012/10/blog-post_14.html