How to prepare a board made in Eagle for production
Preparation for production consists of 2 stages: technology constraint check (DRC) and generation of Gerber files
DRC
Each manufacturer of printed circuit boards has technological restrictions on the minimum width of tracks, gaps between tracks, hole diameters, etc. If the board does not meet these restrictions, the manufacturer refuses to accept the board for production.
When creating a PCB file, the default technology constraints are set from the default.dru file in the dru directory. Typically, these limits do not match those of real manufacturers, so they need to be changed. It is possible to set the restrictions just before generating the Gerber files, but it is better to do this immediately after generating the board file. To set restrictions, press the DRC button
Gaps
Go to the Clearance tab, where you set the gaps between the conductors. We see 2 sections: Different signals And Same signals. Different signals- determines the gaps between elements belonging to different signals. Same signals- determines the gaps between elements belonging to the same signal. As you move between input fields, the picture changes to show the meaning of the entered value. Dimensions can be specified in millimeters (mm) or thousandths of an inch (mil, 0.0254 mm).
Distances
On the Distance tab, the minimum distances between the copper and the edge of the board are determined ( Copper/Dimension) and between the edges of the holes ( Drill/Hole)
Minimum dimensions
On the Sizes tab for double-sided boards, 2 parameters make sense: Minimum Width- minimum conductor width and Minimum Drill- minimum hole diameter.
Belts
On the Restring tab, you set the sizes of the bands around vias and contact pads of lead components. The width of the belt is set as a percentage of the hole diameter, and you can set a limit on the minimum and maximum width. For double-sided boards the parameters make sense Pads/Top, Pads/Bottom(pads on the top and bottom layer) and Vias/Outer(vias).
Masks
On the Masks tab, you set the gaps from the edge of the pad to the solder mask ( Stop) and solder paste ( Cream). Clearances are set as a percentage of the smaller pad size, and you can set a limit on the minimum and maximum clearance. If the board manufacturer does not specify special requirements, you can leave the default values on this tab.
Parameter Limit defines the minimum diameter of the via that will not be covered by the mask. For example, if you specify 0.6mm, then vias with a diameter of 0.6mm or less will be covered by a mask.
Running a scan
After setting the restrictions, go to the tab File. You can save settings to a file by clicking the button Save As.... In the future, you can quickly download settings for other boards ( Load...).
At the touch of a button Apply established technology limitations apply to the PCB file. It affects layers tStop, bStop, tCream, bCream. Vias and pin pads will also be resized to meet the constraints specified in the tab Restring.
Button press Check starts the constraint control process. If the board meets all restrictions, a message will appear in the program status line No errors. If the board does not pass inspection, a window appears DRC Errors
The window contains a list of DRC errors, indicating the error type and layer. When you double-click on a line, the area of the board with the error will be shown in the center of the main window. Error types:
gap too small
hole diameter too small
intersection of tracks with different signals
foil too close to the edge of the board
After correcting the errors, you need to run the control again and repeat this procedure until all errors are eliminated. The board is now ready to output to Gerber files.
Generating Gerber files
From the menu File choose CAM Processor. A window will appear CAM Processor.
The set of file generation parameters is called a task. The task consists of several sections. The section defines the output parameters of one file. By default, the Eagle distribution includes the task gerb274x.cam, but it has 2 drawbacks. Firstly, the lower layers are displayed in a mirror image, and secondly, the drilling file is not output (to generate the drilling, you will need to perform another task). Therefore, let's consider creating a task from scratch.
We need to create 7 files: board borders, copper on top and bottom, silkscreen on top, solder mask on top and bottom, and drill bit.
Let's start with the boundaries of the board. In field Section enter the section name. Checking what's in the group Style installed only pos. Coord, Optimize And Fill pads. From the list Device choose GERBER_RS274X. In the input field File The name of the output file is entered. It is convenient to place the files in a separate directory, so in this field we will enter %P/gerber/%N.Edge.grb . This means the directory where the board source file is located, the subdirectory gerber, original board file name (no extension .brd) with added at the end .Edge.grb. Please note that subdirectories are not created automatically, so you will need to create a subdirectory before generating files gerber in the project directory. In the fields Offset enter 0. In the list of layers, select only the layer Dimension. This completes the creation of the section.
To create a new section, click Add. A new tab appears in the window. We set the section parameters as described above, repeat the process for all sections. Of course, each section must have its own set of layers:
copper on top - Top, Pads, Vias
copper bottom - Bottom, Pads, Vias
silkscreen printing on top - tPlace, tDocu, tNames
mask on top - tStop
bottom mask - bStop
drilling - Drill, Holes
and the file name, for example:
copper on top - %P/gerber/%N.TopCopper.grb
copper bottom - %P/gerber/%N.BottomCopper.grb
silkscreen printing on top - %P/gerber/%N.TopSilk.grb
mask on top - %P/gerber/%N.TopMask.grb
bottom mask - %P/gerber/%N.BottomMask.grb
drilling - %P/gerber/%N.Drill.xln
For a drill file, the output device ( Device) should be EXCELLON, but not GERBER_RS274X
It should be kept in mind that some board manufacturers only accept files with names in 8.3 format, that is, no more than 8 characters in the file name, no more than 3 characters in the extension. This should be taken into account when specifying file names.
We get the following:
Then open the board file ( File => Open => Board). Make sure the board file has been saved! Click Process Job- and we get a set of files that can be sent to the board manufacturer. Please note that in addition to the actual Gerber files, information files will also be generated (with extensions .gpi or .dri) - you do not need to send them.
You can also display files only from individual sections by selecting the desired tab and clicking Process Section.
Before sending the files to the board manufacturer, it's helpful to preview what you've produced using a Gerber viewer. For example, ViewMate for Windows or for Linux. It can also be useful to save the board as a PDF (in the board editor File->Print->PDF button) and send this file to the manufacturer along with the gerberas. Because they are people too, this will help them not make mistakes.
Technological operations that must be performed when working with SPF-VShch photoresist
1. Surface preparation.
a) cleaning with polished powder (“Marshalit”), size M-40, washing with water
b) pickling with a 10% sulfuric acid solution (10-20 sec), rinsing with water
c) drying at T=80-90 gr.C.
d) check - if within 30 seconds. a continuous film remains on the surface - the substrate is ready for use,
if not, repeat all over again.
2. Application of photoresist.
Photoresist is applied using a laminator with Tshaft = 80 g.C. (see instructions for using the laminator).
For this purpose, the hot substrate (after the drying oven) simultaneously with the film from the SPF roll is directed into the gap between the shafts, and the polyethylene (matte) film should be directed towards the copper side of the surface. After pressing the film to the substrate, the movement of the shafts begins, while the polyethylene film is removed, and the photoresist layer is rolled onto the substrate. The lavsan protective film remains on top. After this, the SPF film is cut on all sides to the size of the substrate and kept at room temperature for 30 minutes. Exposure for 30 minutes to 2 days in the dark at room temperature is allowed.
3. Exposure.
Exposure through a photomask is carried out on SKTSI or I-1 installations with UV lamps such as DRKT-3000 or LUF-30 with a vacuum vacuum of 0.7-0.9 kg/cm2. The exposure time (to obtain a picture) is regulated by the installation itself and is selected experimentally. The template must be pressed well to the substrate! After exposure, the workpiece is kept for 30 minutes (up to 2 hours is allowed).
4. Manifestation.
After exposure, the drawing is developed. For this purpose, the top protective layer, the lavsan film, is removed from the surface of the substrate. After this, the workpiece is dipped into a solution of soda ash (2%) at T = 35 g.C. After 10 seconds, begin the process of removing the unexposed part of the photoresist using a foam swab. The time of manifestation is selected experimentally.
Then the substrate is removed from the developer, washed with water, pickled (10 sec.) with a 10% solution of H2SO4 (sulfuric acid), again with water and dried in a cabinet at T = 60 degrees C.
The resulting pattern should not peel off.
5. The resulting drawing.
The resulting pattern (photoresist layer) is resistant to etching in:
- ferric chloride
- hydrochloric acid
- copper sulfate
- aqua regia(after additional tanning)
and other solutions
6. Shelf life of SPF-VShch photoresist.
The shelf life of SPF-VShch is 12 months. Storage is carried out in a dark place at a temperature of 5 to 25 degrees. C. in an upright position, wrapped in black paper.
A board of the required size is made from sheet getinax 1.5-2 mm thick, then a plate of copper foil no more than 0.1 mm thick is cut according to the size of the board. One side of the getinax, as well as the foil, is cleaned with fine sandpaper so that they become rough (the foil should be placed on the glass), then degreased (washed with alcohol, acetone or ether), dried well and the foil and getinax are lubricated with a thin layer of BF-2 glue and air dry (approximately 10 minutes), after which a second layer of glue is applied and the foil is applied to the getinax, making sure that there are no air bubbles between the foil and the getinax. The getinax with the foil glued is clamped between two metal plates, and two or three sheets of whatman paper must be placed between the foil and the metal plate.
As a clamp, you can use clamps or screws, for which holes are drilled along the edges of the metal plates. The package assembled in this way is kept for 1 hour at room temperature, and then for 1.5-2 hours at a temperature of 100-150 ° C. If the size of the workpiece is small, then the package can be pressed against the ironing surface of an electric iron with a thermostat.
If the area of the workpiece is large, then the assembled package is placed horizontally, so that the plate to which the foil is pressed is on top, and a hot iron is placed on it. After exposure at high temperature, the bag should cool to room temperature, after which the foil getinax is removed.
If you disassemble a package that has not cooled down, the foil getinaks may become severely warped.
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When a laser printer is available, radio amateurs use a printed circuit board manufacturing technology called LUT. However, such a device is not available in every home, since even in our time it is quite expensive. There is also a manufacturing technology using photoresist film. However, to work with it you also need a printer, but an inkjet one. It’s already simpler, but the film itself is quite expensive, and at first it’s better for a novice radio amateur to spend the available funds on a good soldering station and other accessories.
Is it possible to make a printed circuit board of acceptable quality at home without a printer? Yes. Can. Moreover, if everything is done as described in the material, you will need very little money and time, and the quality will be very good. high level. In any case, the electric current will “run” along such paths with great pleasure.
List of necessary tools and consumables
You should start by preparing the tools, devices and consumables that you simply cannot do without. To implement the most budget-friendly method for manufacturing printed circuit boards at home, you will need the following:- Software for drawing design.
- Transparent polyethylene film.
- Narrow tape.
- Marker.
- Foil fiberglass.
- Sandpaper.
- Alcohol.
- Unnecessary toothbrush.
- Tool for drilling holes with a diameter of 0.7 to 1.2 mm.
- Ferric chloride.
- Plastic container for etching.
- Brush for painting with paints.
- Soldering iron.
- Solder.
- Liquid flux.
There are a huge number of programs for developing printed circuit boards today, but for a novice radio amateur, the simplest option would be Sprint Layout. The interface is easy to master, it is free to use, and there is a huge library of common radio components.
Polyethylene is needed to transfer the pattern from the monitor. It is better to take a stiffer film, for example, from old covers for school books. Any tape will be suitable for attaching it to the monitor. It’s better to take a narrow one - it will be easier to peel off (this procedure does not harm the monitor).
It’s worth looking at markers in more detail, as this is a sore subject. In principle, any option is suitable for transferring a design onto polyethylene. But to draw on foil fiberglass, you need a special marker. But there is a little trick to save money and not buy quite expensive “special” markers for drawing printed circuit boards. The fact is that these products are absolutely no different in their properties from ordinary permanent markers, which are sold 5-6 times cheaper in any office supply store. But the marker must have the inscription “Permanent”. Otherwise nothing will work.
You can take any foiled fiberglass laminate. It's better if it's thicker. For beginners, working with such material is much easier. To clean it, you will need sandpaper with a grit size of about 1000 units, as well as alcohol (available at any pharmacy). The last consumable can be replaced with nail polish mixing liquid, which is available in any house where a woman lives. However, this product smells quite nasty and takes a long time to dissipate.
To drill the board, it is better to have a special mini-drill or engraver. However, you can go a cheaper route. It is enough to buy a collet or jaw chuck for small drills and adapt it to a regular household drill.
Ferric chloride can be replaced with others chemicals, including those that you probably already have in your home. For example, a solution of citric acid in hydrogen peroxide is suitable. Information on how alternative compositions to ferric chloride are prepared for etching boards can be easily found on the Internet. The only thing worth paying attention to is the container for such chemicals - it should be plastic, acrylic, glass, but not metal.
There is no need to talk in more detail about the soldering iron, solder and liquid flux. If a radio amateur has come to the question of making a printed circuit board, then he is probably already familiar with these things.
Development and transfer of a board design to a template
When all of the above tools, devices and Consumables prepared, you can start developing the board. If the device being manufactured is not unique, then it will be much easier to download its design from the Internet. Even a regular drawing in JPEG format will do.
If you want to go a more complicated route, draw the board yourself. This option is often unavoidable, for example, in situations where you do not have exactly the same radio components that are needed to assemble the original board. Accordingly, when replacing components with analogues, you have to allocate space for them on fiberglass, adjust holes and tracks. If the project is unique, then the board will have to be developed from scratch. This is what the above-mentioned software is needed for.
When the board layout is ready, all that remains is to transfer it to a transparent template. The polyethylene is fixed directly to the monitor using tape. Next, we simply translate the existing pattern - tracks, contact patches, and so on. For these purposes, it is best to use the same permanent marker. It does not wear off, does not smudge, and is clearly visible.
Preparation of foil fiberglass laminate
The next step is the preparation of fiberglass laminate. First you need to cut it to the size of the future board. It is better to do this with a small margin. To cut foil fiberglass laminate, you can use one of several methods.Firstly, the material can be cut perfectly using a hacksaw. Secondly, if you have an engraver with cutting wheels, then it will be convenient to use it. Thirdly, fiberglass can be cut to size using a utility knife. The principle of cutting is the same as when working with a glass cutter - a cutting line is applied in several passes, then the material is simply broken off.
Now you definitely need to clean the copper layer of fiberglass from protective coating and oxide. The best way than processing sandpaper, there is no solution for this problem. The grain size is taken from 1000 to 1500 units. The goal is to obtain a clean, shiny surface. Before mirror shine It is not worth stripping the copper layer, since small scratches from sandpaper increases surface adhesion, which will be needed further.
Finally, all that remains is to clean the foil from dust and fingerprints. To do this, use alcohol or acetone (nail polish remover). After processing, we do not touch the copper surface with our hands. For subsequent manipulations, we grab the fiberglass by the edges.
Combination of template and fiberglass
Now our task is to combine the pattern obtained on polyethylene with the prepared fiberglass laminate. To do this, the film is applied to the desired location and positioned. The remains are wrapped on the reverse side and secured with the same tape.
Drilling holes
Before drilling, it is recommended to secure the fiberglass laminate with the template to the surface in some way. This will allow for greater accuracy and will also prevent sudden rotation of the material as the drill passes through. If you have a drilling machine for such work, then the problem described will not arise at all.
You can drill holes in fiberglass at any speed. Some work at low speeds, others at high speeds. Experience shows that the drills themselves last much longer if operated at low speeds. This makes them more difficult to break, bend and damage the sharpening.
The holes are drilled directly through the polyethylene. Future contact patches drawn on the template will serve as reference points. If the project requires it, we promptly change drills to the required diameter.
Drawing tracks
Next, the template is removed, but not thrown away. TO copper coating We still try not to touch with our hands. To draw paths we use a marker, always permanent. It is clearly visible from the trail it leaves. It is better to draw in one pass, since after the varnish, which is included in the permanent marker, has hardened, it will be very difficult to make edits.
We use the same polyethylene template as a guide. You can also draw in front of the computer, checking the original layout, where there are markings and other notes. If possible, it is better to use several markers with tips of different thicknesses. This will allow you to draw both thin paths and extensive polygons more efficiently.
After applying the drawing, be sure to wait some time necessary for the final hardening of the varnish. You can even dry it with a hairdryer. The quality of future tracks will depend on this.
Etching and cleaning marker tracks
Now comes the fun part - etching the board. There are several nuances here that few people mention, but they significantly affect the quality of the result. First of all, prepare the ferric chloride solution according to the recommendations on the package. Usually the powder is diluted with water in a ratio of 1:3. And here's the first piece of advice. Make the solution more saturated. This will help speed up the process, and the drawn paths will not fall off before everything necessary is etched out.
Immediately the second tip. It is recommended to immerse the bath with the solution in hot water. You can heat it in a metal bowl. Increasing the temperature, as has been known since school, significantly accelerates the chemical reaction, which is what etching our board is. Reducing the procedure time is to our advantage. The tracks made with a marker are quite unstable, and the less they sour in the liquid, the better. If at room temperature the board is etched in ferric chloride for about an hour, then in warm water this process is reduced to 10 minutes.
In conclusion, one more piece of advice. During the etching process, although it is already accelerated due to heating, it is recommended to constantly move the board, as well as clean off the reaction products with a drawing brush. By combining all the manipulations described above, it is quite possible to etch out excess copper in just 5-7 minutes, which is simply an excellent result for this technology.
At the end of the procedure, the board must be thoroughly rinsed under running water. Then we dry it. All that remains is to wash away the traces of the marker that are still covering our paths and patches. This is done with the same alcohol or acetone.
Tinning of printed circuit boards
Before tinning, be sure to go over the copper layer again with sandpaper. But now we do it extremely carefully so as not to damage the tracks. The simplest and affordable way tinning - traditional, using a soldering iron, flux and solder. Rose or Wood alloys can also be used. There is also so-called liquid tin on the market, which can greatly simplify the task.But all these new technologies require additional costs and some experience, so the classic tinning method is also suitable for the first time. Liquid flux is applied to the cleaned tracks. Next, solder is collected onto the soldering iron tip and distributed over the copper remaining after etching. It is important to warm up the traces here, otherwise the solder may not “stick”.
If you still have Rose or Wood alloys, then they can be used outside the technology. They melt just fine with a soldering iron, are easily distributed along the tracks, and do not bunch up into lumps, which will only be a plus for a beginning radio amateur.
Conclusion
As can be seen from the above, the budget technology for manufacturing printed circuit boards at home is truly accessible and inexpensive. You don't need a printer, an iron, or expensive photoresist film. Using all the tips described above, you can easily make the simplest electronic radios without investing a lot of money in it, which is very important in the first stages of amateur radio.
Getinax-sheet material: pressed paper impregnated with bakelite varnish. Days of use at low frequencies they produce getinax with a thickness of 0.2 to 50 mm, at high frequencies; - from 0.4 to 3.8 mm. The latter is characterized by low dielectric losses. In addition, you produce foil-coated (single- and double-sided) getinaks. At home, this material is suitable for the manufacture of not only printed circuit boards, but also casings for breakers, casings of small reinforced blocks; walls and partitions made of filtered getinax are connected by soldering.
Decorative plastic They are getinaks with a decorative, usually one-sided, coating. The coating can have a different pattern, including one that imitates the texture of valuable wood. Sheets with a single-color coating of different colors and shades are also produced. The use of plastics in amateur designs allows you to give a good appearance to front panels, instrument cases, etc. It should be borne in mind that plastic with a one-sided coating tends to warp due to various mechanical stresses, occurring in the plastic base and coating. Under the influence of ambient temperature and humidity, the amount of deformation also changes over time, especially for large parts. Therefore, it is advisable to glue the front panels and doors of various cabinets from two pieces of plastic, cutting them out of sheets that are symmetrically deformed, preferably with a convexity towards the decorative coating, so that the tearing loads would act in the center of the sheets, and not at their edges.
If you engrave light-colored plastic when making front panels, removing the decorative layer to the dark base, the inscriptions turn out to be contrasting without additional tinting.
Textolite- pressed cotton fabric impregnated with bakelite varnish. Textolite is produced in the form of sheets with a thickness of 0.5 to 50 mm and rods with a diameter of 8 to 60 mm. Various sheets are made from sheets mounting strips and boards, fastening elements; fastening posts, bushings, rollers, tool handles and other parts are machined from the rods.
Fiberglass- this is a textolite based on fiberglass, has increased mechanical strength, especially bending. Available in sheets with a thickness of 0.5 to 2.5 mm. Foil-coated fiberglass laminate (single- and double-sided) is most widely used. Used in the same way as getinax. If necessary, the fiberglass sheet can be laminated.
It must be borne in mind that the dust that is formed during processing (cutting, filing, sanding) fiberglass is very harmful to health. Therefore, you should work and clean the workplace wearing a respirator or at least a multi-layer gauze bandage.
Organic glass- thermoplastic plastic is a widespread and affordable material. It is produced in two main brands - TOSP and SOL.
Glass brand TOSP There are colorless and colored transparent” and also colored opaque. Color: red, orange, yellow, green, blue. It is resistant to aggressive environments.
Glass brand SOL- only colorless transparent, has better electrical insulating properties, and therefore low water absorption, so it is less amenable to deep coloring.
Organic glass polished by hand with a clean and dry cloth or cloth with tooth powder. To obtain a shiny mirror surface, organic glass is finally polished with fine-grained polishing mixtures, for example, GOI paste. Using toothpaste also gives good results.
When mechanical polishing, you need to use a semi-oval circle made of cotton, not cloth, since if you carelessly sharply press the part against the cloth rotating circle, the polished surface can easily melt. It is very difficult, and sometimes impossible, to eliminate such a defect.
Celluloid sometimes amateurs also use it for decorative finishing scales, nameplates, elements and parts of cases. This material can be identified by the smell of camphor, which becomes especially noticeable if you run a file or knife blade along the edge of the sheet. When heated to 90-100 °C, celluloid softens and becomes plastic, and when cooled, it hardens again. Celluloid parts are firmly glued together with nitro glue and are well polished. But celluloid is flammable and, in addition, under the influence sun rays turns yellow, therefore, if possible, replace celluloid with another similar to it, but non-flammable, and with a more durable plastic - triacetate film. Triacetate films are usually produced transparent. The technology of dyed celluloid and triacetate film is given below.
Marking sheet material. It is advisable to make markings first on a separate sheet of paper (preferably with a millimeter grid) on a scale of 1:1. Everything is applied to the sheet contour lines holes and other elements mark the future part. The drawing is attached to the workpiece and the necessary points are skewed onto the material using a center punch, in which holes are then drilled. This marking method maintains a smooth surface of the workpiece, without scratches or unnecessary lines.
To mark holes on thermoplastic, especially on organic glass, it is better to use not a center punch, but special nozzle on a soldering iron tip or a special replacement tip. The holes turn out smooth, the organic glass does not crack. The depth of the holes depends on the duration of contact of the nozzle with the part, the temperature of the nozzle and is determined experimentally. For holes with a diameter of I - 10 mm, the sharpening angle of the nozzle should be 30-45°, and for holes with a diameter of 15-25 mm - 100-1200.
When making round parts, markings are made using a marking compass. To prevent the leg of the compass from leaving a mark in the center of the circle, it should be installed in a center inserted into a washing elastic band. In this way you can mark parts and more complex shape, if its elements are circular arcs.
Sheet material cutting possible with different tools depending on specific conditions, part configuration, grade of material, etc. The most convenient are special cutters made from old hacksaw blades.
The cutter is guided along the edge of a tightly pressed ruler, and repeatedly. After the cutter has deepened by 0.2-0.3 mm, the ruler can be removed. Having made a cut to a third of the thickness of the sheet, use a hacksaw to file the sheet along the edges, turn the workpiece over and repeat the operation on the reverse side. After this, placing the sheet on the table so that the cutting line coincides with the edge of the table, break the sheet. The fracture is processed with a flat file. The cutter, the design of which is described in paragraph 6.14, allows you to cut round holes of large diameter.
Parts of complex configurations have to be cut out with a jigsaw using a hacksaw blade for metal.
Plexiglass can be cut using ordinary thread No. 00. The thread is pulled in a hacksaw machine or in a jigsaw. Cuts just like with a hacksaw. Using this method, you can perform shaped cutting of organic glass with great precision. For figure cutting You can also use a piece of nichrome nickel wire with a diameter of 0.2-0.3 mm, stretched on insulators in a hacksaw machine or in a jigsaw and connected to the electrical network through a step-down transformer and an adjustable autotransformer. The temperature of the wire must be selected experimentally by changing the voltage applied to it.
Glass cutting is done with a diamond or glass cutter. This operation is simple and does not require much explanation. If you don't have it at hand the right tool, you can use a quartz plate from a faulty resonator, a piece of corundum stone (from a block or circle) or even a piece of a file. But sometimes it becomes necessary to cut a part of a non-linear configuration from glass. To do this, apply a contour of the desired shape or place a drawing made on paper under the glass, but in both cases so that one side of the drawing is on the edge of the workpiece. This edge is filed with a triangular personal file or a diamond file. Then, with a hot (at full heat) tip of the burning device, slowly, starting from the cut, trace the drawn outline. Under the hot tip, a crack is continuously formed, visible to the naked eye. Next, the excess glass is broken off in small sections using pliers (preferably by immersing the glass in water). The edges can be sanded with an abrasive stone. Then you need to boil the glass in water for at least an hour and let it cool in the water to remove residual mechanical stress. Otherwise, cracks may appear.
Instead of a burning device, you can use specially prepared coal daddies. Birch charcoal is crushed into a fine powder and mixed with a thick and warm paste, or even better, with gum arabic. The resulting doughy mass is rolled thin sticks. Dried sticks are ready for use. The carbon tick is set on fire, inflated, applied to the edge of the glass and guided along the contour of the pattern behind the crack that forms.
Drilling glass always done through a jig (a metal plate 4-5 mm thick with a hole corresponding to the diameter of the drill), pressed tightly against the glass. The glass should lie on a hard and flat surface. Drilling hand drill using one of the methods below, without pressing hard and reducing pressure as the drill comes out.
1st method. Drilling with a regular drill. But it is first re-hardened, for which the tip is heated white, then pressed into the sealing wax with quick movements until the sealing wax stops melting. The drilling site must be continuously moistened with the following composition (in mass fractions): camphor - 8, turpentine - 12, ether - 3.
2nd method. Drill with a flat drill, sharpened with a spatula (preferably re-hardened), rotating the drill alternately in one direction and the other. Silicate glue can be used as an emulsion ( liquid glass). Change the emulsion as soon as it becomes cloudy.
3rd method. The drill can be a copper tube of suitable diameter, slightly expanded at the end with a center punch or other suitable tool. A few drops of silicate glue with emery powder (preferably corundum) are applied to the drilling site. When drilling, the mixture is periodically updated.
4th method. If it is necessary to drill a hole with a diameter of 6.5 mm, you can use a carbide roller from a glass cutter as a drill, securing it to a rivet axis in the slot of a rod or tube with a diameter of 4-5 mm (Fig. 1). The drilling site is moistened with water. Drilling a hole using this method in glass 6 mm thick takes 4-6 minutes.
Fig.1. Drill from a glass cutter roller: 1 - carbide roller, 2 - rivet axle, 3 - rod or tube
5th method. The area on the glass where you want to make a hole is thoroughly washed from dirt and grease with gasoline, acetone or alcohol. Then pour wet fine sand and with a stick sharpened in the shape of a truncated cone, make a funnel in the wet sand to remove the glass. Molten lead or solder is poured into the mold prepared in this way. After 2-3 minutes, the sand and the cone of frozen lead or solder are removed - there will be a through hole in the glass. If the glass has poor thermal strength, you need to try to increase the thermal shock. To do this, you can do the following: firstly, increase the depth of the funnel to 20-30 mm, so that the mass of molten metal has a greater heat capacity; secondly, place the glass on a cushion of the same wet sand, forming a funnel of the appropriate diameter at the site of the future hole; thirdly, pre-cool the sand and glass if possible; fourthly, use a more refractory metal, such as zinc. It should be borne in mind that glass of small thickness (up to 3-3.5 mm) can be processed in this way.
Drilling plastic. When drilling holes in plastic, especially in decorative laminate and getinax, the material on the back side often chips. To prevent this from happening, you should first use a drill whose diameter is approximately half that required. Then, using a drill whose diameter is 0.5-1.0 mm larger than the required one and the sharpening angle is 60-90°, the resulting holes are countersunk on both sides and finally drilled out with a drill of the required diameter. This method completely eliminates the risk of chips and cracks and makes it possible to obtain precise, clean holes that do not require any additional processing.
Carving in plastics can also be done with a homemade tap. To do this, take a steel pin, screw or bolt with the required thread and file the end (2-5 mm) into a cone. The head of the screw (bolt) is cut off with a triangular file or using a drill, and 3-4 cuts are made along 6 olta with a grinding wheel of the appropriate profile to get cutting edges.
The shank of the manufactured tap can be sharpened to fit the driver, or by cutting a 2-4 mm wide slot into it, insert a metal rod and solder it.
Quite satisfactory results, especially for threads M4 and smaller, can be obtained without sawing through the cutting edges, but by sawing off the threads of the screw or "studs on both sides. To make the cut thread cleaner, you need to “go” along the thread of the manufactured tap with the appropriate birdie or nut. A stud, bolt or vit is taken with a thread; not with rolled thread
Bending of thermoplastic sheet material(organic glass, polystyrene, vinyl plastic, etc.) can be carried out only by heating the material, and a good bend of the correct shape is obtained only by uniformly heating the sheet at the bend on both sides at a width of 5-15 mm, depending on the thickness of the sheet.
To warm up, strips of thin aluminum foil of the required width are placed on both sides of the plastic sheet along the bend line and pressed. The ends of the strips are connected to the terminals of a step-down transformer (6-15 V), the network winding of which is connected through a laboratory autotransformer, and the required voltage is selected. Overheating should not be allowed, as this may cause a noticeable change in the transparency or color of the material along the bend line. As soon as the material warms up, the foil is removed, the sheet is bent to the required angle and the workpiece is kept until it cools completely.
getinax, plastic, textolite, plexiglass, fiberglass, celluloid, plastics, polystyrene, vinyl plastic, nylon, nylon, dederon, acrylate, etc. - processing, production of artistic crafts and souvenirs
Thermoplastic casting. The raw materials for casting are recycled materials from polyamides (old nylon stockings, rags from nylon, silone, dederon, dacron, fishing veins, etc.), acrylates (acrylic plastics, organic glass), polystyrene. On nylon stockings, it is necessary to cut off the seams, toe and heel, as they are often made with the addition of other material.
The raw materials are thoroughly degreased in a 10% soda solution at a temperature of 50-60 °C for 1 hour, then washed in warm water, dried, crushed (solid material is crushed to particles less than 5 mm in size) and loaded into a press machine.
The design of a homemade press machine is shown in Fig. 2. The press machine is made from a piece of brass pipe with a soldered
m from bottom to bottom. In the upper part of the pipe, in special slots, there is a crossbar with a central threaded hole M10 or M12, into which a pin bent in the shape of the letter L is screwed in (you can use a screw from a clamp). Using this pin or screw, a piston moves in the pipe, which squeezes the softened material through the sprue into the mold prepared for casting.
Fig.2. Design of a homemade press machine
The raw material softens at a temperature of 30-200 °C. To heat the internal volume of the press machine, a straightened spiral from a household electric stove is placed on a layer of mica on the generatrix of the cylinder, and under its base. The spiral is wrapped with a paste made from mica or asbestos crumbs and silicate glue. Then the cylinder is wrapped with an asbestos cord and placed on a wooden base, placing an asbestos sheet under it. To regulate the heating temperature, the spiral is connected to the electrical network through an LATR and an isolation transformer (in order to ensure electronic safety).
To obtain various decorative edgings, it is necessary to make dies required configuration. The die is screwed onto the sprue. The extruded mass acquires the profile of the die hole. The mass emerging from the spinneret must be cooled in water. This method can be used to produce various insulating gaskets and edgings made of PVC. The softening temperature of PVC is 30-100 C.
Molding from denture plastics. Dental plastics of the acrylic group (for example, protacryl) are an excellent material for the manufacture of handles and keys, sliding bearings, decorative elements and many other parts.
Protacryl- self-hardening plastic based on acrylic polymers of the powder-liquid type. This plastic is resistant to abrasion (not inferior to nylon) and has high adhesion. It makes good bearings sliding for miniature mechanical devices (motors, gearboxes, etc.), which do not require lubrication and operate for a long time without noticeable wear. The electrical characteristics of this material (without filler) are slightly higher than those of organic glass.
Casting molds for producing parts from this plastic can be made from tin, papier-mâché wood (section 4.16, 6th recipe), clay, plasticine, gypsum and other materials.
Plaster makes molds that are sufficiently wear-resistant for repeated use; manufacturing process: characterized by low labor intensity. The gypsum is pre-sifted, mixed in cold water until a creamy consistency forms. A box of suitable size is filled halfway with plaster. The model is pressed halfway into the liquid plaster, having previously lubricated it with thick soap solution so that you can later remove it without destroying the mold. After hardening, 2-3 shallow holes are drilled along the edges of the mold, without touching the contour of the model, which will be the guides for the other half of the mold. This half of the mold, including the opening guides, is lubricated with a thick soap solution and dried. Then a second portion of plaster is mixed and poured into the box. When the plaster has hardened, the halves of the mold are carefully separated and the model is removed.
After this, both halves of the mold are carefully coated with an anti-adhesive substance: greased with silicone oil or rubbed with graphite powder. The ordinary one gives slightly worse results. sunflower oil. The prepared plastic is poured into the first and second halves of the mold and both halves are folded towards the guides. The form is tightly tightened with a clamp or wrapped with a thin wire and placed in a bowl with cold water. The water is slowly heated and brought to a boil
Thermal treatment of parts made of protacryl using such methods is carried out for 1.5-2 hours, and it is better to do this 1-2 days after pouring the plastic into the mold, i.e., when the preliminary polymerization in the deep layers of the plastic is completely completed.
At the end heat treatment the mold is cooled, opened and the manufactured part is removed from it. If required, the part is further processed. To increase the durability of the molds, crushed asbestos is added to the plaster.
When producing a batch of parts, it is necessary to use a metal mold. In this case, the model is made of aluminum or duralumin. The first half of the mold is cast from lead or garth (printing alloy), the second half is cast from an alloy of lead and a low-melting denture alloy (or low-melting solder) in a 1:1 ratio.
If it is necessary to make duplicates of any plastic part, then first a plaster mold is made from the original and a lead duplicate of the part is cast. A metal mold is made from a duplicate; one half is made from an alloy of lead and low-melting solder, the other half is made from low-melting solder.
Homemade "plastics" used in the manufacture of equipment design parts (cases, drawers, platbands, frames), various auxiliary parts (stands, brackets, clips), handles of various tools, as well as for filling holes in abrasive wheels, etc.
These plastics are convenient because they are used not to produce materials, but to produce finished parts. This significantly reduces the labor intensity of the process. True, you have to make a model or mold, but this pays off in the simplicity of processing the finished part. A model (mold) is made from an easily processed material, such as soft wood, foam plastic, and covered with a thin layer of paraffin or wax paste prepared as for waxing wood.
Preparing and working with such plastics is not difficult. Below are a few recipes:
1st recipe Fiberglass and epoxy glue are excellent materials for making various cases, decorative trims, and frames.
The model is covered with paraffin or plain paper; fix it with any glue in possibly small areas, for example at several points, so that the finished product is easier to compress. Then the first layer of fiberglass is laid and glue is applied to it; Place the next layer and make sure that it is well saturated with glue. Impregnation improves if the fiberglass fabric is pressed (smoothed or, as it were, punched) with a hard brush slightly moistened with acetone. It is not recommended to lay more than 4-6 layers of fiberglass at one time. It is necessary to wait for the epoxy glue to harden. Before continuing work, the surface is sanded until fiberglass fibers are detected, otherwise the next molded layers, including putty, will not adhere well. Preparation for the next stage of coating can be simplified if, when finishing work, you dust the last layer with wood flour - dry, finely sifted sawdust or even ordinary flour, preferably rye.
2nd recipe. Homemade “textolite” can also be made on a regular fabric base, impregnated with glue. Use carpentry or casein glue, but always with the addition of an antiseptic substance. Instead of glue, you can use thickened nitro varnish or nitro paint.
From homemade textolite manufacture housings for devices, various casings, back walls and other parts. For small parts, use cotton or silk knitwear (old but clean T-shirts, shirts, etc. are suitable). For large structures it is better to use burlap.
The fabric is pulled over the model, protected from the fabric sticking, hooked and lubricated with glue; then stretch the next layer of fabric, etc. Wood glue is best used when hot. It is convenient to fasten the fabric with long shoe nails, since they are easier to remove when attaching the next layer. Excess material on the curves of the form is cut off so that the fabric on the cut lines can be sewn end to end and so that the joints of the top layer do not coincide with the seams of the bottom. Each subsequent layer is tensioned and secured with nails, having previously removed the nails that secured the previous layer. This is how 4-8 layers are laid and dried for 8-10 days.
Next, the workpiece, without removing it from the model, is puttied with a mixture of hot wood glue and neck chalk with talcum powder and finally dried. You can also use another putty produced for woodwork or prepared according to one of the recipes given in the table. 5.1. The layer of putty should be no more than 0,"2-0.3 mm, i.e., just to hide all the unevenness and structure of the material. Complete drying occurs after 20-25 days, after which there is no longer the danger of warping of the workpieces. The dried workpiece is sanded, cut the edge on it and remove it from the model. You need to remove it carefully, using a wide chisel as a lever. You can separate the workpiece from the model by passing, for example, a metal measuring ruler between them. The removed workpiece is primed and painted on both sides. For final finishing it is better to use nitro varnishes or nitro paints with an appropriate primer, since they dry quickly and the part does not have time to warp.After painting, the part is polished to a mirror shine.
3rd recipe. Homemade “plastic” from strips of paper can be used to make cases, case covers, back walls of complex profiles, and spherical speaker enclosures. For small-sized structures You can use strips of newsprint; for large ones, thin wallpaper.
The model is covered with a thin layer of paraffin and the first layer of strips of paper soaked in hot water is placed on it. Then glue the strips of paper for the next layer. Can be used various adhesives, however, preference should be given to carpentry or casein glue with the obligatory addition of antiseptics.
The paper is allowed to be thoroughly saturated with glue. If the paper has absorbed glue, it is coated again. The next layer of strips is glued perpendicular to the stripes of the previous layer. Having pasted 4-5 layers in this way, do intermediate drying for 24 hours. The process is repeated several times until the required thickness is obtained. The dried workpiece is further processed in the same way as recommended in the 2nd recipe.
4th recipe Thoroughly mix 65 parts by weight of fine sawdust and 35 parts of magnesite. The mixture is poured with 0.1 34-fold solution of magnesium chloride and stirred until a homogeneous dough-like state. The main method of obtaining blanks from this “plastic” is casting into molds and moulds. As the “plastic” hardens, it acquires fairly high strength and at the same time is well processed: it is easy to saw, drill and grind. It is usually used for the manufacture of: stands, brackets, for filling holes in abrasive wheels, etc.
5th recipe. Mix fine sawdust and ground talc in a mass ratio of 5:2, pour in prepared wood glue (sour cream consistency) and stir thoroughly until dough-like. It is advisable to add 0.5 mass fraction of aluminum or aluminum alum to the OD-mixture, which prevents the formation of mold and thereby preserves the strength of the “plastic.” To make the “plastic” more plastic, it is necessary to add 0.5 mass fraction of natural drying oil to it.
You can replace wood glue with casein glue, which must contain an antiseptic substance.
This “plastic” is less durable than that prepared according to the 4th recipe. It can be used to make parts that are not subject to large mechanical loads, platbands, frames, various decorative elements, etc. If desired, the “plastic” can be colored by adding an aniline dye of the desired color to its composition.
After drying, the manufactured part, if required, is puttied, sanded and painted, and it is better to prepare the putty on the basis of the glue that was used to make the “plastic” itself.
A more durable and quick-drying “plastic” is obtained if, instead of glue, you use thickened or thickened nitro varnish (nitro paint). Parts from this “plastic” are also made by drinking.
6th recipe On the day of preparing papier-mâché, grind newsprint, brew it with boiling water and keep it in hot water for 1-2 days. When a suspension of thin consistency is formed, the water is filtered off and the mass is dried. Dried: the mass easily turns into powder, which serves as the basis for papier-mâché. The powder (10 parts by mass) is mixed with finely sifted chalk or talc (3) and poured with a paste made from dry wood grain: (2) and wheat flour (3). For antiseptic treatment, it is necessary to add 0.2 mass fraction of aluminum or potassium alum to the paste. The mass can be colored with aniline dyes.
The prepared mass is applied to the model, previously coated with paraffin. Parts can be cast into molds or moulds. After complete drying, the part is sanded to avoid any unevenness, primed and painted.
7th recipe.“Plastic” with better mechanical properties than papier-mâché can be obtained using the following components (in mass fractions): dry paper pulp - 5; wood glue (dry) - 28; finely sifted chalk - 60; glycerin - 2.5; ethyl alcohol-3.5; dry ocher - 1.0. The dry paper pulp is poured with a warm solution of wood glue, chalk, glycerin, alcohol and ocher are added with constant stirring. After thorough mixing, the resulting mass should not stick to your hands. The further process is similar to the preparation and processing of “plastic” outlined in the 5th or 6th recipe
8th recipe. “Plastic” with good insulating properties can be prepared with 60 parts by weight of cottage cheese and 40 parts of quicklime.
Fresh cottage cheese is wrapped in a clean cloth and placed under a press for several hours to squeeze thoroughly. The squeezed cottage cheese is ground and poured into a deep glass vessel, the lime is carefully ground separately and sent in small portions into the cottage cheese, stirring the mass wooden stick. Reacting with lime, the cottage cheese forms a casein mass - a thick “syrup” that quickly hardens. The “syrup” is poured into molds. The molds should be greased with Vaseline or oil. Casein “plastic” is more durable when hardened under pressure.
It should be taken into account that if the quality of quicklime is poor, the hardening of the mass occurs slowly and is accompanied by abundant release of moisture, the excess of which must be removed. In this case, the ratio of components should be clarified experimentally.
Dyeing of celluloid and triacetate film can be done by boiling them for several hours in water containing an organic: aniline-type fabric dye. However, this method is labor-intensive and does not always give the desired color shade. One way to surface dye these materials is to treat them in a hot solution of acetic acid containing a dye. If photographic film is painted, it is pre-treated with substances that decompose gelatin, for example, a hot alkali solution. Washing the emulsion can be accelerated by cleaning the film with a brush.
The concentration of the dye solution and the approximate dyeing time are given in table. 1. The dye is poured with a large amount of boiled hot water and stirred until a homogeneous mass (infusion) is obtained. Then add the rest of the hot water and 50 ml of acetic acid (95%) to the paste. Instead of acid, you can take 60 ml of vinegar essence per 940 ml of water or 550 ml of table vinegar (9%) per 450 ml of water. The solution is filtered through several layers of gauze, poured into an enamel pan and covered with a lid. Before painting, the surface must be sanded, degreased with gasoline or alcohol and dried. It is also useful to additionally rinse the product in a hot powder solution for: washing natural silk fabrics (2 mass fractions powder per 100 water), and then in warm water. The product is immersed in a dye solution heated to 40-50 °C, and care is taken that it does not touch the bottom of the dish.
Deep coloring of organic glass allows you to obtain a smooth and durable painted surface while maintaining the texture of the material. Dyeing is carried out in aqueous-alcoholic solutions of disperse dyes. The process is simple and allows you to obtain rich shades.
Before painting, the surface of the products must be thoroughly cleaned, otherwise an even color and tone may not be obtained. The surface is wiped with a swab made of soft fabric, soaked in gasoline or alcohol, dry and immerse for 15 minutes in an aqueous solution of detergent. The solution temperature should be within 50-60 °C. Then the product is thoroughly rinsed in cold water and immediately transferred to the dye solution, which is prepared as follows: mix 5-15 g of disperse dye until a homogeneous mass (paste) is formed (when choosing a color, you can use Table 4 1), 2-3 g neutral washing powder (for washing natural silk fabrics) and 20-30 g of alcohol (ethyl, butyl or benzyl) and add hot water to a volume equal to one)" liter. After thorough mixing, the solution is filtered through a nylon fabric folded in half (a nylon stocking can be used) .
One of the conditions for good dyeing is protecting the solution from contamination, continuously stirring it during operation, periodic filtration during repeated use, and adding alcohol as the solution is consumed. Color saturation depends not only on the temperature of the solution, but also on the duration of dyeing. To obtain an average color saturation, the dyeing time should be 15-20 minutes.
After dyeing is completed, the product is thoroughly rinsed in cold water and dried.
Dyeing should be done in dishes made of materials that are resistant to the dye used (glass, porcelain), otherwise the color may not be rich and the dishes will be damaged. You can also use enamel cookware.
Surface coloring of organic glass makes it possible to obtain a film containing a dye and directly bonded to the surface of organic glass, since the dyes used include substances that dissolve glass. The coating is durable and polishes well. There are many coloring recipes, of which we will present the five most acceptable in amateur practice.
1st recipe. The dye of the desired color, from a set of aniline dyes, is dissolved in acetic acid, adding it little by little until the desired shade of color is obtained. The solutions are filtered and mixed in a 1:1 volume ratio with a mixture of toluene (70% volume) and dichloroethane (30%). The resulting mixture is filtered again and organic glass shavings are dissolved in it in such an amount that the resulting dye can be sprayed. Apply the dye to the surface of organic glass in several layers at intervals of 10-15 minutes.
2nd recipe. Mix 30% (by volume) dichloroethane, 60% benzene and 10% acetic acid. The paint is dissolved in this composition. The solution is filtered and organic glass shavings or sawdust are added to it. Painting can also be done with a spray gun.
3rd recipe. In 10 parts by volume of vinegar essence I dissolve 1 part of ballpoint pen paste. With less paste, the solution wets the surface to be painted less well. To obtain a more saturated color, the content of passa in the solution is increased. You can use applied refills of ballpoint pens, cutting them into pieces 6-10 mm long and placing them in a bottle with vinegar essence. To speed up the dissolution of the paste, the bottle must be shaken vigorously periodically.
The dye is applied to the glass with a soft brush using longitudinal, non-overlapping strokes. The dye flows well, forming a uniform layer.
4th recipe. In 6 parts by volume of vinegar essence, dissolve 1 part of sawdust or organic glass shavings and add ballpoint pen paste. It is better to apply the composition with a spray bottle.
5th recipe Dissolve required amount pastes for ballpoint pens in dichloroethane. Apply* the solution to the surface of the part: using a spray bottle, but you can also use a soft brush or a soft cloth swab.
Products painted according to the given recipes are dried for at least 24 hours. All operations must be performed outdoors or in fume hood. Prepared dyes should be stored in a well-sealed container (preferably with a ground stopper)
Coloring organic glass milky color is produced by immersing it in concentrated sulfuric acid for 1-10 minutes. (TOSP glass, resistant to aggressive environments, cannot be treated in this way.) When held for 1-3 minutes, the surface of organic glass does not lose its gloss and acquires a milky color. If you etch the glass further, its surface becomes white and slightly matte. As the acid exposure time increases, the white layer becomes thicker. If this layer is not deep enough, the process can be repeated. After treatment in acid, organic glass is thoroughly washed in running water and dried. You should wash it carefully, as the resulting layer is soft and can be easily damaged. It should also be borne in mind that the mechanical strength of the surface layer during deep processing is insufficient even after drying. To leave transparent areas on the product, these surfaces are covered with a thin layer of wax. After washing and drying, the wax is removed
If the etching time is increased, for example to 20-30 minutes, then after drying the surface wrinkles and takes on the appearance as if it were covered with moiré varnish. Organic glass treated in this way can be painted as described above.
Painting the insulation of installation wires of the MGShV, MGV and PMV types (polyvinyl chloride insulation white) can be carried out in an aqueous solution of a dye for nylon, wool or cotton fabric, and when using a dye for wool or cotton fabric, the color of the insulation is different from the color of the dye. So, for example, in black dye the wire insulation becomes orange, in blue or cornflower blue it turns yellow.
The dye solution is prepared by dissolving a packet of dye in 2-3 liters of warm water. A coil of wire to be painted is immersed in a solution heated to 85-90 °C. The color is determined by a control section of the same wire, periodically removing it from the solution. After dyeing is completed, the wire is washed in cold running water.
To prevent the solution from getting under the insulation, the ends of the wires should be sealed by painting. To do this, melt the insulation at the ends in a flame or dip the ends for a few seconds in Unicum, Moment-1 or BF glue and dry.
On a note:
A small sheet of fiberglass can be peeled off from the corner with a non-sharp knife and divided into two thin sheets. Foil-coated fiberglass can also be used in this manner
Double-sided fiberglass can be made from one-sided foil fiberglass by gluing two blanks with epoxy glue or, in extreme cases, BF-2 glue. The bonded surfaces must be thoroughly cleaned with coarse sandpaper. If the material is thick, you can pre-layer its thinnest sheets (section 4.22).
After two thermal shocks and drying, mica is easily glued into plates up to 0.02 mm thick. To do this, the mineral must be heated to 400-600 °C, immediately cooled in water and the operation repeated.
In the manufacture and repair of various equipment and tools, especially soldering irons, it is sometimes necessary to bend the mica spacer with a small bending radius. In order for mica to become more elastic and not break or crumble, it must be calcined, heated to a light yellow color and allowed to cool slowly.
Bonding dissimilar plastics, such as plexiglass or polystyrene with celluloid, is difficult because dichloroethane, which dissolves plexiglass and polystyrene, does not dissolve celluloid, and acetone (a celluloid solvent) does not dissolve organic glass. A mixture of acetone-based glue and dichloroethane-based glue does not provide high adhesive strength. The strength of the adhesive joint equal to the strength of the materials being glued can be obtained if the celluloid part is lubricated with acetone glue, and the part made of organic glass or polystyrene is lubricated with dichloroethane. After the glue has dried, each part is lubricated again with the appropriate glue and pressed one against the other. Final drying is carried out at room temperature for 4 hours.
In the absence of dichloroethane, you can glue small parts made of organic glass with an aerosol insect repellent - dichlorvos. It must be remembered that such “glue” is no less toxic than dichloroethane. Therefore, work is carried out only in the open air, observing the rules for handling dichlorvos, and the resulting compound, after it has hardened, is thoroughly washed with a brush with soap and water.
Garlic juice does a good job of gluing tight, even surfaces of glass and plastic. To do this, coat the parts to be glued with a cut garlic clove. The gluing area remains transparent.
PTFE does not stick together with any of the adhesives currently used in everyday life.
For gluing or gluing parts made of microporous rubber, the most suitable adhesives are “Moment-1”, 88N, “Unicum”), since they create a “flexible” adhesive seam.
Old rubber products can be restored to softness and elasticity by immersing them for 20-30 minutes in a weak solution of ammonia or for 1-2 hours in pure kerosene. It should be remembered that a long stay of rubber in kerosene not only softens it, but also significantly increases its volume. The softened rubber should be washed in warm water with detergent and wiped dry.
The progression of a crack in organic glass can be stopped if a hole with a diameter of 2-3 mm is drilled at the end of the crack.
Some brands of organic glass, after boiling for several hours in water, acquire a milky color, one!” care must be taken to ensure that the material does not deform when heated.
You can polish glass using a set of abrasive powders. Scratches and other damage to the glass are pre-polished - first with coarse-grained powder, then with fine-grained powder. After this, the surface is polished with a paste, which is prepared by mixing a fine-grained abrasive with a thick lubricant. You can also use an aqueous suspension. If there are no powders, then fine-grained corundum waterproof sandpaper is suitable for grinding, and for polishing - GOI paste, green eider crocus gouache (calcined and crushed iron oxide).
Round glass can be cut if you attach the roller from a glass cutter to one sponge of a used shtash-engirkulya. The other sponge needs to be rested on the glass through the washer and rubber lining. The roller is rolled in a circle several times, after which 3-4 tangents are made with a regular glass cutter, making it easier to chip the glass along the boundaries of the cuts. Sharp edges are cleaned with a file and an abrasive stone under water (or under running water).
To prevent a metal ruler from slipping when cutting glass or plastic, just glue a few pieces of thin rubber to it.
If you stick adhesive tape or even wet newspaper along the groove made with a glass cutter, then tapping is less likely to damage the glass.
Even the smallest glass fragments in the workplace can be removed with a piece of plasticine.
If, when cutting rubber, you periodically lubricate the knife blade with soap, it will be easier to solve, and the edges will be smoother.
Resins with fillers and coloring agents are good material for cold casting. From it you can make an exact copy of a broken handle or other part of the device; make new ones. Miniature plug connectors can be soldered directly at the end of the wire using special molds). In many cases, you can get by with a plasticine mold, making an impression of the desired part in it.
Printed circuit board– this is a dielectric base, on the surface and in the volume of which conductive paths are applied in accordance with electrical diagram. The printed circuit board is intended for mechanical fastening and electrical connection between the leads of electronic and electrical products installed on it by soldering.
The operations of cutting out a workpiece from fiberglass, drilling holes and etching a printed circuit board to obtain current-carrying tracks, regardless of the method of applying the pattern to the printed circuit board, are performed using the same technology.
Manual application technology
PCB tracks
Preparing the template
The paper on which the PCB layout is drawn is usually thin and for more accurate drilling of holes, especially when using manual homemade drill so that the drill does not lead to the side, it is necessary to make it more dense. To do this, you need to glue the printed circuit board design onto thicker paper or thin thick cardboard using any glue, such as PVA or Moment.
Cutting the workpiece
A blank of foil fiberglass laminate of a suitable size is selected, the printed circuit board template is applied to the blank and outlined around the perimeter with a marker, a soft pencil or marking with a sharp object.
Next, the fiberglass laminate is cut along the marked lines using metal scissors or sawed out with a hacksaw. Scissors cut faster and there is no dust. But we must take into account that when cutting with scissors, fiberglass is strongly bent, which somewhat worsens the adhesion strength of copper foil and if the elements need to be re-soldered, the tracks may peel off. Therefore, if the board is large and has very thin traces, then it is better to cut it using a hacksaw.
The template of the printed circuit board pattern is glued to the cut-out workpiece using Moment glue, four drops of which are applied to the corners of the workpiece.
Since the glue sets in just a few minutes, you can immediately begin drilling holes for radio components.
Drilling holes
It is best to drill holes using a special mini drilling machine with a carbide drill with a diameter of 0.7-0.8 mm. If a mini drilling machine is not available, then you can drill holes with a low-power drill using a simple drill. But when working with a universal hand drill, the number of broken drills will depend on the hardness of your hand. You definitely won’t be able to get by with just one drill.
If you cannot clamp the drill, you can wrap its shank with several layers of paper or one layer of sandpaper. You can wrap a thin metal wire tightly around the shank, turn to turn.
After finishing drilling, check whether all holes are drilled. This can be clearly seen if you look at the printed circuit board up to the light. As you can see, there are no missing holes.
Applying a topographic drawing
In order to protect the places of foil on fiberglass laminate that will be conductive paths from destruction during etching, they must be covered with a mask that is resistant to dissolution in an aqueous solution. For the convenience of drawing paths, it is better to pre-mark them using a soft pencil or marker.
Before applying the markings, it is necessary to remove traces of the glue that was used to glue the printed circuit board template. Since the glue has not hardened much, it can be easily removed by rolling it with your finger. The surface of the foil must also be degreased using a rag using any means, such as acetone or white alcohol (the so-called purified gasoline), or any dishwashing detergent, for example Ferry.
After marking the tracks of the printed circuit board, you can begin to apply their design. Any waterproof enamel is well suited for drawing paths, for example alkyd enamel of the PF series, diluted to a suitable consistency with a white alcohol solvent. You can draw paths with different tools - a glass or metal drawing pen, a medical needle, and even a toothpick. In this article I will tell you how to draw circuit board traces using a drawing pen and ballerina, which are designed for drawing on paper with ink.
Previously, there were no computers and all drawings were drawn with simple pencils on whatman paper and then transferred in ink to tracing paper, from which copies were made using copiers.
Drawing begins with contact pads, which are drawn with a ballerina. To do this, you need to adjust the gap of the sliding jaws of the ballerina drawing board to the required line width and to set the diameter of the circle, perform the adjustment with the second screw, moving the drawing blade away from the axis of rotation.
Next, the ballerina's drawing board is filled with paint to a length of 5-10 mm using a brush. For applying a protective layer to a printed circuit board, PF or GF paint is best suited, since it dries slowly and allows you to work quietly. NTs brand paint can also be used, but it is difficult to work with because it dries quickly. The paint should adhere well and not spread. Before painting, the paint must be diluted to a liquid consistency, adding a suitable solvent to it little by little with vigorous stirring and trying to paint on scraps of fiberglass. To work with paint, it is most convenient to pour it into a bottle of manicure varnish, in the twist of which there is a solvent-resistant brush installed.
After adjusting the ballerina's drawing board and obtaining the required line parameters, you can begin to apply the contact pads. To do this, the sharp part of the axis is inserted into the hole and the base of the ballerina is rotated in a circle.
At correct setting using a drawing board and the desired consistency of paint around the holes on the printed circuit board, the circles are perfect round shape. When a ballerina begins to paint poorly, the remaining dried paint is removed from the gap of the drawing board with a cloth and the drawing board is filled with fresh paint. To draw all the holes on this printed circuit board with circles it took only two refills of the drawing pen and no more than two minutes of time.
Once the round pads on the board are drawn, you can start drawing the conductive paths using a hand drawing pen. Preparing and adjusting a manual drawing board is no different from preparing a ballerina.
The only thing additionally needed is a flat ruler, with pieces of rubber 2.5-3 mm thick glued to one of its sides along the edges, so that the ruler does not slip during operation and the fiberglass, without touching the ruler, can freely pass under it. A wooden triangle is best suited as a ruler; it is stable and at the same time can serve as a hand support when drawing a printed circuit board.
To prevent the printed circuit board from slipping when drawing tracks, it is advisable to place it on a sheet of sandpaper, which consists of two sandpaper sheets sealed together with the paper sides.
If they come into contact when drawing paths and circles, then you should not take any measures. You need to let the paint on the printed circuit board dry until it does not stain when touched, and use the tip of a knife to remove the excess part of the design. In order for the paint to dry faster, the board should be placed in a warm place, for example, on a radiator in winter. IN summer time years - under the rays of the sun.
When the design on the printed circuit board is completely applied and all defects are corrected, you can proceed to etching it.
Printed circuit board design technology
using a laser printer
When printing on a laser printer, the image formed by the toner is transferred, due to electrostatics, from the photo drum on which the laser beam drew the image, onto paper. The toner is held onto the paper, preserving the image, only due to electrostatics. To fix the toner, the paper is rolled between rollers, one of which is a thermal oven heated to a temperature of 180-220°C. The toner melts and penetrates the paper texture. Once cooled, the toner hardens and adheres firmly to the paper. If the paper is heated again to 180-220°C, the toner will again become liquid. This property of toner is used to transfer images of current-carrying tracks onto a printed circuit board at home.
After the file with the printed circuit board design is ready, you need to print it using a laser printer onto paper. Please note that the image of the printed circuit board drawing for this technology must be viewed from the side where the parts are installed! An inkjet printer is not suitable for these purposes, as it works on a different principle.
Preparing a paper template for transferring the design to the printed circuit board
If you print a printed circuit board design on ordinary paper for office equipment, then due to its porous structure, the toner will penetrate deeply into the body of the paper and when the toner is transferred to the printed circuit board, most of it will remain in the paper. In addition, there will be difficulties in removing paper from the printed circuit board. You will have to soak it in water for a long time. Therefore, to prepare a photomask, you need paper that does not have a porous structure, for example photo paper, a substrate from self-adhesive films and labels, tracing paper, pages from glossy magazines.
I use old stock tracing paper as the paper for printing the PCB design. Tracing paper is very thin and it is impossible to print a template directly on it; it gets jammed in the printer. To solve this problem, before printing, you need to apply a drop of any glue to a piece of tracing paper of the required size in the corners and glue it to a sheet of A4 office paper.
This technique allows you to print a printed circuit board design even on the thinnest paper or film. In order for the toner thickness of the drawing to be maximum, before printing, you need to configure the “Printer Properties” by turning off the economical printing mode, and if this function is not available, then select the coarsest type of paper, for example cardboard or something similar. It’s entirely possible that you won’t get a good print the first time, and you’ll have to experiment a little to find the best print mode for your laser printer. In the resulting print of the design, the tracks and contact pads of the printed circuit board must be dense without gaps or smudging, since retouching on this technological stage useless.
All that remains is to cut the tracing paper along the contour and the template for making the printed circuit board will be ready and you can proceed to the next step, transferring the image onto fiberglass laminate.
Transferring a design from paper to fiberglass
Transferring the printed circuit board design is the most critical step. The essence of the technology is simple: paper, with the side of the printed pattern of the tracks of the printed circuit board, is applied to the copper foil of fiberglass and pressed with great force. Next, this sandwich is heated to a temperature of 180-220°C and then cooled to room temperature. The paper is torn off, and the design remains on the printed circuit board.
Some craftsmen suggest transferring a design from paper to a printed circuit board using an electric iron. I tried this method, but the result was unstable. It is difficult to simultaneously heat the toner to desired temperature and uniform pressing of the paper to the entire surface of the printed circuit board when the toner hardens. As a result, the pattern is not completely transferred and gaps remain in the pattern of the printed circuit board tracks. Perhaps the iron was not heating up enough, although the regulator was set to maximum iron heating. I didn’t want to open the iron and reconfigure the thermostat. Therefore, I used another technology, less labor-intensive and providing one hundred percent results.
On a piece of foil fiberglass laminate cut to the size of the printed circuit board and degreased with acetone, I glued tracing paper with a pattern printed on it in the corners. On top of the tracing paper I placed, for more even pressure, heels of sheets of office paper. The resulting package was placed on a sheet of plywood and covered on top with a sheet of the same size. This entire sandwich was clamped with maximum force in clamps.
All that remains is to heat the prepared sandwich to a temperature of 200°C and cool. An electric oven with a temperature controller is ideal for heating. It is enough to place the created structure in a cabinet, wait for the set temperature to reach, and after half an hour remove the board to cool.
If you don’t have an electric oven, you can use a gas oven by adjusting the temperature using the gas supply knob using the built-in thermometer. If there is no thermometer or it is faulty, then women can help; the position of the control knob at which pies are baked is suitable.
Since the ends of the plywood were warped, I clamped them with additional clamps just in case. To avoid this phenomenon, it is better to clamp the printed circuit board between metal sheets 5-6 mm thick. You can drill holes in their corners and clamp printed circuit boards, tighten the plates using screws and nuts. M10 will be enough.
After half an hour, the structure has cooled enough for the toner to harden, and the board can be removed. At the first glance at the removed printed circuit board, it becomes clear that the toner transferred from tracing paper to the board perfectly. The tracing paper fit tightly and evenly along the lines of the printed tracks, rings of contact pads and marking letters.
The tracing paper easily came off from almost all the traces of the printed circuit board; the remaining tracing paper was removed with a damp cloth. But still, there were gaps in several places on the printed tracks. This can happen as a result of uneven printing from the printer or remaining dirt or corrosion on the fiberglass foil. Gaps can be painted over with any waterproof paint, manicure polish, or retouched with a marker.
To check the suitability of a marker for retouching a printed circuit board, you need to draw lines on paper with it and moisten the paper with water. If the lines do not blur, then the retouching marker is suitable.
It is best to etch a printed circuit board at home in a solution of ferric chloride or hydrogen peroxide with citric acid. After etching, toner can be easily removed from the printed tracks with a swab soaked in acetone.
Then holes are drilled, conductive paths and contact pads are tinned, and radioelements are sealed.
This is the appearance of the printed circuit board with radio components installed on it. The result is a power supply and switching unit for the electronic system, which complements an ordinary toilet with a bidet function.
PCB etching
To remove copper foil from unprotected areas of foiled fiberglass laminate when making printed circuit boards at home, radio amateurs usually use a chemical method. The printed circuit board is placed in an etching solution and due to chemical reaction copper, unprotected by the mask, dissolves.
Recipes for pickling solutions
Depending on the availability of components, radio amateurs use one of the solutions given in the table below. Etching solutions are arranged in order of popularity of their use by radio amateurs at home.
| Name of solution | Compound | Quantity | Cooking technology | Advantages | Flaws |
|---|---|---|---|---|---|
| Hydrogen peroxide plus citric acid | Hydrogen peroxide (H 2 O 2) | 100 ml | Dissolve citric acid and table salt in a 3% solution of hydrogen peroxide. | Availability of components, high etching speed, safety | Not stored |
| Citric acid (C 6 H 8 O 7) | 30 g | ||||
| Table salt (NaCl) | 5 g | ||||
| Aqueous solution of ferric chloride | Water (H2O) | 300 ml | Dissolve ferric chloride in warm water | Sufficient etching speed, reusable | Low availability of ferric chloride |
| Ferric chloride (FeCl 3) | 100 g | Hydrogen peroxide plus hydrochloric acid | Hydrogen peroxide (H 2 O 2) | 200 ml | Pour 10% hydrochloric acid into a 3% hydrogen peroxide solution. | High etching rate, reusable | Great care required |
| Hydrochloric acid (HCl) | 200 ml | ||||
| Aqueous solution of copper sulfate | Water (H2O) | 500 ml | Dissolve table salt in hot water (50-80°C), and then copper sulfate | Component Availability | The toxicity of copper sulfate and slow etching, up to 4 hours |
| Copper sulfate (CuSO 4) | 50 g | ||||
| Table salt (NaCl) | 100 g | ||||
Etch printed circuit boards in metal utensils are not allowed. To do this, you need to use a container made of glass, ceramic or plastic. The used etching solution may be disposed of in the sewer system.
Etching solution of hydrogen peroxide and citric acid
A solution based on hydrogen peroxide with citric acid dissolved in it is the safest, most affordable and fastest working. Of all the solutions listed, this is the best by all criteria.
Hydrogen peroxide can be purchased at any pharmacy. Sold in the form of a liquid 3% solution or tablets called hydroperite. To obtain a liquid 3% solution of hydrogen peroxide from hydroperite, you need to dissolve 6 tablets weighing 1.5 grams in 100 ml of water.
Citric acid in the form of crystals is sold in any grocery store, packaged in bags weighing 30 or 50 grams. Table salt can be found in any home. 100 ml of etching solution is enough to remove 35 micron thick copper foil from a printed circuit board with an area of 100 cm 2. The used solution is not stored and cannot be reused. By the way, citric acid can be replaced with acetic acid, but because of its pungent odor, you will have to etch the printed circuit board outdoors.
Ferric chloride pickling solution
The second most popular etching solution is an aqueous solution of ferric chloride. Previously, it was the most popular, since ferric chloride was easy to obtain at any industrial enterprise.
The etching solution is not demanding on temperature; it etches quickly enough, but the etching rate decreases as the ferric chloride in the solution is consumed.
Ferric chloride is very hygroscopic and therefore quickly absorbs water from the air. As a result, a yellow liquid appears at the bottom of the jar. This does not affect the quality of the component and such ferric chloride is suitable for preparing an etching solution.
If the used ferric chloride solution is stored in an airtight container, it can be reused many times. Subject to regeneration, just pour iron nails into the solution (they will immediately be covered with a loose layer of copper). If it gets on any surface, it leaves a difficult-to-remove yellow spots. Currently, ferric chloride solution is used less frequently for the manufacture of printed circuit boards due to its high cost.
Etching solution based on hydrogen peroxide and hydrochloric acid
Excellent etching solution, provides high speed etching. Hydrochloric acid, with vigorous stirring, is poured into a 3% aqueous solution of hydrogen peroxide in a thin stream. It is unacceptable to pour hydrogen peroxide into acid! But due to the presence of hydrochloric acid in the etching solution, great care must be taken when etching the board, since the solution corrodes the skin of the hands and spoils everything it comes into contact with. For this reason, it is not recommended to use an etching solution with hydrochloric acid at home.
Etching solution based on copper sulfate
The method of manufacturing printed circuit boards using copper sulfate is usually used if it is impossible to produce an etching solution based on other components due to their inaccessibility. Copper sulfate is a pesticide and is widely used for pest control in agriculture. In addition, the etching time of the printed circuit board is up to 4 hours, while it is necessary to maintain the solution temperature at 50-80°C and ensure a constant change of the solution at the surface being etched.
PCB etching technology
For etching a board in any of the above etching solutions, glass, ceramic or plastic dishes, for example from dairy products. If you don’t have a suitable container size at hand, you can take any box made of thick paper or cardboard of a suitable size and line its inside with plastic wrap. An etching solution is poured into the container and a printed circuit board is carefully placed on its surface, pattern down. Due to the forces of surface tension of the liquid and its light weight, the board will float.
For convenience, you can glue a plastic bottle cap to the center of the board with instant glue. The cork will simultaneously serve as a handle and a float. But there is a danger that air bubbles will form on the board and the copper will not be etched in these places.
To ensure uniform etching of copper, you can place the printed circuit board on the bottom of the container with the pattern facing up and periodically shake the tray with your hand. After some time, depending on the etching solution, areas without copper will begin to appear, and then the copper will completely dissolve on the entire surface of the printed circuit board.
After the copper is completely dissolved in the etching solution, the printed circuit board is removed from the bath and thoroughly washed under running water. Toner is removed from the tracks with a rag soaked in acetone, and paint is easily removed with a rag soaked in a solvent that was added to the paint to obtain the desired consistency.
Preparing the printed circuit board for installation of radio components
The next step is to prepare the printed circuit board for the installation of radio elements. After removing the paint from the board, the tracks need to be sanded in a circular motion with fine sandpaper. There is no need to get carried away, because the copper tracks are thin and can be easily ground off. Just a few passes with abrasive with light pressure are enough.
Next, the current-carrying paths and contact pads of the printed circuit board are coated with alcohol-rosin flux and tinned with soft solder using an electric soldering iron. To prevent the holes on the printed circuit board from being covered with solder, you need to take a little bit of it onto the soldering iron tip.
After completing the manufacture of the printed circuit board, all that remains is to insert the radio components into the designated positions and solder their leads to the pads. Before soldering, the legs of the parts must be moistened with alcohol-rosin flux. If the legs of the radio components are long, then before soldering they need to be cut with side cutters to a protrusion length above the surface of the printed circuit board of 1-1.5 mm. After completing the installation of parts, you need to remove any remaining rosin using any solvent - alcohol, white alcohol or acetone. They all successfully dissolve rosin.
It took no more than five hours to implement this simple capacitive relay circuit from laying out the tracks for manufacturing a printed circuit board to creating a working sample, much less than it took to type up this page.