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Homemade CNC machine for printed circuit boards. CNC PCB milling

In our time, among handicraft people, it is increasingly possible to find new machines that are controlled not by hands, as we are all used to, but by computer software and computerized equipment. This innovation is called CNC (Computer Numerical Control).

This technology is used in many institutions, in large industries, as well as in the master's workshops. An automated control system saves a lot of time and improves the quality of products.

The automated system is controlled by a program from a computer. This system includes asynchronous motors with vector control, which have three axes of movement of the electric engraver: X, Z, Y. Below we will consider what machines with automatic control and calculations are.

As a rule, all CNC machines use an electric engraver, or a milling cutter, on which you can change nozzles. A numerically controlled machine is used to give decorative elements to various materials and not only. CNC machines, due to advances in the computer world, must have many functions. These features include:

Milling

The mechanical process of processing the material, during which the cutting element (nozzle, in the form of a cutter) produces rotational movements on the surface of the workpiece.

Engraving

It consists in applying this or that image on the surface of the workpiece. To do this, use either milling cutters or a chisel (a steel rod with one end pointed at an angle).

drilling

Machining of the material by cutting, with the help of a drill, due to which holes of different diameters and holes with many faces of different sections and depths are obtained.

laser cutting

The method of cutting and cutting the material, in which there is no mechanical action, the high accuracy of the workpiece is maintained, and the deformations performed by this method have minimal deformations.

Plotter

High-precision drawing of the most complex schemes, drawings, geographical maps is carried out. Drawing is done at the expense of the writing block, by means of a specialized pen.

Drawing and drilling PCBs

Production of boards, as well as drawing electrically conductive circuits on the surface of a dielectric plate. Also drilling small holes for radio components.

It is up to you to decide what functions your future CNC machine will perform. And then consider the design of the CNC machine.

Variety of CNC machines

Technological features and capabilities of these machines are equated to universal machines. However, in the modern world, there are three types of CNC machines:

Turning

The purpose of such machines is to create parts according to the type of bodies of revolution, which consists in processing the surface of the workpiece. Also manufacture of internal and external threads.

Milling

The automated operation of these machines consists in the processing of planes and spaces of various body blanks. Milling is carried out flat, contour and stepped, at various angles, as well as from several sides. Drilling holes, threading, reaming and boring workpieces.

Drilling - boring

They perform reaming, drilling holes, boring and reaming, countersinking, milling, threading and much more.

As we can see, CNC machines have a wide range of functions that they perform. Therefore, they are equated with universal machines. All of them are very expensive and it is simply impossible to buy any of the above installations, due to financial insufficiency. And you might think that you have to do all these actions manually, throughout your life.

You may not be upset. The skillful hands of the country, even from the first appearance of factory CNC machines, began to create home-made prototypes that work no worse than professional ones.

All component materials for CNC machines can be ordered on the Internet, where they are freely available and are quite inexpensive. By the way, the body of an automated machine can be made by hand, and you can go to the Internet for the correct dimensions.

Tip: Before choosing a CNC machine, decide what material you will be processing. This choice will be of major importance in the construction of the machine, as it directly depends on the size of the equipment, as well as the cost of it.

The design of the CNC machine depends entirely on your choice. You can purchase a ready-made standard set of all the necessary parts and simply assemble it in your garage or workshop. Or order all equipment separately.

Consider a standard set of parts on the picture:

  1. Directly the work area, which is made from plywood, is a tabletop and a side frame.
  2. Guide elements.
  3. Guide holders.
  4. Linear bearings and plain bushings.
  5. Support bearings.
  6. Leading screws.
  7. Stepper motor controller.
  8. Controller power supply.
  9. Electric engraver or milling cutter.
  10. A coupling that connects the lead screw shaft to the stepper motor shaft.
  11. Stepper motors.
  12. Running nut.

Using this list of parts, you can safely create your own CNC wood router with automated work. When you assemble the entire structure, you can safely get to work.

Principle of operation

Perhaps the most important element on this machine is a milling cutter, engraver or spindle. It depends on your choice. If you have a spindle, then the tail of the cutter, which has a collet for fastening, will be tightly attached to the collet chuck.

The chuck itself is directly mounted on the spindle shaft. The cutting part of the cutter is selected based on the selected material. An electric motor, which is located on a moving carriage, rotates the spindle with a cutter, which allows you to process the surface of the material. The stepper motors are controlled by a controller, to which commands are given from a computer program.

Electronics The machine works directly on the computer software, which must be supplied with the ordered electronics. The program sends commands in the form of G-codes to the controller. Thus, these codes are stored in the RAM of the controller.

After selecting a processing program on the machine (finishing, roughing, three-dimensional), the commands are distributed to stepper motors, after which the surface of the material is processed.

Tip: Before starting work, it is necessary to test the machine with a specialized program and skip a trial part to make sure that the CNC works correctly.

Assembly

Machine assembly do it yourself won't take you too long. Moreover, on the Internet now you can download a lot of different schemes and drawings. If you bought a set of parts for a homemade machine, then its assembly will be very fast.

So let's look at one of drawings actual manual machine.

Drawing of a homemade CNC machine.

As a rule, first of all, a frame is made of plywood, 10-11 millimeters thick. The tabletop, side walls and the movable portal for installing a router or spindle are made only of plywood material. The tabletop is made movable, furniture guides of appropriate sizes are used.

As a result, you should get such a frame. After the frame structure is ready, a drill and special crowns come into play, with which you can make holes in plywood.

The frame of the future CNC machine.

In the finished frame, it is necessary to prepare all the holes in order to install bearings and guide bolts in them. After this installation, it is possible to install all fasteners, electrical installations, etc.

After the assembly is completed, an important step is to set up the machine software and computer program. When setting up the program, the operation of the machine is checked for the correctness of the specified dimensions. If everything is ready, you can start the long-awaited work.

Tip: Before starting work, it is necessary to check the correct fastening of the workpiece material and the reliability of the fastening of the working nozzle. Also make sure that the selected material matches the manufactured machine.

Equipment setup

Adjustment of the CNC machine is carried out directly from the working computer on which the program for working with the machine is installed. It is in the program that the necessary drawings, graphs, drawings are loaded. Which in sequence are converted by the program into G - codes necessary to control the machine.

When everything is loaded, trial actions are performed with respect to the selected material. It is during these actions that a check is made of all the necessary preset sizes.

Tip: Only after a thorough check of the machine's performance, you can start full-fledged work.

Safety

The rules and safety precautions when working with this machine are no different from working on all other machines. Below are the most basic ones:

  • Check the correct operation of the machine before work.
  • Clothing must be properly tucked in so that nothing sticks out anywhere and cannot get into the working area of ​​the machine.
  • You must wear a headdress that will hold your hair.
  • There should be a rubber mat or a low wooden crate near the machine, which will protect against leakage of electricity.
  • Access to the machine by children must be strictly prohibited.
  • Before working with the machine, check all fasteners for their strength.

Advice: It is necessary to approach the work on the machine with a sober head and understanding that if you work incorrectly, you can cause irreparable harm to yourself.

With complete safety requirements for working with the machine, you can find it on the World Wide Web, i.e. on the Internet and check them out.

Video reviews

Overview of the assembly of a homemade CNC machine

Video overview of a simple cnc machine

Overview of the possibilities of a homemade CNC machine

Overview of stepper motors

Review video multi-channel stepper motor driver

I don't like to etch printed circuit boards. Well, I do not like the process of fiddling with ferric chloride. Print there, iron here, expose the photoresist here - a whole story each time. And then think about where to drain the ferric chloride. I do not argue, this is an affordable and simple method, but personally I try to avoid it. And then happiness happened to me: I completed the CNC router. Immediately the thought arose: whether to try to mill printed circuit boards. No sooner said than done. I draw a simple adapter from the esp-wroom-02 lying around and begin my excursion into the milling of printed circuit boards. The tracks were specially made small - 0.5 mm. For if these do not come out, then what for this technology.



Since I personally make printed circuit boards every five years on big holidays, KiCAD is enough for me for designing. I did not find specialized convenient solutions for it, but there is a more universal way - using gerber files. In this case, everything is relatively simple: take pcb, export the desired layer to gerber (no mirroring or other magic!), run pcb2gcode - and get a ready-made nc-file that can be given to the router. As always, reality is an evil infection and everything turns out to be somewhat more complicated.

Getting gcode from gerber files

So, I don’t plan to describe in particular how to get a gerber file, I think everyone knows how to do it. Next, you need to run pcb2gcode. Turns out it takes about a million command line options to produce something acceptable. In principle, his documentation is not bad, I mastered it and figured out how to get some kind of gcode even like that, but still I wanted to be casual. That's why pcb2gcode GUI was found. This, as the name suggests, is a GUI for setting the main parameters of pcb2gcode with checkboxes, and even with a preview.



Actually, at this stage, some kind of gcode was obtained and you can try to mill. But while I was poking at the checkboxes, it turned out that the default depth value that this software offers is 0.05 mm. Accordingly, the board must be installed in the router with at least an accuracy higher than this. I don’t know how it is for anyone, but my router’s desktop is noticeably more crooked. The simplest solution that came to mind was to put a sacrificial plywood on the table, mill a pocket in it to fit the boards - and it would be ideally in the plane of the router.


For those who already know the router well, this part is not interesting. After a couple of experiments, I found out that it is necessary to mill a pocket in one direction (for example, feed per tooth) and with an overlap of at least thirty percent. Fusion 360 offered me too little overlap at first and drove back and forth. In my case, the result was unsatisfactory.

Accounting for textolite curvature

Having leveled the platform, I glued double-sided tape on it, put the textolite and started milling. Here is the result:



As you can see, from one edge of the board, the cutter practically does not touch the copper, from the other, it went too deep into the board, while milling textolite crumbs went. Looking closely at the board itself, I noticed that it was initially uneven: slightly curved, and no matter how you suffer with it, there will be some deviations in height. Then, by the way, I looked and found out that for printed circuit boards with a thickness of more than 0.8 mm, a tolerance of ± 8% is considered normal.


The first option that comes to mind is auto-calibration. According to the logic of things - which is even simpler, the board is copper-plated, the cutter is steel, I attached one wire to the copper, the other to the cutter - here's a ready-made probe for you. Take and build the surface.


My machine is controlled by grbl on a cheap Chinese shield. Grbl has support for the probe on pin A5, but for some reason there is no special connector on my board. Having carefully examined it, I nevertheless found that pin A5 is connected to the SPI port connector (signed as SCL), the ground is also nearby. With this "sensor" there is one trick - the wires need to be twisted together. In the milling cutter, it’s extremely picky, and without this, the sensor will constantly give false positives. Even after weaving, it will continue, but much, much less often.




The command says: start descending down to -10 in Z (this is absolute or relative height - depends on the mode in which the firmware is now). It will descend very slowly - at a speed of 5 mm / min. This is due to the fact that the developers themselves do not guarantee that the descent will stop exactly at the moment the sensor is triggered, and not a little later. Therefore, it is better to go down slowly so that everything stops in time and does not have time to go to the board, do not indulge in the most. It is best to carry out the first test by raising the head to a height of much more than 10 mm and resetting the coordinate system. In this case, even if everything does not work and you do not have time to reach the E-Stop button, the cutter will not lock up. Two tests can be carried out: the first is to do nothing (and when it reaches -10 grbl will issue “Alarm: Probe Fail”), the second is to close the circuit with something while it is going down and make sure that everything has stopped.


Next, you need to find a method how, in fact, to measure the matrix and distort the gcode as needed. At first glance, pcb2gcode has some kind of support for autoleveling, but there is no support for grbl specifically. There it is possible to set the commands for launching the sample by hand, but this needs to be dealt with, and, frankly, I was too lazy. An inquisitive mind might notice that LinuxCNC has the same command to run the probe as the grbl command. But then there is an irreparable difference: all "adult" gcode interpreters save the result of the performed test into a machine variable, and grbl simply outputs the value to the port.


A little googling suggested that there are still quite a few different options, but the chillpeppr project caught my eye:


This is a two-component system designed to play with web based hardware. The first component - Serial JSON Server, written in go, runs on a machine connected directly to the piece of iron, and is able to give control of the serial port via web sockets. The second - works in your browser. They have a whole framework for building widgets with some kind of functionality, which can then be put on the page. In particular, they already have a ready-made workspace (a set of widgets) for grbl and tinyg.


And chillpeppr has autoleveling support. Moreover, in appearance it is much more convenient than UniversalGcodeSender, which I used before. I set up the server, launch the browser part, spend half an hour figuring out the interface, upload the gcode of my board there and see some garbage:



Looking at the gcode itself, which pcb2gcode generates, I see that it uses a notation when the command (G1) is not repeated on subsequent lines, but only new coordinates are given:


F200.00000 X1.84843 Y34.97110 X2.64622 G00 X1.84843 Y34.97110 (rapid move to begin.) F100.00000 G01 Z-0.12000 Y34.17332 X2.69481 Y34.11185 X2.73962 Y34.00364 X2.74876 Y31.85178 X3.01828 Y31.84988 X3.06946 Y31.82249 X3.09684 Y31.77131

Judging by the fact that chilipeppr only shows vertical movements, he sees the line G01 Z-0.12 here, but does not understand everything that comes after F200. It is necessary to redo the notation for explicit. Of course, you can work with your hands or file some kind of post-processing script. But no one has yet canceled the G-Code Ripper, which, among other things, can break complex gcode commands (such as the same arcs) into simpler ones. By the way, he also knows how to bend gcode using the autoprobe matrix, but again there is no built-in support for grbl. But you can do the same split. The standard settings were quite suitable for me (except that in the config I had to change the units of measurement to mm in advance). The resulting file started displaying normally in chilipeppr:



Then we launch autoprobe, not forgetting to specify the distance from which to lower the sample, and its depth. In my case, I indicated that it was necessary to lower from 1 to -2 mm. The lower limit is not so important, you can set it at least -10, but I would not advise: a couple of times I unsuccessfully set the starting point from which to start the test, and the extreme points turned out to be outside the board. If the depth is greater - you can break the engraver. And it's just a mistake. How long it will measure the surface directly depends on the level of the upper boundary. In my case, in reality, the board almost never went beyond 0.25 mm up or down, but 1 mm is somehow more reliable. We press the treasured run and run to the router to meditate:



And in the chilipeppr interface, a measured surface slowly appears:



Here you need to pay attention that all Z values ​​are multiplied by 50 in order to better visualize the resulting surface. This is a configurable setting, but 10 and 50 work well in my opinion. I quite often encounter the fact that any one point turns out to be much higher than you can expect from it. Personally, I attribute this to the fact that the sensor catches the same pickups and gives a false positive. Fortunately, chilipeppr allows you to upload a height map in the form of json, you can fix it with your hands after that, and then download it with your hands. Next, click the "Send Auto-Leveled GCode to Workspace" button - and the corrected gcode is already loaded in the pepper:


N40 G1 X 2.6948 Y 34.1118 Z0.1047 (al new z) N41 G1 X 2.7396 Y 34.0036 Z0.1057 (al new z) N42 G1 X 2.7488 Y 31.8518 Z0.1077 (al new z) N43 G1 X 3.0183 Y 31.8499 Z 1127 (al new z) N44 G1 X 3.0695 Y 31.8225 Z0.1137 (al new z) N45 G1 X 3.0968 Y 31.7713 Z0.1142 (al new z)

Z moves have been added to the code, which should compensate for the unevenness of the surface.

Choice of milling parameters

I start milling, I get the following result:



There are three points to be seen here:

  1. The problem with the unevenness of the surface is gone: everything is cut (more precisely, scratched) almost to the same depth, there are no gaps anywhere, nowhere has it gone too deep.
  2. The penetration is insufficient: 0.05 mm is clearly not enough for this foil. By the way, the boards are some unknown beast from AliExpress, the thickness of the copper was not indicated there. The copper layer is different, the most common - from 18 to 140 microns (0.018-0.14 mm).
  3. The beating of the engraver is clearly visible.

About deepening. It is not difficult to choose how deep to lower the engraver. But there is specificity. The conical engraver has a triangular shape in projection. On the one hand, the angle of convergence to the working point determines how hard it is to break the tool and how long it will live, and on the other hand, the larger the angle, the wider the cut will be at a given depth.



The formula for calculating the cut width for a given depth looks like this (immodestly taken from reprap.org and corrected):


2 * penetration depth * tangents (tool tip angle) + tip width

We count on it: for an engraver with an angle of 10 degrees and a contact point of 0.1 mm with a depth of 0.1 mm, we get a cut width of almost 0.15 mm. Based on this, by the way, you can estimate what the minimum distance between the tracks will be made by the selected engraver on the foil of the selected thickness. Well, and yet, even if you don’t need very small distances between the tracks, you still shouldn’t lower the cutter too deep, since fiberglass very much blunts cutters even from hard alloys.


Well, there is another funny moment. Let's say we have two tracks that are 0.5 mm apart. When we run pcb2gcode, it will look at the value of the Toolpath offset parameter (how much to retreat from the track when milling) and actually make two passes between the tracks, separated by (0.5 - 2 * toolpath_offset) mm, between them there will be (but rather just break) some piece of copper, and it will be ugly. If you make the toolpath_offset greater than the distance between the tracks, then pcb2gcode will issue a warning, but it will generate only one line between the tracks. In general, for my applications, this behavior is more preferable, since the paths are wider, the cutter cuts less - beauty. True, there may be a problem with smd components, but it is unlikely.


There is a pronounced case of this behavior: if we set a very large toolpath_offset, then we will get a printed circuit board in the form of a Voronoi diagram. At least - it's beautiful;) You can see the effect on the first screenshot from pcb2gcode that I gave. It shows what it will look like.


Now about the beats of the engraver. That's what I call them for nothing. My spindle seems to be quite good and, of course, it doesn’t hit so hard. Here, rather, the tip of the engraver, when moving, bends and jumps between dots, giving that strange picture with dots. The first and main thought is that the cutter does not have time to cut through and therefore jumps over. A little googling showed people milling PCBs with a 50k rpm spindle at about 1000mm/min. My spindle gives 10k without load, and it can be assumed that it is necessary to cut at a speed of 200 mm / min.

Results and conclusion

Taking all this into account, I measure a new piece of textolite, start milling and get the following result:



The top one is exactly as it came out of the milling cutter, the bottom one - after I ran a regular grindstone over it a couple of times. As can be seen, the tracks were not cut in three places. In general, the width of the tracks floats throughout the board. This still needs to be dealt with, but I have an idea what the reason is. At first, I attached the board to double-sided tape, and it often departed. Then, in a couple of places, I also grabbed the edges of the heads of the self-tapping screws. It seems to hold on better, but still plays a little. I suspect that at the time of milling, it is pressed against the site and because of this, in fact, it does not cut through.



In general, all this has prospects. When the process is worked out, building a DEM takes about five to seven minutes, then directly milling - a couple of minutes. Looks like you can experiment further. But then you can do drilling on the same machine. Buy more rivets, and there will be happiness! If the topic is interesting, then I can write another article about drilling, double-sided boards, etc.

The question of how to make a CNC machine can be answered briefly. Knowing that a home-made CNC milling machine, in general, is a complex device with a complex structure, it is desirable for the designer:

  • get drawings;
  • purchase reliable components and fasteners;
  • prepare a good tool;
  • have a CNC lathe and drill on hand to quickly produce.

It does not hurt to watch the video - a kind of instruction, teaching - where to start. And I’ll start with preparation, buy everything I need, figure out the drawing - this is the right decision for a novice designer. Therefore, the preparatory stage preceding the assembly is very important.

Works of the preparatory stage

To make a homemade CNC for milling, there are two options:

  1. You take a ready-made running set of parts (specially selected units), from which we assemble the equipment ourselves.
  2. Find (make) all the components and start assembling the CNC machine with your own hands, which would meet all the requirements.

It is important to decide on the purpose, size and design (how to do without a drawing of a home-made CNC machine), find schemes for its manufacture, purchase or manufacture some of the parts that are needed for this, acquire lead screws.

If a decision is made to create a CNC machine with your own hands and do without ready-made sets of components and mechanisms, fasteners, you need the scheme assembled according to which the machine will work.

Usually, having found a schematic diagram of the device, they first model all the details of the machine, prepare technical drawings, and then use them on turning and milling machines (sometimes you need to use a drilling machine) to make components from plywood or aluminum. Most often, work surfaces (also called a desktop) are plywood with a thickness of 18 mm.

Assembly of some important machine components

In the machine that you began to assemble with your own hands, it is necessary to provide for a number of critical nodes that ensure the vertical movement of the working tool. In this list:

  • screw transmission - rotation is transmitted using a toothed belt. It is good because it does not slip on the pulleys, evenly transferring forces to the shaft of the milling equipment;
  • if a stepper motor (SM) is used for a mini-machine, it is advisable to take a carriage from a larger printer model - more powerful; old dot matrix printers had fairly powerful electric motors;

  • for a three-coordinate device, you need three step motors. Well, if there are 5 control wires in each, the functionality of the mini-machine will increase. It is worth evaluating the magnitude of the parameters: supply voltage, winding resistance and the rotation angle of the stepper motor in one step. To connect each stepper motor, a separate controller is needed;
  • with the help of screws, the rotational movement from the stepper motor is converted into a linear one. To achieve high accuracy, many consider it necessary to have ball screws (ball screws), but this component is not cheap. When choosing a set of nuts and mounting screws for mounting blocks, they are chosen with plastic inserts, this reduces friction and eliminates backlash;

  • instead of a stepper motor, you can take a conventional electric motor, after a little refinement;
  • the vertical axis that moves the tool in 3D, covering the entire XY table. It is made from aluminum plate. It is important that the dimensions of the axis are adjusted to the dimensions of the device. In the presence of a muffle furnace, the axis can be cast according to the dimensions of the drawings.

Below is a drawing made in three projections: side, rear, and top view.

Maximum attention - bed

The necessary rigidity to the machine is provided by the frame. A movable portal, a system of rail guides, a stepper motor, a work surface, a Z axis and a spindle are installed on it.

For example, one of the creators of a self-made CNC machine made the supporting frame from the Maytec aluminum profile - two parts (section 40x80 mm) and two end plates 10 mm thick from the same material, connecting the elements with aluminum corners. The design is reinforced, inside the frame a frame is made of smaller profiles in the shape of a square.

The bed is mounted without the use of welded joints (welds are poorly able to withstand vibration loads). It is better to use T-nuts as fasteners. On the end plates, a bearing block is provided for installing the lead screw. You will need a plain bearing and a spindle bearing.

The craftsman determined the main task of the hand-made CNC machine to be the manufacture of aluminum parts. Since workpieces with a maximum thickness of 60 mm were suitable for him, he made a portal clearance of 125 mm (this is the distance from the upper transverse beam to the working surface).

This difficult installation process

It is better to assemble home-made CNC machines, after preparing the components, strictly according to the drawing, so that they work. The assembly process, using lead screws, should be performed in the following sequence:

  • a knowledgeable craftsman begins by attaching the first two step motors to the body - behind the vertical axis of the equipment. One is responsible for the horizontal movement of the milling head (rail guides), and the second for movement in the vertical plane;
  • a movable gantry moving along the x-axis carries the milling spindle and carriage (z-axis). The higher the portal, the larger the workpiece can be processed. But at a high portal, in the process of processing, resistance to emerging loads decreases;

  • front, rear, top, middle and bottom plates are used to fasten Z-axis stepper motors, linear guides. In the same place, make a lodgement for the milling spindle;
  • the drive is assembled from carefully selected nuts and studs. To fix the motor shaft and attach it to the stud, use the rubber winding of a thick electric cable. Screws inserted into the nylon sleeve can be used as a retainer.

Then the assembly of the remaining components and assemblies of the homemade begins.

We mount the electronic filling of the machine

To make a CNC machine with your own hands and control it, you need to operate with correctly selected numerical control, high-quality printed circuit boards and electronic components (especially if they are Chinese), which will allow you to implement all the functionality on a CNC machine, processing a part of complex configuration.

In order to avoid problems in management, home-made CNC machines, among the nodes, have the following mandatory:

  • stepper motors, some stopped like Nema;
  • LPT port through which the CNC control unit can be connected to the machine;
  • drivers for controllers, they are installed on a mini-milling machine, connected in accordance with the diagram;

  • switching boards (controllers);
  • a 36V power supply unit with a step-down transformer that converts to 5V to power the control circuit;
  • laptop or PC;
  • emergency stop button.

Only after that, the CNC machines are tested (at the same time, the craftsman will make a test run by downloading all the programs), the existing shortcomings are identified and eliminated.

Instead of a conclusion

As you can see, making a CNC that is not inferior to Chinese models is real. Having made a set of spare parts with the right size, having high-quality bearings and enough fasteners for assembly, this task is within the power of those who are interested in software engineering. It won't take long to find an example.

In the photo below - some samples of machine tools with numerical control, which are made by the same craftsmen, not professionals. Not a single part was made hastily, of arbitrary size, but fitting to the block with great accuracy, with careful alignment of the axes, using high-quality lead screws and with reliable bearings. The statement is true: as you collect, so you will work.

On the CNC, processing of an duralumin blank is performed. Such a machine, which was assembled by a craftsman, can perform a lot of milling work.

Another sample of the assembled machine, where the fiberboard is used as a work table, on which the manufacture of a printed circuit board is possible.

Everyone who starts making the first device will soon move on to other machines. Perhaps he wants to test himself as an assembler of a drilling unit and, imperceptibly, join the army of craftsmen who have assembled a lot of home-made devices. Technical creativity will make people's lives interesting, varied and rich.

Stepper driver, the dude elegantly made everything without the use of a microcontroller. I read this, looked at my board drill with a tight manual feed, and decided to attach an up-down feed control to it. A driver for a stepper was bought, a suitable stepper from the printer was pulled out of the bins, an expensive one was bought, which I planted on the engine shaft from some kind of printer, then the driver came and the movement began.

Here is the first version of my platform drill:

People with engineering thinking will immediately notice the addictive position of the lever relative to the guides (shiss hundred rubles for a brass tube, and the same amount for a brass rod! Yes, it would be better if I bought linear bearings and two guides in China), because of this decision, the spindle moves unevenly, jerkily , and you can break a number of drills if they are carbide. And for them, everything actually started.

While I was waiting for iron, I muddied a powerful backlight for this machine



The device says that it is VERY BRIGHT. But it’s comfortable to work, I decided not to adjust the backlight

here is a photo at work

I started sawing the Y axis drive. I decided to just add some pieces of wood to the existing structure

Pay attention to the nanotechnological connection of the shaft with the lead screw

For this, a brake signal sensor was bought from some kind of vase, and mercilessly gouged so that only a brass tube remained

It's time for the electronics.
I played with the proteus and on the breadboard with the circuit and code, and etched the board for the future controller


The arduino nano will act as the brains of the machine, because I can’t code for something more serious. Controlled by potentiometer and encoder with button.
The driver itself is called EASY DRIVER on the Internet, which, as it were, speaks of the simplicity of working with it. It's right. It needs two signals - STEP and DIR. First we move with the engine, the second we say in which direction to step. After trying the clumsy library for it, I decided to write everything myself, which turned out pretty well in the end.
All this is powered by a 19 volt laptop power supply. The driver can pass up to 30 volts through itself, and the motor with the cartridge is designed for 24, if I'm not mistaken, it still has not enough revolutions.

Video of the first test:

The encoder can move the spindle up and down along the Y axis, the variable resistor sets the distance that the spindle will move in one click of the encoder, and also sets the feed rate when the “DRILL!” button is pressed. It turned out to be very convenient to use a pre-prepared algorithm for making a hole. I also attached a rolled display for show off. Did you connect it with something like this? to save arduino legs

I screwed all the boards and handles into place, and this is what happened:

look








Having tormented with the code, I made it all work as I need, and here is the finished device.

Now it remains to come up with a new crazy project to try out your product in combat conditions, as well as attach a pedal to free your hands.
If anyone is interested in something in the review, ask, PM, comments, whatever

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The CNC machine is very convenient to use in a home radio amateur workshop for the manufacture of printed circuit boards, both product layouts and small batches of products. The presence of CNC engraving and milling in a home workshop or a small business allows both to reduce the time required to manufacture a printed circuit board in the manufacture of layouts, prototypes of small batches of products, and to improve the quality of manufactured printed circuit boards compared to other manufacturing methods. The use of a numerically controlled machine allows you to perform a full range of operations for the manufacture of a printed circuit board - milling a conductive pattern (tracks), drilling holes both for installing components and for vias, trimming and board contour.

First you need to create a PCB design. To do this, it is very convenient to use the Sprint Layout 6 program, which is very popular among radio amateurs. When developing, it is necessary to take into account the technological features of processing foil textolite on a CNC machine, that is, to trace with sufficiently wide tracks, leaving the necessary gaps for the passage of an engraver / cutter, etc. It is necessary to select the LOWER LEFT CORNER as the starting point of the coordinates, Figure 1.

On layer O, draw the outline (borders) of the printed circuit board along which the finished board will be cut. The thickness of the lines is indicated depending on the diameter of the cutter used for cutting the board. We control the gap between the edge of the board and the tracks so that the contour does not intersect with the tracks. In order to prevent the board from being thrown out of the workpiece after cutting out and not damaged by the cutter, we leave jumpers on which the board will be held in the workpiece. They can then be easily eaten with side cutters when removing the finished board. Turn off the extra layers and pre-examine the board, Figure 2.

figure 2

Open the milling "strategies" settings window, Figures 3 and 4.

figure 3

figure 4

In the "track width" window (Figure 4), we indicate the thickness of our cutting tool. For example, an engraver with a cutting tip of 0.6mm. For the convenience of further processing, check the box “mark holes”. We press "OK". We save Figure 5 in a convenient place for us.

figure 5

After calculating the machining path, the board will look like this, Figure 6:

figure 6

You can clearly track the path of the cutter and the amount of copper that it will remove. For the convenience of displaying the trajectory of the cutter with a thin line, you can press the highlighted button, Figure 7:

figure 7

At this stage, it is necessary to carefully monitor the trajectory of the cutter - to check the absence of a short circuit between the conductive tracks that do not belong to the same circuit. If an error is found, correct and resave the file.
Next, you need to prepare a control program for the machine. Using the Step Cam 1.79 utility (you can download it on the Internet), open our milling file, set the working feed and cutting depth (depending on the machine, tool and material used) and convert it to G-code by pressing the Make G-code key. The program will generate a machining G-code based on the milling file. You can see the result of G-code generation using the Action -> Draw G-code tab. If nothing is displayed, you need to click the mouse in the window, Figure 8.
Empirically, we select the depth of milling, trying to set up the machine so that the cutter / engraver removes only the copper layer, with a slight overcut. This parameter depends on the thickness of the copper foil of the textolite foil used.

figure 8

Click Save G-code. The file is ready.
We load the file in Mach3, we carry out visual control of the loaded file. We set the zeros on the machine, start processing.
For drilling holes in the board and cutting along the contour, the setup and preparation of files is similar. Approximate settings are shown in figures 9 and 10.
Drilling pattern 9:

figure 9

Milling the board along the contour, Figure 10:

figure 10

We save the settings for drilling and milling the contour separately. Uploading to Step Cam. We indicate the depth of processing, depending on the thickness of the textolite used, with a slight overcut. For example, with a textolite thickness of 1.5 mm, we set 1.6-1.7 mm for drilling. It is desirable to perform contour milling in 2 - 4 passes, depending on the characteristics of the cutting tool. To do this, set the immersion depth in Step Cam during milling to 0.5 mm, and then after each pass on the machine, manually lower the tool along the “Z” axis and reset it.

Some nuances of working on the machine in the manufacture of a printed circuit board:
1. The surface of the desktop should be as flat and level as possible. One way to achieve this is to make a "sacrificial table" out of plywood and trim it. To do this, a sheet of plywood is attached to the main desktop of the machine, and then, using a large cutter, a “bed” is milled under the board to a shallow depth (1-2 mm).
2. Fiberglass is not always a perfectly even material, and its thickness can also vary. Therefore, it is necessary to cut with a small overcut. Some experienced people specially make height maps for more accurate processing. The degree of cutting is determined empirically.
3. For milling, you can use a pyramid type engraver with a tip from 0.4 to 1mm. For drilling, there are 0.8-1.5mm drills with a shank for a standard 3.175mm collet. It is best to cut along the contour with a 2-3mm “corn” cutter.
4. The tool is manually changed each time. To do this, after performing, for example, milling tracks, we stop the spindle, leave the machine in hold mode. We raise the cutting tool to a height convenient for replacement, change. After that, we set zero on the Z axis. And so with each change of instrument. X and Y coordinates are not nullable.
5. Do not forget that fiberglass is not the most useful material for the body. Textolite dust is especially harmful to the respiratory tract. Therefore, it is desirable to organize an exhaust or otherwise remove excess dust from the cutting area. It is possible, for example, to periodically moisten the printed circuit board with water or another suitable liquid, using a medical syringe. A wet bandage over the nose/mouth or a respirator will do a good job of protecting the respiratory tract.

The article is for informational purposes, based on the personal experience of the author and is not the only correct and possible solution.

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