Knowing that this is a complex technical and electronic device, many craftsmen think that it is simply impossible to make it with their own hands. However, this opinion is wrong: you can make such equipment yourself, but to do this you need to have not only detailed drawing, but also a set necessary tools and related components.
Processing a duralumin blank on a homemade desktop milling machine
When deciding to make your own CNC machine, keep in mind that it can take a significant amount of time. In addition, certain financial costs will be required. However, by not being afraid of such difficulties and by correctly approaching all issues, you can become the owner of affordable, efficient and productive equipment that allows you to process workpieces from various materials with a high degree of accuracy.
To make a milling machine equipped with a CNC system, you can use two options: buy a ready-made kit, from which such equipment is assembled from specially selected elements, or find all the components and assemble a device with your own hands that fully meets all your requirements.
Instructions for assembling a homemade CNC milling machine
Below in the photo you can see something made with your own hands, which comes with detailed instructions on manufacturing and assembly, indicating the materials and components used, exact “patterns” of machine parts and approximate costs. The only negative is the instructions on English language, but it is quite possible to understand the detailed drawings without knowing the language.
Download free instructions for making the machine:
The CNC milling machine is assembled and ready to go. Below are some illustrations from the assembly instructions for this machine.
“Patterns” of machine parts (reduced view) Beginning of machine assembly Intermediate stage The final stage assemblies
Preparatory work
If you decide that you will construct a CNC machine with your own hands, without using a ready-made kit, then the first thing you will need to do is to choose a circuit diagram according to which such mini-equipment will work.
As a basis milling equipment With CNC, you can take an old drilling machine, in which the working head with the drill is replaced with a milling one. The most difficult thing that will have to be designed in such equipment is the mechanism that ensures the movement of the tool in three independent planes. This mechanism can be assembled using carriages from a non-working printer; it will ensure the movement of the tool in two planes.
It is easy to connect software control to a device assembled according to this concept. However, its main disadvantage is that only workpieces made of plastic, wood and thin materials can be processed on such a CNC machine. sheet metal. This is explained by the fact that the carriages from the old printer, which will provide movement cutting tool, do not have a sufficient degree of rigidity.
In order for your homemade CNC machine to be able to perform full-fledged milling operations with workpieces made of various materials, a sufficiently powerful one must be responsible for moving the working tool stepper motor. It is absolutely not necessary to look for a stepper type motor; it can be made from a conventional electric motor, subjecting the latter to minor modifications.
The use of a stepper motor in yours will make it possible to avoid the use of a screw gear, and the functionality and characteristics homemade equipment it won't make things any worse. If you still decide to use carriages from a printer for your mini-machine, then it is advisable to select them from a larger model of the printing device. To transfer force to the shaft of milling equipment, it is better to use not ordinary, but toothed belts that will not slip on the pulleys.
One of the most important nodes of any similar machine is the milling mechanism. It is its production that must be given Special attention. To properly make such a mechanism, you will need detailed drawings, which will need to be strictly followed.
CNC milling machine drawings
Let's start assembling the equipment
The basis of homemade CNC milling equipment can be a rectangular beam, which must be securely fixed on guides.
The supporting structure of the machine must have high rigidity; when installing it, it is better not to use welded joints, and all elements should be connected only with screws.
This requirement is explained by the fact that welds very poorly withstand vibration loads, to which the supporting structure of the equipment will necessarily be subjected. Such loads will ultimately lead to the machine frame beginning to deteriorate over time, and changes in geometric dimensions will occur in it, which will affect the accuracy of the equipment settings and its performance.
Welds when installing a homemade frame milling machine often provoke the development of play in its nodes, as well as deflection of the guides, which occurs under severe loads.
The milling machine that you will assemble with your own hands must have a mechanism that ensures the movement of the working tool in the vertical direction. It is best to use a screw gear for this, the rotation of which will be transmitted using a toothed belt.
An important part of a milling machine is its vertical axis, which homemade device can be made from aluminum plate. It is very important that the dimensions of this axis are precisely adjusted to the dimensions of the device being assembled. If you have a muffle furnace at your disposal, then you can make the vertical axis of the machine yourself by casting it from aluminum according to the dimensions indicated in the finished drawing.
Once all the components of your homemade milling machine are prepared, you can begin assembling it. This process begins with the installation of two stepper motors, which are mounted on the equipment body behind its vertical axis. One of these electric motors will be responsible for moving milling head in the horizontal plane, and the second - for moving the head, respectively, in the vertical. After this, the remaining components and assemblies of home-made equipment are installed.
Rotation to all components of homemade CNC equipment should be transmitted only through belt drives. Before connecting to assembled machine program control system, you should check its performance in manual mode and immediately eliminate all identified deficiencies in its operation.
You can watch the assembly process in the video, which is easy to find on the Internet.
Stepper motors
The design of any CNC-equipped milling machine necessarily contains stepper motors that ensure the movement of the tool in three planes: 3D. When designing homemade machine For this purpose, you can use electric motors installed in a dot matrix printer. Most older models of dot matrix printing devices were equipped with electric motors with fairly high power. In addition to stepper motors, it is worth taking strong steel rods from an old printer, which can also be used in the design of your homemade machine.
To make your own CNC milling machine, you will need three stepper motors. Since there are only two of them in the dot matrix printer, it will be necessary to find and disassemble another old printing device.
It will be a big plus if the motors you find have five control wires: this will significantly increase the functionality of your future mini-machine. It is also important to find out the following parameters of the stepper motors you have found: how many degrees are rotated in one step, what is the supply voltage, as well as the value of the winding resistance.
The drive design of a homemade CNC milling machine is assembled from a nut and a stud, the dimensions of which should be pre-selected according to the drawing of your equipment. To fix the motor shaft and connect it to the stud, it is convenient to use a thick rubber winding from an electric cable. Parts of your CNC machine, such as clamps, can be made in the form of a nylon sleeve into which a screw is inserted. In order to make such simple structural elements, you will need a regular file and a drill.
Electronic equipment
Your DIY CNC machine will be controlled by software, and it needs to be selected correctly. When choosing such software (you can write it yourself), it is important to pay attention to the fact that it is operational and allows the machine to realize all its functionality. Such software must contain drivers for the controllers that will be installed on your mini-milling machine.
In a homemade CNC machine, an LPT port is required, through which the electronic control system is connected to the machine. It is very important that such connection is made through installed stepper motors.
When choosing electronic components for your homemade machine, it is important to pay attention to their quality, since the accuracy of the technological operations that will be performed on it will depend on this. After installing and connecting all electronic components of the CNC system, you need to download the necessary software and drivers. Only after this is a test run of the machine, checking the correct operation of it under the control of loaded programs, identifying deficiencies and promptly eliminating them.
Now a little more detail about the main assembly.
So, to assemble the frame you will need the following components:
- Profile sections 2020 (two longitudinal, 5 transverse, 2 vertical parts)
- Corners for profile 16 pcs
- T-nuts M3 or M4 for groove - 6mm
- Screws for installation with T-nuts (M3 or M4, respectively, 8...10 mm, plus M3x12 for mounting motors)
- Spacer (45° angle)
- Tool (screwdriver)
Since I started talking about the profile, just in case I’ll repeat about the purchase and cutting of the profile from Soberizavod
This is structural.
I immediately bought a profile kit for 2418 cut to size.
There are two options - an uncoated profile (cheaper) and a coated profile (anodized). The difference in cost is small, I recommend coated, especially if used as guides for rollers. 
Choose desired type profile 2020, then enter “cut to size”. Otherwise, you can buy one piece (whip) per 4 meters. When calculating, keep in mind that the cost of one cut varies depending on the profile. And that 4 mm is allowed for the cut. 
Enter the sizes of the segments. I made the 2418 machine a little larger, these are seven sections of 260 mm and two vertical sections of 300 mm. The vertical one can be made smaller. If you need a longer machine, then two longitudinal sections are larger, for example, 350 mm, and transverse sections are also 260 mm (5 pieces). 
We confirm (must be added to the cutting map) 
Checking the cart 
The profile is obtained for 667 rubles together with the cutting service. 
Delivery is carried out by TK, you can calculate the cost using a calculator, since you know the profile dimensions, the weight is very well calculated in the cutting chart. For the calculation, you need the option “cargo pickup from the supplier.” Delivery via Business lines will cost less, about 1000 rubles.
You can pick it up in Moscow. 
In one place there is an office, a warehouse and a workshop where profiles are cut to size. There is a showcase with samples, you can select a profile on the spot.
So, let's start assembling the frame desktop machine 2418.
Here is the already cut profile.
In this design, I increased the Z axis (a little more by a couple of cm than the others) in order to use the machine as a CNC drill.
In the original, the Z axis is the shortest. You already decide this according to your goals. To extend the working field, you need to buy two sections of the profile (longitudinal pair) more desired length(for example, +10 cm), the guides (+10 cm for a pair of 8mm shafts) and the screw (+10 cm for a T8 screw) are lengthened accordingly. In terms of money, the stated +10 cm comes out very cheap: the cost of a 10+10 cm profile is about 40 rubles, the guides and screw will cost plus $6 (check).
Here are the corners prepared for assembly 
This is how the T-nuts should be installed into the slot. You can not thread it from the end, but install it directly into the groove of the profile sideways, but then control the rotation and installation of the nut, since this does not always happen, some skill is required. 
The profile cut is clean, there are no burrs 
The profile is twenty, that is, from the 2020 series, with corresponding dimensions of 20 mm x 20 mm, a groove of 6 mm. 
So, first we assemble the U-shaped part of the frame, attach two longitudinal parts of the profile and one outer cross member. It doesn’t really matter which side you assemble from, but keep in mind that there is a central crossbar that is moved closer to the back. She is part vertical plane, and the size of the offset depends on the offset of the Z axis and the spindle. Place it so that the spindle rotation axis is in the center of the machine (Y axis).
Next we assemble the middle cross member. It is more convenient to first install both corners on a section of the profile and fix them, and then install them to the frame.
We apply a section of the profile, measure the same distance with a ruler, and tighten the screws. The screws must be tightened slowly, allowing time for the T-nut to turn and take its position in the groove. If it doesn't work the first time, loosen the nut again and repeat. 
We install the last part of the horizontal frame. It's easier to access with a long screwdriver. Don’t be lazy and check the right angles of the resulting structure with a square and the diagonals with a ruler. 
Since the corners of the structure are directed towards each other, it does not matter in what order they are assembled. I did the same as in the basic CNC2418 design. But intuition suggests that it makes sense to increase the distance between the profiles, especially with a higher portal height. Okay, that can be done later. 
Next we begin to assemble the vertical portal mount 
We install the assembled portal on the horizontal part, fasten it with 6 corners (installed in three directions from the vertical profile). 
We establish and maintain the perpendicularity of the segments (along the square). Then I tightened all the screws one by one. 
In the original, a special extrusion angle at 45° is used to strengthen the vertical. I couldn’t find a similar one on sale, so I replaced it with a 3D printed one. The link to the model is at the end of the topic.
Update: It turned out that the original was 3D printed too.
If anything, you can replace it with perforated fasteners from stores, or furniture corners. This will not affect the quality in any way. 
At first glance, the structure turned out to be solid, not shaky. It can be seen that the plate with the engine is shorter than the KP08+SK8 caliper set. I'll spread it wider. 
In fact, this frame is a copy of a similar design of the CNC2418 machine, except that I didn’t directly copy the dimensions, I made it a little larger in order to have less scraps from guides and screws.
The frame assembly is complete, now you can start installing the engines. I use 3D printed flanges to mount the motors. It is advisable to make the upper ones assembled with guide holders, the lower ones - without holders, since the Y axis should be wider. It is advisable to install the Y axis on supports SK8 and KP08, as in the original machine. The calipers themselves can be printed on a printer or purchased (links are at the end of the topic, and were also in the first post).
For one of the axes (the X and Y axes are the same length), I took a “sighting” one. I didn’t yet know my “wants” for the size of the machine. As a result, the scraps from the screw will go to the Z axis; you will only need to purchase a T8 brass nut. 
It was packed in a cardboard box, inside each part was in a bag separately. 
The kit looks like this: a motor with a short wire, a T8 lead screw, two KP08 calipers and two 5x8 couplings. 
There is a similar one, and also without an engine (with calipers and a nut).
If you take without a large margin, then the 400 mm option will work well for the “enlarged version” of the machine
Additional information - photos of the set separately
Engine marking RB Step Motor 42SHDC3025-24B-500, seat Nema17 
A short wire for connection is included. Conveniently, you can simply increase the length without touching the connectors. 
T8 screw, nut 
KR08 calipers. 
Convenient to attach to the profile. If you use a wide flange for installation, then it is better to use the KFL08 version of the caliper; it allows you to attach the screw not to the profile, but to the flange. 
5x8 coupling is a split coupling for connecting the motor shaft to the propeller. 
This is how the engine is originally mounted on the X-axis. On a small aluminum plate.
I did the same thing, only with a printing plate. At the same time it will be a support for the guides.
I have already cut off the extra length of the screw for the Z axis (the Z axis is still in process, the information will be separately, most likely also 3D printed).
Most likely, you will need to lengthen the motor wires in order to carefully route it along the profile to the upper part to the electronics board (most likely there will be a CNC Shield). And it wouldn’t hurt to install limit switches for extreme positions.
The basic information on the assembly is already there, you can start estimating costs))))
Costing
Now, as requested in the comments in the first part, I propose to discuss costing. Naturally, I spent less than indicated, since the engines and most of I had the components in stock. Strongly cheaper it will be if you use homemade printed corners for the profile, calipers, flanges, and so on. For the operation of a machine for drilling printed circuit boards and milling soft materials this is unlikely to have any effect. Another good option is to use perforated plates from construction/hardware stores. Suitable for strengthening corners, including vertical ones, and for installing an engine, provided the central part is drilled for the shaft. In place of the perforated fasteners, you can use homemade ones from aluminum sheet or plywood.
Definitely a must buy profile 2020, otherwise it will be a completely different type of machine. You can do the same thing from an aluminum corner or a rectangular pipe, but only for the love of art))) There are more optimal designs in terms of rigidity for assembly from a corner/pipe.
Definitely needed for the profile T-nuts. You can buy T-bolts, but T-nuts are more universal (since any screw length can be used).
But the rest can be changed at your discretion, you can even replace the chassis T8 screw use hairpin made of stainless steel. Unless the number of steps per mm will have to be recalculated in the firmware.
Engines can be removed from old devices/office equipment and planned seats already for a specific type.
Electronics almost any (Anduino UNO/Anduino Nano, CNCShield, Mega R3+Ramps, A4988/DRV8825 drivers, you can use an adapter board for Mach3 and TB6600 drivers. But the choice of electronics is limited by the software used.
For drilling, you can use any engine DC, which allows you to set collet and has decent revs. The basic version has a high-speed 775 motor. For milling, you can use 300 watt non-reactive spindles with an ER11 collet, but this greatly increases the cost of the machine as a whole.
Approximate cost calculation:
profile 2020 (2.5 meters) = 667r
profile 2080 (0.5 meters) on desktop = 485 RUR
Two 300 mm 2х$25
. A lot of 20 pieces comes out to $5.5 with delivery
approximately 4r/piece if you take a large package. You need at least 50 pieces (mounting engines, calipers). I don’t count the screws for them, usually a few kopecks per piece depending on the quality. Total about 400...500 rub.
Engines 3 pcs $8.25 each
Electronics $2
$3.5
A4988 three pieces for $1
The machine comes out to about $111. If you add a spindle:
$9
$7.78,
That total cost about $128
I do not evaluate 3D printed parts. Can be replaced with perforated plates/corners from crepe markets and similar stores. I also don’t estimate the wires, electrical tape, or time spent.
Let me remind you that not all CNC2418 configuration options have such good 775 engines and, especially, an ER11 collet.
Options cheaper.
And so, as part of this instructional article, I want you, together with the author of the project, a 21-year-old mechanic and designer, to make your own. The narration will be conducted in the first person, but know that, to my great regret, I am not sharing my experience, but only freely retelling the author of this project.
There will be quite a lot of drawings in this article., the notes to them are made in English, but I am sure that a real techie will understand everything without unnecessary words. For ease of understanding, I will break the story into “steps”.
Preface from the author
Already at the age of 12, I dreamed of building a machine that would be capable of creating various things. A machine that will give me the ability to make any household item. Two years later I came across the phrase CNC or to be more precise, the phrase "CNC milling machine". After I found out that there are people capable of making such a machine independently for their needs, in their own garage, I realized that I could do this too. I must do it! For three months I tried to collect suitable parts, but did not budge. So my obsession gradually faded.
In August 2013, the idea of building a CNC milling machine captured me again. I had just graduated from a bachelor's degree in industrial design at university, so I was quite confident in my abilities. Now I clearly understood the difference between me today and me five years ago. I learned how to work with metal, mastered techniques for working with manual metalworking machines, but most importantly, I learned how to use development tools. I hope this tutorial inspires you to build your own CNC machine!
Step 1: Design and CAD model
It all starts with thoughtful design. I made several sketches to get a better feel for the size and shape of the future machine. After that I created a CAD model using SolidWorks. After I modeled all the parts and components of the machine, I prepared technical drawings. I used these drawings to make parts on manual metalworking machines: and.
I confess honestly, I love good convenient tools. That is why I tried to make sure that the operations maintenance and adjustment of the machine were carried out as simply as possible. I placed the bearings in special blocks in order to be able to quickly replace them. The guides are accessible for maintenance, so my car will always be clean when the work is completed.
Files for downloading “Step 1”
dimensions
Step 2: Bed
The bed provides the machine with the necessary rigidity. A movable portal, stepper motors, a Z axis and a spindle, and later a working surface will be installed on it. To create the supporting frame I used two 40x80mm Maytec aluminum profiles and two 10mm thick aluminum end plates. I connected all the elements together using aluminum corners. To strengthen the structure inside the main frame, I made an additional square frame from profiles of a smaller section.
In order to avoid dust getting on the guides in the future, I installed protective corners made of aluminum. The angle is mounted using T-nuts, which are installed in one of the profile grooves.
Both end plates have bearing blocks for mounting the drive screw.
Support frame assembly
Corners for protecting guides
Files for downloading “Step 2”
Drawings of the main elements of the frame
Step 3: Portal
The movable portal is the executive body of your machine; it moves along the X axis and carries milling spindle and a Z-axis support. The higher the portal, the thicker the workpiece you can machine. However, a high portal is less resistant to the loads that arise during processing. The high side posts of the portal act as levers relative to the linear rolling bearings.
The main task that I planned to solve on my CNC milling machine was the processing of aluminum parts. Since the maximum thickness of aluminum blanks suitable for me is 60 mm, I decided to make the portal clearance (the distance from the working surface to the top cross beam) equal to 125 mm. I converted all my measurements into a model and technical drawings in SolidWorks. Due to the complexity of the parts, I processed them on an industrial CNC machining center; this additionally allowed me to process chamfers, which would be very difficult to do on a manual metal milling machine.
Files for downloading “Step 3”
Step 4: Z Axis Caliper
For the Z axis design, I used a front panel that attaches to the Y axis motion bearings, two plates to reinforce the assembly, a plate to mount the stepper motor, and a panel to mount the milling spindle. On the front panel I installed two profile guides along which the spindle will move along the Z axis. Please note that the Z axis screw does not have a counter support at the bottom.
Downloads “Step 4”
Step 5: Guides
Guides provide the ability to move in all directions, ensuring smooth and precise movements. Any play in one direction can cause inaccuracy in the processing of your products. I chose the most expensive option - profiled hardened steel rails. This will allow the structure to withstand high loads and provide the positioning accuracy I need. To ensure the guides were parallel, I used a special indicator while installing them. The maximum deviation relative to each other was no more than 0.01 mm.
Step 6: Screws and Pulleys
Screws convert rotary motion from stepper motors into linear motion. When designing your machine, you can choose several options for this unit: a screw-nut pair or a ball screw pair (ball screw). The screw-nut, as a rule, is subjected to more frictional forces during operation, and is also less accurate relative to the ball screw. If you need increased accuracy, then you definitely need to opt for a ball screw. But you should know that ball screws are quite expensive.
There are a lot of similar stories on the Internet, and I will probably surprise few people, but maybe this article will be useful to someone. This story began at the end of 2016, when I and my friend, a partner in the development and production of testing equipment, accumulated a certain amount of money. In order not to simply waste money (this is a young business), we decided to invest it in the business, after which the idea of making a CNC machine came to mind. I already had experience in building and working with this kind of equipment, and the main area of our activity is design and metalworking, which accompanied the idea of building a CNC machine.
That’s when the movement began, which continues to this day...
Everything continued with studying forums dedicated to CNC topics and choosing the basic concept of the machine design. Having previously decided on the materials to be processed on the future machine and its working field, the first paper sketches appeared, which were later transferred to the computer. In the environment of three-dimensional modeling KOMPAS 3D, the machine was visualized and began to acquire more small details and nuances, which turned out to be more than we would like, some of which we are still solving to this day.
One of the initial decisions was to determine the materials processed on the machine and the dimensions of the working field of the machine. As for the materials, the solution was quite simple - it was wood, plastic, composite materials and non-ferrous metals (mainly duralumin). Since we mainly use metal-working machines in our production, sometimes we need a machine that would quickly process materials that are quite easy to process along a curved path, and this would subsequently reduce the cost of production of ordered parts. Based on the selected materials, mainly supplied in sheet packaging, with standard sizes 2.44x1.22 meters (GOST 30427-96 for plywood). Having rounded these dimensions we came to the following values: 2.5x1.5 meters, working space definitely, with the exception of the tool lifting height, this value was chosen from the consideration of the possibility of installing a vice and it was assumed that we would not have workpieces thicker than 200 mm. We also took into account the fact that if it is necessary to process the end of any sheet part with a length of more than 200 mm, for this the tool moves beyond the dimensions of the base of the machine, and the part/workpiece itself is attached to the end side of the base, thereby processing the end of the part can take place.
Machine design is a prefabricated frame base from the 80th profile pipe with a 4mm wall. On both sides of the length of the base, profile rolling guides of the 25th standard size are fixed, on which a portal is installed, made in the form of three profile pipes welded together of the same standard size as the base.
The machine is four-axis and each axis is driven by a ball screw. Two axes are located parallel along the long side of the machine, paired by software and tied to the X coordinate. Accordingly, the remaining two axes are Y and Z coordinates.
Why exactly did we settle on a prefabricated frame: initially we wanted to make a purely welded structure with embedded welded sheets for milling, installation of guides and ball screw supports, but we did not find a large enough coordinate milling machine for milling. I had to draw a prefabricated frame so that I could process all the parts myself using the metalworking machines available in the production. Each part that was exposed to electric arc welding was annealed to relieve internal stress. Next, all the mating surfaces were milled, and subsequently the adjustments had to be scraped in places.
Jumping ahead, I would like to say right away that the assembly and manufacture of the frame turned out to be the most labor-intensive and financially expensive event in the construction of the machine. The original idea with a fully welded frame is superior in all respects to a prefabricated structure, in our opinion. Although many may not agree with me.
I would like to make a reservation right away that we will not consider machines made from aluminum structural profiles here for now; this is rather a matter for another article.
Continuing to assemble the machine and discussing it on forums, many began to advise making diagonal steel jibs inside and outside the frame to add even more rigidity. We did not neglect this advice, but we also added jibs to the structure, since the frame turned out to be quite massive (about 400 kg). And upon completion of the project, the perimeter will be covered with sheet steel, which will further connect the structure.
Let's now move on to the mechanical issue of this project. As was previously said, the movement of the machine axes was carried out through a ball screw pair with a diameter of 25 mm and a pitch of 10 mm, the rotation of which was transmitted from stepper motors with 86 and 57 flanges. Initially, it was intended to rotate the propeller itself directly in order to get rid of unnecessary backlash and additional gears, but it could not have been done without them due to the fact that with a direct connection between the engine and the propeller, the latter would begin to unwind at high speeds, especially when the portal is in extreme positions. Considering the fact that the length of the screws along the X axis was almost three meters, a screw with a diameter of 25 mm was installed for less sagging, otherwise a 16 mm screw would have been enough.
This nuance was discovered already during the production of parts, and it was necessary to quickly solve this problem by manufacturing a rotating nut, rather than a screw, which added an additional bearing assembly and belt drive to the design. This solution also made it possible to tighten the screw well between the supports.
The design of the rotating nut is quite simple. Initially, we selected two tapered ball bearings, which are mirrored onto the ball screw nut, having previously cut a thread from its end to fix the bearing race on the nut. The bearings, together with the nut, fit into the housing, in turn, the entire structure is attached to the end of the portal post. At the front of the ball screw, the nuts attached an adapter sleeve to the screws, which was subsequently turned assembled on a mandrel to give alignment. They put a pulley on it and tightened it with two lock nuts.
Obviously, some of you will ask the question: “Why not use a rack as a transmission mechanism?” The answer is quite simple: a ball screw will provide positioning accuracy, greater driving force, and, accordingly, less torque on the motor shaft (this is what I immediately remembered). But there are also disadvantages - lower speed of movement and if you take screws of normal quality, then the price goes accordingly.
By the way, we took ball screws and nuts from TBI, enough a budget option, but the quality is also appropriate, since out of the 9 meters of screw taken, we had to throw out 3 meters, due to the discrepancy between the geometric dimensions, none of the nuts simply screwed on...
As sliding guides, 25mm profile rail guides from HIWIN were used. For their installation, installation grooves were milled to maintain parallelism between the guides.
We decided to make ball screw supports on our own, they turned out to be of two types: supports for rotating screws (Y and Z axes) and supports for non-rotating screws (X axis). Supports for rotating screws could be purchased, since the savings due to self-made 4 parts were not enough. Another thing is with supports for non-rotating screws - such supports cannot be found on sale.
From what was said earlier, the X-axis is driven by rotating nuts and through a belt gear drive. They also decided to make the other two axes Y and Z through a belt gear drive, this will add greater mobility in changing the transmitted moment, will add aesthetics in view of installing the motor not along the axis of the ball screw, but on the side of it, without increasing the dimensions of the machine.
Now let's move smoothly to electrical part, and we will start with the drives; stepper motors were chosen as them, of course, for reasons of lower price compared to motors with feedback. On the X-axis they installed two engines with an 86th flange, on the Y and Z axes there was a motor with a 56th flange, only with different maximum torque. I will try to imagine below full list purchased parts...
The electrical circuit of the machine is quite simple: stepper motors are connected to drivers, which in turn are connected to the interface board, which is also connected via a parallel LPT port to a personal computer. I used 4 drivers, one for each engine. I installed all the same drivers to simplify installation and connection, with a maximum current of 4A and voltage of 50V. As an interface board for CNC machines, I used a relatively budget option from a domestic manufacturer, as indicated on the website the best option. But I won’t confirm or deny this, the board is easy to use and the most important thing is that it works. In my past projects I used boards from Chinese manufacturers, they also work, and in their peripherals they differ little from the one I used in this project. I noticed in all these boards, one may not be significant, but the downside is that you can only install up to 3 limit switches on them, but at least two such switches are required for each axis. Or did I just not understand? If we have a 3-axis machine, then accordingly we need to install limit switches in the zero coordinates of the machine (this is also called the “home position”) and in the outermost coordinates so that in case of a failure or lack of working field, one or another axis simply does not failed (simply did not break). My circuit uses: 3 terminals without contacts inductive sensor and an emergency button “E-STOP” in the form of a mushroom. The power section is powered from two 48V switching power supplies. and 8A. The 2.2 kW water-cooled spindle is connected via a frequency converter. The speed is set from a personal computer, since the frequency converter is connected via an interface board. The speed is regulated by changing the voltage (0-10 volts) at the corresponding terminal frequency converter.
All electrical components except motors, spindle and limit switches were mounted in an electrical metal cabinet. All control of the machine is carried out from a personal computer; we found an old PC on an ATX form factor motherboard. It would be better to shrink a little and buy a small mini-ITX with a built-in processor and video card. Given the large size of the electrical box, it was difficult to fit all the components inside; they had to be placed quite close to each other. At the bottom of the box I placed three forced cooling fans, since the air inside the box was very hot. A metal plate was screwed onto the front side, with holes for the power buttons and emergency stop buttons. Also on this panel there was a socket for turning on the PC, I removed it from the case of an old mini computer, it’s a pity that it didn’t work. A cover plate was also attached to the rear end of the box; holes were placed in it for connectors for 220V power supply, stepper motors, spindle and VGA connector.
All the wires from the engines, the spindle, as well as the water hoses for its cooling were laid in flexible cable track-type channels 50mm wide.
Concerning software, then Windows XP was installed on a PC located in an electrical box, and one of the most common Mach3 programs was used to control the machine. The program is configured in accordance with the documentation on the interface board, everything is described there quite clearly and in pictures. Why exactly Mach3, and all because I had work experience, I heard about other programs, but did not consider them.
Specifications:
Working space, mm: 2700x1670x200;
Axes movement speed, mm/min: 3000;
Spindle power, kW: 2.2;
Dimensions, mm: 2800x2070x1570;
Weight, kg: 1430.
Parts List:
Profile pipe 80x80 mm.
Metal strip 10x80mm.
Ball screw TBI 2510, 9 meters.
Ball screw nuts TBI 2510, 4 pcs.
Profile guides HIWIN carriage HGH25-CA, 12 pcs.
Rail HGH25, 10 meters.
Stepper motors:
NEMA34-8801: 3 pcs.
NEMA 23_2430: 1 pc.
Pulley BLA-25-5M-15-A-N14: 4 pcs.
Pulley BLA-40-T5-20-A-N 19: 2 pcs.
Pulley BLA-30-T5-20-A-N14: 2 pcs.
Interface board StepMaster v2.5: 1 pc.
Stepper motor driver DM542: 4pcs. (China)
Switching power supply 48V, 8A: 2 pcs. (China)
Frequency converter 2.2 kW. (China)
Spindle 2.2 kW. (China)
I seem to have listed the main parts and components, if I haven’t included something, write in the comments and I’ll add it.
Machine operating experience: Ultimately, after almost a year and a half, we finally launched the machine. First, we adjusted the positioning accuracy of the axes and their maximum speed. According to more experienced colleagues, the maximum speed of 3 m/min is not high and should be three times higher (for processing wood, plywood, etc.). At the speed we have reached, the portal and other axes are almost unstoppable by resting your hands (with your whole body) on them - it rushes like a tank. We started testing with processing plywood, the cutter runs like clockwork, there is no vibration of the machine, but we also went deeper by a maximum of 10mm in one pass. Although after that they began to go deeper.
After playing with wood and plastic, we decided to gnaw on duralumin; I was delighted, although I first broke several cutters with a diameter of 2 mm while I was selecting cutting modes. The duralumin cuts very confidently, and the result is a fairly clean cut along the machined edge.
We haven’t tried processing steel yet, but I think that at least the machine will be able to engrave, but for milling the spindle is too weak, it would be a pity to kill it.
Otherwise, the machine copes well with the tasks assigned to it.
Conclusion, opinion about the work done: A lot of work was done, but in the end we were pretty tired, since no one canceled the main work. And a lot of money was invested, I won’t say the exact amount, but it’s about 400 thousand rubles. In addition to the costs of equipment, the bulk of the costs and most of the effort went into manufacturing the base. Wow, we've had so much trouble with him. Otherwise, everything was done as funds, time and finished parts became available to continue the assembly.
The machine turned out to be quite functional, quite rigid, massive and of high quality. Maintains good positioning accuracy. When measuring a square made of duralumin, measuring 40x40, the accuracy was +- 0.05mm. The processing accuracy of larger parts was not measured.
What's next…: There is still enough work on the machine, in the form of covering the guides and ball screws with dust protection, covering the machine around the perimeter and installing ceilings in the middle of the base, which will form 4 large shelves for the cooling of the spindle, storage of tools and equipment. They wanted to equip one of the quarters of the base with a fourth axis. It is also necessary to install a cyclone on the spindle to remove and collect dust chips, especially if you are processing wood or textolite, from which dust flies everywhere and settles everywhere.
As for the future fate of the machine, everything is not clear, since I had a territorial issue (I moved to another city), and now there is almost no one to work on the machine. And the above plans are not guaranteed to come true. No one could have imagined this two years ago. Add tags
The question of how to make a CNC machine can be answered briefly. Knowing that a homemade CNC milling machine, in general, is a complex device that has complex structure, the designer would like to:
- acquire drawings;
- purchase reliable components and fasteners;
- prepare a good tool;
- have a lathe on hand and drilling machines CNC machined to produce quickly.
It wouldn’t hurt to watch the video – a kind of instructional guide on where to start. I’ll start with preparation, buy everything I need, figure out the drawing - here correct solution novice designer. That's why preparatory stage, preceding assembly, is very important.
Preparatory stage work
To make a homemade CNC milling machine, there are two options:
- You take a ready-made running set of parts (specially selected components), from which we assemble the equipment yourself.
- Find (make) all the components and start assembling a CNC machine with your own hands that would meet all the requirements.
It is important to decide on the purpose, size and design (how to do without a drawing of a homemade CNC machine), find diagrams for its manufacture, purchase or manufacture some parts that are needed for this, and acquire lead screws.
If you decide to create a CNC machine with your own hands and do without ready-made sets of components and mechanisms, fasteners, you need a diagram assembled according to which the machine will work.
Usually, having found schematic diagram devices, they first model all the machine parts, prepare technical drawings, and then use them to produce components from plywood or aluminum on lathes and milling machines (sometimes it is necessary to use a drilling machine). Most often, working surfaces (also called a work table) 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, you need to provide a number of critical components that ensure the vertical movement of the working tool. In this list:
- helical gear – rotation is transmitted using a toothed belt. It is good because the pulleys do not slip, evenly transferring forces to the shaft of the milling equipment;
- if you use a stepper motor (SM) 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 will need three SDs. It’s good if there are 5 control wires in each, the functionality of the mini-machine will increase. It is worth assessing the magnitude of the parameters: supply voltage, winding resistance and motor rotation angle in one step. To connect each stepper motor you need a separate controller;
- with the help of screws, the rotational movement from the motor is converted into linear. To achieve high accuracy, many consider it necessary to have ball screws (ball screws), but this component is not cheap. When selecting a set of nuts and mounting screws for mounting blocks, choose them with plastic inserts, this reduces friction and eliminates backlash;
- instead of a stepper motor, you can take a regular electric motor, after a little modification;
- a vertical axis that allows the tool to move in 3D, covering the entire coordinate 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 muffle furnace, the axle can be cast according to the dimensions of the drawings.
Below is a drawing made in three projections: side view, rear view, and top view.
Maximum attention to the bed
The necessary rigidity of the machine is provided by the bed. A movable portal, a system of rail guides, a stepper motor, work surface, Z axis and spindle.
For example, one of the creators of a homemade CNC machine made the supporting frame from aluminum profile Maytec - two parts (section 40x80 mm) and two end plates 10 mm thick from the same material, connecting the elements aluminum corners. The structure is reinforced; inside the frame there is a frame made of smaller profiles in the shape of a square.
The frame is mounted without the use of welded joints (welded seams are poorly able to withstand vibration loads). It is better to use T-nuts as fastenings. The end plates provide for the installation of a bearing block for mounting the lead screw. You will need a plain bearing and a spindle bearing.
The craftsman determined that the main task of the self-made CNC machine was the production of aluminum parts. Since workpieces with a maximum thickness of 60 mm were suitable for him, he made the portal clearance 125 mm (this is the distance from the upper cross beam to the working surface).
This difficult installation process
Collect homemade CNC machines, after preparing the components, it is better to 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 motors to the body - behind the vertical axis of the equipment. One is responsible for horizontal movement milling head (rail guides), and the second for movement in the vertical plane;
- a movable portal moving along the X axis carries the milling spindle and support (z axis). The higher the portal is, the larger the workpiece can be processed. But at a high portal, during processing, the resistance to emerging loads decreases;
- For fastening the Z-axis motor and linear guides, front, rear, upper, middle and lower plates are used. Make a cradle for the milling spindle there;
- The drive is assembled from carefully selected nuts and studs. To fix the motor shaft and attach it to the stud, use a rubber winding of a thick electric cable. The fixation may be screws inserted into a nylon sleeve.
Then the assembly of the remaining components and assemblies of the homemade product begins.
We install 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 with a complex configuration.
In order to avoid management problems, homemade CNC machines have the following components among the components:
- stepper motors, some stopped for example 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, connecting in accordance with the diagram;
- switching boards (controllers);
- 36V power supply unit with a step-down transformer that converts to 5V to power the control circuit;
- laptop or PC;
- button responsible for emergency stop.
Only after this, CNC machines are tested (in this case, the craftsman will make a test run of it, loading all the programs), and existing shortcomings are identified and eliminated.
Instead of a conclusion
As you can see, it is possible to make a CNC that is not inferior to Chinese models. 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 technology. You won’t have to look for an example for long.
The photo below shows some examples of machines with numerical control, which were made by the same craftsmen, not professionals. Not a single part was made hastily, with an arbitrary size, but fitted to the block with great precision, with careful alignment of the axes, and the use of high-quality lead screws and with reliable bearings. The statement is true: as you assemble, so will you work.
A duralumin blank is processed using CNC. With such a machine, which was assembled by a craftsman, you can perform a lot of milling work.
