The question of how to make a CNC machine can be answered briefly. Knowing that a homemade CNC milling machine is, in general, a complex device with a complex structure, it is desirable for the designer:
- get blueprints;
- purchase reliable components and fasteners;
- prepare a good tool;
- have a lathe and drilling machines CNC to quickly manufacture.
It does not hurt to watch the video - a kind of instruction, training - where to start. And I'll start with preparation, buy everything you need, deal with the drawing - here the right decision novice constructor. therefore preparatory stage pre-assembly is very important.
Preparatory work
To make a homemade CNC milling machine, there are two options:
- You take a ready-made running set of parts (specially selected units), from which we assemble the equipment ourselves.
- Find (make) all the components and start assembling a 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 drawing homemade machine CNC), find schemes for its manufacture, purchase or manufacture some parts that are needed for this, acquire lead screws.
If you decide to create a CNC machine yourself and do without ready-made sets of assemblies and mechanisms, fasteners, you need the scheme assembled according to which the machine will work.
Usually, finding schematic diagram devices, first simulate all the details of the machine, prepare technical drawings, and then use them on a turning and milling machine (sometimes you need to use a drilling machine) to make components from plywood or aluminum. Most often, work surfaces (also called a work table) are plywood with a thickness of 18 mm.
Assembly of some important parts of the machine
In the machine that you began to assemble with your own hands, you must provide for a number of critical units that ensure the vertical movement of the working tool. In this list:
- helical gear - rotation is transmitted using a toothed belt. It is good in that it does not slip on the pulleys, evenly transmitting 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 - it is more powerful; old matrix printers had powerful enough electric motors;
- for a three-dimensional device, you will need three stepper motors. Well, if there are 5 control wires in each, the functionality of the mini-machine will increase. It is worth evaluating the value of the parameters: supply voltage, winding resistance and stepper motor rotation angle in one step. A separate controller is needed to connect each stepper motor;
- with the help of screws, the rotary motion from the stepper motor is converted into a linear one. For achievement high precision, many consider it necessary to have ball screws (ball screws), but this component is not cheap. 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 conventional electric motor, after a little modification;
- vertical axis, which allows the tool to move in 3D, covering the entire coordinate table... It is made from an aluminum plate. It is important that the axle dimensions are adapted to the dimensions of the device. In the presence of muffle furnace, the axis can be cast according to the dimensions of the drawings.
Below is a drawing made in three projections: side view, back view, and top view.
Maximum attention to the bed
The required rigidity of the machine is provided by the bed. A movable portal, a system of rail guides, a stepper motor, a working surface, a Z axis and a spindle are installed on it.
For example, one of the creators of a homemade 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 structure is reinforced, inside the frame is a frame made of smaller profiles in the shape of a square.
The bed is mounted without using welded joints ( welds it is difficult to transfer vibration loads). It is better to use T-nuts as fasteners. The end plates are provided with a bearing block for mounting lead screw... You will need a sleeve bearing and a spindle bearing.
The main task of a do-it-yourself CNC machine tool was determined by the craftsman to manufacture parts from aluminum. 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 complicated installation process
Collect home-made 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 stepper 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 moving in the vertical plane;
- The movable portal moving along the X-axis carries the milling spindle and the support (z-axis). The higher the portal is, the larger the workpiece can be processed. But at a high portal, in the process of processing, the resistance to emerging loads decreases;
- for fixing the stepper motor of the Z axis, linear guides, use the front, rear, upper, middle and lower plates. 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 hairpin, use the rubber winding of a thick electrical cable. The retainer can be screws inserted into a nylon bushing.
Then the assembly of the remaining components and assemblies of homemade products begins.
We mount the electronic filling of the machine
To make a CNC machine with your own hands and operate 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 everything on a CNC machine functionality, processing a part of a complex configuration.
In order to avoid problems in management, homemade CNC machines, among the nodes, have the obligatory ones:
- 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, connected in accordance with the diagram;
- switching boards (controllers);
- a 36V power supply unit with a step-down transformer converting to 5V to power the control circuit;
- laptop or PC;
- button responsible for the emergency stop.
Only after that, CNC machines are tested (while the craftsman will make a test run by loading 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 With quality bearings and enough fasteners for assembly, this task is within the power of those who are interested in software engineering. You won't have to look for an example for a long time.
The photo below shows some samples of machines with numerical control, which are made by the same craftsmen, not professionals. Not a single part was made hastily, of arbitrary size, but fits the block with great accuracy, with careful alignment of the axes, the use of high-quality lead screws and with reliable bearings... The statement is true: as you collect, you will work.
CNC machining of duralumin blanks. With such a machine, which was assembled by a craftsman, you can perform a lot of milling work.
Now a little more detail on the main assembly.
So, to assemble the frame, you will need the following components:
- Profile segments 2020 (two longitudinal, 5 transverse, 2 vertical parts)
- Profile corners 16 pcs
- T-nuts M3 or M4 for a groove-6mm
- Screws for installation with T-nuts (M3 or M4, respectively, 8 ... 10 mm, plus M3x12 for mounting motors)
- Spacer (angle 45 °)
- Tool (screwdriver)
Once I started a conversation about a profile, then just in case I duplicate about the purchase and cutting of a profile from Soberizavod
It's constructional.
I bought a cut-to-size profile kit for the 2418.
There are two options - uncoated profile (cheaper) and coated (anodized). The difference in cost is small, I recommend coated, especially if used as roller guides. 
Select the desired profile type 2020, then enter "cut to size". Otherwise, you can buy one piece (whip) for 4 meters. When calculating, keep in mind that the cost of one cut is different, depending on the profile. And that 4 mm is laid on the cut. 
Enter the dimensions of the line segments. I made the 2418 machine a little larger, these are seven sections of 260 mm and two vertical sections of 300 mm. Vertical can be made smaller. If you need a longer machine, then two longitudinal sections are larger, for example, 350 mm, transverse ones are also 260 mm each (5 pieces). 
We confirm (it is necessary to add to the cutting chart) 
Checking the basket 
The profile is obtained at 667r along with the cutting service. 
Delivery is carried out by TC, you can calculate the cost using a calculator, since you know the dimensions of the profile, the weight is very well calculated in the cutting chart. For the calculation, you need the option "picking up the cargo from the supplier". Delivery by 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 the profile is cut to size. There is a showcase with samples, you can pick up a profile on the spot.
So, we begin to assemble the frame bench machine 2418.
Here is the cut profile.
In this design, I increased the Z-axis (a little more by a couple of cm than others) to use the machine as a CNC drilling machine.
In the original, the Z-axis is the shortest. It is already up to you to decide according to your goals. To lengthen the working field, you need to buy two sections of the profile (longitudinal pair) more by the required length (for example, +10 cm), respectively, the guides (+10 cm for a pair of 8mm shafts) and the screw (+10 cm for the T8 screw) are lengthened. For the money comes out quite cheaply voiced +10 cm: the cost of 10 + 10 cm of the profile is about 40r, the guides and the screw will cost plus $ 6 (check).
Here are the corners prepared for assembly 
This is how the T-nuts should be installed in 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, you need some skill. 
Profile cut clean, no burrs 
Profile-twenty, that is, from the 2020 series, with respectively 20mm x 20mm dimensions, 6mm groove. 
So, first we collect the U-shaped part of the frame, we fasten two longitudinal parts of the profile and one extreme cross member. Of great importance which side to collect, but keep in mind that there is a central crossbar that is moved closer to the back. It is part of the vertical plane, and the offset is dependent on the Z axis and the spindle overhang. Placed so that the spindle axis of rotation is in the center of the machine (Y-axis).
Next, we collect the middle cross member. It is more convenient to first install both corners on a section of the profile and fix it, and then install it to the frame.
We apply a section of the profile, measure the same distance with a ruler, tighten the screws. The screws need to be tightened slowly, give time for the T-nut to turn and take its position in the groove. If it does not work the first time, loosen the nut again and repeat. 
Install the last piece of the horizontal frame. It is more convenient to crawl with a long screwdriver. Do not be lazy and check the right angles of the resulting structure with a square and a diagonal with a ruler. 
Since the corners of the structure are directed towards each other, it is not important in what order to assemble. I did as in basic design CNC2418. 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 mount of the vertical portal 
We install the assembled portal on the horizontal part, fasten it with 6 corners (installed in the direction of three sides from the vertical profile). 
We install, observe the perpedicularity of the segments (along the gon). Then he tightened all the screws in turn. 
In the original, a special 45 ° extrusion angle is used to strengthen the vertical. I could not find a similar one on sale, I replaced it with a 3D printed one. The link to the model is at the end of the topic.
Update: it turned out in the original 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 design turned out to be solid, not wobbly. It can be seen that the plate with the motor is shorter than the bunch of calipers KP08 + SK8. I will spread it wider. 
In fact, this frame is a copy of a similar design of the CNC2418 machine, except that I did not directly copy the dimensions, I made a little more so that there are fewer scraps from guides and screws.
The assembly of the frame is complete, now you can start installing the engines. I use 3D printed flanges to mount 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 the SK8 and KP08 calipers, as in the original machine. The calipers themselves can be printed on a printer or bought (links at the end of the topic, and were also in the first post).
For one of the axes (the X and Y axes I have the same length) I took "sighting". I didn’t yet know my "wishes" for the size of the machine. As a result, the cuttings from the screw will go to the Z axis, you only need to buy a brass T8 nut. 
Was packed in a cardboard box, inside each part in a bag separately 
The kit looks like this: an engine with a short wire, a T8 lead screw, two KP08 calipers and two 5x8 couplings. 
There is a similar and, as well as without an engine on (with calipers and a nut).
If you take without large stock, then the 400 mm version will work well for the "enlarged version" of the machine
Additional information - photo of the kit separately
Engine marking RB Step Motor 42SHDC3025-24B-500, seat Nema17 
Includes a short wire for connection. Conveniently, you can simply increase the length without touching the connectors. 
T8 screw, nut 
Calipers KR08. 
Convenient to attach to the profile. If a wide flange is used for installation, then it is better to use the KFL08 caliper version, it allows you to mount the screw not on the profile, but on the flange. 
5x8 clutch - split clutch for connecting the motor shaft to the propeller. 
This is how the original engine mounts on the X-axis. On a small aluminum plate.
I did the same thing, only with the 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 in the process for now, the information will be separate, most likely also 3D printed).
It will most likely be necessary to lengthen the motor wires in order to carefully lay it along the profile in upper part to the electronics board (most likely CNC Shield). And it would not hurt to install limit switches for extreme positions.
The basic information on the assembly is already there, you can start estimating the 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 components I had in stock. Strongly cheaper will be, if you use homemade printed corners for the profile, calipers, flanges and so on. To work the drilling machine printed circuit boards and milling soft materials it is unlikely to affect. Another good option is to use perforated plates from construction / utility stores. It will be suitable for strengthening corners, including vertical and for installing the engine, provided that the central part is drilled under the shaft. In place of perforated fasteners, you can use homemade from aluminum sheet or plywood.
Definitely need to purchase profile 2020 otherwise it will be a completely different type of machine. You can do the same from an aluminum corner or 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 you need a profile T-nuts... You can buy T-bolts, but T-nuts are more versatile (since you can use any length of the screw).
But the rest can be changed at your discretion, you can even replace the chassis screw T8 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 scheduled 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 direct current, which allows you to install a collet chuck and has a decent turnover. IN basic version there is a high-speed 775 motor. For milling, you can use 300 watt b / c spindles with an ER11 collet, but this greatly increases the cost of the machine as a whole.
Approximate costing:
profile 2020 (2.5 meters) = 667r
profile 2080 (0.5 meter) on the desktop = 485 r
2 x 300 mm 2x $ 25
... A 20-piece lot comes out at $ 5.5 with shipping
about 4 rubles / piece if you take big package... You need at least 50 pieces (fastening motors, calipers). I don't count the screws for them, usually a few kopecks / piece, depending on the quality. In total, about 400 ... 500 rubles.
Motors 3 pcs $ 8.25 each
Electronics $ 2
$3.5
A4988 three $ 1
The machine comes out for about $ 111. If you add a spindle:
$9
$7.78,
then total cost about $ 128
I don't appreciate 3D printed parts. Can be replaced with perforated plates / corners from crepe market and similar stores. I also don’t estimate the wires, electrical tape, and the time spent.
Let me remind you that not all CNC2418 trim levels have such good 775 engines and, moreover, the ER11 collet.
Variants 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 in the first person, but you should 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., notes to them are made at English language, but I'm sure that a real techie will understand everything without further ado. For ease of perception, 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 able to create various things. A machine that will enable me to make any household item. Two years later, I came across the phrase CNC or more precisely, the phrase "CNC milling machine"... After I found out that there are people who are able to make such a machine on their own for their own needs, in their own garage, I realized that I can do it too. I must do it! For three months I tried to put together the right parts, but I didn’t budge. So my obsession gradually faded away.
In August 2013, the idea to build a CNC milling machine captured me again. I had just graduated from an undergraduate degree from the University of Industrial Design, so I was quite confident in my capabilities. Now I clearly understood the difference between me today and me five years ago. I learned how to work with metal, mastered the techniques of working on manual metalworking machines, but most importantly, I learned how to use development tools. I hope this tutorial will inspire you to create your own CNC machine!
Step 1: design and CAD model
It all starts with thoughtful design. I made some 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 assemblies of the machine, I prepared the technical drawings. I used these drawings to make parts on manual metalworking machines: and.
Honestly, I love the good handy tools... That is why I tried to make sure that operations on maintenance and the adjustment of the machine was carried out as easy as possible. I placed the bearings in special blocks in order to be able to quickly replace. The rails are serviceable so my machine will always be clean when finished.
Downloads "Step 1"
dimensions
Step 2: bed
The bed provides the machine with the required rigidity. A movable portal, stepper motors, a Z-axis and a spindle will be installed on it, and later a work surface. To create the base frame, I used two 40x80mm Maytec aluminum profiles and two 10mm aluminum end plates. I connected all the elements to each other on aluminum corners. To reinforce the structure inside the main frame, I made an additional square frame from smaller sections.
In order to further avoid dust getting on the guides, I installed protective corners made of aluminum. The corner is mounted using T-nuts, which are installed in one of the grooves of the profile.
Bearing blocks are mounted on both end plates to accommodate the drive screw.
Carrying frame assembly
Angles to protect the guides
Downloads "Step 2"
Drawings of the main elements of the bed
Step 3: Portal
The movable gantry is the executive element of your machine, it moves along the X-axis and carries the milling spindle and the Z-axis support. The higher the gantry, the thicker the workpiece that you can machine. However, a high portal is less resistant to loads that arise during processing. The high side posts of the portal act as levers relative to linear bearings rolling.
The main task that I planned to solve on my CNC milling machine is the processing of aluminum parts. Since the maximum thickness of suitable aluminum blanks is 60 mm, I decided to make the portal clearance (distance from the working surface to the upper crossbeam) equal to 125 mm. In SolidWorks, I converted all of my measurements to model and technical drawings. 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.
Downloads "Step 3"
Step 4: Z-axis caliper
In the Z-axis design, I used a front plate that attaches to the Y-axis travel bearings, two plates to reinforce the assembly, a plate to hold the stepper motor, and a plate 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
The guides provide the ability to move in all directions, ensure smooth and precise movements. Any backlash in one of the directions can cause inaccuracies 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 that the guides are parallel, I used a special indicator during their installation. The maximum deviation relative to each other was no more than 0.01 mm.
Step 6: screws and pulleys
The screws convert rotary motion from stepper motors to linear motion. When designing your machine, you can choose several options for this unit: A pair of screw-nut or ball-screw pair (ball screw). A screw nut is generally more exposed to 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 net, and I probably won't surprise anyone, but maybe this article will be useful to someone. This story began at the end of 2016, when my friend, a partner in the development and production of test equipment, accumulated a certain amount of money. In order not to just skip the money (this is a young thing), 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 with the construction of a CNC machine.
It was then that the movement began, which continues to this day ...
Everything continued with the study of forums dedicated to CNC topics and the choice of 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 grow over small details and nuances, which turned out to be more than we would like, we solve some to this day.
One of the initial decisions was to define the materials to be processed on the machine and the size of the working area of the machine. As for the materials, the solution was quite simple - wood, plastic, composite materials and non-ferrous metals (mainly duralumin). Since we mainly have metalworking machines in our production, sometimes we need a machine that would process quickly along a curved trajectory materials that are fairly easy to process, and this would subsequently reduce the cost of manufacturing the 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 off these dimensions, we came to the following values: 2.5x1.5 meters, workspace definitely, with the exception of the height of the tool lifting, this value was chosen for reasons of the possibility of installing a vice and we assumed that we would not have blanks thicker than 200mm. We also took into account that moment, if it is necessary to process the end face of any sheet part with a length of more than 200 mm, for this the tool goes beyond the dimensions of the machine base, and the part / workpiece itself is attached to the end side of the base, thereby processing the end face of the part.
Machine design is a prefabricated frame base from the 80th shaped pipe with a wall of 4mm. 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 size as the base.
The machine is four-axis and each axis is driven by a ball screw. Two axes are located parallel to the long side of the machine, paired by software and referenced to the X coordinate. Accordingly, the remaining two axes are Y and Z coordinates.
Why did they stop at the prefabricated frame: initially they wanted to make a purely welded structure with embedded welded sheets for milling, installation of guides and ball screw supports, but they did not find a sufficiently large coordinate milling machine for milling. I had to draw a prefabricated frame in order to be able to process all the parts on our own with the metalworking machines available in production. Every part that has been exposed to electric arc welding has been annealed to relieve internal stress. Further, all the mating surfaces were milled, and after fitting, they had to be scraped in places.
Climbing forward, I want to say right away that the assembly and manufacture of the frame turned out to be the most time-consuming and financially costly undertaking in the construction of the machine. The original idea with an all-welded frame bypasses the prefabricated structure in all respects, in our opinion. Although many may disagree with me.
I want to make a reservation right away that we will not consider machines from an aluminum structural profile here, this is more a matter of another article.
Continuing the assembly of the machine and discussing it on the 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 additionally bind the structure.
Let's now move on to the mechanical issue of this project. As mentioned earlier, 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 is transmitted from stepper motors with 86 and 57 flanges. Initially, it was supposed to rotate the propeller itself in order to get rid of unnecessary backlash and additional gears, but it was not without them in view of the fact that with a direct connection of the engine and propeller, the latter would start 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, and for less sagging, a screw with a diameter of 25 mm was laid, otherwise a 16 mm screw would be enough.
This nuance was revealed already in the production of parts, and it was necessary to quickly solve this problem by making a rotating nut, and not a screw, which added an additional bearing assembly and a belt drive to the design. This solution also made it possible to tighten the screw well between the supports.
The rotating nut design is quite simple. Initially, two tapered ball bearings were selected, which are mirrored onto the ball screw nut, having previously cut the thread from its end, to fix the bearing cage on the nut. The bearings, together with the nut, were inserted into the housing, in turn, the entire structure is attached to the end of the portal post. In front of the ball screws, the nuts were fixed on the screws with a transition sleeve, which was later turned on a mandrel when assembled to make it taper. A pulley was put on it and tightened with two locknuts.
Obviously, some of you will ask the question - "Why not use a rack as a transmission mechanism?" The answer is quite simple: the 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 - a lower speed of movement and if we take screws of normal quality, then the price, respectively.
By the way, we took ball screws and nuts from TBI firm, enough a budget option, but the quality is also appropriate, since from the taken 9 meters of the screw, 3 meters had to be thrown out, due to the discrepancy in the geometric dimensions, none of the nuts simply screwed on ...
As sliding guides, profile guides of 25mm rail standard size, manufactured by HIWIN, were used. For their installation, mounting grooves were milled to maintain parallelism between the guides.
Ball screw supports decided to make on their 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 bought, since savings due to self-made 4 details came out a little. 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 train... It was also decided to make two other axes Y and Z through the belt gear, this will add more mobility in changing the transmitted torque, add aesthetics in view of installing the engine 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 a lower price compared to motors with feedback. Two motors with an 86th flange were installed on the X axis, on the Y and Z axes for an engine with a 56th flange, only with different maximum torque. Below I will try to present full list purchased parts ...
The electrical circuit of the machine is quite simple, the stepper motors are connected to the drivers, which in turn are connected to the interface board, which also connects through the parallel LPT port to a personal computer. I used 4 drivers, respectively, one for each of the engines. All drivers were supplied the same, to simplify installation and connection, with a maximum current of 4A and a voltage of 50V. As an interface board for CNC machines, I used a relatively budget option, from domestic manufacturer as indicated on the website the best option... But I will not confirm or deny this, the board is simple to use and, most importantly, it works. In my previous projects, I used boards from Chinese manufacturers, they also work, and on their periphery they differ little from the one I used in this project. I noticed in all these boards, one may not be significant, but a minus, 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 figure it out? If we have 3 axial machine, then, accordingly, we need to set Limit switches in zero coordinates of the machine (this is also called " home position") And in the most extreme coordinates so that in the event of a failure or lack of a working field, this or that axis simply does not fail (it simply does not break). In my circuit I used: 3 end sensors without contact inductive sensors and an emergency button "E-STOP" in the form of a mushroom. The power section is powered by two 48V switching power supplies. and 8A. The spindle is 2.2kW water cooled, respectively connected through a frequency converter. The revolutions are set from a personal computer, since the frequency converter is connected via an interface board. The revolutions are regulated by changing the voltage (0-10 volts) at the corresponding output of the frequency converter.
All electrical components except motors, spindle and limit switches were installed in the electrical metal cabinet... All machine control is carried out from a personal computer, we found an old PC on an ATX form factor motherboard. It would be better if they shrank a little and bought a small mini-ITX with an integrated processor and video card. With the small size of the electric box, all the components were hardly placed inside, they had to be located close enough to each other. At the bottom of the box, I placed three forced cooling fans, since the air in the inside of the box was very hot. On the front side, a metal cover was screwed on, with holes for the power buttons and emergency stop buttons. Also on this pad was placed a socket for turning on the PC, I removed it from the case of the old mini computer, it is a pity that it was not working. From the rear end of the box, a cover was also fixed, holes were placed in it for connectors for connecting a 220V power supply, stepper motors, a spindle and a VGA connector.
All wires from the motors, the spindle, as well as the water hoses for its cooling were laid in flexible cable channels of caterpillar type 50mm wide.
Concerning software, then Windows XP was installed on a PC located in an electrical box, and one of the most common programs Mach3 was used to control the machine. The program is configured in accordance with the documentation for the interface board, everything is described there quite clearly and in pictures. Why exactly Mach3, but all the same, I had experience, I heard about other programs, but did not consider them.
Specifications:
Working space, mm: 2700x1670x200;
Axis 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 screws TBI 2510, 9 meters.
Ball screw nuts TBI 2510, 4 pcs.
Profile guides HIWIN carriage HGH25-CA, 12 pcs.
HGH25 rail, 10 meters.
Stepper motors:
NEMA34-8801: 3 pcs.
NEMA 23_2430: 1pc.
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 for 2.2 kW. (China)
Spindle 2.2 kW. (China)
I kind of listed the main details and components, if I didn't include something, then write in the comments, I'll add.
Experience on the machine: In the end, after almost a year and a half, we still launched the machine. First, we adjusted the positioning accuracy of the axes and their maximum speed. According to more experienced colleagues maximum speed at 3m / min is not high and should be three times higher (for processing wood, plywood, etc.). At the speed that we have reached, the portal and other axes resting on them with hands (with the whole body) can hardly be stopped - rushing like a tank. The tests began with the processing of plywood, the cutter goes like clockwork, there is no vibration from the machine, but they also deepened by a maximum of 10 mm in one pass. Although after they began to deepen to a shallower depth.
After playing with wood and plastic, we decided to gnaw the duralumin, here I was delighted, although at first I broke several cutters with a diameter of 2 mm, while selecting the cutting modes. Dural cuts very confidently, and a fairly clean cut is obtained, along the processed edge.
Steel has not yet been processed, but I think that at least the machine will pull the engraving, and for milling the spindle is weak, it's a pity to kill it.
And the rest of the machine does an excellent job with the tasks assigned to it.
Conclusion, opinion on the work done: The work was not small, we ended up pretty tired, since no one canceled the main work. Yes, and a lot of money has been invested, I will not say the exact amount, but it is about 400t.r. In addition to the costs of the assembly, the bulk of the costs and most of the effort went into making the base. Wow, how we got tired of it. Otherwise, everything was done as funds became available, time and finished parts to continue assembly.
The machine turned out to be quite efficient, quite tough, massive and of high quality. Maintaining good positioning accuracy. When measuring a square made of duralumin, measuring 40x40, the accuracy turned out to be + - 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 dust closure - by protecting the guides and ball screws, sheathing the machine around the perimeter and installing floors in the middle of the base, which will form 4 large shelves for the cooling volume of the spindle, storage of tools and equipment. They wanted to equip one of the quarters of the base with a fourth axle. It is also required to install a cyclone on the spindle to remove and collect dust chips, especially if you process wood or textolite, dust flies from them everywhere and settles everywhere.
As for the future fate of the machine, everything is not unambiguous, since I had a territorial issue (I moved to another city), and now there is almost no one to deal with the machine. And the above plans are not the fact that they will come true. No one could have imagined this two years ago. Add tags