Assembling a CNC machine from an aluminum profile. My first cnc machine. Preparatory work

An article on the topic of self-construction of a small woodworking machine (engraving, milling, drilling) with CNC, also suitable for others soft materials such as plastic. Good for milling PCBs and the like. This and the following articles describe general components and techniques for assembling not only CNC machines, but also 3D printers, engravers and similar equipment. There is a lot of information, a lot of links and photos, the project is open, advice and criticism (on business) is welcome.

Here are some photos appearance assembled CNC2418 machine from lots of sellers with Ali

Examples of lots with Ali with laser and ER11 collet (DZT store, Jack's store, IRouter store).

So, I'll tell you about a fairly popular Chinese machine tool under the simple name CNC2418, which means working area 24 mm by 18 mm. As a spindle, it has a simple (collector) revving engine direct current type 775. Managed through GRBL compatible programs, but first things first.

Typically sold in the region of $ 250 ($ 170 to $ 300) in various configurations. There is a version with different spindles ( various variations 775th motor), with different collets (from simple for drills to ER11), can be equipped with a laser module. Usually sellers put in consumables, cutter bits and so on.

Machine features 2418:

1. Working field - 240 mm x 180 mm x45 mm
2. Frame size (bed) - 260 mm х180 mm (aluminum profile)
3. Overall size - 330х340х240
4. Stepper motors: 3pcs Nema17 1.3A 0.25Nm
5. Spindle: Diameter 45mm, model 775, 24V: 7000 r / min
6. The maximum shank diameter of the cutter depends on the installed collet
7. Power: 24V 5.6A

Here is a photo of the $ 250 medium kit (including the laser engraving kit)

The lot usually has a choice of collets: a simple "drill" or a collet of the ER11 type. In more expensive lots, there are both options plus cutters.

Seriously speaking, the market value of such assembly kits is greatly overestimated. I'm not ready to give under $ 300 for such a set. But to assemble it with your own hands three times cheaper - please! Below is a selection of components with Chinese shops, on the basis of which you can safely assemble a similar machine or machine with a larger / smaller working area.

For assembly, you will need to buy a set of guides: rails or polished shafts; lead screws (most often T8, since belts of the GT2-6 type can be installed in laser engravers, their use in a router is not desirable), Nema17 motors, a spindle (most often a DC motor of the RS775 type or more powerful) and various small things such as bearings, calipers , hardware.
The electronics issue is separate: someone uses Arduino Nano / Uno + CNC Shield boards, someone Mega + Ramps, there are options for more serious kits for Mach3.

Paying your attention to the fact that the original kit contains 3D printed components.

The use of such plastic parts is clearly visible in user photos from the Internet, and in lots from sellers.

The printed kit includes a spacer-angle (2 pcs), a screw holder X, a screw holder Y, bearing holders LM8UU (or rather imitations of them) 4 pcs, a nut holder T8.

Separately, I will highlight the assembly of the spindle holder, at the same time the carriage in XY.
She comes assembled with the installed engine.

Inside you can see pressed LM8UU bearings and somewhere a T8 nut. The shafts are drilled from the end and secured to the ends. At the same time they serve as additional support for the structure.

I bring links to the complete set from banguud, since I'm tired of buying 1 lot from different sellers with Ali and waiting for a bunch of parcels that arrive at different times. Prices are comparable to Ali, somewhere cheaper, somewhere it is more convenient to apply points, somewhere to wait for a promotion or coupon. As a result, I received one large parcel with a complete set. I also give keywords for self-search if you need to find a similar one on Ali or Tao.

Now in order. Received a parcel of various kits for machine mechanics.

Polished guide shafts.
Linear Shaft (Rod). Still meets Optical axis(polished axle). There are 5-6-8-10-12-16-20 mm. The current diameter is 8 mm. For 16-20 mm it is better to use round rails like SBR16 or SBR20 as they are supported. Shafts of different diameters are used, for example, in the Ultimaker (6-8-10 mm). By the way, 12mm shafts can be useful for the Z-axis of the ZAV 3D printer and the like.
In the photo 6 mm, 8 mm, 12 mm.

Shafts 8 mm. I took part to size (they are chamfered), part I cut myself

There is a large lot with a choice of shafts from 5 mm to 12 mm and lengths of 300-600 mm

Separate lots are a little cheaper. I try to take a length or a size or much more in order to independently saw 2-3 pieces of the desired size from one shaft.

Here is the cut miter saw... It is advisable to then clean up, chamfer.

Shaft 6x400
Shaft 6х300
Shaft 6x500
Shaft 6x600

6mm shafts can be used in small laser engravers, delta printer, Z axis of desktop CNC machine tools. For example, a 6x300 shaft, sawn in half, went to the "head" of the Z-axis of a small router.

Shafts 12 mm. I took it for ZAV 3D.

Will be installed in a ZAV 3D enclosure

There are several options for attaching the rails. The easiest is to cut the threads at the ends and lock them. SHF08 flanges or SK8 calipers can be fitted. In this case, the length increases by 2 cm for each guide (one flange captures 1 cm of the shaft).
I printed it myself, I won't say that there is a big difference, but the savings are about $ 12. Here is the link to the lot for installing normal SHF08 metal flanges, not plastic ones. Yet a good option fastening not with flanges, but with calipers, directly on the 2020 profile. This is the SH08 (SF08?) caliper.
There is also a "Chinese" mounting option, when a hole is drilled in the center of the shaft and an M3 internal thread is cut. In this case, the installation of such guides is as easy as possible.

Flange supports for shafts SHF8 to SHF20
Flange SHF8
Caliper SK8
Another SK8 support for shafts for installation on a profile

Shaft bearings
Lot with a choice of the size of short linear bearings LMххUU at 6/8/10 mm
Key words: Bearing LMххLUU (at xx mm, long), LMххUU (at xx mm, short), in the case, respectively: SC8LUU and SC08UU.
Extended lot with a choice of type SCSххLUU from 8 to 20 mm.
Still lengthened by 8 mm
Bearings in SC8UU housing
6 mm long LM6LUU and regular LM6UU

Here are interesting kits-sets of axles with guides and bearings
500 mm with extended bearings

The same, plus a T8 screw with a caliper 200mm, 300mm and 400mm

Lead screw T8 ( Lead Screw T8, screw T8 Nut) is a multi-start screw. Better to take immediately with a nut.

If you cut, then you will additionally need to buy more brass nuts
100 mm
200 mm
250 mm
400 mm
Lot with a choice of T8 from 100 to 600 mm with special nut
I usually take more, plus one nut. Cut to size, the rest goes somewhere else

Profile accessories:
corners 2020 Corner Bracket.
To assemble a machine type 2418, at least 16 pieces are required. Take with a margin)))
There are options for plates for reinforcement, it would also be nice to install them in the main corners and on the portal (total 6-8 pcs).

And here is the 2020 profile itself.

Once I started a conversation about a profile, I will tell you in detail about the purchase and cutting of a profile from Soberizavod.

This is a structural aluminum profile from Soberizavod. This is probably the most cheap option, since a profile from China will cost more, and there is a limitation on maximum length parcels by Chinese post (500mm).

I bought a cut-to-size 2020 profile kit for the CNC2418.
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.

We choose required type profile 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).

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 at 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.

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 changes, 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 size depends on the Z-axis overhang and the spindle. 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 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 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 establish, 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 in order to reduce the scrap from the 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 together with the guide holders, the lower ones without the 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 taken without a large margin, 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.


It is 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 fix the screw not on the profile, but on the flange.


5x8 clutch - split clutch for connecting the motor shaft to the propeller.

Costing
Now, as requested in the comments in the first part, I propose to discuss costing. Naturally, I spent less than indicated, since I had the engines and most of the components in stock. Strongly cheaper will be, if you use homemade printed corners for the profile, calipers, flanges and so on. This is unlikely to affect the work of the machine for drilling printed circuit boards and milling soft materials. Another good option is to use perforated plates from construction / utility stores. It will be used to strengthen the corners, including the vertical one, and to install the engine, provided that the central part is drilled under the shaft. In place of perforated fasteners, you can use homemade 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 assembling 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 you can remove from old devices / office equipment and plan seats 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. V 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 4p / piece if you take a large 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.

The question of how to make a CNC machine can be answered briefly. Knowing that a home-made 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 on hand 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 correct solution novice constructor. Therefore, the preparatory stage prior to assembly is very important.

Preparatory work

To make a homemade CNC milling machine, 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 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;
• a vertical axis that moves the tool in 3D, spanning the entire XY 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 are installed on it, work surface, Z axis and spindle.

For example, one of the creators of a homemade CNC machine made a 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 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 for the installation of a bearing block for the installation of the 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 homemade cnc machines, after preparing the components, it is better 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 the horizontal movement of the milling head (rail guides), and the second for movement 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 stud, 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 control it, you need to operate with a correctly selected numerical control, high-quality printed circuit boards and electronic components (especially if they are Chinese), which will allow you to realize all the functionality on a CNC machine, 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 (at the same time, the craftsman will make a test run by loading all the programs), and 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 high-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 numerically controlled machines, 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.

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 change. 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, and later a work surface will be installed on it. 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. High side gantry struts act as levers relative to linear rolling bearings.

The main task that I planned to solve on my CNC milling machine is processing 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 panel that attaches to the Y-axis travel bearings, two plates to reinforce the assembly, a plate for fastening stepper motor and a panel for mounting a 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 subject to frictional forces during operation and is also less accurate relative to a ball screw. If you need increased accuracy, then you definitely need to opt for ball screws. But you should know that ball screws are quite expensive.

The machine itself consists of aluminum profiles and 3D parts, which I myself have created and printed on a printer. I opted for 3D parts because I don't have a variety of tools and equipment that would allow me to create accurate and high-quality elements. crafts... Therefore, my 3D printer helped and simple hand tools for final assembly.

Step 1: Materials

• support for guides ∅ 2cm - 8pcs
• guides ∅ 2cm x 30cm - 2pcs
• guides ∅ 2cm x 60cm - 2pcs
• worm guide 30cm - 1pc
• worm guide 60cm - 1pc
• Z axis for CNC
• caliper with female thread
• smooth bushing
• router bracket
• stepper motors
• adapter coupling for motor shaft (from 1cm to 0.6cm)
• microswitches - 6pcs
• crimp connectors
• contact connectors with fastening nut - 4pcs
• plugs for pin connectors - 4pcs
• cable
• aluminum profile with T-shaped grooves 60x30: for the frame and top - 65cm, for the table - 315cm (profile with holes in the end), vertical - 61cm (+ 4 end caps)
• aluminum profile with T-slots 120x30: sides - 61cm (+ 4 end caps)
• T-bolts M6
• bolts and nuts М6
• bearing 1cm x 2.2cm

Step 2: 3D details

In 3D design software, I created mock brackets that will hold the rails, as well as a mock stepper motor bracket that secures it to the frame. A big plus of 3D printing is that the parts are very accurate and there is no need to adjust them and drill holes. So, having designed the necessary details crafts here in this program, I then printed them on my 3D printer.

Step 3: worm guide holes

I drilled holes in the side end profiles for the worm guide, they should be slightly larger diameter the guides themselves (1cm).

Step 4: assembly

With the help of T-shaped and ordinary bolts, I assembled brain details together.

Step 5: limit switches

On the assembled structure, I fixed the limit switches that will turn off the movement of the cutter carriage at the end points.

The cable was carried out according to the principle of "normally closed", that is, with a short circuit homemade will go to safe mode... To do this, I had to modify the power supply of the control unit and put an emergency shutdown button.

Step 6: adjust Mach3 parameters

To adjust the axis motion values, I used this helpful site and got:
Stepping angle of motors - 1.8 °
Gear ratio of motors and worm guide 1: 1
CNC controller value ¼ step
for Z-axis: worm gear 9.53mm (2.11mm driven), stroke in mm 379.47
for X and Y axis: worm gear 9.53mm (5.08mm driven) x 381mm, travel in mm 157.48

Step 7: the final step

As a final touch, I cut and installed an MDF work surface on which it is easy and quick to place / change the work pieces.

Well, the most the last step there was a connection brainworm to the computer and start it, although it still took a long time to read the instructions for Mach3 🙂

Step 8: rework - body

The first thing I did after all the basic work was the electronics housing, which will protect the electronic parts from dust and other troubles.

Step 9: first try

Testing brainworm went well, but revealed several flaws:

- Y-axis backlash. Y-axis worm is installed in conventional calipers, but later I plan to install backlash-free calipers.

- with fast movement of the carriage along the Y axis, there are slight deviations of the frame. The reason is the unbalanced frame, and I plan to solve it by installing an additional aluminum profile, which at the same time will strengthen the entire frame.

- false actuation of limit switches. Possible cause is pointing from unshielded cable. I had to make changes to the code to reconfigure their operation.

Step 10: Refinement - speed control and emergency shutdown button

Fraser that I installed on mine brainworm, has a fixed rotational speed of the cutter, so it was necessary to install an additional rotational speed regulator, namely an AC control module.

Even in the rupture of the supply wires, I mounted an emergency stop button, which, if necessary, turns off both the milling cutter and the movement of the carriage.

This is my first CNC machine! Thank you for brainwave and good luck with your creativity!