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mini cnc router, complete plans and instructions

by:Transon     2020-09-04
The Mini CNC project is a complete set of plans and instructions on how to build a functional and accurate 3-axis CNC machine.
The mini CNC is very simple and easy to manufacture, if you have all the materials and parts ready, you should be ready to work in less than 5 days.
I think and also need to make this micro CNC machine so I can make faster and more precise parts for my other home projects.
The working area of the machine is X = 450mm (approx. 17. 5 inch)and Y=250mm (approx. 10 inch)
And can grind the part to Z = 110mm (approx 5 inch).
The maximum milling speed on the x-axis is 2400/min.
It is 1800/min on the z axis.
The resolution of each axis is 1/50 or 4mm, and one axis rotation means movement.
The router used by this CNC is Kress 1050.
In addition to screws and nuts, the number of parts used to make this micro CNC machine is 42.
For this project, you need a set of screwdriver and a set of hex keys or Allen keys, bits for some extra holes, metal cutting saws for cutting some custom parts, welding pads or welding guns to connect wires, in this way, they will have good conductivity and multimeter.
All the parts used for manufacturing are purchased from local dealers, so I suggest you do the same if it\'s cheaper (
Parts shipping).
If not, you can find all the parts on eBay.
A ladder cylinder nut was manufactured in a local workshop.
The frame is made of aluminum profiles and the parts are :-
X base parts 2 pieces 400x120x 30mm-
Y frame parts 2 pieces 400x120x30mm 1 piece 380x60x30mm cost: 13. 16$-
Y car 1 piece 120x120x 30mm-
120x120x30 Z carrier 1 piece-
Z frame parts 2 pieces 120x60x 30mm-
The product code for processing aluminum profile item 120x30 aluminum profile is 0. 0. 419.
04 and 60x30 aluminum profiles are 0. 0. 419. 041)
Precision steel shaft :-
20mm precision steel shaft for x axis (
Cut from 1 shaft with 60 inch = 1524mm)
2 pieces 600mm long-
16mm precision steel shaft for Y axis (
Cut from 2 pieces of 30 inch = 762mm axis)
2 pieces 390mm long-
16mm precision steel shaft for z axis (
Cut from 2 372mm axes on the left side of the y axis)
2 pieces 300mm long-
Processing precision steel shaft 6 pieces 2)
Ball bearing/bushing-Ø20mm (
Diameter 32)
4 pieces of ball bearing/bushing-Ø16mm (
Ø 26 outer diameter)
8 pieces of ball bearing/bushing 3)
Ladder screw cut from 1500mm long ladder screw :-
4mm ladder screw for X axis 1 piece 657mm long-
4mm ladder screw for X axis 1 piece 447mm long-
4mm ladder screw for X axis 1 piece 357mm long-
End face processing of ladder lead screw in local workshop 4)
The ladder cylindrical nut I made on the lathe in the local Workshop :-
Nut with diameter of 4mm, length of 32mm, diameter of 32, spacing of mm 1 piece
4mm in diameter, 24mm in length, 2 pieces with mm spacing nut. The motor selected for this project is the 3Nm 8-wire stepping motor, which can be used as a single or bipolar connection, depending on the choice of each person or what driver you have (
Single or bipolar). -
3 3 3 nm stepper motors with two windings per phase and one winding per magnetic field direction.
The motor has only five leads.
The bipolar motor has a winding for each phase.
The current in the winding needs to be reversed to reverse the magnetic pole.
There are two leads in each stage, none of which is common.
The difference is: \"single-pole and double-pole half-coils, because we use fewer coils, will not bring us a lot of low-speed torque, but because of the low inductance, keep the torque at high speed.
The bivolar series uses full coils and therefore has very good low speed torque.
However, the torque drops rapidly due to high inductance.
The full coil is also used by bivolar Parallel, so it has good low speed performance.
Its low inductance allows to keep the torque at high speed.
But keep in mind that in order to get these advantages we have to increase the current by 40%.
\"The step motor driver used is a single-Polar 4-axis driver of a 5A/phase motor with an input power of 20-40V DC (local shop).
Input power 20-
40 v dc stepper motor drive current 1. 5A -
2 or 4-phase, 6 or 8-lead stepping motor with a maximum of 5A.
Size 18x12x6 cm (L x W x H)
The board allows you to control 4 stepping motors and receive input from two limit switches/motors and emergency stop buttons, and has a relay spindle interface for the spindle motor.
The power supply includes a 600 W ring transformer, a 50 amp rectifier bridge and a 20000f capacitor.
For the motor controller, I used the old Keithley236 source measurement unit.
I have taken out all the old stuff to make way for the new motor controller and power supply.
The input of the transformer is 230 v ac current with two 21 v ac current outputs.
The output is connected in parallel and then goes to the bridge of rectifier.
The rectifier bridge converts the input AC current into the DC current on the output.
The output of the front and negative rectifier is connected to the 20000 µF capacitor with positive and negative, smoothCurrent.
Now you can connect to the drive DC input from the capacitor. An 8-
The lead step is like a single-polarity step, but the lead is not connected to the public end inside the motor.
There are many configurations for this motor :-Unipolar. -
Bipolar with series winding.
This provides a higher inductance for each winding, but a lower current. -
Bipolar with parallel winding.
This requires a higher current, but the performance will be better as the winding inductance decreases. -
Bipolar of each phase single winding.
This method runs the motor only on half of the available windings, which will reduce the available low speed torque but require less current.
The motor is a single pole motor, so you need to run 5 wires from the motor controller to each motor.
Two so-called common wires from the motor controller are connected to four (
Red, green, yellow, black)
Wire motor, make a thick ordinary wire.
Some machining of aluminum parts is required before all parts are installed.
Drawings showing you how to modify these parts are in dxf and pdf format, so feel free to use them.
The modifications you have to make must be done on the milling machine, not by hand.
You must cross the screw and the ladder lead screw (
X base, Y side piece, Z piece)
, About 5mm deep holes centered on the precision steel shaft, about 5mm deep holes of the trapezoid lead screw end bearing bracket (
X base, Y side piece, Z piece).
You will also need to make 3 holes in the Y cross section, two of which are for linear ball bearings and one for ladder nuts.
In the two pieces of the x y carriage profile, you have to make 5 pockets in witch, putting 16mm straight ball bearings tightly together with a ladder nut.
For precision steel shafts, you have to do some end screw holes so you can fix them on the aluminum profile frame.
You can make that hole in the lathe.
Because it will be centered and coaxial with the Axis.
The next step will be to process the end of the ladder lead screw so you can install the bearing.
This also requires a lathe to make both ends more accurate so that the bearings do not move in all directions.
The ladder nut is manufactured from scratch and is made of POM or POM, which is \"engineered thermoplastic material for precision parts that require high stiffness, 16mm ladder nut has two types, the first has an outer diameter of 32mm and a length of 32mm (one piece)
The second diameter is 24mm and the length is 24.
Finally, the last component you have to make is the X ball bearing bracket.
You need two pieces, one for each part of the x-axis.
You should do it on the 3 axis milling machine.
All processing operations are carried out in the local workshop.
For this axis, you need :-
1 120x30 aluminum profile-
120x60x30 aluminum profile 2-
2 pieces made of precision steel shaft 300mm m long ø 16-
Ø 4 pieces of 16mm (
Ø 26 outer diameter)
Ball bearing/bushing-
1 piece made of 357mm long ladder screw ø 16-
6000zz ball bearing 2 pieces-
1 ladder nut with diameter of 24mm and length of 24mm-
The last operation is to install the screws into the shaft holes to secure the entire assembly.
For this axis, you need :-
400x120x30 aluminum profile 2-
1 piece 380x60x30 aluminum profile-
2 pieces made of precision steel shaft 600mm m long ø 20-
4 pieces of 20mm (
Diameter 32)
Ball bearing/bushing-
1 piece made of 657mm long ladder screw ø 16-
6000zz ball bearing 2 pieces-
1 ladder nut with diameter of 32mm and length of 32mm-
2 ball holders (see drawing)-
Screw x 40mm Screws 4 PCs-
Screw x 60mm Screws 2 pieces (
For ball holder)
In order to start installing the ball sleeve in 2x32 holes of 380x60x30 aluminum profile, the ladder nut is then installed in 32 holes in the middle of the aluminum profile.
Install 2 pieces 6000zz ball bearings in 2x26 holes and 2 pieces ø 20mm ball bushing for each 400x120x30 aluminum profile.
Now insert the shaft into the mounted ball sleeve, the ladder screw into the ladder nut, and then install 2 pieces of 400x120x30 aluminum profiles at each end of the shaft and the ladder screw.
Fix the shaft on 40mm x 400x30 aluminum profiles with 4 M5x 120 screws.
For this axis, you need :-
400x120x30 aluminum profile 2-
1 120x30 aluminum profile-
2 pieces made of precision steel shaft 390mm m long ø 16-
Ø 4 pieces of 16mm (
Ø 26 outer diameter)
Ball bearing/bushing-
1 piece made of 447mm long ladder screw ø 16-
6000zz ball bearing 2 pieces-
1 ladder nut with diameter of 24mm and length of 24mm-
4-piece M5x 40mm ironing board. The first thing you have to do is install all ø 16mm ball covers and ø 16mm by ø 24mm in the 120x30 aluminum profile and then insert the shaft into the mounted ball sleeve, insert the ladder screw into the ladder nut.
Install the 2 parts of the 6000zz ball bearing in the ø 26 hole of each 400x120x30 aluminum profile.
Next, install 400x120x30 aluminum profiles at each end of the shaft and fix them with 4 M5x 40mm screws.
In order to complete the mechanical assembly, all the shafts must now be installed together.
The X-axis that is first installed on the y-axis is fixed at 400 points of the month, the 120 points, the 380 points, the aluminum alloy profiles are supported with 60x30 aluminum alloy profiles and the monthly ball bushing.
Next, by installing the 120x30 aluminum profile of the Z axis on the 120x30 aluminum profile of the y axis, the y axis is fixed with the Z axis at an angle of 90 °.
Now we have to install the stepping motor on the CNC machine, but first we need to make some motor supports.
I used a screw bar and cut it into small pieces to support the motor.
On the screw bar, I put some smaller aluminum tubes as spacers between the motor and the CNC frame.
Now mount at one end of the rod, one nut, and put the rod with the nut into the 4 mounting holes of the motor.
Between the motor and the screw, I put a rubber hose and put two hose clips on it as a connector.
Now, place the aluminum gasket on the rod and install the motor on the frame, the rod is inserted into the 4 holes in the frame.
Repeat this operation for all 3 motors.
I have made the cable bracket with U-shaped aluminum profile and two steel corner brackets.
For the x-axis, I cut the profile to the desired length and install two steel corner supports at each end of the profile.
After I installed the steel corner brace onto the profile, I installed the cable holder on the CNC machine with 4 screws ant 4 t-nuts.
The same is true for the y-axis, just there I didn\'t use the steel corner brace, I just used two screws and two T-nuts.
As I said in step 11, we will be using a single pole wire configuration, which means there will be 5 wires.
Now the 8 wires of the motor are: First coil-
A is yellow/white, is the beginning of the coil, neg A is yellow, is the end of the coil; Second coil -
Neg C is red, is the beginning of the coil, C is red/white, is the end of the coil; Third coil -
B is green/white, is the beginning of the coil, neg B is green, is the end of the coil; Fourth coil -
Neg D is black, is the beginning of the coil, D is black/white, is the end of the coil.
Now, to make 5 wires from 8 wires, all neg wires between them must be connected and one wire made.
Now we have 5 wires to connect to the controller drive board.
The connection line between the motor and the controller is 1.
5mm thick so they don\'t get hot.
When you connect two cables, because the connection is stronger, weld them together and insulated them with a retractable plastic pipe.
Home switch is used to mechanically set the reference position of the machine at boot time.
In addition, the limit switch is also used to prevent you from moving the table from the end of the ball screw or into the shell of the ball screw bearing.
As you can see, I have used two holes to mount the Z axis limit switches on aluminum pieces and thread them through.
There are two limit switches in the z-axis, one for rise and one for drop.
The two limit switches are connected in series and then connected to the controller via a serial cable.
The Y limit switch needed some extra support, so I had to make two supports with one piece of aluminum.
The X limit switch installed on the X-axis cable suport.
Now, in order to start cutting and drilling in order to operate and use this CNC machine, we have to configure the CNC Software (
My situation is Mach3)
First of all, I set the local unit to mm because I am using the metric coordinates.
Next, the motor output must be configured from the port and pin menu.
As you can see, I have entered the corresponding pin number for each motor step and dir.
This information comes with the controller driver board.
Now that we have the pins configured, we have to configure the limit switch input and the E-stop.
This information is also provided by the controller driver board.
After all the pins are configured, we must set the motor.
Access the motor tuning menu under the configuration menu and fill the step/mm box with how many steps the motor has to turn so that the gantry moves 1mm (
My dose is 50 spets/mm because my screw spacing is 4mm and my stepping motor has 200 steps/turn so when the gantry is moving 4mm, the motor completes 200 steps and 50 steps in 1mm steps).
The speed of the gantry will now be adjusted (
I set it to 1000/min Now)
Accelerate to 50mm/second.
The last picture shows how to configure hotkeys and how to configure soft limits for each axis.
What do you think is missing from this project or what is not clear?
I like to do it better.
Please feel free to let me know if you have some ideas or suggestions.
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