Regular visitors of the site are already familiar with the works of this master. These are such works as “Machine for winding coils”, “Magnetic levitation using a solenoid coil” and the last work, partially overlapping with this CNC-machine “CNC-plotter from readily available materials.”In this article, the wizard will tell you how to build a homemade 3-axis CNC machine with a frame and supports made of PVC pipes and acrylic sheets. The machine has two modes of operation: drawing and laser engraving.
Machine operation can be viewed on the video.
PVC pipes and fittings
-PVC elbow Ø 42 mm – 8 pcs;
-Straight connector for pipes PVC Ø42 mm – 8 pcs;
-Tee PVC Ø 4 2 mm – 14 pcs;
-PVC crosspiece Ø42 mm – 3 pcs;
-PVC cap Ø42 mm – 16 pcs;
-PVC cap Ø60 mm – 6 pcs;
-PVC adapter Ø60mm – Ø42mm – 3 pcs;
-PVC adapter Ø50mm – Ø42mm 2 pcs;
-Two meters of PVC pipes Ø42 mm and Ø60 mm;
-Drilling machine; -Haw; -Hand grinder; -Soldering accessories; -Scissors; Step one: connection
Master used a GRBL based controller for 3-axis CNC machine, and it supports laser control.
Connecting three A4988 stepper motor drivers to the CNC controller at mark positions X, Y and Z.
Connecting cables from the CNC controller to three stepper motors.
The laser module has 3 wires connected to the socket: red (12V +), black (GND), yellow (PWM) and it connects to the 3-pin laser connector on the CNC controller with the same label.
Parameters of this laser module are indicated on the nameplate:
Wavelength: 450 nm.
Output power: 2.5 W.
Step two: making the frame
The master assembled the frame from PVC parts. Frame dimensions horizontally L480 x W480 mm and vertical W480 x H550 mm.
To assemble the frame you need:
10 pcs. PVC tees Ø 42 mm.
PVC elbows Ø 42 mm, 6 pcs.
8 pcs x PVC straight connectors Ø 42 mm.
2 pcs PVC adapters Ø 60 mm – Ø 42 mm.
And some PVC connecting pipes Ø 42 mm and Ø 60 mm.
X and Z axes: mounted on a vertical frame.
Y-axis: mounted on a horizontal frame.
Step three: preparatory work
To assemble the plotter, it is necessary to make holes in the PVC plugs for lead screws and guides. For drilling, he used 8 mm and 22 mm drills.
Need to drill:
-One hole Ø 22 mm on the plug Ø 42 mm – only 14 pcs. (For installing the guides and lead screws of the X and Y axes).
-One hole Ø 10 mm on the plug Ø 42 mm – only 2 pieces (for copper nuts of lead screws). The craftsman used a drill bit 8 mm, then carefully drilled out these holes so that the copper nuts could be tightly inserted into the holes.
-Two holes – Ø 22 mm and Ø 8 mm – on the plug Ø 42 mm – only 4 pcs. (for fixing the Z axis)
– Holes – Ø 22 mm and 8 mm – on the end cap 60m m – only 4 pcs (for mounting the stepper motor of the Z axis and Z axis of the working base). One of them is used to mount the stepper motor, so you need to drill 4 more small holes in it.
Step four: assembly work in the Z axis
All Ø60mm Z-axis end caps must be cut to the desired length to increase the Z-axis workspace.
Installs a Z stepper motor and connects to a 400 mm lead screw using a 5 x 8 mm coupling.
Attaches the motor bases to the remaining end cap and installs the shaft into 8mm holes.
Installs two plugs at the other end.
Step five: X-axis
The X axis is built from 2 PVC crosspieces. After cutting and connecting the 2 crosspieces, he installed 6 Ø42mm end caps with bearings and copper nuts on the six ends of the crosspieces.
The Z-axis will “rest” on the X-axis base. The lead screw and guide assembled in the previous step are installed in this. To prevent it from slipping during work, the foreman installed 2 copper nuts on the upper and lower end caps.
Then the master cut out one acrylic plate measuring 150 x 230 mm, drilled 8 small holes for installation of a stepper motor X and a P-CNC controller. Then this acrylic plate was connected to the CNC frame with two large holes, the diameter of which is equal to the outer diameter of the Ø42 pipe.
Installs connecting tubes in these holes and blocks them with end caps on the working side of the stepper motor.
Sets the Z axis to the working base of the X axis.
Pre-assembles with pulleys with 20 and 60 teeth and a belt 200 mm.
Mounts the X and Z axes to the main frame of the machine.
Step Six: Assembling the Y-Axis
The Y-Axis is made of 2 PVC tees that have been joined together. The foreman installed 4 end caps Ø42 mm with bearings and a copper nut at the four ends of the tees.
As with the X-axis, 4 small holes were drilled on one 50 x 230 mm acrylic plate for mounting the Y stepper motor and 2 large holes for attaching to the main frame.
Pre-assembles the Y-axis with 20 and 60 teeth pulleys and a 200 mm toothed belt.
Installs the Y-axes on the main frame of the machine.
Step Seven: Desktop
As a desktop, the master used a black and white A4 board. Before bolting the X-axis base to the build platform, he inserted 2 5mm thick acrylic sheets to make a gap between the build platform and other supports.
Step eight: laser module holder
In the working base of the Z axis, the master drills two holes and tightens two screws. With these 2 bolts, you can easily switch between 2 modes of operation: pen drawing mode or laser engraving mode.
Then you need to cut off a tube with a diameter of 42 mm from the Ø50mm – Ø42mm connector. The tube is cut and two grooves are cut in its outer part so that they fit exactly on the edge of the laser module.
Then the knot is installed in the cut-off part with a diameter of 50 mm.
Further to the working part of the axle, a 50 mm PVC tube is screwed. The laser module is installed in it.
Step nine: pen holder
To attach the handle, she cuts out a small acrylic sheet and drills 4 holes in it. Two holes are used to install a 10x10mm flexible sleeve (for clamping the handle) and the other two holes are used to connect to the Z-work base.
Step ten: installation and connection of the CNC control board
Then he installs the CNC control board on the acrylic support of the X axis and connects all the wires to the stepper motors and the laser module.
Cable ties, cable windings were used to fasten all the wires.
Step eleven: GRBL parameters
The GRBL parameters for the machine are listed in the table below:
$ 32 1.000 Laser-mode enable
$ 100 1066.667 X-axis travel resolution
$ 101 1066.667 Y-axis travel resolution
$ 102 800.000 Z-axis travel resolution
$ 110 500.000 X-axis maximum rate
$ 111 500.000 Y-axis maximum rate
$ 112 500.000 Z-axis maximum rate
$ 120 20.000 X-axis acceleration
$ 121 20.000 Y-axis acceleration
$ 122 10.000 Z-axis acceleration
$ 130 200.000 X-axis maximum travel
$ 131 200.000 Y-axis maximum travel
$ 132 80.000 Z-axis maximum travel
Set $ 32 = 1 to activate laser mode.
Laser Mode also allows you to use the M4 Dynamic Laser Power Mode. As stated in the LaserGRBL Developer's Guide: “This is a unique feature that automatically adjusts the laser power based on the current speed relative to the programmed speed. In fact, it provides a constant amount of laser energy along the cut, even if the machine can be stopped or actively accelerated. ”.
Step Twelve: Inkscape and the Universal Gcode Platform
For pen mode, the wizard used the following programs:
Inkscape and Gcodetools Extension: Create G-Code Files from Text or Images.
Universal Gcode Platform (UGS): Upload File G-code generated by Inkscape on the P-CNC controller and tracking the work of the Visualizer tab.
For the first testing, he created a G-code file with the text “NEXTPCB”.
Then I tested the device.
Step thirteenth: LaserGRBL software
For engraving on plywood, he used the LaserGRBL program. LaserGRBL can upload and transfer Gcode images to a GRBL based engraver using the built-in tool.
PWM control can be enabled to create grayscale if the laser module supports TTL control connected to Arduino PIN D11.
The composition of the plywood is not uniform, so after several tests, he used the “dithering” tool as suggested in the original LaserGRBL information.
Laser engraving can be different for each particular type of plywood. In this case, it was A4 plywood, and it itself is divided into 2 parts: one is easy to burn, and the other is more difficult with the same settings.
In this case, the wizard used the following settings:
Open the picture with LaserGRBL.
Select the “1bit BW dithering” tool in the transform tool options.
Adjust brightness, contrast and white tint with sliders
Select Dithering Options from the drop-down list:
– Dithering: Atkinsion.
– Direction: Horizontal .
– Quality: 10 Lines/mm.
Click “Next” and a window will open.
Enter the engraving speed, select laser parameters, adjust the size and position of the image in the pop-up window.
Press the “Creat” button and everything is ready to transfer the GCode to the P-CNC controller.
Testing has shown good results. It should be noted that this is the first work of a master to make a laser engraver.
The master is pleased with the result and plans to make a machine more than 1 meter in size. In this case, he will have an inexpensive and good quality plotter and an A0 format CNC engraving machine.
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