Today I’m discussing a mechatronics project. This project is actually a derivation of a video I've already posted here: ROUTER AND PLOTTER WIFI WITH WEBSERVER IN ESP32. I advise you to watch this one first, as it explains how the GRBL program works. This video here discusses a ROBOT OF DESIGN, which is already frequently discussed about on the internet. I’ll introduce today the assembly of a CNC machine for pen drawings.

Step 1: Demonstration

Step 2: Resources Used for Construction (Bolts and Nuts)

• 5 Screws M4x20mm

• 10 screws M3x8mm

• 8 Screws M3x16mm

• 11 screws M3x30mm

• 7 M4 nuts

• 23 M3 nuts

• 2 Threaded rods 7 / 16pol of 420mm

• 8 7 / 16pol nuts

Step 3: Resources Used for Construction (Mechanics)

• Rectified axis (Linear Guide): (R$ 50 approx.)

• 2x 400mm

• 2x 300mm

• 2x 70mm

• 10 linear bearings lm8uu (R $ 4.50 each)

• 9 Bearings 604zz (4x12x4mm) (R $ 4.50 each)

• 2 Meters of GT2 belt 20 teeth (R $ 20)

• 2 pulleys GT2 20 teeth (R $ 12 each)

• 2 Nema 17 engines (R $ 65 each)

• 1 Servo MG996R (R $ 40)

• 4 nylon clamps

• Printed parts (250g ABS approximately R $ 20)

• Only plastic prices

• Total: R $ 370 + freight, approximately

Step 4: Printed Parts Used for Construction

• 1 SheetXE_YixoXY_A. (THE)

• 1 SheetXE_X. (B)

• 2 Motor_Motor. (W)

• 1 Plate_EixoZ_A (D)

• 1 Plate_EixoZ_B (E)

• 1 Lock_Drive (F)

• 1 Trava_Correia_A (G)

• 1 Trava_Correia_B (H)

• 2 BaseBlock (I)

Step 5: Wood Support Base (optional)

Step 6: Mechanical Assembly - H BOT

• The H BOT cartesian movement system is simpler than CoreXY, as it uses a continuous belt length to transfer force to the car.

• The benefit of using this system is the low potential mass of the mobile car due to the stepper motors that are part of the chassis.

• A problem in the HBOT system is that the belt pulls the car on only one side, which can lead to crashes. This can be solved with a more rigid chassis.

Step 7: Assembly of Mechanics - H BOT in CROSS

• We will use the Cartesian system H BOT, but mounted in a cross format. This will help to reduce the frame of the machine and will make it more portable.

Step 8: Assembly of Mechanics - H BOT in CROSS

Working principle

Step 9: Assembly of Electronics

Step 10: GRBL Installation

https://www.fernandok.com/2019/02/router-e-plotter-wifi-com-webserver-em.html

Step 11: GRBL Configuration

• Since this assembly does not use limit switches, we must disable the "homing" cycle of the machine.

• On the "config.h" tab, comment on line 116.

• To use a servo to raise and lower the pen, we can disable the wrist and direction pins that would be used in the Z axis pitch motor.

• On the "cpu_map.h" tab, comment on lines 48 and 52.

• Let's enable the COREXY movement so that the software correctly calculates the movement of the motors to our belt system.

• We will also enable the servo, which will replace the Z axis motor.

• On the "config.h" tab, comment on lines 223 and 228.

• In the "servo_pen.h" tab, you can modify the port that will be used for the servo PWM signal. You can also modify the PWM settings, such as frequency, pulse width, and maximum and minimum range.

• Set the GRBL to use the servo on the Z axis:

• Change the steps per mm of the Z-axis to 100.

• Change the maximum speed of the Z axis to 500 mm / min.

• Change the maximum movement of the Z axis to 5mm.