Mini CNC Laser Wood Engraver and Laser Paper Cutter.
by：Luteng CNC Parts2020-09-18
This is a note on how I used the old DVD drive 250 mW laser to make an Arduino-based laser CNC woodcutter and a thin paper cutter. Maximum 40mm x 40mm in game area. Isn\'t it fun to make your own machine with old things? Laser safety glasses must be used in this project. Most of the parts were salvaged or shipped from China via a website called Bongo. Two DVD drive mechanisms are required, one for X- The second axis of the y and y axesaxis. Using a small Phillips head screwdriver, I removed all the screws and separated stepping motors, sliding rails and follower. The stepping motor is 4- Pin bipolar stepping motor. In order to measure the resolution of the CD/DVD driver stepping motor, a digital splitter is used. The distance along the screw is measured. The total length of the screw using a thousand-meter, originally 51. 56 mm. Determine the lead value, that is, the distance between two adjacent threads on the screw. Within this distance, the thread is calculated as 12 threads. Lead = distance between adjacent threads = ( Total thread length/number = 51. 56 mm)/ 12=4. 29mm/rev. The step angle is 18 degrees, which is equivalent to 20 steps/turn. Since all the required information is available, the resolution of the stepping motor can be calculated as follows: resolution = ( Distance between adjacent threads)/ (N Steps/rev)= (4. 29mm/rev)/ (20 steps/rev)= 0. 214 mm/step. This is 3 times the required resolution of 0. 68mm/step. For sliding rails, I used 2 extra rods for better, smoother performance. The main function of the slider is to slide freely on the rod, and the friction between the rod and the slider is minimal. I spent some time letting the slider slide freely on the bar. Using some acrylic sheets, I made two main frames for the stepping motor and the sliding guide. The stepping motor has a gasket between the main frame and the base, which is necessary for the shaft. Using super glue first, I try to adjust the proper position of the track so that the follower can make proper contact with the stepping line. Contact should be appropriate, not too tight, and not too scum. If the contact between the follower and the thread is not appropriate, the steps will be skipped, or the motor will consume more current in the running state than normally. It takes some time to adjust. Once it is adjusted, I fix them with epoxy glue. For the stepping motor, I used the old usb cable because it had 4 wires inside with a lid on it and it was more flexible and easier to use. The continuity mode is used in the multimeter to determine 2 coils, coil A and coil B. I made two pairs of wires by selecting color, one pair of coil A and the second pair of coil B. Weld them and use heat shrink tubes on top. X and Y co- Coordinate the movement. I have attached the slider for X and Y Using some spacing between them, the axis is perpendicular to each other. A thin metal grill is also attached to it as a working bed. Use nd magnet as a workpiece holder. The part used by the driver is: in GRBL, the numbers and analog pins of the Arduino are retained. The \"step\" pins of the X-axis and y-axis are connected to the digital pins 2 and 3, respectively. The \"dirty\" pins of the X-axis and y-axis are connected to the digital pins 5 and 6, respectively. The D11 is used for laser enabling. Arduino is powered via a USB cable. A4988 drive via external power supply. All the ground has a common connection. The VDD of the A4988 is connected to the 5 v of the Arduino. The laser I use runs on 5 v and has a constant current circuit built in. Constant 5 v power supply for external power supply LM7805 voltage regulator. Radiator is a must. The IRFZ44N N- When receiving a digital high signal from the Arduino\'s pin D11, the channel MOSFET is used as an electronic switch. Note: the 5 v of the Arduino nano cannot be used because the laser absorbs more than 250 mA and the Arduino Nano cannot provide that much current. Configure micro stepping for each axis. MS0 MS1 MS2 microstep resolution. Low full step. Half Step high and low. Low quarterly steps. The eighth step is high and low. High level 16. The3 pins ( MS1, MS2 and MS3) It is one of the five-step resolutions selected according to the above truth table. These pins have internal pull So if we get the resistor disconnected, the board will run in full step mode. I used a 16-step configuration to smooth and noise-free. Most ( But certainly not all) Step motor 200 steps per turn. By properly managing the current in the coil, the motor can be moved in smaller steps. Pololu A4988 can move the motor in 1/16 steps- 3,200 steps per revolution. The main advantage of micro-stepping is to reduce the roughness of motion. The only exact location is full. step positions. The motor will not be able to hold the torque in one of the intermediate positions with the same position accuracy or the same holding torque as the entire step position. In general, full steps should be used when high speed is required. I made a laser bracket with a slender metal strip and some plastic L brackets with brackets. Then, install everything on the board using M4 screws, nuts and bolts. The connection between the stepping motor and the driver is also completed. The laser I am using is the focusable laser module 200-250mW 650nm. The external metal housing is used as a radiator for laser diodes. It has a focused lens for adjusting the laser point. Using two Zip- I installed the laser with the bracket. The laser radiator can also be used, but my laser is not overheating, so I am not using it. Connect the laser wire terminals to the laser socket on the drive board. You can get a motor that reaches a high step rate, and if there is no active current limit, the motor supply is usually much higher than allowed. For example, the maximum rated current of a typical stepping motor is 1A and the coil resistance is 5Ω, which indicates that the maximum power supply of the motor is 5 v. This motor using 12 V will allow a higher step rate, but in order to prevent damage to the motor, the current must be actively limited to less than 1A. The A4988 supports this active current limit, and the fine-tuning potentiometer on the board can be used to set the current limit. One way to set the current limit is to put the driver in full- Step mode, measuring the current through a single motor coil without timing the step input. The measured current is 0. 7 times current limit ( Because these two coils are always on and are limited to 70% of the full current limit settingstep mode). Note that changing the logic voltage Vdd to a different value will change the current limit setting because the voltage on the \"ref\" pin is a function of Vdd. Another way to set the current limit is to directly measure the voltage at the top of the potentiometer and calculate the resulting current limit ( The current sensing resistance is 0. 1Ω). The current limit is related to the reference voltage as follows: current limit = VREF × 1. For example, 25 if the reference voltage is 0. 6 v, the current limit is 0. 75A. As mentioned above, in full step mode, the current through the coil is limited to 70% of the current limit, so full step mode is obtained The current of the stepping coil is 1A, and the current limit should be 1A/0. 7=1. 4A, VREF corresponding to 1. 4A/1. 25=1. 12 V. For more information, see the A4988 data sheet. Note: The coil current may be very different from the power supply current, so you should not set the current limit using the current measured by the power supply. The appropriate position to place the ammeter is connected in series with a stepping motor coil. Lock the workpiece on the workbench using four small nd magnets and set X and Y- Axis to initial position (home). Powered by an external power supply to the drive board, the Arduino Nano power the computer through the USB a to USB Mini B cable. Also power the circuit board through external power supply. SAFETY FIRST. We also need a software to send G- For this I used laser GRBLLaserGRBL, one of the best Windows GCode streamer for DIY Laser engraving machine. LaserGRBL is able to load and stream GCode paths to arduino and engrave images, pictures, and logos using the internal conversion tool. Download laser GRBL. LaserGRBL constantly checks the COM ports available on the machine. The port list allows you to select the COM port your Control Board is connected. Please select the appropriate baud rate for the connection according to your machine firmware configuration (default 115200). Grbl settings: $- Check the Grbl settings and after connecting to Grbl, Type $ and press enter. Grbl should respond with a list of the current system settings, as shown in the following example. All of these settings are persistent and saved in the EEPROM, so if you power off, the settings are reloaded the next time you power the Arduino. $0=10 ( Step pulse (usec)$1=25 ( Step idle delay (msec)$2=0 ( Reverse shield of stepping Port: 00000000)$3=6 ( Dir Port reverse mask: 00000110)$4=0 ( Steps to convert, Boolean)$5=0 ( Limit pin conversion, Boolean)$6=0 ( Probe pin reversal (bool)$10=3 ( Status report Shield: 00000011)$11=0. 020 ( Connection deviation (mm)$12=0. 002 ( Arc tolerance (mm)$13=0 ( Report inch, Boolean)$20=0 ( Soft boundaries, Boolean)$21=0 ( Hard limit, Boolean)$22=0 ( Cycle of automatic search, Boolean)$23=1 ( Looking for dir reverse mask: 00000001)$24=50. 000 ( Feeding (mm/min)$25=635. 000 ( Finding (mm/min)$26=250 ( (Msec)$27=1. 000 (homing pull-off, mm)$100=314. 961 (x, step/mm)$101=314. 961 (y, step/mm)$102=314. 961 (z, step/mm)$110=635. 000 ( X max rate (mm/min)$111=635. 000 ( Maximum rate (mm/min)$112=635. 000 ( Maximum rate (mm/min)$120=50. 000 ( X accel, mm/sec ^ 2)$121=50. 000 ( Y accel, mm/sec ^ 2)$122=50. 000 ( Z accel, mm/sec ^ 2)$130=225. 000 ( X max travel, mm)$131=125. 000 ( Max Travel, mm)$132=170. 000 ( Max Travel, mm) The most difficult part of the project has come. - Adjust the laser beam to the minimum point that may exist on the workpiece. This is the trickiest part, it takes time and patience to use the trail and error methods. - Adjust the GRBL settings to $100, $101, $130 and $100 to $110 = $. 000$101=110. 000$130=40. 000$131=40. 000I tried engraving 40mm square meters and so many errors and adjusted settings grbl, I got the right 40mm line engraved X and Y-axis. If the resolution of X and Y The axes are different and the image will be scaled in either direction. This is a long and time consuming process, but the results are very satisfactory when adjusting. LaserGRBL UI import allows you to load any type of image in LaserGRBL and convert it to a GCode instruction without the need for other software. LaserGRBL supports photos, Clipart, pencil strokes, logos, icons and tries to do the best for any type of image. You can call from the file, open file menu by selecting an image of jpg, png or bmp type. The settings for engraving are different for all materials. Define engraving speed and quality per mm- The line that comes with each mmVideo is time- Failure of the whole process. This 250 MW laser can also cut thin paper, but the speed should be very low. e. The beam should be adjusted appropriately for no more than 15 mm/min. The attached video is time Failure of the whole process. I made some custom vinyl stickers. Boarding speed varies with the color of the vinyl used. Dark colors are easy to handle, while light colors are tricky. The picture above shows how to use vinyl stickers made using CNC. ♥Special thanks to GRBL developers :) I hope you enjoy this project, please let me know in the comments if you have any questions, and I would also like to see a photo of your CNC machine! Thanks! ! Thank you for your support