Introduction: Mr.Engraver : the Desktop Laser Engraving Machine

About: Brain of an Engineer, Heart of an Artist. I love building creative tech!

Introducing "Mr. Engraver," a DIY portable desktop laser engraving machine designed to engrave on wood and plastic, as well as cut through foam sheets and paper. The machine has a work area of 38mm x 38mm, with a particular emphasis on laser safety. A dedicated cabinet has been constructed to shield users from direct laser exposure, incorporating an "Automatic Laser Shutdown" feature for enhanced safety.

The concept behind the Automatic Shutdown is to address potential hazards associated with Class 3B lasers and higher power levels. To prevent accidental exposure, especially when the cabinet door is opened during operation, a limit switch is used in the design to immediately cut off power to the laser, ensuring a rapid and secure shutdown.

The resulting laser engravings showcase the precision and clarity achieved with this machine.

Step 1: Demo Video

Here is the video that goes over the features of "Mr-Engraver"

Step 2: Bill of Materials

To construct this CNC the following materials are required:

  1. L-Braces - 2 units
  2. CD or DVD RW - 3 units
  3. EasyDriver Modules - 3 units
  4. Arduino Uno (or any compatible version) - 1 unit
  5. Plywood
  6. Roll of Leather
  7. 12V 3A SMPS Power Supply - 1 unit
  8. Basic hardware building supplies

Step 3: Salvaging ROM

To begin, disassemble the ROMs to extract the rails. The three rails obtained will be used to drive the three axes. Additionally, retain the metal casing as it will be utilized in the next steps.

It's also worth noting that other valuable components can be salvaged from the ROMs, such as:

  1. Laser Diode on the sled
  2. DC Motors
  3. Optical materials like lenses, which can be used for capturing unique macro shots
  4. Strong Neodymium Magnets, typically found near the laser focusing unit on the sled


Step 4: Build the Y Axis

Now that we have the rails and casing in hand, let's dive into the construction process. The initial step is to assemble the Y-axis:

  1. Mark the hole positions on one of the metal casing boxes.
  2. Drill the holes using a 5mm metal drill bit and smooth out any burrs.
  3. Proceed to drill two holes for the "L Braces" on the opposite edge of the metal casing. (Refer to the provided photos for guidance)

The platform will be added later in the process.

Important: Ensure that the Y-axis is positioned straight and close to the edge. Deviations in placement may result in distorted images in the final outcomes.

Step 5: Build the Z Axis

It's time to construct the Z-axis of the CNC. Here's how you can do it:

  1. Cut a piece of polycarbonate sheet to an appropriate size, ensuring it's just enough to accommodate the Z-axis.
  2. Drill four holes on the vertices and one at the center of the sheet.
  3. Secure the Z-axis onto the polycarbonate sheet using screws, nuts, and washers.

Once again, pay close attention to the alignment of the Z-axis; it should be as straight as possible.

Tip: I opted for polycarbonate due to its low density, making it light in weight. This is crucial as the stepper motors of the ROMs can't lift heavy loads.

Step 6: Combine the Z Axis and X Axis and Mount Them

Once the Y-axis and Z-axis are constructed, proceed to mount the Z-axis onto the X-axis:

  1. Carefully make a hole on the X-axis's sled.
  2. Gradually drive a screw into the sled, ensuring the screw thread securely embeds into the plastic.
  3. Remove the screw inserted in step 2 and attach the Z-axis onto the X-axis.
  4. Apply a generous amount of hot glue to the joint between the X and Z axes to secure them in place.
  5. For precision, hot-glue two washers onto the sled before mounting the Z and X axes. This helps maintain alignment by preventing distortion. This step is recommended.
  6. Take both axes (X and Z) and mount them on another metal casing box, ensuring they are positioned as straight and close to the edge as possible.

Note: Exercise extreme caution while tightening the screws on the sled. Overturning may lead to the sled splitting into two parts.

Step 7: Y Axis Bed

The bed, in CNC terms, refers to the platform where the object being worked on is placed. For the bed, I opted for a polycarbonate sheet.

  1. Cut a small yet appropriate size of the polycarbonate sheet.
  2. Eliminate any burrs on the piece by sanding.
  3. Drill a 5mm hole precisely in the middle of the sheet.
  4. Secure the screw into the bed using washers and nuts.
  5. Next, drive a spare screw into the Y-axis sled. Be gentle, as the screw threads will embed into the plastic sled.
  6. Mount the bed onto the sled.

Please look at the pictures above for more guidance.

Step 8: Combining All Three Axes

Now that we have all the axes ready, mount them at 90 degrees with the help of "L-Braces."

  1. Adjust the axes to be perpendicular to each other.

Ensure that the Y-axis doesn't collide with the Z-axis.

  1. Drill holes into the metal case of the ROM.
  2. Secure the axes with L-Braces using nuts and bolts.

Note: Emphasize the perpendicular alignment of the axes. I am repeating this because it is crucial; you won't achieve desirable results unless the alignment is perfect.

Step 9: Build the Control Circuit

We've constructed the "Hands and Feet" of the CNC, but now we need a brain to control them. For this, we'll be using an Arduino Uno (or any compatible variant) as the CNC's central processing unit.

  1. Build the circuit as depicted in Picture 1.
  2. Connect the respective stepper motors for each axis to their drivers. Here is a quick table:

Axis X Y Z

E.D pins ------------ (GND) (STEP) (DIR)------------

ARDUINO (GND, 2,5) (GND, 3,6) (GND 4,7)

(digital pins)

  1. Connect the power pins.
  2. Recheck all connections.
  3. Place the circuit at the back of the X and Z Axis Case for portability.
  4. Wire a relay driver circuit to Arduino pin 12 to control the laser.

Step 10: Ventilation Fan for the Stepper Drivers

The EasyDrivers can become quite hot during operation, so we need a way to cool them down.

  1. Take the back-plate cover of the CD-ROM casing and mark 6x6 holes equidistant according to the fan size.
  2. Drill out the holes.
  3. Sand off any metal burrs.
  4. Attach the fan to the metal case.
  5. This attachment will serve as a backplate for our CNC body.
  6. Wire the fan to appropriate 12V connections, then install the backplate onto the CNC body.

Step 11: Install the GRBL Library

Alright, now that we have the hands, feet, and the brain, let's infuse some soul! The next step is to flash the Arduino with the GRBL library.

  1. Download the GRBL library provided below.
  2. Extract and copy the entire folder to the Arduino main folder, for example: C:\Program Files (x86)\Arduino\libraries.
  3. Open the Arduino IDE and navigate to File >> Examples >> GRBL, then click GRBL.
  4. Click the Upload button to flash the library to the Arduino. Ensure your Arduino board is connected to the computer during this process.

Attachments

Step 12: Build the Laser Module

To assemble the laser module, we are going to create it from scratch. I've included a 3D CAD design to provide additional clarity.

There are two major steps involved:

  1. Extracting the Laser Diode from a DVD Writer. You will need a DVD Writer for this extraction; CD ROMs won't work.
  2. Carefully extract the laser diode from the sled of the DVD Rom.
  3. You can also salvage useful components from the track, such as a lens, which we will need for the housing we are constructing.

You should be able to extract the diode safely. Do not apply unnecessary pressure on the diode to avoid damage. Additionally, review laser safety instructions before proceeding to the next steps.

  1. Building the Housing and Driver:
  2. Take a small 6V DC motor extracted from the ROM.
  3. Disassemble and salvage the outer case of the motor.
  4. Use thermal paste to secure the laser diode; the motor case serves as a heat sink.
  5. Glue a lens from the sled to a washer and secure it to the motor casing using small screws and springs from a ballpoint pen.

For the laser driver, we use an LM317 to create a constant current ranging up to 350mA. Avoid exceeding the current supply beyond 400mA, as the diode lacks a good heat sink and may burn out if the current surpasses this limit.

Step 13: Laser Mounting

I mounted the laser on the Z-axis following these steps:

  1. I crafted an attachment for the Z-axis sled using a piece of flat metal shaped like a L.
  2. I secured the fixture in place using hot glue.
  3. Subsequently, I soldered a small hose clamp to the fixture, completing the installation.

Step 14: Laser Control Circuit

The laser control circuit is attached above. The first picture illustrates the relay control through Arduino.

The second picture shows the laser driver circuit. Connect the driver to the relay and power pins to control the laser.

Step 15: Laser Safety

The laser used in this project is a Class 3B laser, which can cause serious damage if misused or handled carelessly.

It's essential to understand and respect the power of a laser diode/beam. Even with a seemingly low power rating of 300mW, a laser can cause harm if not treated with caution. The laser has the potential to burn eyes, making protective eyewear a necessity.

Class 3B lasers are hazardous if the eyes are exposed directly. While diffuse reflections, such as those from paper or matte surfaces, are generally not harmful, direct viewing of the laser beam requires protective eyewear. Class 3B lasers are equipped with a key switch and a safety interlock. It's crucial to use safety goggles to shield yourself from laser radiation.

Step 16: Building the Housing

To achieve a professional appearance and add protection from laser beams, I built a wooden cabinet to house the CNC machine. Precise measurements of the CNC dimensions were taken to construct a wooden box. The design of the cabinet incorporates a charming curved aesthetic, combining functionality with visual appeal.

The 3D design of the cabinet


Step 17: Ventilation Fan

To maintain a cool environment inside the cabinet, a ventilation fan needs to be added.

  1. Mark the locations for the holes on the cabinet.
  2. Drill the marked positions using a 6mm bit.
  3. Attach a 230V mini exhaust fan to the drilled holes.

Step 18: Some Leatherwork

To enhance the cabinet's aesthetics, a touch of leather will be added.

  1. Cut the leather to the appropriate dimensions.
  2. Apply synthetic rubber (SR) adhesive to all leather pieces and affix them to the body.
  3. Once the adhesive has dried, create holes in the leather for the ventilation fan.

Tip: Ensure clean cuts for an appealing final look. Utilize your creativity, be patient, and take your time. Things may get messy, but the end result is worth it.

Note to use the glue in a well-ventilated area as the fumes from the drying SR glue can cause nausea and headaches.

Step 19: Power Supply

Steps to add power source:

  1. Thread a power cable through the hole.
  2. Connect the power cable's terminals to the power supply by screwing them on.
  3. Power the 230V fan using the same line.

NOTE: Exercise caution when wiring the polarity of the drivers, as the EasyDriver lacks reverse protection.

Step 20: The Early Failures

I embarked on this project with the intention of creating a pen plotter or a "draw-bot" capable of drawing with a pen. After finalizing my model, the initial trials yielded strange images, with circles resembling stairs! Extensive troubleshooting led me to discover that updating the GRBL Library resolved this issue.

As my interest grew, I decided to incorporate a laser for engraving. Research revealed that a burning laser could be crafted from an old DVD writer. However, extracting a working diode proved challenging—I had to open up FIVE DVD Writers before finding a functional diode.

Focusing the laser presented another challenge, compounded by my limited optical resources. Additionally, the laser's heat posed a risk of melting standard adhesives used to secure the lens. To address this, I extracted a lens from a DVD sled, employed heat-resistant adhesive, and successfully achieved focus.

Step 21: Final Results

I etched the Instructables logo onto a piece of wood to show off Mr Engraver's capabilities. The details it can capture are truly inspiring given it was built using recycled materials. This machine, despite its limitations with a work area of 38mm x 38mm, opens up endless possibilities. It serves as an entry-level exploration into the world of CNCs, making the project both enjoyable and enlightening for anyone seeking a glimpse into this fascinating realm.

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