Me and my son invented/developed a new concept of "On-The Fly" 8bit Laser Diode engraving photos over two years ago. With this concept, the Laser Diode never turns off through the whole photo engraving process. It just varies the power up and down to produce the image and shading on the engraved material. We have came a long way since those days at the beginning of our experimentation and here is the instructions of our latest build on a Shapeoko 2.
Photos can now be engraved on different materials using a variable intensity controlled Laser Diode to get 8bit shading. The materials we have tested successfully so far is, wood, white stained wood, white painted aluminum, mirrors, white leather and white Artist Canvas. White materials gives us the best 8bit shades of gray and on mirrors we actually get shades between white and silver or the reflection. The mirror also gives us a lithophane effect with some back lighting, but looks very good without back lighting as well.
The standard laser photo engraving process prior to our development was to TTL modulate (Pulse) the material with burnt spots/dots using a dithered black & white image to get the allusion of gray shades.
Commercial CO2 laser engraving machines are still are using this old school method today to engrave photos. Higher end CO2 engraving machines do use 256 (8bit) separate power levels to 3D engrave. With the excessive laser power of these machines, it's like a bull in a china shop to be able to implement our 8bit photo engraving process successfully like when using a considerably lower wattage Laser Diode.
Since our development of this concept, many hobbyist, makers and businesses has followed our progression and applied this very unique process on there own CNC machines to engrave 8bit grayscale images/photos using a Laser Diode. Two of them are presented here and here on Instructables, one very successful campaign on KickStarter, and manyhobbyist throughout the world that are using our very unique 8bit engraving process. More examples of our Laser Diode engravings can be seen here using this concept.
This method of varied intensity of a laser diode requires a proper "Image to Gcode" program, a Computer Numerical Controlled (CNC) machine, motor controller, MA3 Absolute Magnetic Shaft Encoder or a DAC, varied modulation laser diode driver and a Laser Diode in the 1W-5W range to do the 8bit shading on the materials. We prefer a 445nm wavelength Laser Diode and the one we used in this project has a max output power of 2.5W.
With the years of experimenting on different CNC machines with ball screws, linear ways, stepper & servo motors and controller software, we decided to experiment with a stepper belt drive Shapeoko 2 run by an Arduino UNO R3 this time.
We are the second owners of this Shapeoko 2 and our very good friend John Champlain purchased it new from inventables. This is the actual machine that he used for the development of our grbl related engraving software programs. John uses an electronic 8bit DAC circuit he designed and built for varying the modulation voltage to the laser diode driver for varied intensity Laser Diode control. His DAC takes the output of the step & direction ports from a breakout board or the pins on an Arduino UNO and converts it to a 0-5 DC voltage from axis movements in the Gcode and outputs it to the variable modulation input on the Laser driver.
John is the first to be successful using our varied Intensity controlled Laser Diode concept with grbl and an Arduino UNO. The Arduino UNO R3 that we are using on this build was purchased by John from Radio Shack and shipped to us for our testing and experimentation.
We used the stock 3 axis v5 grbl shield that came with the Shapeoko 2, the UNO is flashed with grbl 9g, our Image to Gcode raster engraving program PicLaser Lite, our PicEdit Lite image editing program and our PicSender program to handle streaming the large raster gcode files to the Arduino & grbl. We also use our PicSet program to quickly change to different grbl settings depending on what type of Laser Diode photo engraving we are performing.
These four outstanding software programs were written by our very good friend, John Champlain for the Arduino grbl controlled CNC engraving machines and PicLaser Lite has the option to generate Gcode for other CNC controllers as well. John is also the author of our full featured "Image to Gcode" program PicEngrave Pro 5 + Laser.
We are really surprised of the performance and excellent results we are able to achieved with our Laser Diode photo engraving experimentation using the Shapeoko 2 controlled by an Arduino UNO.
Some modifications to the Shapeoko 2 and allot of experimenting with the settings was needed to get everything tuned in just right and here is our instructions how we were able to achieved success. We prefer to use the "Standard grbl 9g" as there are so many variations/branches of grbl out there that may not work as successfully for this application.
A special thank you goes out to Sonny Jeon (chamnit) also for his dedication and excellent work on grbl to make this all possible controlling our Shapeoko 2 CNC machine smoothly. We use the X-Loader for flashing his grbl 9g to the Arduino UNO.
After we finished this project, we have changed our Shapeoko 2 over to a J-Tech Photonics Laser System and started using Andy's PWM LaserMode grbl to control it and we are getting excellent results. Details of it can be seen here..
As a machinist for 40 years now, clamping materials in machines comes natural for me. The MDF board table that comes stock was just not to my liking, so a new table was needed with a way to clamp my engraving materials in place precisely.
We found McMaster Carr sells aluminum T-slot track for a .250" (6.35mm) bolt, so I calculated how many we would need to cover the travel of the Shapeoko with 1" spacers in-between them. Nine was what we needed with the 12" (305mm) travel of the X axis. The lengths are 24" (609.6mm) long and sticking out the front and back, but this was not a problem.
The 20mm (.7874") square aluminum extrusion framing on the Shapeoko 2 for the original MDF bed had slots on all four sides. I needed only 2 slots 180 degrees from each other and the other two sides without slots to screw the T-Slot track down to. McMaster Carr also sells this 20mm (.7874") framing just as I needed. So we could attach these on the end plates for the Y axis MakerSlide supports and to tie the center of the table together. We ordered 3 of them 24" (609.6mm) long. Again, these being longer then the original ones, sticking out the sides further did not effect anything. No cutting to a shorter length was necessary. The McMaster Carr part number for the T-Slot track is 1850A14 and the 20mm (609.6mm) square framing is 5537T117.
The spacers we used in-between the T-Slot track is .500" (12.7mm) square aluminum tubing and we used two between each T-Slot track. We had that in stock here at our shop leftover from a previous job and just cut them to the same 24" (609.6mm) length.
To tie all these table parts together, it took some calculating and drilling holes in the T-Slot track & 20mm (.7874") framing for #8 Pan head sheet metal screws. I included a drawing with these general dimensions. The Shapeoko's dimensions between end plates may vary slightly, so some dimensional adjustments may be required.
We ran all the screws in loosely, then used a bar clamp to tighten all the T-Slot track and spacers up tight and made sure everything was square and flush then tightened up all the #8 screws.
As shown in the picture, two pieces of aluminum stock was added for the material starting reference place and to insure the material would be square in the Shapeoko. We added a Shop Fox Cam Clamp to hold the material in place and it's placement is adjustable in the T-Slot Tracks.
Safety is number one priority for everyone here including our pets, so we added a Laser light shield to the Shapeoko 2 and mounted them with L brackets from our local hardware store.