Laser Engraver

Years ago I made a laser-cut puzzle as a Christmas gift, and I’ve dreamed of having a desktop Dremel or cutter of some sort, in contrast to a 3d printer that builds by layers. Now, I finally got my hands on one, and here is a brief writeup about the process of bringing my baby laser engraver online.

THE MACHINE

The engraver is made by a Taiwanese maker called EleksMaker A3 Pro, equipped with a 2.5W, 445 nm laser. The total engraving area is about 50mm by 50mm.

THE PROCESS

It took me roughly 3 hour-long sessions to get it up running. As there are plenty of instructions to be found online, I will only talk about the challenges, failures and what works in the end.

1.ASSEMBLY

The 1st session was assembly, probably the easiest of all three sessions. putting the parts together. The only challenge was figuring out how to tighten the belt as it uses an unusual belt construct. Unlike the 3d printer where the belts loop around, here the belt is about the length of the axis, tighten by physically holding down the two ends with screws and acrylic block. Unusual, but uses less belt, so not a bad design.

2. SOFTWARE

The 2nd session was software installation and getting the system up running, where I probably spent the most time. There are 3 things are essential to get the machine up running: 1) driver for the microcontroller likely a nano, so the controller is seen by the PC or MAC, 2) firmware for the software to talk to the controller, and 3) pin assignment or software setting to control the motor and the laser.

• The working driver I end up using is CH341SER.inf, if you need to google. Once the driver is installed, the driver manager (on windows) and query
  “ls /dev/*usb*” (on mac) will show the controller on a serial port.
• The working firmware is a .hex file… you need to flash the driver so the software can connect to the controller
• Lastly is the parameter setting. This I will spend more time fine-tune in the 3rd session. But for starters, the laser is connected on pin 11, and

Now onto the software, the recommended software is EleksCAM available on windows. Being a mac user, my 1st attempt, of course, was to look for mac alternative. EleksCAM software allows the user to both import an image and to control the laser, so to find a replacement, I’ll need separate software to perform each step.

2a. MAC

The drawing step is easy. Inkscape does the job, although it’s a bit jaggy to run, and buggy when an external display is connected. However, it is nice that Inkscape has several plug-ins, e.g. inkcut (pip3), jtech photonics, and gcode export (sp). The last of the three works the best — note that I still need to know the control pin in order to get it to work.

To send the gcode, I wasn’t so lucky. I can see the serial port as /dev/tty.usbserial-1420, made working by installing the .exe driver using winehq. However for the life of me, I can't get the two things to talk to each other — I suspect later that I lack the firmware. I tried minicom, and screen, neither worked. Then I remember Cura also allows sending gcode, and that was a failure. After much frustration, I powered up a good old windows machine.

2b. Windows

I first installed eleksCAM but encountered lots of missing dll. After some research, I found its ancestry was BenBox, which perform essentially the same function: importing images and controlling the stage / the laser. BenBox gives an end to my struggle with the software.

Before fully committing to BenBox, I also tried to draw in inkscape (on windows it runs much smoother) and export the gcode using the plugins and send the gcode through BenBox, but the scale is off by ~1.5x.

Another wonderful thing with BenBox is that I was able to test all parameter settings and pin assignment. In the first laser power-up, I overestimated the power of cardboard box, and I burned through the test card and then the cardboard and left a small burn mark on my desk. After, I salvaged my old bookshelf divide and used it as the substrate to protect the desk.

The final working protocol goes like this:

• draw in Inkscape and export it png (300 dpi)
• convert png to jpg (or bmp, tbc)
• open jpg in BenBox

3. TUNING

The 3rd session was laser power testing. To control the burning there are a few different ways: 1) absolute laser intensity, 2) laser head moving speed (mm/min in BenBox or mm/s), 3) pulse width, 4) the number of passes. This session wasn’t bad, as it is more methodical than complex — it reminded me of the grad school years, coming up experiments, making observations, validating hypothesis, and drawing conclusions.

FUTURE WORK

a few things are on my mind:

• given the amount of fume the engraver generates, the most immediate thing I want to do is to build an enclosure with a fan and extend the exhaust to outside
• engraving is cool, but cutting is way cooler! I’m thinking relief with parts engraved and parts cut out. I experimented a bit, but yet to find the right parameter setting for cutting yet.
• making large engraved artwork — not sure about the practicality because laser is great for making small features
• making a 3d sculpt out of 2d cuts
• and more…

So much for this post. Let the burn start!