Category Archives: 3D Printing

JTech 2.8W Laser Upgrade Kit Part 3

Simply reflashing the smoothieboard with the latest firmware caused the PWM to start working correctly. Quite an anticlimactic result considering i picked up a new Rigol scope to troubleshoot the issue!

As seen, a 0-100% duty cycle reflected correctly on both the scope and the observed intensity of the laser.


Here’s a quick video of the kit cutting up some dense 1/2″ open cell foam.

I am still trial-and-erroring the focal depth of the laser. Right now it takes 5-6 passes to cut all the way through the foam. It starts around 12mm off the bed and moves down 1mm per layer. This is pretty dense foam though.

For basic shapes like circles for these marbles I’m simply creating a cylinder in Google Sketchup, exporting it to cura, generating the gcode, and then manually editing the gcode in Notepad++.

Here are some of the results:


JTech 2.8W Laser Upgrade Kit Part 2

I created a simple mount for getting the laser attached to the Rostock Max V2 effector by modifying another mount I found online. two bolts and nuts hold the heat sink to the effector. I used the default aluminum standoffs from the original Rostock effector.

Documentation for configuring the Smoothieboard to work with a laser is available on their site.

I attached the signal wires to the 2.4 pins on the smoothieboard through the small MOSFET plug. I configured the board as follows:

# Laser module configuration
laser_module_enable                          true            # Whether to activate the laser module at all. All configuration is
                                                             # ignored if false.
laser_module_pin                             2.4             # this pin will be PWMed to control the laser. Only P2.0 - P2.5
                                                             # can be used since laser requires hardware PWM
laser_module_max_power                       1               # this is the maximum duty cycle that will be applied to the laser
laser_module_tickle_power                    0.0             # this duty cycle will be used for travel moves to keep the laser
                                                             # active without actually burning
laser_module_pwm_period                      200             # this sets the pwm frequency as the period in microseconds

Executing some laser moves showed preliminary success. I couldn’t get a PWM signal less than 100% to get the laser to activate though. After some IRC conversations I moved the signal wires to the 2.4 pin on the board instead of the MOSFET in an attempt to get a regular 3.3V signal to the laser driver. Since the laser driver supplies its own power to the laser there isn’t a need for an “amped up” signal. Unfortunately the problem persisted. I will need to check the signal getting sent from the Smoothieboard to the laser driver to continue diagnosis.

It will be a few days before my new oscilloscope arrives, so in the mean time I have gotten to calibrating the laser with the smoothieboard. I found a few sample DXF files online that I plugged into Sketchup, converted to STLs and put through Cura.

Here are some of the results using a 0.2mm “nozzle”, shell thickness at 0.2mm, and 100% infill.

I noticed some “delta arm blues” symptoms with the infill not making it all the way to the edge of the print. I rotated the model 90 degree and printed it again. The infill was not the same, meaning the STL and gcode weren’t at fault. At first glance it looked like there was an issue with the X axis belts. I went around and tightened everything up, still the same result.


Looking at the arc around the wolf the line the infill makes is too “perfect”, I think this is not necessarily a hardware issue.


If you look closely at the top arch of this trial you can see different shades of laser. I changed the speed of the print several times during the arch. The curve the infill made stayed the same, making me further believe this isn’t a hardware issue. Slower speeds should result in less of an effect due to the effector not moving as quickly.


Getting closer with every print :), stay tuned for part 3.