My board won't connect/ software says no firmware detected:

  • Do you see a drive show up in Computer?
  • What USB cable are you using? Is it the one that came with the K40?  Try another known working high quality one.
  • What can you find in Device Manager or in Devices and Printers?  Should be some entries for Smoothieboard, and there should be a COM Port with a #.  Make sure that's the same one that's select in software.


"My axis is skipping" or "the output looks nothing like what it should"

  • On the A4988 Stepper Driver module is a potentiometer.  By default the flat is facing outward, or to the top of the module.  With power off, ground yourself, and ideally using a ceramic screwdriver, adjust the potentiometer 45 - 90 degrees clockwise. Do this for whichever axis is experiencing stutter, or for both axes.  Do not turn the potentiometer past the flat facing right.  Note that with both pots at 90 degrees (facing right) we are now at around the current limit that the k40 power supply can provide, so be careful and start at 45 degrees. 


"My pwm isn't working" or "I'm trying to do something with various % laser power and the grayscale output all looks the same"

  • Every laser is different and it is important to tune your PWM.  
  • Set pot to 10mA. Then run G1 X10 S0.4 F600 line in Console.  Vary the X value - new target coordinate and S value - power level between 0 and 1.  Each time, your head should move while firing.  
  • Here is an example set of commands you can run that will move the head and fire at a number of power levels. 
  • G21
G0 X0 Z0
G0 X0 Y10
G1 X10 S0.1 F600
G0 X0 Y15
G1 X10 S0.2 F600
G0 X0 Y20
G1 X10 S0.3 F600
G0 X0 Y25
G1 X10 S0.4 F600
G0 X0 Y30
G1 X10 S0.5 F600
G0 X0 Y35
G1 X10 S0.6 F600
G0 X0 Y40
G1 X10 S0.7 F600
G0 X0 Y45
G1 X10 S0.8 F600
G0 X0 Y50
G1 X10 S0.9 F600
G0 X0 Y55
G1 X10 S1 F600
G0 X0 Y0 Z0
  • You may be able to see different amounts of burn, but you should definitely see the mA gauge needle go to a somewhat different value each time.  For example, S1 is 100% and with the pot at 10mA, I would expect to see the needle close to 10mA.  S0.4 is 40% and I would expect to see the needle somwhere around 4mA.  Laser power is not linear, so it won't be exact, but you should be in roughly this range. 
  • If your laser is not behaving as expected (a common occurrence would be it is firing at full power regardless of the S value) try tuning the PWM period in the config file on the MicroSD Card in the Cohesion3D Mini.  The default value for the pwm period is 200 and this works for quite a few machines. However, you may need to set it to 400 for your machine to start responding to pwm and outputting proper "gray" burns:
    laser_module_pwm_period                       200


  • After you have changed the 200 to 400, you must save the config file, close it, safely eject the drive in Computer (another term for this is unmount) and reset the Cohesion3D Mini using the small yellow button on the top right corner of the board.
  • Repeat the burn lines procedure and observe whether the machine is now burning at the proper power levels.