Benbox Laser Machines/CO2 Lasers/3D Printers

Zax posts a current version of GRBL firmware configured for a typical laser etching machine. If you don't know it, GRBL is a GCODE interpreter designed to run on a 328 CPU. It has some non-standard options (mostly run-time configuration) but provides a reliable, well behaved, solid opensource platform for diode laser operations. Both BLT & T2  work seamlessly with it.

If you have 2 motors on the Y and 1 on the X axis you need approximately twice the current on the Y. Try setting the X to 0.4 and the Y to 0.8. Test and adjust as necessary.

I'm going to go with power supply problem. Looking at the picture the X and Y start and end look correct.

The addiction has taken over!!!!!

Is your post two pictures of the same etching or did it behave the same on separate burns?v Is the finished height correct?


The list of possible causes is quite long:
  Host OS
  USB
  Software
  Firmware
  Power Supply
  Bad wiring
  Diode module
  Belts
  Wheels
  Rails
  Misaligned carriages
  Phase of the moon

I think I have experienced most of the above since I started etching about 3 years ago. The hardest to find was the misaligned carriage. Had one wheel spacer wrong.

I would start by getting or generating some test patterns of similar size. A simple vector style X/Y cross hatch in gcode would be a small file and would test the rails, wheels, and belts without and host application. Then I would convert that that to a raster image file and try again with T2, There have been a number of test patterns posted on this forum. If you need/want help just ask.

Colored cardstock is a great test medium. Cheap and burns with low intensity. I use both 4x6 inch index cards and 8.5x11 inch sheets, Available in almost very stationary or craft store. I also have a stack of scrap cardboard just for this purpose.

They should not change the intensity. What they do is keep the laser OFF until the CPU has initialized the interface which can take up to 2 seconds. The intensity is determined by the PWM (Pulse Width Modulation) HIGH time relative to its duty cycle. If the duty cycle is 1000 usec and the pulse width is 250 usec you have approximately 25% power. It is not linear and the effective burn is very much dependent on the medium, focus, and speed. GRBL typically uses a value of 0 thru 255 and in firmware scales it to the configured range.

That opens another possibility. Use the 3-pin headed for connection to the controller and solder the resistor to a 2-pin connector and insert in the 2-pin header. Sad situation where the manufacturers overlook a $0.02US solution.

This is a well known problem. The laser ON state is active HIGH and the PWM line floats high without an active drive. Solutions is to add a pull-down resistor between the PWM and GND. I use 3.3K but almost anything between 1K & 10K should work. You can solder the resistor on the laser module, on the controller, or on the cable. I prefer the the laser module as then it is protected if the PWM is disconnected. Advantage to putting it on the controller is you can reliably swap laser modules. Perhaps adding  4.7K to both the controller and the diode is best.