Trouble Calibrating 3.8w Laser

[picengravertoo]

The Variable Feed Rate profile is for lasers that are CW (Constant Wattage), not Varied Intensity. With the 3.8W J-Tech, you should be using the Analog/PWM profile instead and be moving very fast depending on the material being engraved. The Min Laser Value should be 0-10, Max 255 and a Feedrate 120-150IPM to start. There again, this is based on the material your engraving on. 45D engraving angle works the best
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I’m not sure what your referring with the F60 and the J-Tech grbl. There is some recommendations on the grbl settings changes to make with the J-Tech grbl 9g here:

Where is the laser engraving category?

I don’t have a spindle on our Shapeoko, only a laser, but I do test different versions of grbl back and forth quite extensively with PicSender. You can switch to the grbl 9j for your spindle or vector laser gcode files, then switch to the J-Tech PWM grbl for raster laser engraving. After connecting to the com port in PicSender, select the yellow GRBL button, then Display Settings, then Save. Name the file something like X-Carve GRBL 9j. Return to the main screen, select Close, not Exit. Open …

There is allot of other good information in that thread to get you up to speed for laser engraving photos with your J-Tech Laser & PicEngrave Pro 5.