If you are getting tired of measuring -62mm before you start you laser engraving job then this is for you.

It's a simple guide that you stick (with double stick tape or glue) to the top of the laser shield on the right side. The pointer on the end of the guide will show you where 0,0 on your print job will be, just manually move the head with the power off and position the arrow over the lower left of your work piece. That's it!

For extra simplification of the engraving process, modify the firmware to remove the software endstop minimum for the Z axis:

// Min software endstops constrain movement within minimum coordinate bounds

define MIN_SOFTWARE_ENDSTOPS

if ENABLED(MIN_SOFTWARE_ENDSTOPS)

define MIN_SOFTWARE_ENDSTOP_X

define MIN_SOFTWARE_ENDSTOP_Y

//#define MIN_SOFTWARE_ENDSTOP_Z <----- comment out this line

define MIN_SOFTWARE_ENDSTOP_I

define MIN_SOFTWARE_ENDSTOP_J

define MIN_SOFTWARE_ENDSTOP_K

endif

Recompile and install the firmware.

Using a serial cable and a control program (like Pronterface or Octoprint) you can now position the Z axis wherever you want WITHOUT having to rehome the printer. Once you get it set to the proper height power the printer off. (If it stays on unplug the serial cable).

While the power is off move the head into your start position. Power the printer back on and start your job.

If you like this method it will save a lot of cable plugging if you cut the power lead so it can't power the motherboard from the USB cable. On the Raspberry Pi you can do this by picking a USB port and snipping the rightmost wire looking in from the back of the socket. Or you can pick a dedicated USB cable and find the power wire and cut it - it's usually red but check to make sure.

You may have to adjust the Y axis length a bit to compensate for your filament and printer combination. Print one first and measure it, the tip should be 62 mm from the laser head. If you are using a foam based mounting tape don't forget to allow for it's thickness.