So recently I got a paid commission.  A Facebook acquaintance of my wife's needed a quick bunch of balloons cut out of plywood for a party.  It was a rush job that I put together in one day, and I ended up putting a few hours on it as well as using a full sheet of wood so I charged $30.  If it was a repeat cut that I could take a few days on I would have charged $20.

Between that job and all my cardboard elephant cutouts I have been pushing the laser extra hard recently.  For starters it is 110 F in my garage, and that is making it difficult for the laser to stay cool.  I'm only running it at 80% power, but the housing is hot to the touch.  I can still hold my finger on it, but it is uncomfortable and probably too high if I want my diode to last a long time.

Another issue is my on going struggle to get Lightburn to work well with my grbl controller.  I can't tell you how frustrating this is. Every other sender is happy to work in a virtual coordinate mode as well as an absolute mode with a properly homed system.  Lightburn on the other hand is overly picky and that makes this a really frustrating experience.  

• First, for some reason, they insist on only using a positive coordinate system, that is that 0,0 is the lower left corner of the machine. You can actually tell it that 0,0 is the upper right corner of the machine, but then they insist on inverting the direction your axis move.  That does not even make sense, who sets there machine up backwards?  Homing on the upper right corner is the norm for half the machines that lightburn runs on. On top of this, you can read the coordinate system out of the controller, so we should not even need to tell lightburn how the machine is setup.
• Next they insist on having soft workspace limits, even if the machine is not homed (or can not be homed).  So you have to input the max coordinates of the machine, but when lightburn starts up 0,0 is set randomly based on how the machine was powered on, making this hard limit totally pointless.  Other senders take care of this by leaving the machine in a locked state, and letting you either manually unlock it, jog to 0,0 and reset the coordinates, or by forcing you to home.  Lightburns official recommendation is to manually move the laser to 0,0 and restart the machine and lightburn.
• Finally jogging is annoying at best.  Often times I turn on the machine and can only jog in one direction.  Or even worse the machine will move backwards!  That forces me to shut down lightburn and use UGS to jog the machine to a better spot then start lightburn back up again.  And with continuous jog mode enabled you can't adjust the z height of the laser, why I don't know.

The recommended solution is to home the machine and mess with the coordinate system to force it into a positive workspace.  Previously I had made a macro to do this, but it still trips you up if you forget to home the machine, or if the moon is in retrograde and so on.

This is my 3rd (5th?) attempt to fix this.  I reset all of Lightburn settings back to there defaults and made a new macro that not only resets the coordinates, but homes the machine and then moves the laser to 0,0 in preparation of the first cut.  Since I have my new laser bed with a fixed edge that is very reliable I can set this up with some precision.  I ended up switching the laser to absolute coordinates at the same time.  That makes 0,0 be the farthest lower left corner of the machine no matter where I place the part on the lightburn workspace. Hopefully that will reduce instances of the cut start point moving around at random on the machine.

$32=1 ; turn on laser mode
$10=0 ; set coordinates to work position mode (virtual coordinates)
$H ; Home the machine
G10 L2 P1 X-340 Y-433 ; set work offset to -340,-433 or lower left corner
G90 X0 Y0 ; fast move to 0,0 position

Above is my macro, with comments.  I'm not sure that lightburn can handle comments, you may need to strip those out if you use this. And be sure to home the machine using UGS and then jogging over to your lower left (safe) edge to get the -x,-y values, don't use mine or you will most likely crash.

This seems to be working ok, now that homing is built into the macro it is more difficult to mess things up.  However there are still issues, for example if I move a design off the lower left corner of the workspace even by a fraction of a mm then the whole object won't be cut.  Yet Lightburn won't prevent me from moving off the corner, or snap to the corner properly either, and I only get a hint about the problem when I go to engrave, rather than having the object blink or turn red.

Hopefully this helps in the long run, but I find it very frustrating that I have to keep messing with this and there are no aids to help get it going.  I don't see how most CNC users manage to get Lightburn to work safely out of the box.  Especially when tools like  UGS seem to get it right the first time straight out of the box.  There doing things in the name of safety, but I never have UGS shoot off in a random direction while Lightburn has crashed into the side of my machine several times for no apparent reason.