Hi all. My first post here. I came across LW while searching for a solution to cut and raster engrave using one software solution. I built a laser engraver from the 3dpBurner engraver design. I have a 3.5w 245nm laser that runs on GRBL. I’ve upgraded and configured GRBL 1.1e for my setup. I am really digging LW3. It seems to be the perfect solution for my needs. Thanks to the developers!!! And I see here that LW4 is in the works. I’m pretty excited about finding LW. I have one issue that maybe someone can help me with. LW works great as long as I don’t home the machine twice. If I try to home more than once, GRBL seems to lock up and won’t respond to anything unless I disconnect and reconnect. I’ve tried sending the unlock command and home commands via the terminal, but GRBL just does nothing. There’s no alarm or error code that GRBL sends when this happens. Only after the very first home I get an alarm 6, which doesn’t really make sense to me. Maybe I have a firmware setting screwed up? It will engrave fine as long as I send the gcode after the first home. I appreciate any help! Thank you. I attached a photo of my machine for no good reason 
Thanks for the comment. I checked the terminal and after the second home button click, all data that is coming through the terminal stops as if GRBL freezes. Only a power reset or unplugging the USB will reset it. Maybe a setting I have screwed up in GRBL 1.1e or a firmware issue. I’ll run through my firmware settings again. Thanks for the help.
Also worth noting, I tried a different GRBL controller and the same issue is present.
Peter, nope genuine Arduino Uno.
I could try another Uno I suppose. Thing is, when I flash back to GRBL 0.9, it works fine. Of course that’s not compatible with LW though. I really like LW so I’m going to keep pressing at this issue until I get it resolved and can use LW with a normal workflow.
Thanks Peter.
I’m sorry for the delay. I was the whole day with a customer. I will check uf the lock is caused by LW or Grbl. If Grbl, i’ll open an issue there, if LW I could probably solve directly 
Claudio, I don’t think it is LW issue as I get the same issue with different GRBL controllers. Thanks.
Did you read the details about homing on Grbl Wiki? (https://github.com/gnea/grbl/wiki/Grbl-v1.1-Configuration#22---homing-cycle-boolean)
Claudio, I have. I will have more time this weekend to run through my settings again. I could probably take a video of the issue I am encountering. One question: in config.h the comments for the Z axis homing says “REQUIRED” (//#define HOMING_CYCLE_0 (1<<Z_AXIS) // REQUIRED: First move Z to clear workspace.). I have the Z axis commented out and have only this line for homing #define HOMING_CYCLE_0 ((1<<X_AXIS)|(1<<Y_AXIS)).
Found that my Arduino is the issue. I didn’t have an extra Uno, so I wired up a nano to the GRBL CNC Shield and it worked fine for a while. Then I found that it was freezing up at random points while running gcode. Thanks to Peter for mentioning the CH340 issue, because I’m pretty sure that is the issue now with the Nano. I have an Uno in the mail that should be here today and my issues should all be resolved! Thanks for all of your help. Wish I knew what happened to the original Uno. I tried re-flashing the firmware to the atmega 8u2 USB chip but that didn’t work either.
Well, I am at a loss. New Uno was working great. I did a bunch of test runs. I decided to change the axis direction and homing cycle direction to reflect the view in LW. Immediately after changing $3=3 and $23=3, the same issue I had before started happening immediately. I just don’t get it. I changed the values back, but the problem is still there now. Previous settings for $3 and $23 are $3=1 and $23=1. Any thoughts? It was working for a good couple hours perfectly until I changed those values and now it freezes the arduino every time i home. I appreciate any input you all can provide.
So the easy fix I guess is to disable homing. No issues after I do that.
I have tested homeing over the weekend and it’s working on my machine, but it’s not so easy to configure because the informations are spread over multiple places. I will talk to @Sonny_Jeon about that, so he could extend his documents.
Homing on Grbl is a little different than what common on 3d printers and laser cutters, but it’s similar to how production CNC milling machines are instead. See (Frequently Asked Questions · gnea/grbl Wiki · GitHub). I think this issue is related to how Grbl homes and what LW3 expects. Not particular to Grbl itself. I haven’t heard of any homing lockup issues. This theory can be checked by using something like UGS and home there. It should work fine.
Remember that $3 and $23 don’t alter where the machine origin or [0,0,0] is set. IF you change $3, your axes will be backwards. If you change $23, it’ll still set the origin in the back-right-top corner of your machine. If you want to have it home and set the origin in the front-left-bottom corner, you’ll need to enable the HOMING_FORCE_ORIGIN config.h option and re-upload Grbl.
Thank you @Sonny_Jeon . That’s what I have done to get mine working. You could probably add some hints on the wiki and http://settings.md for the needed changes of config.h (or a link to the faq’s you posted).
I don’t see any issue with homing in LW3 if correctly set up in Grbl, as we only send $H and use work coordinates by default. I have configured it with home switches in negative direction, but it should work as good with switches im positive direction (default in Grbl) and a corresponding G10L2.
@Arion_McCartney Can you post your ‘$$’ Grbl settings and your $I build info on a Grbl issues thread? Also, detail your limit switch setup and whether or not you altered the homing cycle (for example, 2-axis machines need a config.h alteration). I’d like to make sure there is nothing funky going on.
Thank you for all of the response. I’ll post my $$ settings as soon as I return home. Things I have done are try a different GRBL controller, but same issue is there also. Doesn’t matter how many times I reflash grbl to the Uno, the issue has not gone away. The only thing I don’t get is why it works just fine on a new Uno, but once I changed those settings the issue shows up and does not go away even after reverting back to the old settings and after reflashing. I will also try to take a video of the issue with a working Uno and replicate the issue if that would help.
$$ Settings:
: $0=10
: $1=255
: $2=0
: $3=3
: $4=0
: $5=0
: $6=0
: $10=6
: $11=0.020
: $12=0.010
: $13=0
: $20=0
: $21=0
: $22=1
: $23=3
: $24=200.000
: $25=4000.000
: $26=0
: $27=0.000
: $30=255
: $31=0
: $32=1
: $100=200.000
: $101=200.000
: $102=0.001
: $110=12000.000
: $111=12000.000
: $112=12000.000
: $120=1000.000
: $121=1000.000
: $122=12000.000
: $130=315.000
: $131=400.000
: $132=10000.000