@Andy_Shilling yes that’s definitely worth a try. Installing CNCjs is dead simple. It’s an executable that does the install. In the black command area, you can issue gcode commands and it’s a great debugging tool.
For example
$H ; home
G1 x20 y20 F800 ; goto 20,20 at a speed of 800
M4 ; turn on the laser
G1 x40, y20 F800 S255 ; goto 40, 20 at 800, with a laser power of 255
M5 ; turn off
$H ; Home
Alternatively you can use S0 as laser power zero to turn off the laser, it’s not actually turning of but makes it safe that there is no laser beam (since it’s infra and you cannot see it. BTW you can use you mobile phone camera to see the laser beam!)
@Paul_de_Groot Ive just swapped over the sheilds and nothing has changed but what I have now realised is I don’t thinkit is the sheild or R4, I have run a couple of test jobs and it seems the only time the laser stays turned on is if the job doesn’t complete.
If I abort the job the Laser will continue to fire but if I let it finish it does in deed turn it off, would that be a grbl issue or a LW one?
Hi Andy I have never encountered such an issue with the board myself. If you can run that same gcode via CNCjs, does it do the same? You can check the gcode in a non run execution mode with gerbil. Issue a C command and then run the gcode. Gerbil will report back whether it encountered an invalid gcode. Let me know your findings. I am curious about it.
@Paul_de_Groot Both LW and CNCJS run the code fine to completion turning the laser off, but neither of them will kill the laser once I have aborted the job. Here is a link to the G-code file I was using, created in LW. It’s just a greyscale eye.
https://drive.google.com/open?id=1LnGUACzNvayv-ECrJ3mdyc9O_5VuEk_x
Here’s a random thought, If i abort a job the laser remains on and I have to disconnect and reconnect the control but if I send M3 from the console within LW after aborting the job it will turn the laser off.
It’s as though there isn’t a link in the LW code to turn the laser off when aborting a job. Should I raise this issue in the LW community to see if anybody else has had this problem?
@Andy_Shilling M3 is actually reversing the spindle which translate in turning off. Ideally you should use M5. Did you try to run the gcode in non-execution / check mode? I am stuck here and scratching my head. I would suggest raising it on the awesome.tech k40 forum to see whether someone has encountered the same issue and maybe they figured out how to make that work. It almost sounds like the Laser On relay on the k40 shield is sticking. Did you try the other shield from your daughter? Does it do the same?
@Paul_de_Groot I have tried both Shields and it happens with both, I have also tried M5 in the g code settings within LW and in the command console and this does nothing. The only way to stop the laser is to complete the job, disconnect and reconnect or run M3 within the console.
How do I run in non-execution mode? I take it that’s in cncjs, until you told me about that program I had never heard of it so I don’t know my way around it, sorry.
I will get on the forum either tomorrow or Sunday when I get time and see what we can come up with.
@Andy_Shilling yes it is in cncjs, where you issue a $C via the command line. Then run the gcode via the run button and gerbil checks the gcode and post back the results. See my wiki https://github.com/paulusjacobus/grbl/wiki/Configuring-Gerbil-Grbl-v1.1e or issue a $ and it returns the available commands.
@Paul_de_Groot Well what can I say, after getting no where with this bloody thing and no response on the forum I decided on a drastic coarse of action last night.
I removed every wire from every possible switch, plug and port I could and replaced the whole lot checking every connection. I also removed and reloaded LW on my pc and …
I now have a working K40 laser running on GERBIL. I have no idea what the problem was and what actually fixed it but with the first results I am very happy.i will keep you updated as I continue to play.
Hi @Andy_Shilling sometimes it can be just a bad connection or just interference between wires and powersupply. Remember this is the cheapest laser on the market. Some machines are very well put together and others never get to work well. Someone called it a clever design but assembled by monkeys😂
@Paul_de_Groot I hear you but you doubt yourself when you’ve already rewired and upgraded the hell out of it lol.
@Andy_Shilling so true. My machine is pretty good from start. But i have seen machines that were deadly and sloppy… considering to develop an entire machine as a new product, so I don’t have to support k40 engineering faults like bad psu’s and skewed xy frames. K40 does not pay me but I’m doing their support 
@Paul_de_Groot to true, where else can you build a machine and say we’ve done nothing about safety or training but we’ll let thousands of you loose with a potential lethal weapon. 
I think I need to do some more testing as I have been running a few files and it seems something is wrong on one of the motions. When I cut a circle it doesn’t join up, on the return it ends up a couple of mm out.
@Andy_Shilling that’s typical symptom for a skewed frame or loose belts. Or in the cutting plugin, a delay has been set in the user interface. Set this to zero. Can you post a photo of this misalignment?
@Paul_de_Groot sorry I’ve not got back to you I have been away, I have done a little testing with the circles but last night my 6 month old psu died on me. I’m not having much luck with this thing at the moment.
From the few tests I managed to run I am not convinced either way where the problem lies but I can not do any more until I rewire the old psu back in or get the supplier to cough up on a replacement.
Once I’m back up and running either way I will get back in contact. Thanks for the replacement board that is sat here on stand by should the need be there ( hopefully not).
No worries, I am traveling at the moment and will be back on the 9th of June😁