A laser line of 1.1mm is way wider than I would expect. My laser has a kerf of about 0.2 mm for cutting, and I would expect your laser (since it only has one diode) to be tighter than that.
Air assist… can you have too much air?
For engraving, you don’t need much air. You are only trying to keep the smoke away from your stock and your lens. Air assist provides additional benefits when cutting by blowing out the charred material so the laser can get to fresh wood. For cutting, too much air means that pieces cut out can be blown out of their “socket,” potentially getting in the way of the laser or even stopping the laser. I’ve had both happen to me.
I really struggled with figuring out the focus distance for my laser module. The best method I found (for me) was:
Tape a piece of black poster board to a horizontal on/near my machine
Remove the laser from the mount and set it on the spoilboard pointing at the poster board.
Turn the laser on to a low setting.
Move the laser forward and backward looking for the smallest spot and when I saw a bit of burning.
Measure the distance. I repeated this a few times, and the measurements were within .5mm of each other.
I hesitate to own up, but with the laser set low (1 or 2 out of 255), and pointing at a black surface, I made the determination without my glasses on. Normally, I’m obsessive about wearing my laser glasses, but I just could not tell the size or the charring with them on. To get just a bit of charring, you will likely have to go to a higher setting than 1 or 2, given your laser is half the power of mine.
Since you now have Lightburn, you can run some engraving tests. There are multiple YouTube videos on how to set them up in Lightburn. These are going to tell you a lot about your laser. Note you want to set up Lightburn to use inline commands, and you will need an M3 I at the top of your g-code files. You can have that g-code command added automatically to every script by placing it in the start g-code section.
Hmm… It seems odd that basically there appears to be little output below around 70/80 PWM.
There is output… as in you can see a dot, but it doesn’t do anything to the surface you are pointing at.
More investigation required, but I have yet to get a ‘thin’ line to speak of. Maybe the MDF isn’t the best target to be using as a gauge.
Update…. just had another tinker (basically undoing my days work!).
The Wiki page for this laser says 55mm for cutting and 33mm for Etching, taken from the bottom of the lens?. The manual that came with it said 35mm from the top
So, I lifted the laser up on it’s highest Z, set the power to 1 and lowered it slowly while pointing it at a piece of darkened acrylic (gave the best visual). You can see the dot go from square, to rectangle to a small dot. There is however a range where the dot is indistinguishably small and you cannot really see a difference.
The Wiki laughably says it can cut 18-20mm at 55mm. Yea, I seriously doubt that.
I have yet to make it leave more than a 0.5mm deep line in some fairly soft timber.
I am assuming for cutting, the speed must either be madly slow (but wouldn’t it burn?), or multiple passes.
The spec says 100mm/s at full power cuts 6mm ply. I don’t believe that for a minute.
Keep tinkering I suppose. Shame there is no easier way to find the focal point. And why make the goddam lens adjustment so hard to access! Make it a larger diameter so it is outside the housing.
I adjust the focus of my 5W laser for each job. I have pnly done etching with it so far, so I adjust the pinpoint focus to the top of the material. For cutting, I would arrempt to center the focus in the material, or at least where I expect the center of the cut pass to be.
I am looking at doing some foam cutting, which I think I can do with the 5W laser. If not, I will do it with the NEJE 40(10W) laser.
OK. Another morning+ on the MPCNC… and I have decided enough is probably enough
It’s just hogging far too much of my workshop time. The laser is ‘kinda’ dialed in, but still not perfect and a lot of other things need to be put in place for it to work. Definitely days more need to go into it yet.
The Z max has stopped working and I can’t see why. Now the touchscreen isn’t working either, and that is because of the horrible PlatformIO I am sure (something somewhere has got messed up).
Spent days on this now, so been looking around for a second hand commercial laser I can grab.
Thanks for the assistance. I 'll hang around to watch what others get up to.
There is no ZMax support in the firmware for the Primo. There also isn’t a proscribed mounting solution for a ZMax limit switch. If you have figured out or can figure out a switch mounting solution, you can wire that switch in parallel with your touch plate (which uses ZMin). You then need to enable probing (G38.2) in the firmware. There are a couple of topics that explore different settings to turn this functionality on. I explore one way in this topic, but my solution uses the Z_SAFE_HOMING firmware setting, which may not be what you want.
After going to all the work of setting up the bitsetter and later Z probing up, I’ve barely used the bitsetter.
Note that limit switches are only used during homing or probing. They are not active when you are running your jobs. Ther is a potential for soft switches (to limit router movement to the working area) to be active, but the way most people set up their jobs, soft switches are disabled.
On focusing your laser: If you use black cardstock and the right laser setting, you can watch the glow of the paper starting to burn increase and decrease as you change the focus distance. I also found the spot size is the same over a larger range, though selecting the middle position of when the spot appears smallest should be very close.
Thanks Robert. I am burned out on this. Haven’t got near the laser today because of the MPCNC issues.
I had a Z max limit switch in place since I built it, connected to the Z Max pins on the Rambo 1.4. Now, it doesn’t do anything.
Z min works fine. It was never wired in series with Z min.
The switch works (NC at the Rambo board), but clearly something in the config is now disabled.
Z max doesn’t even report a state with M119… only Z min.
I can’t see what is disabled for Z max. It used to stop the Z carriage from rising too far and hitting the bearings. Now it does zip.
Can’t see anything in config, adv_config, Rambo.pins etc. The Z Max input must be turned off somewhere, but I can’t see it and Google hasn’t helped.
If you still have the configuration.h and configuration_adv.h from the previous version you were running, post them to the forum, and someone here can take a look. There are a variety of compariance/difference tools available on the net, and comparing the old files and new files will identify how the old one was set up. Personally, I use Meld for comparing code files.
All I know about Marlin is from this forum and reading comments in the files. A look leads me to two setting, that when enabled, might give you what you want. The first is enabling this flag/define in configuration_adv.h:
// If you want endstops to stay on (by default) even when not homing
// enable this option. Override at any time with M120, M121.
//#define ENDSTOPS_ALWAYS_ON_DEFAULT
Then you have to turn on the ZMAX endstop plug in configuration.h:
I found that Robert… finally. That was the issue. For some reason, the version I opened in PlatformIO had that line still commented out.
So the Z max is now working, and I have kinda dialed in the laser focus point (26mm from the bottom of the laser housing).
But… I still need to walk away (at least for now). I have lost best part of 4 days on this thing and that is 4 days not making progress on anything else that might get me a job or make me money!
I have the free version of Lightburn, but that doesn’t connect to the MPCNC at all. The console just throws up:
Waiting for connection… echo:Unknown command: “” ok
and no G-code commands are recognised. No idea why. I think all the settings are correct, but I had to do them manually as it could not ‘auto-find’ the Rambo board.
So I am guessing this is another pile of work to get it to work. Not sure why it can’t see the Rambo board and I have not found an online solution.
I’m not trying to pressure you to spend more time with your CNC by posting a reply, but I’m going to make some comments while your post is fresh for your future use.
I don’t connect Lightburn to my CNC. I save the output to a file and deliver it like my CAM files. Cutting is always relative to the current position:
I give up a couple of (obscure) Lightburn features by running from a file, but I want the process that I use for my Primo to be the same between tools (I make less mistakes that way).
As for your connection, based on the limited information, I expect the baud rate is wrong in Lightburn. It needs to be set to 250000:
I know I’ve mentioned it before, but you want inline commands:
And you need the M3 I to be at the top of the file. I put mine in Device Settings/GCode/Start Code so that it is automatically added to each file.
Note that the “Free version” of Lightburn is really a fully functional “Trial version” that is good for about a month.
I’ve been using my MPCNC for a bit under four years. In that time, I don’t remember that feature (max Z endstops all the time) ever being enabled in the V1 maintained version of the firmware. Is it possible you enabled this feature when you added the max Z limit switch? Putting a limit switch on Z is not a standard MPCNC design.
Yes… I must have enabled it ages ago when I built the MPCNC. Just not sure why the version I opened with the date of when the MPCNC was built has it uncommented. Hey ho.
All your suggestions for Lightburn are as I have them set.
It can’t find the board when you ask it to find your laser either, which you would think it would.
Baud rate is correct, as are the other settings (I have literally tried them all).
I don’t want to have to add other processes/software into the mix to get the laser working. It’s already too damn complicated.
I won’t purchase Lightburn if it’s not going to work or be temperamental.
I am trying to simplify my workshop area. Got tired of constantly messing around/fixing my Rostock Max v2 delta 3d printer and my Flashforge 3d printer.
They got binned and I just bought a new Prusa (because I used them at work and seemed pretty reliable).
I don’t want a computer in my shop, so I’ve always run my jobs using SD card, so the processing of saving the g-code file is identical to how I deal with Fusion-360-created g-code. But I just took my laptop out to the shop, and Lightburn connected and controlled my Primo without an issue. If you haven’t done so, in Lightburn you need to create and use a Marlin device and select the right COM port. I don’t imagine the default GRBL device will connect.
It can’t see the Rambo board/MPCNC (I have set it up).
If you load an image, and press Play… the MPCNC starts up and seems to move correctly.
I did a quick test cutting out a square in some 3mm plywood and it worked fine.
But the comms window doesn’t report back correctly or allow me to enter any direct G code commands… unless I am missing something I need to put in the comms window first.
The best I could focus was at 26mm. According to the spec, that should cut 3mm ply at 120mm/m.
It didn’t. I cut through, but it took multiple passes. The cut however was pretty nice with no burning and nice and thin.
So, I am guessing either their specs are a little optimistic, or I am still not entirely dialled in correctly.
I suspect the first one.
I’m looking at a spreadsheet I created with cutting parameters just after I purchased my laser. I purchased, from Amazon, some 3mm plywood pieces billed as “Baltic Birch plywood.” I did not do an extensive test with these (I was just starting out and did not know what I was doing), but my laser successfully cut that plywood at 210mm/min at 100% power, so, with your laser that at roughly 1/2 the power of mine, it is not out of the realm of possibility that the “right” plywood with the right focus distance could be cut in a single pass at 120mm/min.
Later I purchased a sheet of 1/8" (3.175mm) plywood from Home Depot and did some projects. This plywood was substantially harder to cut than the “Baltic Birch plywood.” Looking at the cut settings for one project using the Home Depot plywood, I had to use two passes at 144mm/min.
Note that for real projects I slow things down to be sure I cut all the way through everywhere, plus I tend to use 90% power rather than 100% power to extend the lifespan of the laser module.
Focus also makes a big difference. Setting the focus to the middle of the plywood, and/or using an active Z (multiple passes with the laser descending each pass), notably improves performance.
My suggestion is to figure out how to author cut tests in Lightburn and test, test, test. Even the weather (i.e. the humidity in the wood) will make a difference. The same wood might cut differently in another season. I wish I’d been more methodical in the beginning by archiving photos of each test and doing a better job of my spreadsheet.
But the comms window doesn’t report back correctly or allow me to enter any direct G code commands… unless I am missing something I need to put in the comms window first.
I don’t have a clear idea of the issues you are facing. Maybe screenshots would help. In my test this morning, I was able to directly send both movement commands and direct g-code commands using the Lightburn interface. But if you are setting up your job in Lightburn as “Current Position,” you don’t need to enter any commands. You just position the laser by hand and click “Run GCode.”
If you cannot tell, I love making projects with my laser. I wish you joy with your laser projects.
Well the laser is all setup, and things appear to mechanically work correctly.
However, no luck setting up Lightburn to work.
Just have to continue tinkering. Not going to purchase an air pump or Lightburn until I get this sorted out.
The console doesn’t allow me to talk to the MPCNC at all. Surely I should be able to type G code in here and the MPCNC responds?
I read that maybe change the baud rate to 115200? But then I need to update the Rambo to the same baud rate.
She’s working. But something keeps stopping the G-code during a routine.
It will runs for like 3 seconds, then the MPCNC LCD shows ‘Click to resume’ on the screen, yet I have not told it to pause.
You un-pause the print in Lightburn and it re-pauses again seconds later.
