Hello and thank for taking the time to review my post. Just bought my first laser cutter which is a Creality Falcon 2. So I am completely new to laser cutting and Lightburn and finding the initiial learning curve steep,
I want to use my laser cutter to help me manufacture prototype printed circuit boards PCBs. The process involves masking the the copper side of the circuit board using spray paint and then using the laser to burn the paint off in selective areas. The board is then chemically etched and the copper is eaten away in the areas of copper exposed by the laser. I have looked online for advice on this but haven’t managed to find anything that shows me the detail setting to get this working. Obviously Light burn is very flexible and powerful and as such the finer points of configuring it allude me at the moment and I need some help and advice getting started please.
The problem that I am encountering at the moment is the I am getting the raster scan lines burned into areas where I dont want them. Also the line thickness burned in the Y direction are of a different thickness and clarity to those X. Basically lines at 90 degrees to the scan are poorly defined. Tried various setting and the only one that appeared to make some difference is the selecting pass through mode.
My process is to print the images as PDF at 3600 DPI. I then convert them to PNG and import them into light burn. I am also using lightburn to produce a negative of the image. Not sure what other information I can provide as most things I have left at default. Note the image I am burning is small. The thickest lines are 1mm and the thinnest 0.02mm. I didnt expect the fine lines to work but was just trying to define the limititations of the machine with various line widths.
Welcome to the Lightburn Community! You will find a wealth of info here if you do searches or ask for help.
I am an electronics guy and I do I know what you are doing. I am a relatively new laser guy, but I know what is giving you grief.
This is most likely a GRBL parameter that needs to be $31=1. It allows the laser to be shut off on G00 moves. How it can be changed depends on your controller.
This has to be fixed in the drawing. The laser spot is rectangular, not round or square. My laser is specified as .06mmx.08mm, which is a 3:4 ratio. As far as I have seen, the diode lasers are all narrow in X and wide in Y. The Sculpfun S30 Pro is the leader of the pack in dot resolution, but your work is limited by positioning accuracy of the machine. Photo-resist would be limited by the laser dot size.
Here is a video that does a superb job of explaining raster scanning. Technically, you are greyscale, but only with black and white. In this case, pass-thru would be your best option. All the other modes are dot firing modes as far as I know.
Good luck and have fun! Keep us posted on how it goes. A picture or two of your work would be nice.
Solid-state lasers produce a rectangular spot, not the nice circular one you’re thinking of, so the narrowest cut will be different in the X and Y directions.
Stripping paint off copper will require testing to find the ideal combination of speed & power. A few Material Test patterns should help you get better results:
Also: make sure the machine has using good ventilation!
That is excessive, because the spot size will be on the order of 0.1 mm, which is 10 pixel/mm or 254 DPI. Using higher resolutions won’t produce much benefit.
The first picture looks like you haven’t yet measured and enabled the Scanning Offset correction:
How do you design the pcb? What kind of output does that software have?
How much of the paint you burn off is probably related to paint color, thickness and type. If these vary, so probably will your results.
Here’s a slick video on making pcb boards in an odd way, with a fiber … probably not applicable in your case, but not any less fascinating. Just an fyi…
Thanks for the great replies. To pick up on some of the comments:
I am using software called Kicad and it will output a number of different file types depending on if I choose the print or plot outputs. It will produce PDF and also SVG files. I gave up using SVG and PDFs because Lightburn displays them as vectors and just shows lines and squares for the pads. I know it possible to process these SVG files to make them work, but this appeared to be a level of complexity and time consuming I wasn’t ready for yet. So I print using a high resolution print driver to a PDF and then convert to a PNG. If there is a better way please advise.
I am still confused why Lightburn only appears to be able to show the PDFs and VGA as just vectors as other PDF programs translate the vector image into something that actual looks correct. I am not blaming Lightburn there is stuff going on here I don’t understand yet. But is there a setting that would allow Lightburn to interpret the PDV as an actual image with track width rather than vectors. I can post a picture here if people aren’t sure what I am saying (I not sure either). I believe this can be corrected in software something about “stokes” but don’t understand the correction process. It looks a pain in the bum either way.
I select the high resolution possible as file size isn’t a thing anymore and wanted to ensure lack of resolution wasn’t an problem especially as I may have a few image manipulation in the tool chain.
Your Comment “This is most likely a GRBL parameter that needs to be $31=1. It allows the laser to be shut off on G00 moves. How it can be changed depends on your controller.”
I am not sure what controller is being used I will have to investigate it. I assume it something proprietary to Creality who manufacture my Falcon 2. Not sure how to change this parameter but would be a bit concerned about upsetting the GRBL parameters. Is this a tick box that Lightburn can control so I have a way of getting it back to stock if it goes wrong. Having used GRBL on my CNC machine I am aware of being able to download the parameter as a precaution etc.
Ok great reminder on the dot being rectangular. I looked on the specification on the Creality website and they just list the spot size as 0.1mm and 254 DPI. It doesn’t specify this dimension of the laser. I have microscope for my electronics work is it possible to measure the dimension of the laser and apply a correction factor within Lightburn.
My final question for today. Is there a way to make Lightburn trace my image perimeter of my lines and then fill in the internal part. I don’t want to produce the image as a raster scan but trace the image. This would appear to be quicker as most of the timer the laser is just moving over dead space that not being cut.
Thanks for the replies those are great and a big help.
You can get an idea of the aspect ratio of the beam by defocussing as much as you can, this should enable you to measure the height and width with a rule. It won’t tell you the actual size when focussed but it will give you an idea of the shape.
Yes, LB has a trace function so you should be able to trace your image then set the layer to ‘Fill’. You might want to try ‘Flood Fill’ as well as this might save some scanning over blank space However, it can also produce a lot of undesirable changes of direction.
Thanks Marcus - My laser has sensors so it doesnt like being picked up or moved by hand and its well shielded so hard to defocus ? or do I just move it to the top of the sliding gantry and set the power to full and blast away.
I think I can try just punching a dot into metal foil then measuring it with my microscope. I assume foil should be dimesionally stable etc. Once I have measured the do size I will post a picture and we can look at how I adjust this offset.
From a previous post - have had already run some speed and power runs so its just the dimensional issues that are a problem. On my first run I did manage to cut entirely through the PCB and my work bench. Glad this wasnt done on the kitchen table or I would be dead now!
Although I’m not familiar with your actual machine I’m guessing you can just wind the laser head up as far as it will go (like I did with my Ortur). I wouldn’t give it the full 100% laser power though. I’d start with maybe 5% and if that isn’t bright enough then increase it in maybe 5% increments.
I made a few of these with both the co2 where I etched the coating then soaked it to that nasty stuff to etch off the copper and tried it with an old file on the fiber, was way too stinky…
I use Eagle, which is pretty much for electronic design only and I believe Kicad has a wider scope of applications…
The various file format outputs that are available may be more applicable to how these machines operate.
In simple logic. The resulting pcb isn’t a grayscale, it’s black and white.
Look for a file format that you can import into Lightburn and use it like a vector file, then you can fill in those vectors.
The first thing I’d like to do is rotate the photographs of your work 90 degrees clockwise so the output is oriented in an intuitive way showing how your original art was produced.
(Edit… Ok… I did rotate the two pictures and I have your originals if needed)
This may make Ed’s comment about the Scanning Offset somewhat more compelling.
Slowing down may also help reduce this artifact. What speed are you testing at, what are the units of speed and % power?
LightBurn doesn’t have a line-weight setting because of the behavior of the laser itself. On most materials, the amount of power dictates the line weight.
It may be reasonable to use the offset line tool to add the additional parallel lines to increase the line weight if it’s only a few traces.
Instead of the produced vector file, you may want to start with an image and trace it.
An image file can be produced by a laser engraver in a rasterized way (scanning left to right), but the trace can scrub out all the noise and you can fill the vectors you produce with LightBurn.
I’m attempting a solder mask for my first SMD board.
Did you try to change the layer setting to “fill” instead of line, once imported? To me, it sounds like you want to fill the areas, which you need to tell LightBurn explicitly.
Maybe you can provide an example SVG? Then we could check
Thanks for the post. More information to follow but to answer the SVG question first. I have include a picture of my plot format selection options in Kicad.
I can export this in various formats including SVG. I normally choose to print a high resolution PDF at 1200DPI then convert it to PNG.
However when I import them into light burn I only see vector lines and the text elements shows multiple times for some reason. Not sure if I have attatched the SVG file correctly but its the small black picture
I think I did try to change the line type to fill but it didnt make any difference or I didnt select it correctly. If you could take a look that would be great. I want it to look like the PNG file shown below although I would invert the image in production as I want to burn off the white and leave the black as a mask.
I see. No, I don’t think the fill mode will help here. Only for the pads. You would need outlines for the traces as well. Hairlines can’t be filled. You can mark all the lines and then use the offset tool to create a similar effect:
So I made a new image as the old one didnt fit under the microscope. The new image is 12mm wide the tracks are 1mm 0.5mm and 0.2mm. This was printed to PDF at 1200 DPI then converted to PNG and then cropped.
I imported this into light burn and selected Threshold. Speed was 6800 and laser power 10% . This burned the image see below. I noticed the scan lines are staggered is this an issue with DPI and its trying to print a gray scale?
I moved the material to the side then did a 90 degree rotation and burned the image again. The image distorted was in the same direction as the previous image in line with the scanning direction.
Finally I selected pass through setting. This didnt have the distortion but did show perhaps my laser dot is not round. Pass through mode looks better but it also change the image scale and it got a bit bigger. Note I have tried printing at various speed and power and this has no effect on the issue i am having.
No I dont think I have any options. I see some people import it into another drawing package and edit the “strokes” but that looks like a lot of work. The fact it nearly works in pass through modes makes me think it can work I just dont have the setting right.
Sorry I didnt manage to get good pictures of my laser dot. I couldnt unfocus it enough. Picture shows me doing a pulse onto copper with a black paint over the top. There is one of my hairs for scale, note its not gray im just very distinguished!
Thanks for the support from all you trying to help. These laser things take some driving!
