Using a Diode Laser and CNC router to laser etch lines on 3D topographic map

Hi all,

First time on this forum. Thanks to anyone who can help!

I am carving very intricate three dimensional topographic maps. I would like to use the laser/LightBurn to etch lines into the carved map (e.g. borders, roads etc.). This would require the point of focus of the laser to maintain a fixed distance from the surface of the map, so x,y and z will be constantly changing. Is this something I can do in LightBurn? Fusion 360? Workaround?



If I understand, you are asking about support for “live-focus” controllers like this:

LightBurn does not currently provide any “live-focus” specific features, no. Which controller do you have?

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Thanks Rick. That’s pretty cool, but not what I had in mind. I can I think, in fusion 360, use the “project” tool to project a line drawing from a .svg file onto a 3D surface (.stl file) to then create a 3D tool path that traces the line drawing. Basically, I want to do the same thing, but with a laser instead of a router bit. For instance, if I wanted to engrave a line (with a router bit) at a fixed depth across a topographic map using a CNC router I could do so with this feature. Lightburn would have to be able to read a 3D path to make this work.

And thus the issue. :slight_smile:

Got it- well thanks anyway. I still make good use of it.

At the end of the day the GCode for a router and the laser are basically the same. Spindle speed sets the power of the laser.

Maybe just have F360 export the file, check to see what spindle speed it sets (if any) and then make adjustments for the power you want. I’d suspect you’d get some overburned areas because your speeds will be off as you climb and descend the terrain. Not sure how F360 calculates that.

Can’t hurt to try. Very neat idea, if it works out I might want to try it.

rethinking this… I’d like to do the same thing at some point.

I don’t know if it would be better to do fill or vector drawing but either way the toolpath generated by LightBurn to put down the detail for the laser would need to be merged with the Z axis information from a similar surface clearing toolpath.

I use Kiri:Moto for CNC toolpath generation and the author has been adding things like image bump map capabilities so maybe he’d have ideas. Since Kiri:Moto slicers(CAM, FFF, Laser) all can use 3D models there might be way to do this and the author is on par with LightBurn’s OZ with features showing up quickly once recognized.

Thanks guys. I agree with Jay- I think the best way will be to implement Fusion 360 “project” 3D tool path and play with the spindle speeds to turn the laser on or off. Here’s the issue, there are only two places in Fusion to set the spindle speed: “Spindle Speed” and “Ramp Spindle Speed”. Even if “ramp spindle speed” is set to “0”, and milling is set to “0-255” as needed, the g-code is still going to activate the laser during lead-in, lead-out, plunge, etc… One hack I can think off is a clever macro to edit the g-code and reset any non-milling operation to zero so that the laser is only on during “cutting” operations. Another thought- I can try and make the “cuts” continuous, so that they link to minimize transitions. I can also make the transition heights as high as my machine will allow in order to defocus the laser. I’m not confident this will work because the focal depth of my laser is quite large. Fusion can definitely handle the x,y,z topographic changes. Last problem is, the files are huge and Fusion is horrible with .svg’s. Would be great if LightBurn offered an integrated solution.

More to follow.


If you are not wed to Fusion 360 for every part of this… Kiri:Moto does STL slicing/toolpath generation and because the developer does toolpath generation for CNC, 3D printing and Laser Cutting he’s quite adept at solving problems like this. He’ll be available for voice chatting in 4 minutes(12noon EST):

I’ll be hanging out in the lounge on the Grid.Space Discord server at 12pm (noon) EST today, which is a voice channel, if anyone wants to drop by and chat. Voice isn’t necessary if you want to stick to text chat.

If you haven’t yet joined the server, an invite link is here

Thanks Doug. Not wed to any program- just familiar with Fusion, and getting familiar with LightBurn. I’ll look at Kiri:Moto too.

Running into issues with Discord.

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Well, I was able to do everything in Fusion. Really didn’t expect it to be this simple. Setting the ramp spindle speed to 0 and the cutting speed to the desired laser power. Thanks guys for being so helpful. I would say that the workflow is pretty horrible, and I wish LightBurn could handle 3D files so I could do it in your environment. Also, it’s pretty binary in Fusion- “on” or “off” is about all the control I have. I do think there’s probably a sizable market for contouring of 3D objects with laser cutters and engravers, but you guys are the experts. Thanks again!

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@peterd I spent a good hour talking with the Kiri developer and while most of it was about laser cutting machines and firmware controllers he sounded interested in adding the feature of doing SVG overlays on 3D models. Kiri:Moto already takes in STL files and my first design using Kiri:Moto was a 3D model of a plaque made in F360. I’d just exported the STL and imported that into Kiri to generate the various tool paths. And his interest is full laser control(grayscale, etc) not just on/off.

I had a difficult time getting into Discord for the session too. Later found out they sent an email I had to use to validate the connection and then I was let in.

Cool, thank you. I will still take a look at Kiri:Moto. Sounds like it may be well suited to my use case (which admittedly is very niche). You guys are awesome!

i don’t have a diode laser

but on a co2 laser, depending on the line width required, i would have thought the first choice would be to try a 4” focal length lens.

the spot size remains in reasonable focus across a 2” Z- distance.

i’ve used this method to engrave curved objects.

Due to the intricacy of the labelling, I need it to be as accurate as possible. I believe following the topology is my best bet. Anyway, it works. I may try keeping a constant Z on a throwaway piece just to see how much time it would save me. Thanks!

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Pictures? How did it turn out?

I just did a test burn on a rough map. I’ll post the final product eventually. Basically, it’ll be like this, but with the geographic lines burned in:

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Actually, in my opinion the topo lines are one height per line, which you could do in lightburn, … drop 1mm after or before each line? The lines of each height would have to be on a seperate layer.

I meant to say the country borders and place names. You are correct, topo lines would be easier.

Wow, that looks amazing. I have been curious about similar ideas but wondered how to control the laser from burning too deep. I have a 150 watt and 80 watt laser and my laser has a movable Z axis. Out of curiosity - did you draw every single contour line in something like Illustrator or did you find the file somewhere?