Thoughts on merging CNC and laser(3D and 2D)

DougL · February 3, 2021, 11:10pm

I could not find the F360 SIG since this has lots to do with 3D designs but hopefully @tim.peachey and others who do 3D CAD modeling will chime in with thoughts and project ideas.

Having seen a few in the group adding diode lasers to their CNC, it’s been on my mind how valuable/interesting it would be if we could overlay a 2D design(SVG, DXF, etc) over our 3D design and generate a toolpath which not only controlled the laser and X,Y positioning but also Z so focus can be maintained. I’ve not seen this in any software yet. Aspire has a plugin but it appears to only work with 2D files. ie they make a psudo 3D design from a 2D image(bump map) and then apply the lasering based on the original 2D black and white bump map.

What I’d like to see is the ability to bring in a 3D file( STL ), generate toolpaths for all the CNC milling and then import/overlay a 2D design over the 3D design and generate another toolpath for the lasering.

One example would be to get GIS data for Lake Hodges and turn that into a 3D STL file using something like this tool( HGT 2 STL Converter by DWilbourn - Thingiverse ). And then get street and trail data to create the 2D SVG drawing of the streets and trails and be able to have toolpaths for all the 3D routing to create the topography followed by the toolpath which applies/burns in the roads and trails using the laser.

Any thoughts, interest, projects?

tim.peachey · February 4, 2021, 2:22am

Hi Doug

The Fusion 360 SIG is being renamed to the Design SIG as we hope to broaden its applications and appeal. Hope to see you online Monday evening February 8 as we relaunch this SIG.

I really like your idea. I recently picked up a little 3018 CNC “engraver” and noted that diode laser modules are an available add on. I thought about using the Z-axis leadscrew to help focus the laser. Your suggestion goes way beyond this. I’ve had an interest in doing 3D terrain models for almost 30 years, with various approaches for creating the 3D shapes. Adding laser engraved detail is a great improvement.

How to generate the g-code will be interesting. We will undoubtedly need to find an interested party with good software/scripting skills

For a first stab at a workflow:

Bring in the 3D GIS profile and generate G-code to carve it like we would any STL file.
Use a script to take x-y data of the street/path detail, and add in z axis information from the profile, creating g-code as output. Would likely need to limit x-y segment lengths so that the z data is applied at a good resolution.
An offset to represent where the laser is mounted relative to the spindle would need to be applied.
Z calibration of the laser would be carried out just like a tool change.

I also have a crazier idea. I would like to be able to use the laser to etch designs onto irregular surfaces, like driftwood, or miscellaneous objects. But in this case I am missing the 3D data of the target object. Would we be able to incorporate some type of distance sensing into the laser head and use the z-axis leadscrew to dynamically raise and lower the laser head as it moves along the uneven target surface? I see 2 possible approaches, maybe someone has better ideas:

We convert the g-code that drives the laser into very sort segments, and generate and add the z data into each segment dynamically before sending it to the CNC controller.
We remove the z-axis control from the CNC, and use a little custom controller, perhaps Arduino or similar, to dynamically drive the z-axis from live sensor data.

Creative juices going? Haven’t even had Happy Hour yet…

DougL · February 4, 2021, 3:51am

Tim, check out this ‘thing’ and in the description the author links to sites and tools used to create the 3D model from GIS data. I remember doing this a number of years ago creating part of Mt Soledad. Would love to do it again and route and annotate it in digital tools. Mount St. Helens (with lava chamber) by sitts314 - Thingiverse

As for engraving and/or lasing on uneven wood YES! There’s no reason why we could not use the CNC to scan over the material, create a point cloud, then a 3D model/STL and then we are back to the workflow I was talking about for the laser part. The developer of the Kiri:Moto gcode slicer/toolpath generator likes the idea and said he was going to look into adding the capabilities to Kiri:Moto. Kiri is a browser based slicer so you don’t even have to install it on your computer to use it. It’s quite amazing.
Take a look: http://grid.space is the webpage

Thanks for the feedback and love the ideas.

tim.peachey · February 4, 2021, 4:02am

A few more random thoughts on this:

STL models of some areas can be found online, but I am keen to check out the tools used by the Mount St. Helens modeller so it can be applied anywhere we can find the GIS data for
we should be able to project the annotations onto the 3D surface in CAD, I’ll investigate. We might even be able to figure out how to generate the g-code for the laser directly in CAD, perhaps by faking a CNC router tool
my brother pointed out that if we create the wood stock with alternating layers of differing wood, we would get a contours map effect. It would be relatively easy to calibrate the layer thickness to a published contour interval

DougL · February 4, 2021, 4:11am

I was discussing in another forum with a guy who did use Fusion 360 to get his laser to turn on/off by setting the ramp spindle speed to zero and the cutting speed to the laser power level desired. Close but I think we’d want full grayscale capabilities and standard laser type controls.

Makes sense for topotype maps to use different veneers layered to make great contour lines. Cool idea and better yet actually calibrating the layers. The scale can be etched on the piece with the laser along with the other map details.

And I too would like to get a workflow which allows us to pick the area and generate the 3D model ourselves instead of someone elses prepackaged areas.