Laser Engraving then CNC

CNC Machines Shapeoko
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I’d like to make items where I laser engrave an image or text on a piece of wood, then use my Shapeoko to add holes, engraving and cut out shapes.

Been trying to find a way to get the laser engraved piece to line up perfectly (or as close as possible) with the CNC. My laser engraver X,Y 0 is upper left. Only practical to have X,Y 0 on the Shapeoko to be lower left.

Designing projects in identically sized workspaces gets me close, but sometimes mm off, and I’m tired of making $20 pieces of firewood out of clear maple! Has anyone done anything like this and have any alignment tips? Was thinking something like registry marks engraved with the laser, or trying to line up an end mill with a known spot engraved by the laser?

Thanks
Tim

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I’m doing it with LightBurn and CC. Recently, the folks at both companies coordinated to make sure that they export and import SVGs that retain their sizes…this made it possible to do what we’d like to do.

I usually start in LightBurn and layout the overall size and all of my burns. I put in the elements and placeholders for the stuff I’m going to do in CC. In Lightburn you can choose to not output design elements, so I only output the items I really want to burn. The rest of them are there so that the SVG that I export from Lightburn will contain all of the reference objects.

The most important object, by far, is the bounding box. Design a box (that you won’t burn, but you’ll export in the SVG) around your entire design. If you’re not going to have a center point on your stock that you can use to align both your CNC and your Laser, then you will use the lower left corner of that box to be your origin. The important thing is that, when you import the SVG into CC, the box comes with it and you now have a reliable spot upon which to start your cut.

When I cut, I generally do the CNC routing first. Mark the lower left corner and zero there (it won’t likely be the lower left corner of your actual stock, but it could be). Run your cuts. Then, without moving the piece, mount your laser, zero on the origin, select your correct origin position in LIghtBurn and do your burn. It will be right on, as long as you are precise in zero-ing both processes.
EDIT: The reason I start with the CNC is that often I will cut the exterior of the bounding box to be my final cutout (with tabs), which gives me a perfect spot to zero x&y. Either way, you have to be careful to consider where you’re putting your origin and that the process before it won’t obfuscate any marks you put on your wood (like cutting away the mark with the router - or burning it away with the laser).

If you want to laser first, you could burn the bounding box onto your stock, if you’re going to rout it away anyway…and use the burn as the xy point for the router.

I’m not sure if my process is really clear here…I can get into more detail…but the key is the bounding box coming across in the SVG and becoming your reference point for aligning your origin.

Sorry: I keep editing this thing.
If you’re burning an image, and you want to use that image as part of your CNC cutout, you can trace the image in Lightburn and export the trace (not the image) in the SVG file. Then you can use the tracing to layout your toolpaths.

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I would do as @GJM suggested with the bounding box, mostly. I’d do my CNC first complete with outside profile. Put a piece of cheap ply into my laser and burn the same profile onto it. Put my finished profiled part into laser aligned with burned profile. Do my laser engraving. I do this all the time with odd shaped/sized pieces, works great! If you have a laser equipped with a camera you can also align it that way, I have a camera, but prefer the profile burn alignment. I also use a bounding box, but only to maintain consistent origins between machines/pieces.

Dan

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I have been doing the design in Vcarve with a bounding box for the CNC portion, exporting as SVG, then importing to Visio to do the laser engraving part. I am using two different machines, with the laser having the X,Y zero at top left, and the CNC X,Y zero at bottom left. I suspect that may be my issue, and I’ll just have to figure out how to get the laser to start X,Y zero at bottom left and see how it works!

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I have been making a 32 pack of wood guitar picks.
I place the wood in the laser. I do a light imprint of the box around it and center lines. I also imprint outline of the guitar picks. I flip it over and do the opposite side. Then I CNC, first setting the starting position on the crossed center lines. (I also make a center circle 1/8 inch match my starting bit). I run the cut. I cut out less than halfway through the part, flip over and line it up and cut again. I do a 3D profile using Meshcam. I can tell quickly if it is cutting perfectly because it will be inside the laser marks. I cut less than halfway through leaving a thin support around each guitar pick.
Then I place the pack of guitar picks back in the laser and cut out each pick. If I had changed setting on the laser and need to check before I cut I put tape on the metal base of the K40 laser and do a light imprint and line up my wood. If still not certain I place paper over the wood and trace it to see if it lines up. Careful not to catch it on fire.
I can also engrave on all the guitar picks before I cut it out. I can also engrave with the laser then fill with resin and then cnc then come back to laser and cut it out.
Lots of options. Much faster using laser to engrave.

I also do this technique with custom cup coasters I’m making for Christmas gifts.

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By the way, we had had the discussion of how to automatically maintain the origin if you’re using the same machine to do both the CNC-ing and the lasering…and we had discussed creating a GRBL macro that moves the head the offset of the laser attachment. Obviously, that won’t work if you’re using two different machines to do the different functions, but if you’re going to use a shapeoko, you’d just need to measure the precise offset of your laser from your router spindle and then execute the command to move the X and Y to reposition the next tool to precisely the same origin. Then you get rid of all of the unnecessary re-zeroing.

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I’m actually not using the same machine though. I suspect that to be my problem. Got a pretty good system down now though, using boundary boxes and having to be very careful about blank sizes exactly matching work sizes so that the X,Y zero works at both top and bottom of my pieces.

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btw one interesting thing to consider is that there are lasers that go into the collet of the router… that should make it easy to keep the same X/Y

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