CNC 'dimples' on circular forms?

I’ve just started experimenting with the CNC functions of my Snap 2.0

I’ve recently noticed some “dimple” shapes when I cut circular forms. Has anyone else run into this and have any suggestions to avoid it in the future?


It looks like you’ve generated the toolpath with Luban?

What bit size did you use? I have the impression that it’s because of the toolpath chosen en size of the bit. If I’m correct, Luban generates a toolpath always going from the left to the right, and doesn’t do a circular motion along the lines of the circle. Hence you get “rounding errors” which become visual like that. If you look closely, the circle edge isn’t smooth anywhere.

Can you share the gcode (and your Luban settings) to confirm? You should be able to improve by using a smaller bit and using a smaller step-over.

But most likely, you’ll get the best results using other software that is able to generate more efficient toolpaths. (Fusion 360, vcarve, carbide create…)

Hey @brvdboss,
I think you may be right about that. I have noticed I get better results the lower I make the step-over. Although it dose increases carving time.

I attached the settings and g-code. I’m using the standard 3mm ball-end bit that comes with the machine.

You mentioned some other software. Can any of these create circular paths? Which would you recommend?


07506724_46888047.cnc (928.4 KB)

Based on the gcode, it’s indeed the size of the step-over that’s causing this.
You can do multiple toolpaths with a first roughing pass that uses a larger stepover first and then afterwards do a final one that has a much smaller stepover just as a finishing pass. However, I’m not really sure how well this works in Luban nowadays as I don’t really use it anymore (and definitely not for cnc)

Quality never comes for free :slight_smile:

Personally I’m often using Fusion 360 (which is free for personal use), but if you created that path from an image, I’m not really sure if it that’s easily possible with Fusion360. (ornaments like that aren’t really my use case)

Other software is Vectric Vcarve, Easel, Meshcam, estlcam, carbide create, kiri:moto
I personally haven’t tried those. Not all of them are free btw. And depending on the use cases, one might be more suited than the other. Some might need small changes to the gcode to work well with the SM.

There are also others that are officially supported and you can find profiles for that software on the github page:

Thanks @brvdboss I really appreciate it!

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