Carving extra area outside of the image


I have finally started experimenting with the CNC, and have been able to troubleshoot my way to some decent results - using a very simple design for now so I can understand what each change in setting does.

The issue I have is with a circular image I’m trying to carve. The toolhead insists in doing a sweep on the entire width of the workspace, and since the material isn’t completely flat is creates an unintentional carving.

Hope the images below show the problem. The areas of concern are to the right and left of the circle. The preview shows the toolhead doing the right thing, but on the workspace preview you can see the grey lines (non-carving) to each side of the circle, which produce a visible issue in the final product.

Any ideas how to stop the tool from going to the edges of the workspace at every path?

I’ll be interested in the responses also since I had the same issue a few weeks ago. I took the easy way out and edited the Gcode with a find and replace for the z height only going to 0; I set it at 10. It worked but seems like there should be a better way. I’m not sure why it thinks it has to go to the edges before starting another line. Lots of wasted time for all that movement.

The simple answer is that Luban sucks for cnc. It’s barely a beta. If you want control over your toolpaths you need to use something else for your CAM. Fusion 360 is the usual choice.

As far as Luban goes, it’s probably an extra layer or shape in your graphic file that it’s seeing that you need to get rid of. It doesn’t differentiate between something white or transparent.
If you can’t figure out how to change your graphics file, one workaround is to raise your work origin so it’s not making contact with material when it’s carving the outside areas.


Thanks both of you for the feedback. I can certainly understand why you say Luban is barely a beta version!!

Because transparent backgrounds are interpreted as white, there is no way to delete the square around the image, even if you delete the background then the software converts it to white.

I’ll try editing the Gcode, sounds like a good workaround. I did try placing the origin higher than the material, but then the overall carving depths get messed up.

Thanks for the info!

Probably because you’re using a jpeg file. Try png or svg.

Shouldn’t be a big deal. Raise the work origin 1mm. Add 1mm to the depths.