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How to avoid CNC crashes Answered


I am wondering if it is possible to define particular areas on the bed of my CNC machine which I do not want the toolhead to pass over.

My setup is an Arduino powered CNC pen plotter running GRBL. I am generating GCode in inkscape.

I know I can set a safe height for the tool to pass over work safely but what if that height doesn't suffice. Can I define an area that the tool must not pass through?

As a simple example:

Before running a file the tool is at the origin. On sending the file the tool will take the most direct path to the first line to cut/draw. Imagine there is an obstacle that would cause a collision if the tool takes this direct path. Can I do something to ensure the tool navigates around that obstacle?

I hope that makes some sort of sense :)

Any ideas appreciated


Its always a problem, I use $6000 CAM software to generate tool-paths - and its possible to create exclusion areas in THAT, but not in hand-crafted Gcode.

I have had a play on RhinoCAM, from what I understand is very similar to VisualMill, and have found avoid areas. I'm not sure they are able to do what I want them to. When I add an avoid area all that seems to happen is that the clearance height increases to avoid the region, is there a way to navigate around the region instead. My gantry has a greater clearance than my tool, so it would be good to be able to generate gcode that moves around obstacles, rather than over them. Is there a way to do this in VisualMill/RhinoCAM?

I'm not able to add an image here for some reason so here is a link to a render that might aid my explanation: https://postimg.org/image/clnmh0oed/

Thanks for your help :)

Thanks, I just had a look on MechSoft's website and I can demo their software. Can you give me any clues as to how I can setup these exclusion zones? Any videos or sources that may help?

Will VisualCAM/VisualMill be suitable for creating a Gcode file from a vector line drawing such as a .dxf .dwg .svg file?

If you use the Artcam extension, I think so. Their non-paid for programming is pretty limited sadly.

If you create a polyline surrounding the area you want to exclude, and surround it with a polyline where you want to work, when you select the machining operation, and click the two polylines, it should automatically exclude the area you have walled off.

Thanks for you reply. I think for now the only way I can think might work is to generate seperate Gcode files for areas I want to work in and join them with a piece of Gcode that navigates a safe path between.

Not sure if that is going to work though!

I have four CNC machines and only one works. They have been in and out of the repair shop

more than I care to think. Fantastic when they work. Good luck.