Create outline to cut around object with CNC

Ok, all let me preface this by saying I’m a absolute newbie when it comes to rhino so bare with me in my caveman terms trying to get across my issue.

We currently use Rhino V5 and RhinoCAM to send models to CNC Mills.

What im trying to accomplish is having rhino outline the object (using MeshOutline) and have the mill use this as a “cutout” path for the object.

Issues i have ran into is mesh outline isnt really creating a object to mill.

  • After using mesh outline i used extrude closed planar curve (my thinking was make the outline a object and it will work) this didn’t work as its the same size as the object to begin with.

  • After these attempts i used the above steps and then tried scaling the outline that had been extruded to be very slightly larger than the original outline was. This just didn’t work the way i thought so kind of a dead end with this attempt.

So I am just trying to get a outline created and maybe have it scaled 2 or 3 mm wider than the original to have the mill ‘cut’ out along the outline.

Any help is greatly appreciated, and again sorry for the caveman terminology to what I am trying to do.

Also if there are any plugins or something else offered from Mcneel that could help with this please let me know.

Hello - can you please post an example file? There are several commands that might help.


Basically, you can do it all with RhinoCAM… In the profiling operation, you just need to set a positive stock to leave in XY of whatever “spacing” you want the tool to stay away from the outline. That’s exactly what that setting is for.

I feel we may be under utilizing RhinoCam, our stock is set to none as we really only use it to generate the tool path for the CNC machines.

What Helvetosaur is advising you to do is a very efficient way of creating the cutting instructions (G code) you need to leave your actual finished part oversize but it will not change the size of the part in Rhino. If you want to change the size of your part in Rhino you can use “offset” to increase the size of the planar outline curve that you will extrude. You will need to create a “bridge surface” from the offset curve back to the original curve to avoid a gap. Then the part geometry you send out for CNC can be specified as exactly the 3d model you are sending. If I am cutting the part myself I would just use the profile cutting offset setting in Rhinocam as described by Helvetosaur. If I am sending the part out to someone else to cut for me I would want the geometry I send out to be exactly what I want to receive back to communicate clearly.

Well, that’s what it’s for, yes… :stuck_out_tongue_closed_eyes:

However, there are a huge amount of options/possibilities once you know the program. Cutter radius compensation and stock to leave are the abc’s of 2 1/2 D toolpathing, I suggest that you investigate those functions a bit.

Ok guys im going to try a few of these suggestions today. Im sure ill have a few more questions, but thanks for the quick assistance.

Actually needing to create the outline its self. This is where my problem comes in, when using MeshOutline, and then generating the the tool path in in Rhino Cam it doesnt create the outline (or what im trying to achive with the outline is a cutout). Each model worked with is completely different and this is why MeshOutline seemed like exactly what i was looking for.

Can you be more specific about what problem you are having with the mesh outline? Why is this not working? Also it would help if you could post a sample file.

I hope you understand my english (my native lanquage is dutch)
Do I understand your problem correct? You want to mill the last without using Rhinocam?
If that is the case, You have to slice the last in several layers and you have to make a outline of each layer. additional you have to make a outside offset of half the mill diameter and that will be the line to follow with the mill.

I made this example of my hand in foam, scand it, sliced (mesh Split) it in very thin layers, did this every 5mm in height, mesh outlined each layer. (To show it, I added a color to each mesh) Additional you had to add the offset line.

I work with a Biesse CnC for wood panels cutting, and I wanted to have a quick contour utility. This cluster will maybe help you.
It integrates scripts gleaned from this forum that allow to extract the external and internal contours, and to give them the necessary clockwise and counter-clockwise meanings for cnc cutting, it also extracts the dimensions of the part. It avoids entry points into inner corners, it moves geometries to the general origin point. Even if the part is in position in space, indicating the plane formed, for example, with the main face of the bounding box, everything is brought back to the origin point. These contours can be exported in dxf for example to be transferred with the machine software. For my part, I am working on a component allowing to write a native CIX format from Biesse.