Planes and working with 3d mesh data

Hi Group

is there any really good tutorial / demo videos on using and controlling cplanes / sketch planes in rhino 6?
I want to totally understand and control them in all ways and on all surfaces, meshes etc…
currently i want to be able to set up a sketch plane on or in front of a 3d Mesh file section so i can make a sketch then extrude that sketch through the mesh data and make a cutout so i can then work on it. so any methods of controlling sketch plans with meshes will really help.
I have attached a picture of a 3d scan mesh with the textures applied in rhino 6, you will see a green line that I have sketched on the mesh surface which is tracing round pen marks on the mesh texture that I need to cut out. but ideally, I would like to make a flat sketch on a sketch plane not a wobbly 3d sketch on the mesh scan. I hope that makes sense)

I have used Rhino for years but mainly for 2d work and quick visualization of 3d files. (I have other packages that I work in on 3d work) so i have not really needed to place sketch planes in weird places…

I would like to learn more on this if anyone can point me in the right direction.


“Sketch planes” are called CPlanes in Rhino, and you can create them in many different ways. There is some info in the Help here:

The user manual does not seem to cover CPlanes extensively though.

Thankyou for your reply, i will try to find some videos on youtube as well.

regards A