Trim tool issue

Hi I seem to be having some issue with trim tool - still learning so may be i m doing something wrong - pls give me some pointers if you see that.

hello Jessica
Rhino will have trouble sometimes trimming a surface with another surface in this situation. Try duplicating the edge of the cutting surface and use those to trim.

Hi Jessica- as Tone suggests you may have better luck with the edge curve - you can duplicate the edges as a curve with DupEdge or simply select the curve directly by Ctrl-Shift clicking on it as the trimming object.

The difference is that if you choose the surface/polysurface as the trimming tool for the larger object, Rhino tries to intersect the two objects to make a new curve to trim with. Since the cutting surface edge just sits on the cylinder and surface-surface intersection is subject to tolerance, it may well be, and frequently is, that the intersection curve used bt trim will be incomplete - you can test this by using Intersect on the two objects and see what the curve looks like. My guess is that it does not form a closed loop. If you use that edge curve directly, it is (probably) a closed loop, or can be made so by selecting a chain of edges. As long as that curve is close enough to the cylinder, the trim should work.

Please post a file with the two objects if you do not get this to work.

You can always try SolidWorks ; )