Trimming surfaces

[mjcook]

I am trying to trim one side of a circular surface by using a projected line that forms my trimming line. The original surface is simply a circle that is swept along a path (like a tube/cylinder). When trimming by using the projected line it wants to cut all the way through the surface (i.e. both sides of the tube/cylinder) but I only want it to cut out one side. Is there a way of allowing this or do I create two semi-circular surfaces, therefore only cutting/trimming in effect one side?

[JD Mather]

Attach your file (or a file representative of your geometry) here.

[mjcook]

Hi,

 

I've attached a slimmed down file with the untrimmed tubular surface and the intersecting surface. If you try trimming the larger surface with the smaller one (only 2 surfaces in the file) both sides of the tubular surface are trimmed, which is not what is required. I have subsequently rebuilt the larger surface in two halves and trimmed it ok, but if there is a way of trimming the original surface I would like to know, thanks.

trim problem.dwg