Help extruding 3d profile

[cadenc8NGPD]

I am running into a frustrating situation. 

In the attached file, there is a gap between "piston" body and the "future fin" body which is located in the "full twin right:1" component. The surface inconsistencies are causing a lot of problems with boolean operations. My intension is to create a compression mold with the "futures fin" being the part to be molded. I want the gap to be closed to create a uniform surface. 

It seems that the blue surface needs to be extruded down, however, being a 3d profile I am unsure how. In essence "piston" needs to extend up to the blue highlighted area. Sketch extrude to body is not working due to the surface inconsistencies. 

I have attached my file as well as a screen shot showing exactly where I'm having issues. Thanks in advance. 

[johnsonshiue]

Hi! Though I cannot locate the exact 3D profile shown in the image, there is a simple workflow to "protrude" a 3D profile. Go to Surface tab -> Create -> Ruled Surface -> pick the edges and change the type to Direction -> pick a direction and specify the distance. The selected loop will be protruded along the direction as a ruled surface.

Many thanks!

[cadenc8NGPD]

Hmm yes that is very helpful. I have sucessfully extruded the surface down as needed. But now have to figure out how to turn the surface into a solid. 

Thanks!

[g-andresen]

Hi,

Before you rack your brains any further, you should free the contours from the numerous interfering control points.
The general rule for splines is:
As many control points as necessary, but as few as possible.

There are also numerous non-tangential transitions.

günther