Problem with Extrusion
 

well actually 2, but I will post the other later. Basically what I have here is a sphere, and I have extruded some of the faces to create a ridge. The problem as you can see in the middle there, is that one of the ridge sections is smoothed, I don't want that, I want it nice and angular like the rest. any idea what might be going on? (the render uses no lights, just final gather from a grey environment, and a white lambertian material)

and here is my other problem. Again extrusion, but this time a cylinder, which I have extruded a few times to make this shape. Again I am getting that annoying smooth edge problem, this time though an additional one: in the centre you can see all those faces, but really I just want that to be a hollow tube (I don't want to use pipes because this is just a demonstrator of the problem) again, anything I can do?

for problem number 1 you need to go to polygons->normals->soften/harden

Yeah, select the geometry, and harden all the normals.

As for the second one...do u have a picture of the object before extrusion?

no, no, no ploygons > tool options > keep faces togeather.

trust me i had the same problem.