Double rows of vertices?

[JimB_again]

4) Related to the above, I've tried to cut segments off a model to in order to keep nothing but that which will show. I'm unable to use the "knife" though. I click "knife", "slice surfaces" and then I need to "set" knife. "Line" comes up and then "knife: knife cannot slice itself -- please deselect the knife". All right, I'm clueless; how do I perform the simple task of slicing an object in two and discard the part that I don't want to keep?

I have just purchased the 6.5 upgrade and I cant get the "Knife" tool to work either,please can someone shed some light on this problem?

[Hans_Petter]

Originally Posted by JimB_again

I have just purchased the 6.5 upgrade and I cant get the "Knife" tool to work either,please can someone shed some light on this problem?

Yes, by now I've figured it out and find the knife very useful.
1) Make a rectangle that intersects your model where you want to split it. Leave it marked as the selected object.
2) Select "knife", define the rectangle as being the knife and check / tick all of the other boxes but do not execute the operation yet.
3) Now comes the less intuitive point -- select the object you want to cut rather than the rectangle! Then execute the knife operation. When I got "knife cannot cut itself" I failed to switch the object selection from rectangle (knife) to the model to be cut prior to the final operation.

[JimB_again]

Thanks Hans it does seem a little complicated.