why does "blend" not work here?

 From:  Michael Gibson
4993.8 In reply to 4993.1 
Hi Mike,

> I cannot blend that curves. Why?

It's because of the original curve cutting objects that you've still got sitting there - they are on the exact same spot as the edges and they are getting in the way of selecting the edges - in order to generate a surface blend you've got to select the edge of the surface and not the original curve objects.

The easiest way in this case to be able to get at the edges is to hide all the curve objects - you can do that by going to the Scene Browser, Types section and click on the eye icon for the "Curves" entry there - that will hide all curve objects.

> I always have problems with differencation of "construction" splines
> and "work" splines. Which are which? And which can I delete after
> f.e. trimming?

You can delete or hide the curves you used as the cutting objects after doing a trim. Sometimes it can be convenient to actually move the curves a distance away from the object that is being cut and let them project on to it (just using the projection built into trim, not as a separate project step), then with them some distance away from it they can be easier to select later on.

> And so often I use the "joint/verbinden" command and then
> I still can select the individual splines. So they did not joint.
> I cannot understand that.

Yeah the "Merge" command is different than "Join" - Merge right now only works to combine fragmented edges of a solid together into longer edges, it does not do anything on curve objects although I do want it to work for combining curves in a similar way in the future.

One other tip - in this case if you're going to do a blend later on it can be good to get the curve you are using as a cutting object to be all one single segment so that you will then have the edges that are generated from it also just be one piece after the Trim - you can use the Rebuild command on your segmented cutting curve to do that:

- Michael