Can't modify the spine of a blend, as described in Illustrator C I B.

[birckcmi]

I'm in AI 25.4.1, on a Mac Pro running Mojave, and the most recent Illustrator Classroom in a Book I have is for AI CC. It would be very helpful if I could turn a straight blend, say, right-to-left, into a curved, or arched series of shapes. The CIB section tells me I should be able to see the blend spine in outline mode, but that doesn't work. No spine show up. No spine, no alteration= a straight blend. Can anyone point me to a solution for this?

[SJRiegel]

You are not seeing a line between your two blend shapes? Can you show a screen shot of what you do see?

Here is what my blend looks like in Outline View.

In any case, you should be able to draw a new line, and use Replace Spine to move the blend onto the new line.

  

[birckcmi · Accepted solution]

SJRiegel and Monika, I went through the steps again and this time it all worked correctly. I think the problem was both my ineptitude and a problem or problems I was having with my Wacom tablet and Safari. I trashed the prefs on both and that seems to have corrected the problems. At least now if I switch to Outline I can see the spine, replace it, and get the desired result. Thanks for the help, guys. I've included a screenshot, based loosely on SJR's example.

[Monika Gause]

There are 4 cases in which the spine does not get biuld. But that should not matter. Just draw an open path and replace the spine via the Object > Blend menu

[birckcmi]

Thanks, Monika. I'll bash away at it with these instructions in mind until I get it right. I was having either computer problems or internet problems earlier, so I couldn´t respond with or without screenshots. I was on  deadline, so I had to do the blend-on-a-curve  by hand. It worked, but it took asbout 15 minutes. 

[Monika Gause]

Great that you could solve it!

So for anyone who is curious about the 4 cases:

1. If there are at least three paths selected, and at least one of them is an open, unstroked, unfilled path, and at least two of them are not, then the open unpainted path is used as an initial spine and the other objects are moved onto it.
2. If the bounding box of the anchor points of each object encloses the bounding box of the anchor points of all the objects above it in the stacking order, then no spine path is created. (This is the ‘nested objects’ case.)
3. If the intersection of the bounding boxes of the anchor points of all the objects contains the center points of all the objects. (This is the ‘nearly concentric objects’ case.)
4. If all of the objects are open paths.

(this was a question in Andrej Herasimchucks big Illustrator quiz on his weblog back in 2004)