This is a little challenge for you. I have solved this puzzle myself, as you will see, but at this point, I have utterly and completely forgotten how!
I'm joining together three pipes at one point. The question is where to cut each pipe for them to fit together perfectly. The attached file contains the pipes.
There are three cases (from left to right):
1. The original cut that I did myself at one point. On the helper layer you will see the planes with which I've done the cut, but I no longer know how to create these planes exactly (!)
2. Where the third pipe cuts the angle between the first and second pipes in half (like the original one)
3. Where the pipes approach the point from random directions
This may not seem difficult to you, but please notice that the edges on the original meet up 100 % precisely, regardless of the level of zoom. On every attempt I've made with the others I've been left with gaps, however microscopic. The gaps are not due to manual approximation, as you may think - I'm using sound geometry through and through.
I know I've used trim/split in some way, but this very quickly becomes exceedingly messy...
I should say that in the solution there should be no more than two points where all three pipes meet up (like on the original) - if at all possible.
Give it your best shot! :)
Oh my god, I finally did it again! Oh, the power of trim! :) :) I guess I got so confused by all the extra surfaces which, well ... surfaced, when using trim before.
Well, I might as well post the instructions here! Let's see...
(If you are dealing with solids, make sure you are working with only three surfaces at a time. Explode the solid and hide the rest for later.)
1. Select the pipe (#1) which should dominate the joint; center it in your view (ghost mode in perspective seen from above)
2. Trim away the ends of the other pipes (#2 and #3) that stick beyond #1. Little pieces will remain inside #1, trim away only those pieces that lie in the triangle of the joint belonging to #1 (two to four clicks depending on where the longitudinal edges are). The outermost part of #1 is now finished
3. Select pipe #2 and trim away the end of #1 and everything that is inside #2, making sure to keep within the triangle of the joint that belongs to #2! This may take around five clicks.
4. Do the same for pipe #3
5. Done! :)
And here's the file with the proper cuts. Sorry for spamming!