Yet another shape.

 From:  Michael Gibson
694.26 In reply to 694.21 
Ok, some more steps.

I went back and drew a new trim curve that was a little better. To remove the old trim, I selected it and hit delete. If you select all the curves that make up a boundary for either the outer edge of a surface or an interior hole, you can then hit delete to "untrim" it.

Then I drew a sphere in the top view to make a dimple. I positioned it in the top and front views so that only a small portion of it was sticking into the surface. In this case since you have a pretty shallow dimple there, you don't want very much of the sphere to poke through. Another thing that can cause problems right now is if you end up with the "seam" edge of the sphere only poking through the surface by just a small amount, that will tend to confuse the filleter so I made sure here that the edge of the sphere was not poking into the surface. After positioning one sphere on the upper piece, I used Transform / Mirror to make the other side one, and then used Transform / Copy to copy the sphere to the origin (first pick was on the center of the sphere with center snap, second pick was on the origin snap), and then dragged it down and into the lower position. At this point this is what it looks like:

On the spheres there you can see that "seam" edge that I was talking about. Every NURBS surface is fundamentally a type of 4-sided surface like a sheet of paper. For a sphere, it is like you rolled up the piece into a tube so that opposite edges were touching (this is the seam), and then pinched the top and bottom edges down to a point (these are called singularities or poles). Anyway, if that edge sticks through by only a really small amount, a fillet will go only as far as the seam edge goes and no further, so a little tiny edge poking through can limit the fillet to only working on a small area. Here is what I mean:

This is one of many fillet limitations and bugs that I hope to get corrected in future geometry library updates. Some will take a while to get corrected though.

Ok, the next step is to cut everything up into pieces. To do this we will use Edit/Trim. In many cases you can also use the booleans to cut things with one another, but they generally will discard pieces and we want to keep pieces here. In this case we want to cut everything up, we're not just cutting the big sheet, we're cutting both the big sheet and the spheres as well. So before running Trim, select everything. Then run Edit/Trim. Now here's the part that you wouldn't know about without a tutorial or documentation - (I need to fix up this prompt) - at this point the Trim prompt will say "Select cutting objects". In this case just push "Done" (or right-click) without selecting anything (there is nothing else to select anyway). This signals to trim that you are doing a "mutual trim" operation where each object is being both trimmed itself as well as cutting something else. So after you have pushed "Done" to signal mutual trim, then comes the prompt to select pieces to discard. In this case it is kind of difficult to pick the interior pieces to discard, so just push Done again here without picking anything to cut everything up and leave all the pieces behind.

Now select these pieces and push delete:

That throws out the big parts of the spheres. Now select these little "sheet" pieces, and push delete again:

That will get you to here:

Now we want to blend the sharp edge where the sphere intersected the sheet. Normally at this point I would select all the pieces and use Edit/Join to glue them together at common edges, and then fillet the edges. However I ran into a problem with that, the edge-based filleter refused to fillet this kind of cramping my style here. This is another one of those situations that I hope will get better with geometry library updates after V1. So I switched to the back-up filleting plan - when the "joined edge" filleter gets confused, there is a way to run a different style fillet which usually will work. The different style one is called a surface/surface fillet, it works if you have 2 completely separate surfaces selected and then run Fillet. So that's what I did in this case, I left the objects as separate surfaces, selected 2 at a time and ran Fillet. I used a radius of 4.0 and G2 blend style shapes to make this:

Now you can select those pieces up and join them. You want to make sure to join pieces before you do a polygon mesh export because when you join pieces MoI will do extra work to make sure that the created mesh has aligned vertices along those common edges. If you just export unjoined surfaces each surface gets meshed without knowledge of the others and it can have slightly different vertex spacing along those edges.

To get an outer rim I just did something quick and dirty - I turned on grid snap and drew a shape like this:

Then I scaled it down and positioned it off to the side of the object:

Then select the oval shape, run Construct / Sweep, select the outside edge of the surface as the rail and that will make a tubular type sweep shape. I think I mentioned auto-place mode in a previous tutorial - again, when you do a sweep you can have the profile totally off to the side of the rail and MoI will automatically place it on the rail for you.

Here's the result:

Then it looks like you had some small spheres glued into the middle, with some more fillets on them, I'm skipping that part here...

This one was kind of difficult because the filleter did not want to cooperate in some parts. Until that gets better you may have to employ some work-arounds. One is to try and rotate or position things to avoid little edges sticking through. Another one is you can use surface/surface fillet instead of edge-based fillet if edge-based fillet is giving you problems.

Another possibility instead of using fillet here would be to trim things back so there is an empty gap between the dimple surface and the main sheet, and then use Construct / Blend to create a blend surface to fill in the gap - this is the way that Eddi was showing in a previous post.

- Michael