Boolean Madness

 From:  Michael Gibson
2728.14 In reply to 2728.13 
Hi Will,

> Michael, is there a reason why those small line segments
> show up in your models? (Especially since they're not
> usually intentional!)

In this case it was basically a side effect of trying to deal with an inaccurate portion of the model.

If you look at this spot here where these 2 surfaces meet:

You can see there that those surfaces are not tangent with one another, that is a slight kink there where they meet.

Having that kink means that it is harder to make a sweep that follows that as just simple pieces without any juncture between them. But since the kink is pretty small I decided to just delete a curve control point at that spot to smooth out my sweep so it could be just one surface through that spot.

However, doing that causes the sweep to be slightly different in shape in that area from the base surface, and with edge running along the side of it, the edge now doesn't hug right exactly along the surface so when it is cut in the boolean (edges are cut in booleans same as surfaces) it will result in some small pieces.

Here is a zoom in on that area before doing the boolean so you can see how the edge is situated, and why that results in a small fragment after intersections:

Really the best way to avoid this is to ensure a greater accuracy in your original curve structure before building surfaces, so that segments there are set up to be tangent to one another rather than only slightly creased.

Otherwise, any inaccuracies in your original curves tend to become magnified as you try to build more and more stuff hanging off of them. Tangency is especially important for things that involve some kind of offset from them, like fillets, sweeping tubes, etc...

Things that are only off from a few degrees of tangent are not good for the filleter, because it creates kind of micro gap between different fillet segments that the filleter has to try to deal with.

It's a lot easier to solve these issues by taking some care that your initial curve framework is accurate and pieces are not just "eyeballed" to look pretty tangent.

But it also depends on what you are doing, if you are not going to be hanging more things off of that stuff (like fillets, sweeps, etc..) then you can get away with kind of sloppy junctures a little more.

- Michael