Brians Mouse Making Problems

 From:  Michael Gibson
1010.5 In reply to 1010.3 
> 1. I find it almost impossible to set up the "adjustment" scenarios you show---is
> there a lot of my learning missing?

Hi Brian, do you mean to just get the screen to look the way I show in the screenshots above?

What I did there was to select your solid, then used Edit/Separate to break it up into individual surfaces. Then with individual surfaces it is possible to select them and use Edit/Show pts to turn on the control points, that's what you are seeing there.

> 2. It seems almost impossible to exclude these "minor" things when working.
> Is there a simple way to avoid them or, truly, is it an exercise where one could
> expect, normally, to have to go back and correct these "nuances"?

It's much harder to correct later on because of pieces being all connected to each other.

It's really something that you want to try and avoid making much earlier on by snapping or constructing your original curve pieces accurately to ensure smoothness.

So for instance when you drew this curve here:

It looks like that was drawn using one of the arc tools. But my guess is that you used maybe the arc through 3 points tool, and it just got kind of positioned so it looked pretty good. The problem with that is that something that is only 4 or 5 degrees off still tends to look pretty good even though it is not really accurately smooth.

Instead of doing that, in this case if you use the Arc continue tool:

That helps you draw an arc that is guaranteed to be tangent coming off from an existing curve. So with arc continue, pick the first point over here:

And the second point over here, and the result will be an arc that is not just eyeballed to be smooth but is guaranteed to be smooth with the start curve:

This kind of guaranteed accuracy starting with the original curve structure will help a lot.

I reconstructed your mouse using these more precisely tangent arcs, and now the fillet will work up to radius 0.3, it starts to run into the top piece much more than that:

The reconstructed mouse is attached as

I did the reconstruction process by restoring your original sphere and top surfaces by selecting all the trim curves on those surface fragments and then hitting delete to remove the trimming boundaries (this restores the original underlying surface), then extruding the new outline up, and booleaning it with the top surface and the sphere. Also I noticed that this version allows for a smaller radius than 2 along the top edge there too, so I think your other fillet problem was related to this same issue.

I certainly agree that it would be better if you didn't have to worry about any of this, but unfortunately filleting is a quite complex area of calculation, it is pretty sensitive to this situation. When things are either truly smooth or sharp with one another it will function a whole lot better.

Other operations are not as sensitive to this, like for example you could probably chop away a ton of booleans right through that area without a problem.

There are also some other techniques to ensure smoothness - you can use the Draw curve / Freeform / Control points tool, and place the first point on the end of the other curve, then use the tangent snap to place the second point along the same tangent direction as the existing curve.

Another way to guarantee smoothness is to fuse different segments into a single segment. You do this by using Edit/Join to join 2 curves into one segmented curve, then turn on control points and delete the control point where the 2 segments touch. This will fuse the 2 segments together into one smooth segment, removing any crease where the 2 segments were touching.

- Michael