Hi Olga,

> I do AutoCAD without 3D so I fell I need to get a hold
> of the 3D drafting concept.

Just a quick note for you - there are some 2D AutoCAD drawing functions that you can use in MoI as well, for example for the second point of a line you can type @3,2 to place the point at a relative distance of 3 units in x and 2 in y from the start point (normally this would be done in MoI by using r3,2 with the "r" for relative, but the @ works also for people used to AutoCAD). Similarly you can use polar coordinates like typing in 5<45 for a second point 5 units and 45 degrees away from the start point.

There are a few differences though, like to extend 2 lines to match each other don't use Fillet 0 radius, instead select the 2 lines and use the Edit/Extend command.

If you find things in MoI for 2D type operations that do not feel comfortable for you with your AutoCAD background, please let me know. Of course for 3D modeling there are a lot of different things.


> How do you show surface control points like on ring_fillet8.jpg?
> First I click on the 3d surface and than on “Show pts”? This does
> not work for me – am I missing something?

If you have a solid that is made up of surfaces joined at trimmed edges, then MoI will not show points for that because it would be too easy to pull those points and open up holes along what are supposed to be shared sealed edges.

If you use Edit/Separate to break that solid up into individual surfaces, then you will be able to turn control points on for an individual surface because there is no longer any worry about it being pulled apart from a connected piece.

Please take a look at this answer for a more detailed explanation including some illustration. That also gives some more background on how trimmed NURBS surfaces work with "underlying surface" and "trim curves".

In the case of that one surface, I noticed some strange shading glitches near the bottom which is often a strong clue that there might be a problem with the surface in that area. Examining the control points for a surface can help to see if there is a problem with the way they are organized, they normally shouldn't have a kind of chaotic arrangement for the surface to work well.


> What is Network?

Network is another command to create surfaces, kind of in a similar way to sweep except the mechanism for it is a little different. But it does work by using a grid of curves that cross each other kind of similar to the way you would have sweep rails (and scaling rail) and sweep profiles that cross each other.

It builds the surface more in a "direct" sense, more similar to lofting. Instead sweep works in a way of making the profiles actually travel along the rails.

Check out here for some examples of Network.


> All these problem areas effecting fillet – are they going to
> effect other manipulations of the surface such of Booleans, sweeps?

Yes, for some of these operations.

The tightly curved area should not be a problem for booleans, but it will have a strong effect on Shell or Offset operations, they need to go a constant distance away in the same way as Fillet. Fillet actually incorporates an offset calculation inside of it.

The kind of messy surface at the tip probably means that the surface is kind of zig-zagging back and forth across itself down in that area, that kind of overlapping "folded on itself" type surface will cause problems for boolean operations.


I haven't had a chance to look at your attachment yet, I will take a look shortly and see if I can give you some comments more specifically on that. But just a quick note - really the Stretch command in AutoCAD is the same thing as turning on curve control points and doing a window select to only select the points inside that area, and then moving those to the side.

For example for things like rectangles and lines you should see the same behavior between AutoCAD Stretch and that above procedure in MoI of Control Points + window select + move.

- Michael