The Magical Fill Surface
The Fill Surface is different from the other types of features like loft, boundary and sweep. The main difference is that Fill is magical. Honestly, you can make the Fill surface do things that are hard to believe, and certainly things that the other features won’t do.
- degenerate patches (less than 4 sides)
- irregular patches (more than 4 sides)
- open patches (using Fix Up Boundary)
- control curves (full or partial)
- atomic bomb fillet
The main thing that Fill is supposed to do is to fill an n-sided patch. The patch can be filled with tangency, curvature continuity or simple contact at the edges. The boundary around the Fill can be edges or 2d/3d sketches.
Fill can even just make something up if there is an open loop. This uses the Fix Up Boundary option. This is something you don’t want to use often, because the software just gives you an arbitrary fill-in curve between the last open points of your boundary selection.
You will find me using the word “boundary” a lot in this post. I’m usually not referring to the Boundary feature, but to the boundary around the patch that Fill is filling. To make matters worse, the Solid Edge equivalent to the Fill feature is called Boundary. And the SE equivalent to SW’s Boundary is called a BlueSurf. Unfortunate naming isn’t the sole domain of any single software developer, it seems.
Fill is generally only used when other surfaces already exist, you could possibly use it as the first feature in a part, but it would be awkward and certainly not playing to any of its strengths.
Some of the surprising things about the Fill surface:
- you can’t control the UV direction
- no connectors
- can knit together bounding surface bodies
- can create a solid from a closed surface body
- can perform the equivalent of a Replace Face on a solid body
Downsides
There are a couple of downsides to the Fill feature. Each magic wand has its weakness.
- The first downside with Fill is that you cannot assign connectors like you can with Boundary. You can actually get some control of the shape by using Constraint Sketches, but there is nothing as easy as connectors to control the flow.
- Fill surface does not have tangency weighting around the boundary like Loft and Boundary and splines. This is an option in those features that helps you control the shape.
- You cannot control the flow, aside from some isolated circumstances with Optimize Surface setting. Bummer.
- There is no inherent symmetry in this feature. Even if the boundary and tangency settings are symmetrical, you don’t have any guarantee that the finished surface will be symmetrical, especially since you can’t control the UV directions.
- When it doesn’t work, it doesn’t work. It’s very difficult to trouble shoot this feature since it is so automatic. All you can do is change the tangency settings, or go back and fix the boundary.
Examples
The recent and on-going improvement of the Dezignstuff Episodes eCourse has given me a lot of opportunity to make some models that I might not normally get the chance to make. Some of these make great examples for showing off certain features in the software. Examples are the best way to talk about why Fill is such a magical feature so here we go.
Bike Frame – Irregular Patch
The classic example from my stuff has always been the bicycle frame. There are a couple that can be shown, but the one at the bottom bracket is maybe the most impressive. Notice that the surface has to be completely surrounded, and that the UV mesh doesn’t line up with any of the geometry around the patch. One of my favorite aspects of this feature is that no matter how crazy the shape, Fill usually comes through for you.
Bottle Bottom – Dome
Another classic Fill feature example is the indentation on the bottom of a bottle. This one isn’t even tangent, it just raises a dome with the help of a 3D sketch point. You can’t see it in this image, but there’s a little sketch point raised up above the origin slightly which is used as a Constraint Sketch. The surface has to touch the constraint sketch. Constraint sketches can be continuous (like an arc all the way across) or discontinuous (like a point or an arc that doesn’t touch either edge.
Sunglasses – Cap Off End
This technique can be extended to the ends of handles or sunglasses, as shown here. In this sunglasses example, there was a continuous constraint curve, which went across the shape from one side to the other. The sunglasses actually made a lot of use of the Fill surface in several examples.
Corvette – Atomic Bomb Fillet
The ’63 ‘Vette Stingray model had a couple examples of the Fill surface. One of them is shown here, with the semi-circular patch in the middle of the image where all of the rounded edges come together at the point of the cyclone. In this case, you just trim away all of the geometry that has to blend together, and allow Fill to do it for you automatically.
Really, how else would you do something like that?
Throne – Egg
One of the more outlandish models I created for the Episodes eCourse site was a throne. one of the simpler features on the throne gives us a good example of the Optimize Surface setting in the Fill feature.
One of the reasons you use the Fill feature is to avoid degeneracies/ singularities where all of the U or V lines come to a single point. Both of the images below are of a Fill feature, but you will notice that the one on the right is degenerate.
One of the strengths of the Fill surface is that it doesn’t require a 4 sided boundary, but when you do have a 4 sided boundary, you can force the UV to match the surrounding surfaces by using the Optimize Surface option. I’ve rarely found this to be useful, and this is one of the times when it was actually a bad idea. The UV arrangement on the left is preferable because it doesn’t have the degenerate points (like north and south poles on a globe) of the one on the right.
Razor Handle – Multiple Conditions
The razor handle example has a nice shape in it that was created by a Fill surface that used all of the tangency options in a single feature.
Two edges of the boundary of the Fill are on edges that need to be contact only. One uses Tangent, and one uses Curvature. Again the edge that appears to have no boundary face is using an extruded reference face to take the place of the symmetry plane. Notice that although this feature gets mirrored (and the mirror works), the UV mesh does not line up nicely with the symmetry plane.
Rubber Ducky – Irregular Raised Area
The wing of the Rubber Ducky was created from a hole trimmed in the body, and then a Ruled surface being created to control tangency. Then the wing was made from a fill surface with a 3D sketch point as a constraint curve.
Again, if not for the Fill surface, how would you make a shape like this in SolidWorks?
Cowboy Boots – 3 Sided Rounded Toe
The Cowboy Boot model was a decided change in direction for me. While I have modeled footwear before, it was always, for some reason, high heel women’s shoes. I don’t own high heels or cowboy boots. All of the surfaces shown in blue were modeled with Fill surface. The toe, as a 3 sided surface with a rounded point, is a particularly good example of what you can do with Fill.
Several of these models are detailed in the Episodes eCourse. We have dozens of people signed up. If you find this kind of stuff interesting, you should subscribe to the site and learn about these tools in more breadth and depth.