Model A: Running Boards
The next part of the Model A to tackled are the running boards. I’m not particularly proud of the way they turned out. With each project you do, you learn a little bit from your mistakes. This project offered many such opportunities for learning.
From the previous post, I already had the layout sketch showing the main profile of the running boards. This gives us a great chance to have a look at some really cool functionality in the Boundary feature.
I started with the spline from the layout, and then added a few planes perpendicular to the spline at the endpoints and various points along the spline. Then I drew an arc on one of the planes, used Pierce to make the spline from the layout sketch intersect a point added on the arc, and then copied the 3pt spline to each plane using a derived sketch, and reestablish the pierce relation at each one. Two of the arcs later became straight lines. This was the result:
Now realize that when you actually do stuff like this, you (or I anyway) don’t just take a straight line path through a model top to bottom. One of the things I dislike so much about tutorials like this is that they make every thing seem simple. Well, I’ve got news. NOTHING is simple. No matter what you do, you want to change it. Making stuff the first time is easy, but editing becomes something else entirely. Anyway, enough of that.
Next, I broke the feature up into 3 separate features. The reason for doing this is that getting a straight section in a single loft or boundary is never easy when the rest of the feature is so curvy. Doing this a second time, I would create the straight section first as an extrude, then build the other sections off of that.
Notice in the FeatureManager that the layout sketch (sketch4) is reused. I don’t recommend doing this exactly this way. In this case, I reused the original layout sketch. This means that instead of the layout sketch being at the top of the tree, it is now hidden under a feature somewhere. I wish SW could do something about this. There are a million or more enhancements that I think need to happen to keep the FeatureManager relevant at a time when history free modeling is coming back into vogue. The ability to assign spots in the tree would be one of those enhancements. Whether you want stuff to sink to the bottom or float to the top, users need more control over history.
On top of the layout sketch (sketch4) being reused, it is also being shown as a contour. This means that not all of the sketch was used for the feature. Remember that the layout also includes the sizes and positions of the wheels, but the Boundary surface doesn’t use the wheel circles. The SelectionManager is used to select portions of sketches for use in the loft and boundary features. This is an essential piece of information if you use either feature.
Notice also that some of the sketches are listed as derived. And then notice that Boundary 3 does not show any direction2 sketches, only direction1, which is the shared layout sketch spline. This is because the direction2 curves are actually the edges of the boundary surfaces around the wheels. I could have reused the sketches used to create the earlier boundaries, but I didn’t. It’s a trade off between best practice from an organizational standpoint (reusing sketches) or best practice from a “making good geometry” standpoint. So confusing.
There are more interesting things here too. Let’s look at the boundary feature itself.
Lots going on here. The first thing you have to do with Boundary is to turn off the Curvature Combs, there at the bottom. Why SW doesn’t just turn this off, I can’t say. Notice that the Direction2 curve (purple) extends past the Direction1 curves. This is one of the great things about Boundary that I don’t think has sunk in for the general populace. You can make surfaces with curves shaped like the letter X. You just can’t do that with anything else. You have the option of using the Trim By Direction1 setting, or not. Once you play with this feature, the modeling possibilities open up that never existed before in SW.
There are a couple of things to watch out for here. Sometimes when editing something unrelated, the Boundary surface would flip connectors on one of the Direction1 curves. This was annoying because randomly the feature would fail, and you would have to edit it, RMB on the correct curve and choose Flip Connectors, and then it would work. Anyway, it was really annoying, and unnecessary, especially considering that SW rebuilds features every chance it gets, and you’ve got to count the edit time as part of the rebuild time.
The next thing that was annoying with this was that when shaping the ends of the runningboards/fenders, SolidWorks refused to trim one end. It would only allow me to keep the side I wanted to get rid of. Very annoying. To fix it, I went back and recreated a portion of the trim sketch. I was using a Spline On Surface to trim (with the Intersection option). I instead used a 2D sketch with the Projection option. Things like this happen, and you just have to be able to work around them. If you are the kind of modeler with no patience, and you expect everything to work (much less working right, much less working right the first time), you should just sit at home on the porch swing and sip lemonade. Surface modeling in SolidWorks ain’t for the faint hearted. This is not point-and-click, drag-and-drop modeling. You have to swear and pound the table furiously and then in the end just come up with alternative methods to get some of this stuff to work.
More Model A modeling in a later episode. This is where we are so far:
