Back in the saddle

Now that the euphoria of being officially promoted to the level of “SolidWorks Advanced Beginner” has finally worn off, and most importantly, that I’ve had some time to sleep, I can  go back to learning more about SolidWorks. I can once again explore a bit on the intermediate and advanced topics and techniques, confident that I have successfully managed to cover the basics. Yeah!

So, this week, I’ve decided to spend some time learning more about lofts and sweeps, since I’ve been intrigued by those two features from the very beginning.  Basically, what intrigues me the most is how to use lofts and sweeps with non-planar paths and profiles, with guide lines, and 3D sketches in general. But before I can do any kind of sweep or loft, I have to learn about how to create such non-planar curves and sketches.  I decided to try my luck first with the one that attracted me the most: the projected curve.

Basically, the projected curve command creates a 3D curve by means of projecting a sketch onto a face or  a sketch onto a sketch. Projecting a sketch onto a sketch  simply means that it will project those two sketches in space and create a 3D curve that will pass through the points where the two sketches intersect.  This reminds me a lot of the way we used to create isometric  drawings and perspectives back in the day, by projecting three different views, more or less the same way, and finding the points where they intersected each other. 

To create my projected curve, however, I only need two views of my sketch, or a sketch and the surface that I want to project it on. First, I tried to experiment projecting a sketch onto a sketch.  I decided to copy (or at least try) the plastic mask that my older son uses to inhale his medication (my son has Asthma). He’s got something very similar to this, and I only tried to recreate the mask, not the complete OptiChamber.

 

You can’t see it very well in the picture, but the way this mask looks suggests a loft from the edge that is in touch with the patient’s face, to the cylindrical part that goes into the OptiChamber.  The edge that touches the face of the person would be the 3D sketch that I needed to create by using the project curve command.  So, first I created  sketches of how the edge would look like when seen from the front and from the right.

By applying the project curve command  to Sketch 1 and Sketch 2, the result was  the 3D sketch that defines the edge of the mask. Just what I needed!  In the image below, you can see the 3D sketch colored in yellow, and the two 2D sketches in green.

Next, I sketched a circle on a plane parallel to the Right plane, and a couple of guiding lines joining both profiles.  The guiding lines would help shape the loft between the 3D sketch and the circle, so the transition between them wasn’t plain and straight, but rather curvy, like in the real mask.

The next step was a little shock, because SW would not allow me to create a solid loft using this profile, so I had to use a lofted surface and thicken it to a solid.

After adding the cylinder that connects the mask to the OptiChamber, it looked a bit more like the real thing. I’m just missing the “cushion” that goes around the edge and that makes the mask comfortable for the child.

For an example of the sketch that projects onto a curve, I tried to recreate a funky path for a circular sweep that I had read about in  a tutorial, some time ago. The path is supposed to go around, like a knot. There was no SolidWorks file with this tutorial, so I couldn’t actually see the part and roll it back. I just had to come up with my best approximation to it from what I remembered about the instructions I had read. Please, pardon my less than stellar use of surfaces and splines here!

According to this tutorial, the idea was to first create a surface by extruding a couple of arcs, like the one in the following image. The sketches that would create the path for the sweep would be projected onto that surface.

Next, the two curves that were sketched as a 2D line and a spline on the right plane, are projected onto the surface using the projected curve command.  This is very simple, really. All that is need to do is to select the sketch I want to project and the surface, like in the following image.

 

The two resulting curves are shown in red. The lines in blue are the 2D sketches that I projected onto the surface.

The next step is to combine both curves into one by using the composite curve command (Insert, Curve, Composite Curve).

Now we can hide the surface and use that composite curve as the path for a sweep feature. Mine didn’t turn out as nice as the one in the tutorial, but you get the idea.

The “knot” is created by making a circular pattern of the sweep, with only two instances, around Axis 1, like in this image.

The use of a sketch projected on a surface as a path for a sweep feature doesn’t need to be this funky all the time, but I thought this exercise was kind of neat and that’s why I wanted to try it.

Yes, I still have a lot to learn about all the different ways in which you can create curves in SW. I'm beginning to think that the more I know about this particular, the better my sweeps and lofts will turn out. What do you think?

Comments

[matt]

Gabi,

Thanks for a fresh perspective on what can be a very complicated topic. Curiosity is a great way to investigate things.

[Gabi]

Thanks, Matt! Believe me, it is a very complicated topic for me, and that's why I'm so intrigued by it. All these different ways to create curves... You said you had a chapter on splines in your new book, right? I can't wait to see it. Also, I was a bit surprised when it turned out I couldn't do a solid loft with that profile, but a surface would do. Here I was thinking I didn't really need to explore much about surfaces to get by. That I could accomplish pretty much anything with solids. Now I really can't wait for your book!