Join Gabriel Corbett for an in-depth discussion in this video Spline creation, part of Surfacing with SOLIDWORKS.
- Splines are one of the most interesting and complicated of all the Sketch Entities. To go ahead and start drawing splines, let's take a look at the Sketch menu. Up here under Sketch you can see I have Spline right here. If I click on the dropdown you can see I have Spline, a Style Spline, which is really great for creating a very smooth, flowing curves. I have a Spline on a Surface, which is what you see down here in this view window here. Here's a surface and here's this drawn directly on top of it. Then you have Equation Driven Curve. So those are our basic types of splines that we can draw.
To get started, let's jump over here and I'm gonna take this spline here and just hide it, so see that, and I'm gonna go down here, and I'm gonna hide this for right now. Same thing with this line right here, which is that 3D curve, go ahead and hide. Go up to the top plane. I'm gonna click on Normal To, and then go over here and start a spline. Now any time you start a spline, it's gonna start with a single point, so you just click once. Now as soon as you have clicked, you now have the spline attached to your cursor. You know you're in Spline Tool because you have a pencil with a little spline directly below it.
Now in my next point, which is going to be right here, notice as soon as I click on that point, I have a line that's now drug through those two inflection points. You can think about a spline very similar to something like a piece of wood, a piece of spruce that was bent around a couple of nails in the floor. That's originally how splines were defined when they were doing boatbuilding. Then you'd take a piece of wood, and they would bend it around a couple of nails in the floor to get a nice smooth, flowing curve. So that's exactly what we got here.
Now if I click on a couple more points, you can see I've got it so it's bending through all those points. As I move it around it flexes that spline in a variety of ways. Now I'm gonna add one more point here and then finish it off. Then my last point here, notice it's still attached to my cursor. If I hit escape it will end that feauture and there's our shape. Now I have a lot of options here. I can grab the endpoints. I can move them around, drag them around here. I can move the other points here, move them up and down.
I got a lot of control over this. Now if you also click on the spline itself, you can see I've got these little control anchors all over in every one of these little points. I can grab any one of the little arrows and drag them out to influence the amount of force that is applying to the spline. I can also rotate these so I can rotate the little anchors around and around to get a little more power, adjust how it's affecting the spline. Now notice if you change one, all of the inflection points will automatically adjust and the entire spline will be adjusted as well.
So that's a very powerful curve that we've got there called the spline, and it has a lot of features you can add, and that's not it. You can even add-- You can right click on it and you can see over here I've got all these things you can add into it. So Tangency Control, Insert Spline Point, all these little things here that will make it a little bit easier to build the spline that you're looking for. One that I really like to show is Show Curvature Combs. As soon as I do that, notice that I got these little lines protruding from my spline showing me the shape.
You see if you've got big lines up here on the top, you get a nice smooth curve. If you start moving your spline around, you can start getting things that don't look as smooth. Like you'll see over here it's gonna extend out a little bit. So it's really more of something you can use to lay out your spline and see if it's gonna be a smooth curve, and if it's not, you can adjust it using those combs. You can turn those off just the same by coming down here and turning those back off. Anyways, that's your basic spline. Now let's go ahead and exit out of that.
There's our spline. Now the next one we're gonna do is we're gonna draw a spline on a surface. So let's go down and show that surface, which I've already created, there it is. Now I want to start a spline directly on top of that. I'm gonna go over here to the dropdown next to Spline, come down to Spline on Surface, choose the surface I want to draw on, and then I can literally just start drawing. Sometimes it's a little easier if you spin this around a little bit so you can see what's going on. There it is and a couple more.
When you're finished, go back to the original point, connect it and you've got a nice enclosed boundary drawn directly on that surface. So that is the Spline on Surface, and you have all the same controls on that that you did on a regular spline. So you can grab the endpoints, you can drag it around, move it around, but anytime you're dragging or moving, it's always to be dragging it on that surface itself. The next one I'm gonna look at is if you pick a different plane, let's just say something like the Front Plane here. I'm gonna start again a spline, and I'm gonna say Style Spline, okay? This time I'm gonna click Normal To, so I just use the spacebar and click on Normal To.
This time I'm gonna grab a couple points and just drag it out. But notice when I draw a Style Spline, I'm not actually adding the inflection points, I'm creating a control polygon. I'm gonna click and escape out of that. Then I can drag these points here to control the shape of that style spline, which gives you a nice, very smooth flowing curve. I can grab the endpoints as well to move things around, but it gives us a lot, a little bit more control over that spline to kind of get those smooth curves and make it really a nice looking shape.
This is a really great tool for when you're doing like product design or like injection-molded tools that you want a Class A surface that's gonna be coming out of this thing, and a little bit more control over it, but not too much control. Sometimes when you get with regular splines, you end up with too many points and too many control vertices you're pulling on, and it starts looking a little bit funky. The Style Spline gives you a little bit less control but a little bit smoother curves. That's kind of the basis behind that tool. So those are your basic types of curves. The last one I wanted to point out here is this Equation Driven Curve.
Now I don't really have an equation to set up for this example here, but if you do have something that you really need to actually plot some type of an equation, that's what you'd use this for. There's actually a few other types of equation driven curves that are already pre-defined here. If you go to Tools, and you come down here to Entities, Sketch Entities. You notice over here I've got Ellipse, Partial Ellipse, Parabola, and Conic. Those are things I can draw automatically using the Sketch Tools inside of SOLIDWORKS.
Notice they're grayed out right here. That's because I'm already in a sketch, so if you go back over here to Tools, you come back over here to Sketch Entities, there they all show up and you can create a new sketch based on any one of those things. Notice you also have the ability to get the splines in here as well. So those are the basics for spline creation. It's a very, very powerful curve and there's a lot that goes into it. There's a lot of controls you can add to a spline. It's really used exclusively for doing surfacing and product design that you're using, maybe injection molding and things like that, that you really want smooth flowing curves, very aesthetic-looking shapes with a lot of control over the shape of the spline as well as the surface you're gonna be creating from that spline.
- Defining planes for surface creation
- Creating splines and 3D curves
- Making revolved surfaces
- Building boundary and lofted surfaces
- Offsetting a surface
- Trimming and untrimming surfaces
- Adding fillets
- Fixing corners
- Deleting, moving, and replacing faces