Create and modify sketches — part 1

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Create and modify sketches part one.

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After completing this video,

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you'll be able to

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create advanced sketch entities,

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create intersection curves,

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and create advanced sketch constraints.

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To get started in Fusion,

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we want to open the supply dataset,

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Sketch sample.

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F3D.

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When we take a look at this file,

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it only has a single sketch currently and a couple

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of other features that were added in the timeline.

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Things like an extrude,

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a filet,

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a pattern,

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as well as a new plane that was created.

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In this video specifically,

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we're gonna talk about sketches and some of the sketch

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options that we have available to us in Fusion.

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For example,

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making parameters and linking those to sketches.

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The first thing that we want to explore are intersection curves.

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So to get started,

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we're going to select the visible construction plane,

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right click,

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and create a new sketch.

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When we think about intersection curves,

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there's a couple of things that we need to understand about fusion.

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I'm gonna rotate this model,

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and I'm gonna use the slice option inside the sketch palette.

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The slice option is going to be a temporary section view through the model.

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The section view happens on the sketch plane that's currently active.

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While fusion does allow us to create 3D sketches for all of our sketches,

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in this case,

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we want that option turned off and look at this just as a 2D sketch.

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When we look at this as a 2D sketch,

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we can go to our Create menu

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down to Project Include,

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and we can use the intersect option.

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When we enable the intersect option,

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we can either select specific faces or use

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the bodies's option to select entire solid bodies.

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The projection link will ensure that we have a

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link between the solid body and the sketch itself.

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We can say,

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OK,

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and if I temporarily hide the solid body,

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we can see that we're left behind a sketch

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that has 4 separate entities.

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Uh,

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the reason that this is 4 separate arcs instead of a single circle is because

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there were 4 individual faces on the body that we use the intersection on.

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If we toggle off the slice option,

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we can see that our intersection curve is being created.

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The intersection tool is extremely handy when trying

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to get information about a solid body or surface

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that is cut on our section plane.

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Make sure that we understand that the intersection curve

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isn't the only way that we can get intersections.

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The intersection curve

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option

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allows us to have intersections between multiple 2D sketches

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and create a 3D curve.

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This requires us to have 3 individual sketches,

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and we can talk about that a little bit more.

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But to understand this better,

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let's go ahead and finish the sketch,

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and let's create a new sketch.

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We're going to create a new sketch on our front plane,

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and we're going to simply use a line.

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I'm gonna create a line that's going up at an angle.

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And then we'll finish this and finish the sketch.

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Next,

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we're going to create a 3rd sketch.

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This time,

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pick any plane you want.

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I'm going to use the top plane

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and rotate this around.

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Let's hide the solid body for now and go to our create menu

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to project include

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an intersection curve.

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The intersection curve differs from intersect,

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because we're not looking at the intersection of our sketch plane in a solid body.

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In this case,

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what we're looking at is the intersection of curves with a curve or a face.

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For example,

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if we take this set of arcs here,

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As we begin to select them,

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notice that our first selection can only be a single curve,

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and it automatically goes to selecting the other three curves for our projection.

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So let's go ahead and cancel this out,

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and instead,

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let's go ahead and select one of the curves,

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and for the curve or face,

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we'll select this one up here.

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What ends up happening is now what we're doing

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is we're projecting this curve normal to its sketch plane

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to the intersection of our secondary curve normal to each sketch plane.

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So if we look at this from the front,

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it simply looks like the line that we created.

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If we look at it from the top,

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it simply looks like the arc we selected.

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But if we rotate this around,

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we can start to see that what we've done is we've projected this arc into 3D

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based on the projection of other curves.

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I'm gonna select cancel because we don't need to say this,

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and then we can finish our sketch.

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Let's go ahead and hide sketch 4 and sketch 3,

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as they aren't needed for the rest of our examples,

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and we'll bring back the solid body.

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So mainly we want to make sure we understand that we can create an intersection

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of our sketch plane and a solid body for this example,

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or we can create an intersection curve

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that is a projection of different curves into 3D

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based on their normal or or their sketch plane projection.

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Now that we have a basic understanding of the intersection,

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let's also talk about projections.

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I'm going to select the top face of this part,

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right click,

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and create a new sketch.

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In this case,

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what we want to do is go to project include and project.

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Note that by default project has a shortcut key P on the keyboard.

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For this,

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what I'm going to do is I'm going to select the arcs that we created

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with our intersection curve by just working

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my way around and making those selections.

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What the projection tool will allow us to do is project curves or solid bodies,

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in this case a silhouette of a solid body,

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onto our current sketch plane.

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When we do this,

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what we're doing is instead of creating an intersection between

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our sketch plane and let's say a solid body,

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what we're doing is we're taking that geometry and

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we're projecting it up to our current sketch plane.

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This can be extremely handy for transferring things like

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bolt hole locations or specific geometry from one body

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to a sketch plane creating a secondary body.

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Now that we've got a basic understanding of intersections,

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intersection curves,

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and projections,

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let's talk a little bit more about advanced sketch entities.

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So when we consider

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advanced sketch entities are typically going to be things like splines,

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conic curves,

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or blend curves.

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The blend curve is actually found on the modify menu under blend curve.

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That'll create a curvature continuous or tangent curve between two selections.

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This is going to be very similar to us creating a spline between two things.

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To better understand these,

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let's start by selecting conic curve.

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A conic curve allows us to start by selecting two points,

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then we'll select a third point,

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and finally,

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we'll define what's called the row value.

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The conic row value,

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or the conic curve in general,

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is going to be a section or slice through a cylindrical cone

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that's cut at an angle.

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The higher this conic row value is going all the way up to 0.99,

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The closer to vertical we are at slicing through that cone directly in its center.

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The closer to zero this is,

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the further that plane angle is going to be,

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and the closer we are to a horizontal line.

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So,

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these conic curves are a great way to get started,

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creating a very nice curvature continuous curve

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that can be used as the starting point for geometry.

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I'm going to right click and select OK to create that curve.

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Next,

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I'm going to create a line.

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When we create a line,

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a line doesn't have any curvature.

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It's not curvature continuous.

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There's going to be zero radius of curvature on it.

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If we create something like an arc,

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an arc has a consistent radius of curvature.

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We generally will define an arc by a radius value.

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An arc that's completely 360 degrees is going to be a circle.

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So,

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when we think about curves in general,

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we've got lines with zero radius of curvature,

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we've got an arc that has a consistent radius,

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then we've got tools like a conic curve that has a variable radius of curvature,

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and this is defined by ar conic row value.

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When we get into some of these other advanced sketch entities like our splines,

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we've got fitpoint and control point splines.

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A fitpoint spline is a spine that has points that lay directly on it.

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If I start at the end of my conic curve,

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for example,

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and I end at my straight line,

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It just simply looks like it's a straight line itself.

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But if we had escape to get off our spine tool and we take a look at these green handles,

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what these handles are doing is they're defining the tangency direction

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and the weight.

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We can snap that or apply a constraint such as colinear or tangent or parallel

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to some other geometry like a line.

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We also have the option to select tangent

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and apply it to a curve,

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and this will automatically determine the direction of that handle.

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If we use other constraints like curvature,

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this will help us define the constraints such as the tangency direction,

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but also the weight of that handle.

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I'm gonna hit escape to get off of this since we already applied tangency,

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and we can control that tangency by moving and manipulating the tangency handle,

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which is also going to change the control points for our conic curve.

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When we think about the other spine type that we have available,

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this is called a control point spine.

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Now,

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a control point spine is very similar in nature to a foot point spine.

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However,

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this is going to have an external cage

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that's going to control the tangency direction of the spine.

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So we can build out

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complex curves with this external cage structure,

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or we can build out complex curves with these internal point structures.

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Now

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our fit point spine example only used to start at an end point,

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but in reality it can have multiple internal points.

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But in general,

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when you create complex curves,

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you want to limit the number of control points

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we have because the more control points we add,

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the harder it's going to be to control the curvature of our curves.

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We can see this by turning on curvature combs and inspecting these.

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Once we have curvature combs on,

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we can manipulate the handles and see how they change the curvature,

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which is going to be an indicator of the radius of curvature and also the direction.

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When the curvature comb crosses the spine,

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this is going to represent an inflection point where we

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go from convex to concave on our spine itself.

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Working with advanced sketch entities like splines,

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conic curves,

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and even blend curves can be a very difficult task and does require a good bit of time.

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The main thing that we want to understand for our certification

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is going to be the differences between some of these entities,

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for example,

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a fit point spline having points laying on the curve,

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and having these handles that we use to control

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the tangency direction and the weight or influence.

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While as a control point spine has this external cage that's gonna be

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used to drive the tangency and the overall weight of that tangency,

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however,

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it's just done in a different fashion.

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Because the sketching topic is going to be so large,

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we're going to break this up into two separate videos.

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So that'll conclude our look at intersection curves,

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intersections,

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projections,

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as well as using some more of these advanced sketch entities.

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So make sure that you have a good understanding at

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this point on the basics of things like spine creation,

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as well as the ability to create intersections and projections.

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Once you're done,

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make sure that you do save your design before moving on to the next step.