- [Kevin] In just 25 minutes, you'll know the foundational concepts to working with T-splines in Fusion 360. This video is sponsored by thangs.com, a new 3D model community. Stick around to learn more about them and the second 3D modeling challenge this time with more prizes. (air swooshes)
(logo chiming) Before we start modeling
we need to spend a minute to cover some terminology. Fusion 360 is unique in
that it offers three types of modeling all in one program. In the Design workspace you'll see that we have
the solid modeling tab. Solid modeling is the first type and they represent solid
water-tight bodies. Surfaces are the second type of modeling. Surfaces represent
infinitely thin surfaces, usually making up only the
exterior surface of something. And you guessed it, the
third type is T-splines. However, you'll not see a
T-splines workspace or tab. We'll discuss what defines
a T-spline in a minute, but let's first enter
the T-spline environment. The only way to enter is
by selecting the purple create form icon. Fusion 360 will convert your
T-splines into a solid body once you're done working with them, that is why they're
located in the Solid tab. In some cases, they'll
turn into a surface body which we'll look at later on. Notice how we're now in
the form contextual tab. In Fusion 360, the term Form
is synonymous with T-splines. You may hear some refer to Fusion 360's T-splines as sculpting. Now this is in part because
the T-spline environment used to be called the Sculpt workspace. However, the term sculpting
doesn't best represent the type of modeling that T-splines offer. It misleads many to think
that they're working with a polygon mesh program
where one can simply drag their mouse around to
digitally sculpt things. Let's get started with this
simple jack-o-lantern model. This is a great practice
object because the result is organic and there really is no perfect result to shoot for. There are three ways to
start a T-spline design. The first way is to use one
of the primitive shapes. The second is to start with a single face. And the third is to use one
of the core modeling commands, Extrude, Revolve, Sweep, or Loft. The most important best
practice with T-splines is to start as close to the
overall shape as possible. This will help you avoid
unnecessary issues or errors and it's where I see most go
wrong from the very beginning. Many attempt to start with a
primitive, such as the box. This method is better reserved for intermediate and
advanced users as you often have to break or split the primitive before manipulating it
into the overall shape. It takes more experience and strategy. Starting with a single face works best when you have a bunch
of sketches to reference or for very specific
shapes and I recommend this for intermediate users as well. The third and final option is what we'll take a look at today. I recommend this as the best
starting point for beginners because it's most similar to
Fusion 360's solid modeling. Working with T-splines
takes a different mindset than solid modeling and this
route helps bridge the gap. Looking at our object we can
consider the different ways that the overall shape
can be formed as a solid. In our case, we could
sketch out a side profile of the pumpkin followed by revolving it around 360 degrees. Thus we'll use the Form Revolve command, which works similarly to the solid and surface Revolve commands. We need to first sketch out
the pumpkin side profile. Now you can create sketches
while in the Form environment just like we would with a
solid in surface environments. Sketches are independent
of the modeling types so it's important to call out that they can be created at
any point in your workflow. We'll first use create sketch followed by selecting
the front origin plane. I'll start with the line command and I'll turn on the Construction option in the Sketch Palette. We're simply going to create
an 80 millimeter center axis, starting from the origin point. This will just help us start
the model at a desired scale. Once complete we can hit
the escape key to clear out of the Line command. Because the side profile
of a pumpkin is not perfect we're going to use the spline tool instead of an arc or ellipse. I'll find this spline fly out folder under the create dropdown, and then
the Control Point Spline. Now you could use either spline
tool to get the same result. However, I find the control points make it easier to define the shape. We're going to start by clicking on the center axis near the bottom. Now a best practice with splines is to use the fewest
amount of points possible. This will give us more
control over the curvature. We'll click about four
times to create half of the pumpkin and we'll
finish with the last point ending away from the center axis which will leave an opening
at the top of the pumpkin. To commit the spline we then
have to hit the Enter key or the green check mark. Before using Revolve,
let's hit the Escape key to clear all commands. We'll then adjust the
spine points until you feel that you have a side profile of a pumpkin. Don't worry about this too much as we'll use the T-splines
to further define the shape. One important thing to
note, just like surfaces, the form or T-splines tools do not require a fully-closed profile. We can now activate the
Form Revolve command from the Form tab under
the create dropdown. We'll select the spline for the profile. We'll then need to
activate the axis selector followed by the construction line. If we now look at the model, you'll see that we're starting with the shape pretty close to the overall shape of a pumpkin. With just a few simple
steps we're much closer to our end goal than if we had
started with a box primitive. This allows us to leverage
manipulating T-splines to refine the shape instead
of creating the shape. Let's click okay to
confirm the Revolve command and then we'll take a minute
to discuss what T-splines are. Looking at the model you'll
see that it's divided into several faces which we can click on. Notice they are selected in blue. Each face is made up of edges and all the edges converge
to create a vertex, but let's simplify it
and call these points. T-splines have faces, edges and points. T-splines are a type of NURBS surface. Now you don't have to know
what NURBS stands for. Just simply know that
it's one mathematical way that computer programs represent a three-dimensional surface. Some other CAD programs use
different mathematical ways to represent surfaces. Traditional NURBS surfaces require that all faces have four edges. T-splines can be considered a subset or type of NURBS modeling. The difference is that
T-splines can have three plus sided intersections resulting in a T or a star point where many faces converge. Essentially, all you need to
know is that T-splines offer more flexibility than
standard surface modeling as they reduce the amount
of math required to define the model. In return, that makes it easier to manipulate and control the surfaces. We now want to create the
creases or ridges in a pumpkin. Manipulating T-splines
will most often be done with the Edit Form command. After activating the Edit
Form command, I'll hold the Shift key followed by
selecting the two edges. The Edit Form command has a lot of icons and it looks pretty crazy, but it's much simpler than it appears. These icons simply allow us to move, rotate or scale in all
three coordinate directions. If I drag the single directional arrow, you'll see that I can drag the edge out or I can push it back in. However, you'll find that
we don't have enough control to make the ripples. This leads me to the second
best practice of T-splines. Remember number one is
to always start as close to the overall shape as possible. Number two is that we always
want to use the fewest number of faces possible, knowing that it's always
easier to add faces and it's much harder to remove faces. With that in mind, let's
hit cancel to undo. There are a couple of ways that we can create more faces. In our case we want there
to be additional faces around the model so we can have
more control over the shape. We'll go to the Modify dropdown and we'll select the Subdivide option. From here, we can select a face and you'll see that it divides it. In our case we want to control
the pumpkin all the way around so we can hold
the Command key on Mac or the Control key on Windows. We can then double click
on the face next to it, which will select the entire model. We want the insert mode
set to Exact as Simplify will affect the shape too much. We can then check the specify option, which allows us to define how
many faces in each direction. Let's change the length to three and notice how that adds
an extra row of faces. Instead of changing the width, we'll leave it set as two. Let's click okay and I want to show you a second common way to create
more faces. (energetic music) Before that let's talk about
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turn on the symmetry. That's going to allow us to manipulate multiple
parts of the pumpkin at the same time. Under the symmetry dropdown we'll activate the Circular - Internal option. Now, internal simply means
the symmetry pertains to this one part, while duplicate will
multiply the object itself. We then have to select a face
which simply tells Fusion which T-spline body we
want to add symmetry to. You'll then see that we
have these numbered options which can be confusing. Instead, let's use the dropdown
selector in the dialogue. Notice how the number
we choose will dictate how the symmetry is applied. All these green lines signify that we have symmetry turned
on at each of these edges. In our case, we're going
to crease the pumpkin all the way around so we'll want to use
the 16 sided symmetry. We can then click okay to confirm. Remember T-splines are made
up of faces, edges and points. All three of these can be manipulated. We want to subdivide
our faces even further so we can push some of the
edges towards the center, leaving us with a rippled edge. Under the modify dropdown you'll find the insert edge command. This feature lets us select existing edges to use as the starting point
for creating new edges. Because we have symmetry turned on we can double click on
one of the green edges. Notice how double-clicking
selects the entire edge. We can then use the blue
slider to position the edge, or we can type a location
between zero and one. Zero represents the existing edge and one represents the
next available edge. Let's type out 0.25. We'll also change the
insertion mode to Exact to make sure Simplify
doesn't alter our shape. Notice how after I clicked Okay,
it inserted the edge at all of the same edges around the pumpkin because we have symmetry turned on. We now have enough faces that allows us to better push them toward the center. We'll want to Shift
click four or the edges, omitting the first and
last edge in each column. We're omitting these so we
don't affect where the faces converge at the top and the bottom. Again, because we have symmetry
on we only have to select them once and it selects them everywhere. We can then right-click
to select edit form. One quick note, to follow
along without any issues you'll want to select the edges that match the direction of the X axis. This is so we can push
the edges straight in without twisting them left or right. We can then either use
the single direction arrow to push them inward or we
can type out a specific value such as negative eight millimeters. Let's click okay and see
what this looks like. We can also remove the symmetry with the Clear Symmetry command. Selecting the model and
hitting okay will turn it off. Overall, this is a good
start for the pumpkin shape. Another critical concept
that I want to point out is the idea of T-splines being converted to a solid or surface body. To leave the T-spline
environment, we're required to hit the Finish Form
button in the toolbar. I want you to watch what
happens as I select Finish Form. Notice how we're left with
a gray and yellow body. If we check the body in the browser, you'll see that we have an
orange icon for the surface body. This is because we left an opening at the top of the pumpkin. When a T-spline is not fully-closed it will result in a surface body. When a T-spline is fully-closed it will turn into a solid body. To re-enter an existing Form environment we can double-click on the
purple Form icon in the timeline. Let's continue by creating the stem. If I double-click on this inner edge it will select all the way around it. Once again, I can activate
the Edit Form tool. This time we'll use the
universal scaling icon in the center, which means it will scale
the faces in all directions. Watch what happens as I
drag this left or right. Notice how it scales the
faces in both directions. I'll hit command plus Z to undo and this time I'll hold
down the Option key. If you're on Windows, you'll
want to hold down the Alt key. Notice the difference? Holding the Option or Alt
key will extrude the faces at the same time ensuring
it doesn't affect the position of the pre-existing faces. Same thing for heading to the top. If we simply pull straight up, then it will affect the surrounding faces. However, if we undo and hold
down the Option/Alt key, it will extrude the faces
without effecting the others. We can then use that center scaling icon to give a taper to the stem. Once that is complete, we can click okay to
leave the Edit Form mode. At this point, we need to
close off the top of the stem so we end up with the solid body. We'll then alter the
shape a little bit more to make it asymmetric. Under the Modify dropdown, we'll find the Fill Hole command. We simply need to select one edge of the hole and it will detect the rest. Notice how we end up
with this funky shape. To fix this we can try out
the types, and in our case, the collapse method will give us the most appropriate result. If we now Finish Form we'll
end up with a solid body. However, let's first adjust the T-splines. A common question I get is why can't I use selection filters with T-splines? The answer is that you can, but they have their own filters located within the Edit Form dialog. Notice the selection filter section and in this case, we want
to select the Faces option which means we can only select faces. We can then select over
the top of the stem which allows us to rotate
or reposition the stem. Take a moment to experiment with this to see how you can alter it. You can even experiment with
changing the overall shape so it's not symmetrical. Lastly, we have the option
of using the Thicken command to define an internal thickness if we want the inside to be hollow. To 3D print this I want the thickness to be about three millimeters. Under the Modify dropdown
you'll find the Thicken command. I'll select the body and type out three millimeters, before clicking okay. We can now Finish Form and we should end up with a solid body. If I use the Section Analysis tool, you'll see that the inside
of the model is hollow. But if we look at the Browser,
we do have a solid body. That means we can now use any
of the solid modeling tools to add the final touches. This is the third best practice when it comes to T-spline modeling. T-splines are intended to
get the core shape done, and the details should
be done with the solid or surface modeling tools. For example, we can create an offset plane off one of the Origin Planes, which allows us to sketch
a face on the front. I encourage you to have fun with this and to spend time sketching
out a unique face. You can then Extrude cut
the face out of the pumpkin. For the sake of time, I want
to jump ahead to show you how I cut out the lid of the pumpkin, as well as flattened the bottoms. Starting with the bottom
we'll create an offset plane off the bottom Origin plane. We can then use the Split Body
command from the tool bar. This allows us to select the pumpkin as the Body and the plane
as the Splitting Tool. We end up with our split body in the browser and we can
right-click and remove this. To cut the lid out we want
to cut all the way around at an angle, ensuring the
lid cannot fall inside. I'll first create an Offset Plane near the top of the pumpkin. Now on this plane, we'll sketch a circle with a diameter of 60 millimeters. We can then create a sketch
on the side Origin Plane, allowing us to draw a straight line. We're simply creating a line
at a 30 to 45 degree angle so we can surface sweep
it around our circle. Under the Surface tab,
we'll use the Sweep command. The profile is our line and the path is our 60 millimeter circle. There are two reasons I
created this as a surface. First, we avoid needing
a closed profile sketch. Second, we can now use the
parametric Thicken command to apply a clearance, ensuring the final 3D
printed lid will fit. I'll type out a clearance
of 0.5 millimeters, which is what works well with my printer. Of course, you may need
to test your tolerances as every printer is different. We can then use the Split Body command just as we did to the bottom. This time, we'll have to
remove the two extra bodies. At this point we'll have to
clean up the bottom of the lid so it can print separately
and then we're done. I'll select the body and use the Move tool
to position this above. Anytime we have a funky bottom, you can try to select it and delete it. In this case, it ends up
leaving us with a cone shape but we at least have the proper angle so we can create a Construction Plane and once again, split this
body to clean up the bottom. Now we have a nice flat body so we can print the lid separately. We can also try to clean
up the bottom surface of the pumpkin by selecting
that followed by the Delete key. Because this one has a
surrounding flat surface, it should automatically self heal itself leaving us with one flat surface. You're now ready to save each body as an STL file for your slicing software. By the way, I've also placed
a link with my STL file down below if you would
like to print it out. In summary, we looked at working with T-splines in Fusion 360, including some best practices
and foundational workflows. We also looked at using surface
and solid modeling tools as post-production to add
the remaining details. This is a key point as
you'll rarely ever do all of the modeling work in
the Form environment alone. (energetic music) Last but not least I wanted
to give a special thanks to all the new Patrons;
Bob, Gerard and Kevin... and thanks to Billy and
Justin for buying me coffee. Be sure to hit that red
subscribe button for me, it's not only a great way to support me and the content for free, but you'll get to see the
latest and greatest tutorials in your YouTube feed. You can also check out
that playlist in the lower right corner to watch
more T-spline tutorials.
