autocad_2011_surface_modeling_for_consumer_products.pdf

1 Surface Modeling for Consumer Products in AutoCAD 2011

Surface Modeling for Consumer Products

using AutoCAD 2011

Guillermo Melantoni Senior Product Manager: AutoCAD

Using AutoCAD, Inventor and Showcase

In this exercise, well explore the power of surface modeling in AutoCAD, and the potential for

interoperability with Inventor and Showcase.

Well use AutoCAD for the design of a case for a shaver. The shaver was previously designed in Inventor.

In this case, the scenario would be about a small shop that is creating the design for the case, and have

not yet moved into a high end design application like Alias Design. This shop receives the skin of the

shaver in a dwg file created in Inventor, and they will start the design for the case from there.

Towards the end of the design, well explore the option to do the whole project in AutoCAD or to send

the conceptual design into Inventor in order to proceed with the final touches on design and move to

fabrication.

Showcase will be used for visualization and overall design validation of the solution.

Well focus on the AutoCAD portion of the exercise. However, there will be basic explanations of steps

done in Inventor and Showcase too, but these do not attempt to be a tutorial about the use of Inventor

or Showcase.


Contents

Using AutoCAD, Inventor and Showcase .................................................................................................. 1

1. From Inventor into AutoCAD .................................................................................................... 3

2. Surface Modeling in AutoCAD .................................................................................................. 4

3. Building the Case in Inventor .................................................................................................. 44

4. Visualizing with Showcase ...................................................................................................... 47


1. From Inventor into AutoCAD

In order to export this part from Inventor into AutoCAD, we can take two paths.

Export an SAT file that can then be opened in AutoCAD with ACISIN command. SAT format is a

very good way to send information about solid models, and still the only way to get a solid from

AutoCAD into Inventor.

Theres also another option called AEC Exchange. From Tools > AEC Exchange, we can use the

option Export as DWG Solids, and well have a native dwg to directly open in AutoCAD.

If you have Inventor, you can try the process by opening the file Housing Left.ipt


2. Surface Modeling in AutoCAD

2.1. Changes in Visual Styles

Well now open the file 00 shaver.dwg in AutoCAD 2011. This is the model you should see upon opening

the file. If you change into 3D Modeling workspace, you will get a new Materials UI on the right. Close it

or minimize it for the time being.

The first thing well do is to check the new options for Visual Styles within AutoCAD. The Visual Styles

panel moved from the Render tab into the View tab (they can also be found in the Home tab).


Depending on what you need to do, you may want to use Realistic visual style (the one presented in the

file by default). This is great when in need to show materials to a non technical audience or for

communication in general.

However, being able to see edges or isolines may also be interesting. In surface modeling in particular,

visualization of the rows of UVs is very important, so we may want to target for a visual style that

already has a setting that allows the visualization of isolines.

In this particular case, well use X-Ray, which not only shows the structure of the surfaces and solids, but

also has some level of transparency, that allows a better understanding of the object.

We are using Perspective View by default. Once we get into the creation of the curves, we may want to

be in Parallel View. Well do this by right clicking on the ViewCube, and selecting Parallel View. The

background color will also be regular, and identical to the one in 2d wireframe. This way, we wont see

any changes when moving from an orthographic view into an isometric view.


2.2. Spline enhancements in AutoCAD

So lets start working in the design of the case.

First of all, we need to talk about splines. These curves have been enhanced in AutoCAD 2011, and offer

a quite powerful set of options that you need to understand in order to make the best use of them. The

old SPLINE command built a spline through Fit Points. Now, the construction of a spline through Fit

Points is one of the three methods presented in the Curves panel in the Surface tab.

We will now check the new Spline CV option. This is the SPLINE command with a macro that overrides

the selection of the Method. The two available Methods are Fit Points and Control Vertices (CVs). Fit

Points belong to the curve (when Tolerance is set to 0), while CVs are points located outside of the

spline. A change in a Fit Point is much more local than a change in a CV, which can affect pretty much

the whole spline.

Each method of creation has its own options. When defining the spline through CVs, we can select the

degree, for example.

Depending on the reference geometry we have, one of the two methods will make more sense. If we

know the location of specific points of the spline, then Fit Points will be better.

Well use both methods in the exercise.

However, we talked about three methods. The last one is the old SKETCH command, now defined as

Spline Freehand. This command has been updated, and can now produce not only lines, but also

polylines and splines. We can also determine the Tolerance and the Increment. These options will make

a lot of sense when using Spline Freehand. The bigger the Increment, the less CVs the spline will have. If

you want a lot of control over the curve and need more control of smaller details in the geometry, a

smaller Increment will help. Tolerance will determine how close the curve to the points that define it is.

Tolerance in 0 will force the curve to be interpolated through the points.

In 3d modeling workspace, go to Home tab, View panel, and choose Right view.

We could have achieved something similar by clicking on the face named Right in the ViewCube, with

the exception that this does not make the UCS follow. Thus, if you chose Right View through the last

method, you wont have the XY plane in the right place. This is only relevant if you want to use the

Spline Freehand option, which only allows a sketch on the XY plane.

Now create a layer called Case_Bottom. Make it current, and turn the wire 1 layer on. You may want to

lock it, so you dont mess up the points.


In the Surface tab, under the Curves panel, select Spline CV.

Make sure you have Node as an option in the OSnap Settings. You may notice, when you do so, that

there are also 3DOsnaps! But lets talk about them later.


Now just create the spline through the points in the wire 1 layer. Start in the last point at the bottom

and move up (in order to get the same results as the screen captures). You will notice that only the

first and last points belong to the curve. The rest are controlling the spline from outside.

You can also use Show CV option in the Control Vertices panel in the Surface tab in order to see the

control vertices. You can either select the command and then click the spline, or do pick first. Then,

youll notice that you can see the control vertices at any time, and not just when the spline is

selected.

Click on a CV, and youll be able to move it on the plane or even in space. Try to play around with

the position of the CV for a while, and see how the spline reacts. For the exercises sake, keep the

point in its place once you try this for a while.

If you hover over a CV in the spline, youll also notice that you get options for adding, removing or

refining vertices. The key idea to keep is that you may first approach the construction of the spline

with a basic sketch, and start refining it.


Try these options, and get comfortable with the whole workflow. Stretching a vertex is basically

moving the position of the CV. Add and Remove are quite self explanatory. Refine Vertex produces

two CVs without altering the spline. This adds control to the curve for further editing.

Another interesting option is Rebuild (Control Vertices panel in the Surface tab). This command

enables you to change the degree and the amount of CVs in a spline. It also works on surfaces. If you

have a spline with many CVs (maybe you created it with Spline Freehand), CVREBUILD will let you

define the number of control points. Of course this may have an effect on the shape of the surface,

but this is controlled by the Preview, which shows the maximum distance between the original and

rebuilt spline. This is called Maximum Deviation, and will help you decide if the change is acceptable

or not.

Try the setting that is depicted in the image above, and click on Preview. You will see two splines,

and a representation of the Maximum Deviation. Of course, by removing a CV, we are changing the

spline quite drastically, but it may be exactly what you need.


If you hit Escape, the dialog box will appear again, and you will see the value of the Maximum

Deviation. If you had clicked Enter, you would have deleted the original spline and kept the rebuilt

one (since Delete original geometry was checked in the Rebuild Curve dialog).

Now lets turn the wire 2 layer on, and do the same process with another Spline CV. You may want

to turn off wire 1 layer first.

Click on all the points, and you should get a result like the one depicted below. Feel free to try a

stroke with Spline Freehand, and see if you can get comfortable with that command. If you have a

tablet and a stylus, this option may become a very good friend.

You may have noticed that if you click on the spline, there are a couple of new graphics attached.

The pink cross defines the starting point of the spline, while the other graphic will let you move

between CVs and Fit Points. Sometimes you will notice that creating a spline through CVs is what

you want, but at some point you want a specific Fit Point of the spline to be moved to another

location. Thats when you will like to have Fit Points displayed. The options in the Right Click menu

will also change depending on the type of control the spline currently has. And yes, you dont need

to type SPLINEDIT anymore. Its just a right click away.


Lets complete the two remaining curves by turning wire 3 and wire 4 layers on. I would suggest to

do one curve at a time, and keep the rest of the points in the other layers off, in order to decrease

complexity.

Move into an isometric view, and use Spline CV to complete both curves. The end result should look

like this.

We only have half of the shaver, which is good enough to get an idea of how to design the curves

that will define the whole case. Anyway, you may want to get the whole shaver and we also need to

get the curves for the other side of the case, so lets use 3DMIRROR to get the other half of the

shaver and the two curves on the side. If you use the YZ plane as the symmetry axis, just click on any

point in the shavers section, and it will do the right thing.

And wheres 3DMIRROR? You can access it from the Home tab and Modify panel, or simply type the

command. Remember that if you start typing and use Tab, AutoCAD will suggest commands, so if

you just type 3dm and use Tab, youll get the 3DMIRROR command as a second option (since they

come in alphabetical order, and 3DMESH will come first).


After mirroring the geometry, you should have something like this.

Its time to start with surfaces. The first one will be a Network Surface. However, this kind of

surfaces needs curves on both directions. Well create the bottom of the case with them. This means

that we need to create some curves along the opposite direction to the bottom curve and the two

bottom curves at the sides. Since we know that the spline should have the three endpoints as part

of the curve, we will use Spline Knot.

Just select the Spline Knot option, and make two curves by clicking on the endpoints of the

previously mentioned splines. The result should be something like the image below.


2.3. Creating surfaces in AutoCAD

Even more important than learning the commands and different surface objects, is to know when to

apply which surface. Let me explain the whole process by showing you the final result and identify

the surface types.

The first surface well do is a Network Surface using the three longitudinal curves and the two curves

we did between them. A Network Surface needs curves on both directions, and they dont even

need to be intersecting. Of course, if they intersect and have coincident vertices, then the surface

will look exactly like we want. If not, there will be some interpolation done by the computer, which

we wont exactly control.

Now well complete the sides. We will use a Loft for this purpose, and well consume the remaining

spline, and the edge of the surface we just created. Why? Because the selection of a surface edge

will allow us to control the continuity between the surfaces. In this case, we want a perfect

curvature between these two surfaces, so well need G2 continuity. If we had selected both splines

for the loft, we would not have had the chance to define continuity. Thats also the reason why we

needed the Network Surface first.


The next operation is a loft, but in this case we can use the splines (the top spline and the top

splines from the sides). Why? The answer is simple. We just need to have coincident edges, but not

continuity, since this top surface will be a second part of the cover. We can also use the surface edge

with G0 continuity. If we do this, well have associativity between the surfaces.


The last operation will consist in closing the gaps on both ends. This will be done with Patch Surface.

Patch can operate with surface edges or curves, but in this case well use surface edges, even

though well force the solution to be a G0 (with no continuity in curvature or tangency).

Lets start with the modeling, then.

The first surface well do is the Network Surface. You need to select two sets of curves, which have

different directions. Once you finish selecting the first set of surfaces, youll click enter (or whichever

method you have for this), and then the second set of surfaces.

Lets take a look at the Ribbon. The option for Surface Associativity is on. This means that if you

change the position of the elements that originated the surface, the Network Surface will also

change. The control lies within the original curves. This is a great differentiator with strict NURBS

modelers, which create a NURBS surface once you click OK. Please note that you can also do this, by

selecting NURBS Creation. In this case, all associativity is lost.


Lets create our first surface using the Network command on the Create panel in the Surface tab.

Remember to select the first set of curves in one direction, and then the other set of curves, after

clicking Enter.

If you have Properties open (if not, you can get it in many ways, but a simple one is through the

Quick Access Toolbar), you will notice that if you select the surface, it is not only a Surface, but its

called a Network Surface. AutoCADs surfaces (if not created with the NURBS Creation option) are

explicit surfaces. It means that at any time, they keep the properties of the method they were

created with. Well see more value to this when we check the loft and the patch.


So we already talked about NURBS surfaces, Associative surfaces and Explicit surfaces.

Any surface created with the option NURBS Creation on, or converted into a NURBS surface will be

defined only by the grid of UVs. They are the most flexible in terms of editing.

However, you may prefer to work with Explicit surfaces when the method of creation is clear, and

there is no need to change it (Revolve, Extrude, Loft, Blend, Patch). These surfaces maintain the

relationship with the method used for their creation. For example, a revolved surface will let you

change the angle of revolution any time after its creation. If it was a NURBS surface, this would not

be possible that easily.

But we also have Associative surfaces. An Explicit surface could have been done without the Surface

Associativity option. In that case, a change in the geometry that originated the surface will not

change the surface. An associative surface is controlled by the original geometry. This means that if

you used two splines to generate a loft, the control for the edges of the loft will not belong to the

surface, but to the splines used for its creation.

Summarizing, a surface can be both Associative and Explicit at the same time. It can also be

Explicit only. A NURBS surface cant be associative.

And we could also talk about Parametric surfaces, but this exceeds the purpose of this tutorial.

Youll be able to check them in the Parametric Modeling with Surfaces exercise.


So we have the base of the case, but we now need the sides. Well use the Loft command. LOFT has

been around since 2007, but it has been enhanced, so lets check some of these enhancements. In

our example, we are going to use a curve and a surfaces edge. In the past, loft was only possible

with open or closed curves, and they had to be planar, at least the initial and final profile.

In 2011, we can loft non planar profiles, and when one of the profiles is a surfaces edge, we can

control the continuity.

Select the LOFT command in the Create panel on the Surface tab, and then click on the top spline

on the side. Then, using Ctrl, click on the surfaces edge. As usual, Ctrl enables access to subobject

level, and in the case of a surface, to its edges. We need to select the edge, in order to get access to

the option for continuity. If we had selected the spline coincident with the surface edge, we could

have done the loft, but it would have worked as a G0, since the command does not detect the

adjacent surface when choosing the spline.

Once you finish selecting both profiles, you will get several options. Lets focus on Continuity. The

options are G0, G1 and G2.

G0 (position) continuity means that there are no gaps, but theres a sharp angle.

When you create G1 (tangent) continuity, it means that the surfaces have equal angles in their

tangency.

When you create G2 (curvature) continuity, theres not only equal tangency, but also equal radius in

the curvature on both surfaces. These are the surfaces that dont show any flaws when lights are

reflected on them. Thats why Zebra analysis is so important in these cases.


You will also notice that when you click on the loft, youll get a couple of new icons. If continuity

among surfaces is involved, then you will get at least three of them.

The one depicted below (the one to the right) will define the continuity. This is the one that will only

appear if at least one surface edge is selected as start or end profile. Please remember that you can

change this setting at any time.

The following icon provides different options for the loft operation:

You can decide between a smooth fit and ruled loft (the latter will have G0 continuity between all

internal profiles).

You can also define if the loft is normal to any of its sections.

Draft Angle can also be triggered from here, although well see that the last control is basically a

Direct Manipulation element for Draft Angle.

The last option is to close the surface or solid, which can also make a periodic surface.


The control for Draft Angle can also be accessed via Direct Manipulation. Once you click on the

triangle, you will get a handle that will control the magnitude of the draft angle, and reach very

interesting results.


As you can see, AutoCAD 2011 has worked a lot around Direct Manipulation. This means that you

can do pretty much any editing operation without having to go anywhere else than the object itself.

However, you can access most of these options from the Properties palette too. Lets take a look at

it.

First of all, AutoCAD recognizes the surface type as a loft. This

is an Explicit surface.

Under General, we will get the usual object properties, such as

Color, Layer. Please note that theres a new option called

Transparency.

3D Visualization will let us access to the Material and to

control how the object casts and receives shadows.

Geometry is where we find the most interesting information in

terms of editing. Some options are grayed out, since they cant

be changed from this palette. Changing the number of cross

sections would not make any sense, for example. Other

options, like Trimmed surface, are not relevant until we dont

have such a scenario (trimming elements).

Under Surface Normals, we can change the way the loft

behaves (Ruled, Smooth, etc). Its the same control we had on

the object.

End Magnitude will control the Draft Angle. It may be

interesting to drag the control using Direct Manipulation, and then be able to fine tune it by typing

a more precise value in the Properties Palette.

The number of isolines does not affect the control of the surface, so just change it if you want to

have a different understanding in visual terms. Maybe a bigger amount of isolines along one

direction will help to make the surface more legible.

End Continuity is also a control we saw over the object. If we had used continuity with two

surfaces, we would have had Start and End Continuity (and Start and End Magnitude).

We can also see that the loft is not closed (under Misc)

Surface Associativity enables us to control if the surface will keep associativity, and we can also ask

AutoCAD to show associativity. If we change this value into Yes, you will see how the spline and

surface edge highlight (image below, to the right)


We have already solved the bottom and the sides. Lets see what to do with the top. Why the top

first? Because we have all the data to create the next surface. And we need this new surface in order

to close the gaps at both ends. Thats the rationale.

We will do another loft. This time, using three splines. Why do we choose to use the splines and not

the other surfaces edge? Simply because we want them to be adjacent, but they dont need to

share continuity. As it was mentioned before, you can still use surface edges and apply G0

continuity.

First, lets make a new layer called Case_Top, and change its color, so we can easily recognize both

parts of the object.

Well use the LOFT command again, this time with the two top splines on the side, and the top

spline we first did. Please note that we need to select the cross sections in order.

When you select the first spline, you will notice a new icon over the cursor. It tells you that there is

more than one element of geometry there, and its called Selection Cycling. You can also toggle it on

and off from the Status Bar (the last icon to the right).

Selection Cycling will display any geometry that coexists in the point that you clicked, unless the

option is too obvious. For example, when selecting subobject in a Box, and you click over an edge,

AutoCAD will assume you want the edge, and not the two faces that converge into that edge.


In our case, if we want to select the spline, AutoCAD will also find the previous loft. So thats exactly

what it will show in an adjacent box. You can hover over the options, and youll see them

highlighting on screen.

A couple of tips on Selection Cycling.

First of all, if the first choice that is displayed is the right one for you, you can keep selecting the

other elements, since AutoCAD will take the default one as the one selected. If it is not, just move

your mouse over the options, and click on the one you like.

If you are in a drawing thats too busy, you may want to turn it off. Just do it from the Status Bar.

The results from this loft should look like the following image.


You may want to go back to visual styles, and select Realistic, which will tell you if there are any

collisions with the shaver. You wont find any problems with the geometry, of course.

But lets create some problems, and take a look at surface editing. While the surface is a loft, and its

associative, we still have control of the splines that were used as cross sections.

Select the top spline and youll get the Selection Cycling box, since both the spline and the loft share

the same space. Depending on the angle of your perspective, youll probably also get the network

surface done for the bottom, and the shaver (solid).

Once you have the spline selected, hover the mouse over one of the CVs, and you will see that the

Gizmo will move to that location. Now move the CV along the axis normal to the surface (depending

on how you did the exercise, this may vary). Make sure you go down, towards the shaver. The whole


point is to have part of the shaver to appear through the top of the case. Turning OSnaps off may

also be a good idea.

The problem here is quite obvious, but in many cases, it wont be so clear. You can now use

INTERFERE in order to get any collisions. The command INTERFERE is in the Solid tab, in the Solid

Editing panel.

Once you invoke the command, make sure you first select one set of elements to analyze (in this

case its just one the top of the case-), and after clicking Enter, choose the second set of elements

(both sides of the shaver). You should see something like this. The portion in red shows the collision.

You can now undo until you get to the correct loft (before editing). We now need to close the

shaver.

Lets use the option called Patch. A Patch is a surface type that will create a surface that closes a

gap. The boundaries can be either curves or surface edges. Please note that you cant mix curves


and surface edges. When you use surface edges, the patch will ask for the type of continuity. You

can also constrain the patch with additional geometry. For example, you want the patch to go

through a specific point, or an ellipse. In this case, were going to make it simple, but feel free to try

some of these options.

Change the current layer to Case_Bottom, and then use the Patch option (SURFPATCH command),

which is on the Surface tab, in the Create panel. Select all the surface edges at the bottom (in no

particular order), and you should get something like this.

Before the command ends, you are prompted for three different options. You can control the

continuity (as we already learnt with the loft), you can define a Bulge magnitude, and add a

Constraint.

Select Continuity, and play a little with G1 and G2. You will notice that the surface changes

according to the continuity you select. For the exercises sake, keep it in 0.


If you have G1 or G2, the Bulge will help you define the shape of the patch. Try to change it from the

Properties palette, and put it in 1 (remember to change continuity too). This is what it looks like with

G2 and Bulge in 1.

Go back to the Patch in G0, and do the same to the other end. It looks like we have a nice

conceptual design for a shavers case!


2.4. Building the Case in AutoCAD

We could now have two very different approaches. One would be to build the whole case in AutoCAD,

and then send this to someone else for fabrication. The other option would be to complete the work in

Inventor, which already has very specific functionality for detailing and building these kinds of objects.

Well start with the first approach, in which well create the solids in AutoCAD. Well do the two parts of

the case, and will also add some ribs to support the shaver.

Then well replicate it in Inventor. As I said at the beginning, this is not meant to be an Inventor tutorial,

so I will not go through all the steps, but basically explain some general concepts.

As a first step, open 05 shaver with surfaces.dwg

How about creating a solid out of the whole thing? Just imagine how you could have done something

like this in AutoCAD before. Maybe not impossible, but very complex. Lets use the Sculpt option

(SURFSCULPT command) in the Edit panel of the Surface tab.

Before doing this, select both lofts on the sides and change continuity to G0. Since the patches at the

ends are G0, it will make much more sense. You can also open the file 06 shaver with G0 continuity.dwg,

which has this step already done.

Lets first create a layer called Case_Bottom_Solid. You may also choose not to delete surfaces upon

creation of the solid. Type DELOBJ, and set it to 0 (it wont delete the surfaces). After doing the

command, set it back to 3.

Now simply select everything, and AutoCAD will create the solid. Sculpt works with any set of surfaces or

solids which enclose a space which is watertight. This means, no gaps whatsoever. Self intersections

arent welcome either. After just one click, you should get this solid.


We now need to get the two parts of this model (top and bottom of the case). Well slice the solid,

so we need a surface for that purpose (since no slicing plane would work here).

Lets explore a couple of interesting functionalities. Well first extract the edges of the solid. Using

the curves that come from that operation will ensure us that the slice will work perfectly.

Turn off all layers except Case_Bottom_Solid.

In the Solid tab, under Solid Editing, theres an option called Extract Edges (XEDGES command).

Quite a powerful one, and pretty unknown. Once you invoke the command, select the model and hit

Enter, youll get the solids edges. We need to make a surface with them.

In order to start the next step, lets hide the solid.

You may wonder how to do that, since the curves and the solid share the same layer. Simple! There

are some new commands in AutoCAD 2011 that will help you to do this very easily. Lets check it

out.

If you right click on the solid, youll see a new option called Isolate. Within that option, we will

choose Hide Objects, and the solid will hide, without any impact in any other entities that also

belong to its same layer! Theres also an option for isolating objects, regardless of the layer, which

can be very useful, and well actually use it afterwards. At any time, if you want the rest of the

objects back, you can make a long right click (if you have time sensitive right click), and youll see the

option Isolate again. Within it, you need to choose End Object Isolation.

But what we wanted was to hide the solid, and the next image shows how this looks like. We now

want to make a network surface that will be used for slicing the solid, and well also use for

generating the ribs inside the case.


The Network Surface will be done with the four splines at the top. Just select two in one direction

first, click enter, and then select the other two. Easy.

Sometimes, when extracting edges, AutoCAD may not be able to generate a single spline from a

surfaces edge. In that case, you need to use the JOIN command. It has been really enhanced, but for

the time being, just keep that info in mind, since we wont need it for this particular exercise.


Once we finish the object isolation, we have our solid and our surface. I just colored the surface in

red, so as to know exactly what were doing.

Use the command SLICE, from the Solid tab, in the Solid Editing panel, and once it prompts for the

slicing plane, right click (long one), and choose Surface. Youll now select the network surface (with

the invaluable help of Selection Cycling), and then the SLICE command will prompt which part of the

solid you want. Just hit Enter, since you want both parts.


Well create a new layer called Case_Top_Solid, and well change its color, in order to better

understand what we have now.

After assigning the top part of the solid to this new layer, it should look like this.

So how can we get just the skin with some thickness? Well use the bottom solid, do a shell, and

remove the top face. You may wonder why we did not just thicken the surfaces. If you do that, you

may get many complex intersections between faces. When we do a shell, AutoCAD solves all of

these problems.

Create a copy of the solid, and hide it (using the new Hide option).

You can find Shell in the same panel you found Slice. Once you select the solid, AutoCAD will show

the model completely triangulated. You need to now click somewhere on the top of the solid, and

you should see how that part gets deselected (see image below)


When Shell prompts for the thickness, type 2.5. Please note that the whole model is in mm. The

result should look like the image below (after you move back to Realistic visual style).

Lets make some ribs on the case, so as to get a structure. We are not going to solve every detail, but

at least lay down the basics, since the ribs will help explain some other functionalities.

We are going to use a new functionality called Project Geometry, which works both for surfaces and

solids. We want to make the ribs, and in order to obtain their geometry, we are going to project

some simple lines into the solid. Actually, since the rib is going to be internal, we dont want the

solid we currently have, but the result of the subtraction of the main solid with the shell. This is

what you have to do now.

Unhide the solid, and create a copy of the shell.

Make a subtraction between the solid and the shell. Select the solid first, click Enter, and then select

the shell. This will create a solid that corresponds to the enclosure.

Then we will have exactly the shape over which we want to project. Doing this before would have

implied a huge amount of Boolean operations with auxiliary geometry.

In order to draw the lines, go to the Right View using the drop down in the View panel on the Home

tab. Im not suggesting doing it through the ViewCube, since this does not make the UCS follow. We

want the UCS aligned with this view.

We want to draw some lines that are perpendicular to the model (if you see it from the Right View).

I suggest making a perpendicular based on an imaginary plane that touches the four top vertices of

the case (the bottom part of the case).


Make an offset of 2mm, and copy both lines 50 mm from the first ones. If you move to an isometric

view, it should look like the image below.

Now use the option Project to UCS, available in the Project Geometry panel in the Surface tab. Start

the command, and select the four lines, click Enter, and AutoCAD will prompt for the solid or surface

where you will project the geometry. Select the solid, and youll see the lines projected in the solid.

Pretty exciting, and quite difficult to do before (you may have had to create an auxiliary plane

through the geometry, imprint it in the solid, and extract the geometry).

Remember to use the solid which is produced by subtracting the original solid with a shell. Make

sure you still keep a version of the shell, which will be your real part.

Now you can use the new option for hiding geometry, and isolate the curves. It should look like this.


If you keep working with the model youve been developing, you may find that the loft can have an

issue on the bottom of the rib. You can easily correct this by generating three guides as seen on the

next image.


These are just splines that we may want to join, in order to make a single operation. Use the JOIN

command to create four closed curves, and then use LOFT in order to get the results you can see

below. You can open the file 11 shaver and ribs part3.dwg, which has everything already prepared

for the rest of the exercise.

Once you have the lofts done, you should patch them. If the cross sections had been strictly planar,

we could have created a solid, but well need to make one using the Sculpt option.


Use Sculpt after everything is patched, and you will get the two solid ribs.

Now unhide the rest of the objects, and you should have the bottom part of the case and the ribs in

place.

Next, turn the shaver on, and well subtract it from the ribs.

You will need a copy of the two parts of the shaver, since the subtraction deletes the object that

subtracts. Do one half at a time.


Once you subtract, you will notice that the shaver left some internal parts of the rib. If you click on

them, all the part will highlight.

Use the command Separate, which is under the drop down next to Shell, in the Solid Editing panel

of the Solid tab.

After this command, you can delete the internal parts of the ribs, and were done!

Of course, you may want to do more detail, or even notice that you cant take the shaver away of

the case with these ribs. You can keep adding more detail, or in this case, subtracting parts, but it

would exceed the purpose of this exercise.

The last thing to do is to use the command Thicken on the top part of the case. Thicken is in Solid

Editing panel in Solid tab. Use a small value, like 1 mm. Since you want the thickness to be done

towards the inside, you should type -1mm.

The top part of the case should look like the image below.


So what about documenting the shaver and case? Lets use the SECTIONPLANE command, which is

available in the Section panel, inside the Home tab.

Go to the Front view (if you are in WCS), and create two Section Planes similar to the image below.

They dont need to be in the axis of the shaver. Just make sure you have a longitudinal and a

transversal section.

Once you have done the two section planes, you can then right click on them, and get the Generate

2D/3D Section option.

Create a 2D Section, using the default settings, and insert it somewhere on the screen. Make sure

you hit Enter three times (for rotation, scale on X and Y).

Create the second 2D Section, and locate it not too close to the other one.


You can also right click again on the Section Plane, and activate Live Section. By simply clicking on a

Section, you can also get a contextual tab in the Ribbon, where you can get to that command too.

Live Section lets you examine the object much easily, without the need to make a subtraction. You

can also control the extents of the Live Section, if you click on a drop down that appears when you

select the Section Plane, and you choose Section Volume. You can then adjust exactly what you

want to see.

You can now create two viewports in Paper Space so as to display the two sections.

You could also start to document the case, by adding diverse annotations, but it largely exceeds the

purpose of this tutorial.


2.5. Visualizing the Case in AutoCAD

AutoCAD 2011 introduces a new Materials UI, and new materials that share properties with the ones

available in Revit, Max and Inventor. These applications will share the Materials Library that will be

installed only by the first of these applications. This means that any material generated from scratch in

AutoCAD 2011 should be understood in these applications, with no need to reassign the material.

The 3D Modeling workspace includes the UI, but if you have closed it, you can always open it from the

Render tab, under Materials panel. The option is called Materials Browser.


The file 16 shaver complete with materials.dwg has the materials already applied. You may want to

keep on working with the file you have, or open the previous one (15 shaver complete with

docs.dwg)

Once you have the Materials UI on screen, you will want to see the categories, which is the list

which appears in the image above at the left of the material swatches. If you cant see it, you can

make it appear by clicking on the top left button, just below the Material Browser title.

In this particular exercise, we will work with different plastics, but you should know that materials in

AutoCAD have been quite enhanced in many aspects. One of them is its viewport representation.

You can now visualize bumps in real time, with no need to render. Other enhancements can be seen

when editing any material. Depending on its category, the options will be absolutely appropriate to

the material class.

Lets start with the cover. Its going to have transparency. We could use a transparent plastic from

the Plastic Category. Once you click on Plastic on the left, youll see all the materials under that

category.

Look for the material called Transparent Black.

There are many options for applying materials. If you have the object selected, you can right click on

the material and choose Assign to Selection. You can also drag and drop the material over the

object. In some cases, especially in complex models, or with many objects sharing the same space,

dropping a material may be confusing.


Now apply Smooth Black for the bottom of the case and the ribs (also found in Plastic), and Smooth

Navy for the shaver.

If you render using Medium preset, the whole model will look like the image below.


3. Building the Case in Inventor

This part is not a tutorial on how to build the case in Inventor. It just tries to explain the different steps

to get to the same result we did in AutoCAD.

You will notice that some of the workflows are similar, but others differ, and become much more

discipline specific in Inventor. A product like this makes certain operations much easier. If you choose to

use Inventor for generating the details and preparing the case for fabrication, you can still rely on

AutoCAD as a great tool for generating the conceptual design. The flexibility found in AutoCAD will be

quite helpful at the beginning of the process, while the power at specific operations found in Inventor

will help in the rest of the process.

Once we save the solids or surfaces in AutoCAD, well export an SAT file, which well open in Inventor. I

recommend setting the sysvar ACISOUTVER to 0 before exporting.

In this case, we imported the bottom of the case as a solid.

Now well do a Shell in Inventor, with the same settings as the ones we had in AutoCAD.

Inventor will also ask for faces to remove, and well select the top face.


The results of the shell should look like the image below.

Now its time for the ribs. Instead of all the operations we did in AutoCAD, we will just define two

lines in auxiliary workplanes in Inventor, and use the command Rib, which will solve the unions for

us.

Finally, by copying the body of the shaver into the part and using the Sculpt command, we can get

rid of the parts of the rib we dont need.


At the end of this process, this will be the assembly. Inventor would be much more suitable if you

want to continue developing the part for fabrication, since it also has a powerful set of tools for

plastics, and of course, for making the mold that you may need in order to make mass production of

these parts.


4. Visualizing with Showcase

Showcase is a great tool for Design Validation and overall communication for your idea. You can import

the dwg done in AutoCAD or the iam done in Inventor into Showcase, and create stunning presentations

for your product.

Once you import the model into the scene, you can change the materials using Showcases Material

Browser (the shortcut is M). It is organized into Categories, just like the one in AutoCAD, so youll notice

that any work in materials will have an almost nonexistent learning curve.

You can also define the Scene (the shortcut is S). The lighting coming from the scene impacts in the

model, since Showcase uses Image Based Lighting. You can select any of the images offered in

Showcase, or import a new scene. You will need an HDRI image for this.


You can also control the scenes scale, and the position of the model with respect to the scenes floor.

Once you have the model finished, you can generate Shots and make small animations like the ones that

can be done in AutoCAD with Showmotion.

autocad_2011_surface_modeling_for_consumer_products.pdf

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