SolidWorks 2007 bible phần 8 doc

The last two functions of the Split feature are addressed in Chapter 28, and these are the most troversial areas of its functionality.con-The part of the Split feature that concerns this

Cut feature

A Cut feature may create multibodies, either intentionally or unintentionally When it does happen,the Bodies To Keep dialog box appears to enable you to select which bodies you intend to keep.The Bodies To Keep dialog box is shown in Figure 26.17 This dialog box was formerly calledResolve Ambiguity, which was not as descriptive as Bodies To Keep

FIGURE 26.17

The Bodies To Keep dialog box

Notice that the Bodies To Keep settings are also configurable, and so different bodies can be kept indifferent configurations, which is very useful

Split feature

Of all of the features in SolidWorks, the Split feature is one of the most contentious and sial In some situations, it is positively dangerous, and can cause a lot of data loss if you are notaware of the workarounds to make it work properly Endless forum discussions are devoted to thisone feature that most SolidWorks users probably do not even use

controver-The Split feature has essentially three functions:

The last two functions of the Split feature are addressed in Chapter 28, and these are the most troversial areas of its functionality.

con-The part of the Split feature that concerns this chapter is the first function mentioned, which issplitting a single solid body into multiple bodies using a sketch, a plane, or a surface body

Splitting with a sketch

When using a sketch, the Split process works like this:

1. Create a sketch with an open or closed loop; even a mixture of open and closed profileswill work If it is open, then the endpoints have to either be on an exterior edge or hang-ing off into space; they cannot actually be inside the boundaries of the solid

2. Initiate the Split feature from the Features toolbar or from the menus at Insert ➪Features ➪ Split You can do this with the sketch active, with the sketch inactive butselected, or with nothing selected at all

3. Click the Cut Part button This does not actually cut anything; it only previews the split.When this is done, the resulting bodies appear in the window below, and callout flags areplaced on the part in the graphics window These flags are often useless because they tend

to point to the borders between two different bodies in such a way that it is completelyambiguous as to which body they are indicating However, in the example shown inFigure 26.18, the result is very clear

FIGURE 26.18

Using the Split feature

Check marks next to the body in the list indicate that the body will be split out The lack of a checkmark does not mean anything For example, in Figure 26.18, notice that two boxes are checked, butthis will result in a total of four bodies Body 3 and Body 4 are free If only Body 1 were selected, thenthe result would be only two bodies.

The callout flags and the bodies list where <None> is shown are looking for a path and filename tosave the body out to a file Again, this functionality is covered in Chapter 28 with the MasterModel information

The Save All Bodies button simply puts check marks in all of the boxes If the Resulting Bodies boxcontains more than ten bodies, then the interface changes slightly, as shown in the image to theright in Figure 26.18 In past releases, the list box did not contain the slider bar; only the Next 10button appeared, and it was easy to miss, not being a usual interface technique for accessing liststhat were longer than the box in which they appeared

The Consume Cut Bodies option removes, or consumes, any of the bodies that have a check mark

If you used the Split feature a couple of releases ago, the default was for it to consume all bodies.The current situation is a big improvement

Splitting with a plane

Splitting with a plane gives the same type of results and uses the same options as splitting with asketch However, you never have to worry about the plane being extended far enough, because thecut is made from the infinite planar extension of the plane The only thing you have to worry aboutwith a plane is whether it intersects the part

Splitting with a surface body

Surface bodies are used to split solid bodies for a couple of reasons In the part shown in Figure26.10, a surface body was used to make the split instead of a sketch or a plane, because both ofthose entities split everything in an infinite distance either normal to the sketch plane or in theselected plane A surface body only splits to the extents of the body If you look closely at the part,you will notice that a plane or sketch would lop off one side of the sphere on top of the object, butthe small planar surface is limited enough in size to only split what is necessary

Another advantage to using a surface body is that it is not limited to a two-dimensional cut Thesurface itself can be any type of surface, such as planar, extruded, revolved, lofted, or imported.Taking this a step further, the surface is not limited to being a single face, or a body resulting from

a single feature; it could be made from several features that are put together as long as it is a singlebody and all of the outer edges of the surface body are outside the solid body If you examine themouse part shown in Figure 26.1, you will notice that it has splits made from multi-feature surfacebodies

For more information about surface bodies, see Chapter 27.

Insert Part feature

The Insert Part button can be found on the Features toolbar, or you can access this feature throughthe menus at Insert, Part

Insert Part enables you to insert one part into another part When inserting the part, you have theoption to also insert axes, planes, cosmetic threads, and surface bodies All solid bodies from theselected part are automatically brought into the current part The PropertyManager interface for theInsert Part feature is shown in Figure 26.19

FIGURE 26.19

The Insert Part PropertyManager

This feature has two major functions: inserting a body as the starting point for a new part, andinserting a body to be used as a tool to modify an existing part Notice that the basket part shown

in Figure 26.11 and Figure 26.12 also uses Insert Part to put together bodies to form a finishedpart

When you use Insert Part, there is no Insert Part feature that becomes part of the tree Instead, apart icon is shown with the name of the part being inserted

Also notice in Figure 26.19 that the Launch Move Dialog option displays at the bottom, and is on

by default This option launches the Move dialog box after you insert the part This Move feature isthe same as the Move/Copy Bodies feature, with the same options (translate or rotate by distance or

CROSS-REF

Secondary operations

One of the commonly used techniques has to do with secondary operations For example, you mayhave designed a casting that needs several machining operations after it comes from the foundry.The foundry needs a drawing to produce the raw casting, and the machine shop needs a differentdrawing to ream and tap holes, spot face areas, and so on

Although you can use configurations to do this, using Insert Part is another way This has nothing

to do with multiple body techniques, but this is the only place where Insert Part is covered inmuch detail One of the advantages of using Insert Part is that you no longer carry around theoverhead of all of the features in the parent part It is as if the inserted part were imported Theconfigurations method forces you to carry around much more feature overhead Of course, thedownside is that now there is an additional file to manage, but this can be an advantage becausemany companies assign different part numbers to parts before and after secondary operations

Starting point

Looking back to the mouse shown in Figure 26.1, the main part has been split into several bodies.You can use Insert Part to insert the whole mouse into a new part where all of the bodies exceptone are deleted, and then the remaining body serves as the starting point for a new part Manyadditional features are needed on all of the bodies that make up the mouse, such as assembly fea-tures, cosmetic features, functional features, and manufacturing features

Managing Bodies

Managing bodies in SolidWorks is not as clean a task as managing parts in an assembly As youwork with bodies, you will discover some real surprises in how bodies are managed Hopefully inthis section, I can prepare you for some of the more problematic surprises

Body folders

The top of the FeatureManager includes a pair of folders, one called Solid Bodies, and the othercalled Surface Bodies These folders are only there if you have solids or surfaces in the model, andthey reflect the state of the model at the current position of the Rollback bar As a result, the folderscan change and even disappear as you roll the tree back and forth in history Figure 26.20 showsthe top of a FeatureManager that has both solid and surface body folders Notice that the number

in parentheses after the name of the folder shows how many bodies are in that particular folder

An odd fact about these folders is that you are allowed to rename the folders, but the namechanges never remain If you go back to rename the folder again, the name that you assigned is dis-played; you cannot name another feature with the name that you assigned, but it is never displayed

FIGURE 26.20

Body folders in the FeatureManager

By right-clicking either of the bodies folders, you can select the Show Feature History option,which shows the features that have combined to create the bodies This view of the

FeatureManager is shown in Figure 26.21 This option is very useful when you are editing or troubleshooting bodies

FIGURE 26.21

Using the Show Feature History option

Figure 26.21 also shows the other options in the RMB menu All of the bodies in the folder can

be alternately shown or hidden from this menu, as well as deleted While the Hide or Show state

of a body does not create a history-based feature in the tree, the Delete feature does, as discussedpreviously

You can expand the Display pane in parts, in order to show display information for bodies InFigure 26.22, the Display pane shows the colors assigned to the solid bodies, as well as the factthat several surface bodies exist but are hidden.

FIGURE 26.22

The Display pane showing information about solid and surface bodies

The folders also make bodies easier to identify, especially when combined with the setting found atTools, Options, Display/Selection, Dynamic Highlight From Graphics View This setting quicklyturns the body outline red if you move the mouse over the body in the body folder

Hide or show bodies

You can hide or show bodies in one of several ways I have already described the method of usingthe bodies folders to hide or show all of the bodies at once, but you can also RMB click individualbodies in the folders to hide or show from there as well Also, if you can see a body in the graphicsarea, then you can RMB click the body and select Hide under the Body heading This works forboth solids and surfaces

When you are hiding or showing bodies from the FeatureManager, and not using the bodies ers, but rather using the features themselves, things get a little complicated If you want to hide orshow a solid body, then you can use any feature that is a parent of the body to hide or show thebody For example, you can use the Shell feature in the mouse model to hide or show all of thebodies of which it is a parent

fold-Although this technique works well for solid bodies, surface bodies are a different story In order to

show or hide a surface body using features in the FeatureManager, you have to select the very last

feature that was used on that particular body For example, in the mouse model, Fillet 5 was thelast feature to touch that particular body, but Surface-Offset1 was the first feature of that body, and

Other facts that you need to know about bodies and their hide or show states are that the Hide orShow feature is both configurable and dependent on the rollback state As a result, if you hide abody, and then roll back, it may appear again, and you will have to hide it Then, if you roll for-ward, the state changes again Also, a body can be hidden in one configuration, and then when youswitch configurations, it remains hidden This makes it rather frustrating to work with bodies To

me, it would be nice if bodies had simple on/off toggles that were neither intelligent nor tricky

Some features exclude bodies if the bodies are hidden when you edit the feature Be careful of this, and be sure to show all of the bodies that are used in a particular func- tion before you edit it For example, if a body is hidden, and you create a new extrude that touches the hidden body, then the new body does not merge with the hidden one even if the Merge option is

on If the hidden body is then shown and you edit the second body, then the bodies will merge upon the closing of the second body.

up the organization of the tree, which could be useful if there are many bodies in the part Otherusers insist on keeping the tree free of extraneous bodies, and so they immediately delete bodiesthat have been used To me, this technique replaces one kind of clutter with another, and meansthat tools that should be available to you (solid or surface bodies) are not available unless youreorder the Delete Body feature down the tree and/or roll back In any case, this is really a matter ofpersonal working style, and not of any great importance

Renaming bodies

Notice that the bodies that you see in the folders have been named for the last feature that touchedthat body That naming scheme is as good as any, except that it means that the body keeps chang-ing names Even if you deliberately rename a body, the name will change with the next feature that

is added to it This is particularly true when a feature results in a body being split into multiple tures or when the feature combines bodies This means that body names are also rollback state-dependent, like body colors, and the Hide or Show feature

fea-Tutorials: Working with Multibodies

CAUTION

CAUTION

Merging and local operations

This tutorial gives you some experience using the Merge Result option and using features on ual bodies to demonstrate the local operations functionality of multibody modeling Try these steps:

individ-1. Start a new part, and sketch a rectangle on the Top plane, with the Origin at the midpoint

of the line at one end of the rectangle Size is not important for this exercise

2. Extrude the rectangle to roughly one-third of its smaller dimension

3. Open a second sketch on the Top plane Hide the first solid body by right-clicking it ineither the FeatureManager or the graphics window

4. Show the sketch for the first feature, and draw a second rectangle on the far side of therectangle from the Origin Make sure that the second rectangle gets two coincident rela-tions to the first sketch, at two corners so that the rectangles are the same width Whenthe sketch is complete, hide the sketch that was shown

5. Extrude the second rectangle to about two-thirds of the depth of the first rectangle

Notice that the Merge option was not changed from the default setting of On for the second extrude, but because the first extrude was hidden, the second extrude did not merge with it Be careful of subsequent edits to either of the features if the first body is shown, because this may cause the bodies to merge unexpectedly.

In this tutorial, the bodies are later merged intentionally In this case, the tutorial uses a bug in the software as an advantage, but ideally what you should do (in case the bug is fixed at some point) is to deselect the Merge option of the second extrude.

6. Shell out the second extrusion by removing two adjacent sides, as shown in Figure 26.23.One of the sides is the top and the other is the shared side with the hidden body Thebody that should be hidden at this point is shown as transparent in the image for refer-ence only The body was made transparent to make it easier to select the face of the sec-ond body

FIGURE 26.23

Shelling two sides of a block

NOTE

7. Show the first body either from the Solid Bodies folder at the top of the tree or from theRMB menu of the first solid feature in the tree.

8. Shell the bottom side of the first body, so that the cavities in the two bodies are on site sides

oppo-9. Combine the two bodies using the Combine tool found at Insert ➪ Features ➪ Combine.Select the Add option and select the two bodies Click OK to finish the feature Figure26.24 shows the finished part

FIGURE 26.24

The finished part

Splitting and patterning bodies

This tutorial guides you through the steps to delete a pattern of features from an imported body,

separate one of the features, and then pattern it with a different number of features This duces some simple surface functions, in preparation for Chapter 27 Follow these steps:

intro-1. Open the Parasolid file from the CD-ROM called Chapter 26 – Bonita Tutorial.x_t

2. Using the Selection Filter set to filter Face selection (the default hotkey for this is X),select all of the faces of the leg You can use window selection techniques to avoid click-ing each face

3. Click the Delete Face button on the Surfaces toolbar, or access the command through themenus at Insert ➪ Face ➪ Delete Make sure that the Delete And Patch option isselected The selected faces and the Delete Face PropertyManager should look like Figure26.25 Click OK to accept the feature

FIGURE 26.25

The Delete Face PropertyManager

4. Repeat the process for a second leg, leaving the third leg to be separated from the rest ofthe part and patterned

5. After the two legs have been removed, click the outer main spherical surface, and thenfrom the menus, select Insert ➪ Surface ➪ Offset Set the offset distance to zero Noticethat a Surface Bodies folder is now added to the tree, near the top

A zero distance offset surface is frequently used to copy faces.

6. Hide the solid body You can do this from the Solid Bodies folder, from theFeatureManager, or from the graphics window

7. Hiding the solid leaves the offset surface, and there should be three holes in the surface.Select one of the edges of the hole indicated in Figure 26.26 and press the Delete key TheChoose Option dialog box appears Select the Delete Hole option rather than the DeleteFeature option The Delete Hole operation becomes a history-based feature in the model tree

FIGURE 26.26

Using the Delete Hole option

TIP

Delete Hole is really a surface feature called Untrim Untrim is discussed more in Chapter 27, but you can use it to restore original boundaries to a surface.

8. Once you delete the hole from the surface body, change the color of the surface body inthe same way that you used to change colors of parts, faces, and features

9. This is not a necessary step, but many people choose to use it Click the surface body inthe Surface Bodies folder and either press the Delete key, or select Delete from the RMBmenu Then click OK to accept the feature This places a Delete Body feature in the tree

It keeps the body from getting in the way when it is not needed

If you delete a body in this way and then need it later down the tree, you can delete, suppress, or reorder the Delete Body feature later in the tree.

10. Now show the solid body You will notice the color of the surface conflicting with thecolor of the solid This mottled appearance is due to the small approximations made bythe rendering and display algorithms

11. Initiate the Split feature through the menus at Insert ➪ Features ➪ Split, or on theFeatures toolbar Use the surface body to split the solid body Click the Cut Part button,and select the check boxes in front of both bodies in the list Click OK to accept the fea-ture Notice now that the Solid Bodies folder indicates that there are two solid bodies

12. From the View menu, turn on the display of Temporary Axes Initiate a Circular Patternfeature, selecting the temporary axis as the axis, and the split-off leg in the Bodies ToPattern selection box Set it to four instances, as shown in Figure 26.27

FIGURE 26.27

Patterning a body

TIP NOTE

Beginning to understand how to work with multiple bodies in SolidWorks opens a gateway to anew world of design possibilities However, like anything else, not everything is perfect Like in-context design, multibody modeling is definitely something that you have to go into with your eyesopen You will experience difficulties when using this technique, but you will also find new possi-bilities that were not available with other techniques The key to success with multibodies tech-niques is discipline and circumspection

When using a model with the multibody approach, make sure that you can identify a reason fordoing it this way rather than using a more conventional approach Also keep in mind the list ofapplications or uses for multibody modeling that are mentioned in this chapter

From a CAD point of view, a solid is defined as the volume enclosed by

a surface boundary To enclose a volume, the boundary must have nogaps or overlaps The skin or surface of the boundary itself is infinitelythin, and has no volume, although it has a surface area In this way, surfaces

are one of the building blocks of solids

In many respects, there are no real differences between a solid model and a

surface model If you export a SolidWorks part to IGES format and read it

into another capable modeler, or even back into SolidWorks, then that file

can be read in as either a solid or a surface There is no way to distinguish

which it was when it left the originating modeler The real difference

between the two is how the modeler handles the data internally

It is possible to drive a car without knowing how the engine works, but you

cannot get the most possible power out of the car by only pressing harder on

the gas pedal; you have to get under the hood and make adjustments In a

way, that is what working with surfaces is really all about

Surface modeling can start from a blank screen, from imported geometry,

from native SolidWorks solid and surface features that have been built side

by side, or from a native or imported solid that has been deconstructed into

surfaces

The goal of most surface modeling is to finish with a solid In the same way

in which we learned to refer to solids as “solid bodies,” surface features can

IN THIS CHAPTER

Why do you need surfaces? Understanding surfacing terminology

What surface tools are available? Using surfacing techniques Tutorial: Working with surfaces

Working with Surfaces

even have the option to be knitted (the surface equivalent of the solid “merge”) together, butrequire an additional Knit feature to do this.

Why Do You Need Surfaces?

In the end, you may never really need surfaces It is possible to perform workarounds using solids

to do most of the things that most users need to do However, many of these workarounds are veryinefficient and cumbersome Although you may not look at some typical things that you now do asbeing inefficient and cumbersome, once you see the alternatives, you may change your mind Thegoal for this chapter is to introduce surfacing functions to people who do not typically use surfaces,and for everyday modeling Here I am not trying to show how surfaces are used in the context ofcreating complex shapes, although the same techniques can be used, regardless of the complexity

of the shape

The word surfacing has often been used (and confused) synonymously with the creation of

com-plex shapes Not all surface work is done to create comcom-plex shapes, and many comcom-plex shapes can

be made directly from solids Many users think that because they do not make complex shapes,they never need to use surface features This chapter shows mainly examples that are not complexshapes, in situations where surfaces make it easier, more efficient, or simply possible to do the nec-essary tasks

While some of the uses of surfaces may not be immediately obvious, by the end of this chapter,you should have enough information and applications that you can start experimenting to increaseyour confidence

Understanding Surfacing Terminology

When dealing with surfaces, different terminology may often be used that is not typically used withsolid modeling It is important to understand the terminology, which makes the techniques easier

to understand This special terminology also often exists for surfaces because of important tual differences between how solids and surfaces are handled

concep-These terms are fairly universal among all surfacing software The concepts underlying surface andsolid construction are generally uniform between the major software packages What varies fromsoftware to software is how the user interacts with the geometry through the software interface.You may never see some of these terms in the SolidWorks menus, Help files, training books, orelsewhere, but it becomes obvious as you use the software that the concepts are relevant

It also has an option to create a solid if the resulting surface body meets the requirements (a fullyenclosed volume without gaps or overlaps) However, unlike the solid bodies in Combine, whichmay overlap volumetrically, surface bodies must intersect edge to edge, more like sketch entities.

Knit is also sometimes used in the same way that the zero-distance offset is used, to copy a set ofsolid faces to become a new surface body

One nice option that enables you to quickly see where the boundaries of a surface body lie isfound at Tools ➪ Options ➪ Display/Selection ➪ Show Open Edges Of Surfaces In DifferentColor By default, this color is a medium blue, and you can change it at Tools ➪ Options ➪Colors ➪ Surfaces ➪ Open Edges

Trim

The Trim function in SolidWorks is analogous to the solid Cut Also much like the Cut, internally,Trim simply creates an additional boundary for the surface The underlying surface is defined by atwo-dimensional mesh, and for this reason, it is usually four-sided, but may be other shapes Whenthe underlying surface is trimmed, the software still remembers the underlying shape, but com-bines it with the new boundary, which is typically how face shapes (especially non-four-sidedshapes) are created

Untrim

Untrim is predictably the opposite of Trim All it does is remove the boundary from a surface Itcan remove the boundary selectively (one edge at a time, interior edges only, and so on) or removeall of the edges at once Untrim even works on imported geometry, as described in the tutorial inChapter 26 Figure 27.1 shows how Untrim works

FIGURE 27.1

Untrimming a surface

Hybrid modeling

Modeling software has long divided itself along Solid/Surface lines with products such as Rhino(strictly surface modeling) and early versions of SolidWorks (strictly solid modeling) However, inthe last several years, modelers are increasingly enabling both methods, and allowing them tointeract This hybrid modeling is a combination of solid and surface modeling These days, veryfew mechanical designers or engineers model exclusively in surfaces Surface modeling is slowbecause you model each face individually, and then manually trim and knit Cutting a hole in asurface model is much more involved than cutting a hole in a solid Solid modeling is fasterbecause it is essentially highly automated surface modeling; however, as any software user knows,automation almost always comes at the expense of flexibility, and this situation is no different.Solid modeling tends to limit you to a type of parts with square ends or a flat bottom becausesolids are creating all sides of an object at once For example, think about an extrusion: regardless

of the shape of the rest of the feature, you have two flat ends Even lofts and sweeps typically end

up with one or two flat ends Surfaces enable you to create one side at a time Another way of

look-ing at it is that uslook-ing surfaces requires you to create one side at a time.

You will find times when, even with prismatic modeling, surfacing functions are extremely useful,

if not complete indispensable I do not propose that you dive into pure surface modeling just tobenefit from a few of the advantages, but I do recommend that you consider using surface tech-niques to help define your solids This hybrid approach is sensible and opens up a whole newworld of capabilities I have heard people say after taking a SolidWorks surfacing class that theywould never look at the software in the same way again

NURBS

NURBS stands for Non Uniform Rational B Spline NURBS is the technology that most modernmechanical design modelers use to create face geometry NURBS surfaces are defined by curves inperpendicular directions, referred to as U and V directions, which form a mesh The fact that per-pendicular directions are used means that the surfaces have a tendency to be four-sided Of courseexceptions exist, such as three-sided or even two-sided patches Geometry of this kind is referred

to as degenerate, because one or more of the sides has been reduced to zero length Degenerate

geometry is often, but not always, the source of geometrical errors in SolidWorks and other CADpackages

Figure 27.2 shows some surfaces with the mesh displayed on them You can create the mesh withthe Face Curves sketch tool

FIGURE 27.2

Meshes created with the Face Curves sketch tool

An example of a competitive system to NURBS surface modeling is point mesh data This comesfrom systems such as 3DSMax, which create a set of points that are joined together in triangularfacets, and can be represented in SolidWorks as an STL (stereolithography) file When displayed inSolidWorks, this data looks very facetted or tessellated into small, flat triangles, but when viewed

in software that is meant to work with these kinds of meshes, it looks smooth Many advantagescome with this type of data, especially when it comes to applying colors and motion However, themain disadvantage is that the geometrical accuracy is not very good, and most of all, the data is notparametric, feature-based data that lends itself to changes in the definitions of features Point meshdata is typically used by 3D graphic artists, animators, and game developers

By using a SolidWorks extension such as ScanTo3D, it is possible to take point mesh data and ate a NURBS mesh over it This feature is not completely automatic, but it offers capabilities wherenone previously existed ScanTo3D is beyond the scope of this book, but you should find it useful

cre-if you are interested enough to read about NURBS and point meshes

Developable surface

Developable surfaces are surfaces that can be flattened without stretching the material Theseinclude planar, cylindrical, and conical shapes It is not a coincidence that these are the types of

Degenerate point

Ruled surface

Developable surfaces are a special type of a broader range of surface called ruled surfaces

SolidWorks has a special tool for the creation of ruled surfaces that is described in detail in thenext section Ruled surfaces are defined as surfaces on which a straight line can be drawn at everypoint A corollary to this is that ruled surfaces may have curvature in only one direction Ruled sur-faces are far less limited than developable surfaces, but are not as easily flattened

Gaussian curvature

Gaussian curvature is not referred to directly in SolidWorks software, but you may hear the termused in more general CAD or engineering discussions It can be defined simply as curvature in twodirections As a result, a sphere would have Gaussian curvature, but a cylinder would not

What Surface Tools Are Available?

Surface feature equivalents are available for most solid features such as extrude, revolve, sweep,loft, fillet, and so on Some solid features do not have an equivalent, such as the Hole Wizard,shell, and others Several surface functions do not have solid equivalents, such as trim, Untrim,Extend, Thicken, Offset, Radiate, Ruled, Fill, and Boundary

The surface features are listed here in the order in which they appear in the Tools ➪ Customize ➪Commands list for the Surfaces toolbar This is not a comprehensive guide to complex shape mod-eling, but it should serve as an introduction to each feature type and some of the details about how

han-Swept Surface

Swept surfaces work much like their solid counterpart, and the sketch rules and available entitiesare the same The main difference here is going to be that swept surfaces usually use an open con-tour for the profile, while swept solids use closed contours

Lofted Surface

The main difference between lofted surfaces and lofted solids is that the surfaces can use edges andcurve features to loft, rather than simply sketches and faces

If several edge or sketch segments combine to form one side of a direction, then you must use theSelectionManager to form the edge segments into a group This works like the former SmartSelection, but the SelectionManager is somewhat better.

The interface for the Boundary Surface is shown in Figure 27.4

FIGURE 27.4

The Boundary Surface PropertyManager

messages, and, most of all, it often does not work in situations where the Fill feature works farmore quickly and easily.

The types of models where you end up using the Boundary Surface are highly curvy models thatare modeled mainly with surface features, and require a four-sided patch

Still, I expect to see this feature improve in future releases I have run into one situation whereBoundary Surface created a better-looking patch than any other feature that does roughly the samething when analyzed with the various tools for evaluation such as Deviation Analysis and ZebraStripes The main advantage of Boundary Surface over Loft is that Boundary Surface (in theory) canapply a Curvature boundary condition all the way around, while Loft cannot apply curvature onthe guide curves Fill surfaces also can apply a Curvature boundary condition

For this release, if Loft cannot do what you need it to, then try Fill first, with Boundary Surface as alast resort before moving on to more drastic workarounds

Offset Surface

The Offset Surface has no solid feature counterpart, but it does in 3D what the Offset Sketch tion does in 2D; it may also fail for the same reasons For example, if you offset a 25-inch radiusarc by 3 inches to the inside, it fails because it cannot be offset up to or past a zero radius Thesame is true of offsetting surfaces Complex surfaces do not have a constant curvature, but aremore like a spline in having a constantly changing curvature If the offset is going in the direction

func-of decreasing radius, and is more than the minimum radius on the face or faces being func-offset, thenthe Offset Surface feature will fail

One of the ways to troubleshoot a failing Offset Surface is to use the Check tool to check for mum radius Remember that minimum radius is only a problem if the curvature is in the samedirection as the offset If a small radius will increase when it is offset, then that small radius is notthe problem The problem comes from the other direction where you are offsetting to the inside of

mini-a smmini-all rmini-adius

Unlike the Sketch Offset function — and as was shown in Chapter 26 — you can offset surfaces by

a zero distance This is usually done to copy either solid or surface faces to a new surface body

Zero-distance offset and Knit are sometimes used interchangeably, although Knit causes a problem

if you are selecting a surface body that is composed of a single face Knit assumes that you are ing to knit one body to another, and so, by default, it selects the body, and then fails with the mes-sage that you cannot knit a body to itself

try-Knit does have two functions that Sketch Offset does not One of these is the option to create asolid from the knit body if it forms a closed body The second option is somewhat more obscure,

mind later if you want to, changing the number from zero to something else With Knit, you donot have this option.

When talking about copying surface bodies, you must also consider the Move/Copy Bodies feature,which is described in Chapter 26 When simply copying a body without also moving it, this fea-ture issues a warning that asks whether you really intend to copy the body without moving it This

is an annoying message Also, the Move/Copy Bodies feature does not enable you to copy only apart of a body (selected faces) or to merge multiple bodies into one like the Knit and Sketch Offsetfeatures

All things considered, I recommend using the zero-distance Sketch Offset feature to copy bodies orparts of bodies unless your goal is to immediately make a solid out of it (in which case you shoulduse the Knit feature) or when using a Radiated surface (typically in a mold-building application)

Radiate Surface

The Radiate Surface is not one of the more commonly used surface features It has been largelysuperseded by the Ruled Surface This is because Ruled Surface does the same sort of thing thatRadiate Surface does, as well as a lot more, and is also more reliable Radiate works from an edgeselection, a reference plane, and a distance The newly created surface is perpendicular to theselected edge, parallel to the selected plane, and the set distance wide It is probably most com-monly used in creating molds or other net shape tooling such as dies for stamping and forging,blanks for thermoforming, and so on

Figure 27.5 shows the PropertyManager and selection for creating a Radiate Surface

FIGURE 27.5

The Radiate Surface PropertyManager

The Radiate Surface feature does not give you a preview of the finished surface, only the small arrows that indicate the direction in which the surface will radiate At times, you may need to switch the arrows to the other side, which you can do by using the arrow button next to the plane selection.

When creating a Radiate Surface, the use of a loop in the edge selection always causes

an error, because the feature only uses the initial edge that was selected for the loop As long as individual edges are listed in the selection box, you should be okay.

The one application where the Radiate Surface has a very interesting usage is when you combine itwith the Knit function, as mentioned earlier Figure 27.6 shows a part surrounded by a RadiateSurface in which the Knit feature is being used to select all of the faces to one side of the radiatedsurface The second smaller selection box in the PropertyManager that contains Face<1> is called a

seed face and causes the Knit to automatically select all the faces on the same side of the model as

the selected seed face The requirement here is that the Radiate goes completely around the modeland separates the faces into faces on one side of the Radiate and faces on the other side of theRadiate The use of the Radiate with the Seed Face selection is extremely useful for mold creation

Radiated surface selected

Seed face selection

CAUTION

CAUTION

TIP

problem has been fixed, and failure to knit a solid results in an error (as it should) To fix the error,you can fix the model, fix the selection, or turn off the option.

You can also make a solid from a surface using two other functions The Fill Surface has an option

to merge the fill with a solid or to knit it into a surface body; if the knit surface body is closed, then

it gives you the option to make it a solid This is very nice, complete interface design, with optionsthat save you many steps The Fill Surface feature is described in more detail later in this chapter.The other function that also creates a solid from a surface is the Thicken feature If a surface bodythat encloses a volume is selected, then an option, Create Solid From Enclosed Volume, appears

on the Thicken PropertyManager, as shown in Figure 27.7 You can access the Thicken featurefrom the menus at Insert ➪ Boss/Base ➪ Thicken

FIGURE 27.7

The Thicken PropertyManager

Planar Surface

Planar surfaces can be created quickly, and are useful in many situations, not just for surfacing

work Because they are by definition planar, you can use them to sketch on and for other purposes

that you may use a plane for, such as mirroring Further, you can create a planar surface in a waythat many users have long wanted to use, by selecting two co-planar edges or sketch lines

However, more commonly, planar surfaces are created from a closed sketch such as a rectangle.You can create multiple planar surfaces at once, and the surfaces do not need to all be on the sameplane or even parallel This is commonly done to close up holes in a surface model, such as at thebottom of cylindrical bosses on a plastic part, using a planar circular edge A good example of this

is the bike frame part in the material for Chapter 27 on the CD-ROM, named Chapter 27 – bikeframe.SLDPRT

Remember that a planar surface was used in Chapter 26 with the Split feature to split the leg off of

an imported part This was more effective than a sketch or a plane because the split was limited tothe bounds of the planar surface, and not infinite like the sketch or the plane

The planar surface does not knit itself into the rest of the surface bodies around it automatically,and so you have to use the Knit feature to do this

Extend Surface

The Extend Surface feature functions much in the same way that the Extend function works insketches Figure 27.8 shows the PropertyManager interface and an example of the feature at work

FIGURE 27.8

The Extend Surface PropertyManager

The only item here that requires explanation is the Extension Type panel The Same Surface optionmeans that the extended surface will simply be extrapolated in the selected direction A planar sur-face is the easiest to extend because it can go on indefinitely without running into problems Acylindrical surface can only be extended until it runs into itself Complex lofted or swept surfacesare often difficult to extend Extrapolating a complex surface is not easy to do, and often results inself-intersecting faces, which causes the feature to fail

When the Same Surface setting works, it creates a nice result because it does not create an edgewhere the extension begins; it smoothly extends the existing face

The Linear option is more reliable than the Same Surface option because it starts tangent to theexisting surface and keeps going in that direction, working much like a Ruled surface, which is

to be trimmed by the Trim tool When you select the Mutual Trim option, both surfaces act as theTrim tool, and both surfaces are trimmed

For an example of trimmed surfaces, open the mouse example from Chapter 26 and step throughthe tree This shows examples of a couple of types of trimmed surfaces, as well as extended sur-faces and others

Fill Surface

The Fill Surface is one of my favorite tools in SolidWorks I often refer to it as the “magic wand”because it is sometimes amazing what it can do It is alternately referred to as either Fill or Filled,depending on where the reference is made You will find it listed as both in the SolidWorks interface

The Fill Surface is intended to fill in gaps in surface bodies It can do this either smoothly or byleaving sharp corners You can use constraint curves to drive the shape of the fill between the exist-ing boundaries It can even knit a surface body together into a solid, all in one step Beyond this,you can use the Fill Surface directly on solid models and integrate it directly into the solid auto-matically (much like the Replace Face function which is described later in this chapter)

Several rather complex examples of the Fill Surface are found in the bike frame example that wasoriginally shown in Chapter 12 One of these fills is shown in Figure 27.9

The first thing you should notice about the Fill Surface is that it is creating an oversized, four-sidedpatch and trimming it to fit into the available space This is one of the reasons why I consider this

to be such a magical tool The four-sided patch referred to earlier in the section on NURBS isshown very clearly in this feature preview Also, the trimmed surface concept is illustrated nicely

by this feature Not surprisingly, if you Untrim the fill surface, then you return to the surface that ispreviewed here In this one function, SolidWorks gives us some useful insight about what is going

on behind the scenes

FIGURE 27.9

The Fill Surface PropertyManager and the results of applying it

When using the Fill Surface, it is best to have a patch completely bounded by other surfaces, asshown in Figure 27.9 Fill Surface can work with a boundary that is not enclosed, but it works bet-ter with a closed boundary

You can set boundary conditions as Contact, Tangent, or Curvature Contact simply means that thefaces touch at an edge Tangent means that the slopes of the faces on either side of the edge match

at all points along the edge Curvature means curvature continuous (or C2), where the fill surfacematches not only tangency, but also the curvature of the face on the other side of the boundaryedge This results in a smoother transition than a transition that is simply tangent

When you select the Optimize Surface option, SolidWorks tries to fit the four-sided patch into theboundary Notice that on this part, even though the Optimize Surface option is on, it is clearlybeing ignored because the boundary is a six-sided gap, and cannot be patched smoothly with afour-sided patch It is not necessarily an improvement to make a fill surface optimized, even when

it works

Constraint curves can influence the shape of the fill surface An example of this is shown in Figure27.10 The construction splines shown on the faces of the part were created by the IntersectionCurve tool, and enabled the spline used for the constraint curve to be made tangent to the surface

FIGURE 27.10

The Fill Surface feature with constraint curves

Mid-surface

The Mid-surface feature is not used very often It is intended to be used on parallel faces of a solid

If the faces have opposing draft (such that a wall is wider at the bottom than at the top), then theMid-surface will not work It works on linear walls and cylindrical walls, but not on elliptical orspline-based shapes The PropertyManager for the Mid-surface is shown in Figure 27.11

The intended application for this feature is to create a model for mid-plane type stress analysisusing 2D elements

Similar to the Planar Surface, you can also use the Mid-surface to create a surface that can be usedlike a plane No plane type can create a symmetrical plane, but using a Mid-Surface, you can create

a symmetrical planar surface between parallel walls

geom-If you were to manually perform the functions that are done by Replace Face, then you would start

by deleting several faces of the solid, then extending faces, and then trimming surface bodies, andfinish by knitting all the trimmed and extended faces back into a single solid body

This is a very powerful and useful tool, although it is difficult to tell which situations it will work

in Figure 27.12 shows a part before and after a Replace Face feature has been added The surfaceused to replace the flat face of the solid has been turned transparent The first selection box is forthe solid face or faces, and the second selection box is for the surface body The tool tips for each ofthe boxes are Target Faces For Replacement and Replacement Surface(s), which seem a littleambiguous I like to think of them as Old (top) and New (bottom)

FIGURE 27.13

The Ruled Surface PropertyManager interface

The Ruled Surface works from the edge of a solid or surface body The feature has five basic types

of operation that it can perform:

Using the Normal to Surface setting, because the surface is lofted with a five-degree draft angle atthe big end, making a Ruled surface that is normal to the surface means that it tilts up five degreesfrom the horizontal Be careful of using this setting because it looks close to what you may be hop-ing that it is, but it is slightly off One of the other options may be a better choice, depending onwhat you are looking for

The Tapered to Vector setting needs a plane or axis selection to establish a direction, and then theRuled surface is created from that reference at the angle that you set With a combination of theAlternate Side button and the arrow direction toggle button next to the plane selection, you canadjust the cone created by this setting The interface to make the changes is not exactly clear unlessyou use this function often, but it does work

The Perpendicular to Vector setting is a better option than the Normal to Surface setting when thesurface has been created with some sort of built-in draft angle This is also the setting that looksmost like the Radiate Surface feature, although it works much better than Radiate Surface

The Sweep setting makes a face that is perpendicular to the surface created by Perpendicular toVector It is as if a straight line were swept around the edge This is actually a great way to offset anedge or 3D sketch, by using the edge of the surface as the offset of the original

The Ruled Surface is useful in many ways, including for construction geometry, reference geometry,draft for complex surfaces, and more I discuss it in the next section of this chapter, which con-cerns techniques and applications where these tools are useful

Using Surfacing Techniques

Instead, what I show here are a few broad categories of techniques that you can apply to particularsituations.

Using the Up to Body setting

Another familiar situation is when you have a feature to place and you want to use an Offset fromSurface end condition, but the feature spans two faces In that situation, you can knit the necessaryfaces together (or use offset), and then extrude offset from that surface body

Using Up to or Offset from Body rather than Face often avoids the common error sage, “The end face cannot terminate the extruded feature,” especially if the feature

mes-TIP CROSS-REF

extruded The part that was used in Figure 27.15 is on the CD-ROM in the materials for Chapter

26, and is called Chapter 26 – Up To Body.SLDPRT

FIGURE 27.15

Extruding text

Cut With Surface

Sometimes you may need to make a cut that is more complex than what a simple extrude can do.For example, the cut may need to have shape in multiple directions You could make the cut withmultiple cut features, or even with a surface Figure 27.16 shows a part that is cut with a surface

FIGURE 27.16

Using the Cut With Surface feature on a part

When cutting with a surface, the edges of the surface must be outside of the body that is being cut.With sketches, it is advisable to have more sketch than you need so that you are not trying to cutline-on-line The same applies to cutting with a surface, where it is advisable to have more surfacethan you need to make the cut.

Replace Face

The Replace Face feature can be used on imported or native geometry You can use it to add orremove material from a part When it adds material, it must be able to extend faces adjacent tothose that are being replaced, which can be a limitation A face or faces do not need to be replacedwith the same kind or same number of faces, but the entire face that is being replaced must beremoved If you only want to replace a part of a face, then you can use a Split line to scribe theface, and then replace the part you want

Figure 27.17 shows that the multiple faces of the letter U on this part have been replaced with asurface from an inserted part Replace Face is a fantastic tool that you can use in a number of situa-tions, although it is a little particular sometimes and you cannot always predict when it will or willnot work

FIGURE 27.17

Using Replace Face

Fill Surface in action

The Fill Surface is by far the most complete surface function in SolidWorks It was a good toolbefore, but has become even better With SolidWorks 2007, this feature is even more predictable,meaning that:

n It works more often

n It does what you asked it to do more often

n It includes more options than before

The Fill Surface is an advanced surfacing function Sometimes, when talking about advanced surfacing functions, or indeed any software function, users have a tendency to sound a little cynical This is because the tool is often expected to work on very complex geometry It

is not always the software’s fault when it cannot perform a particular task, or does not do what you imagine you want it to do Sometimes, the tool is simply not meant to perform certain tasks, there may be an unseen flaw in the geometry that prevents it from working, or the user does not under- stand the settings completely The more complex the work, the more frequently you need to find workarounds to get something done Avoiding problems does not make them go away, and it does not help you as a user to know how to handle them when they happen In this book, I have chosen to take a realistic look at most of the features, and if there are problems, then I tell you.

Figure 27.18 shows the Fill Surface blending an intersection between tubes The image to the leftshows the before condition with the tubes coming together at an edge The center image shows theedge trimmed out using the Trim feature, and the right image shows the hole blended over by theFill Surface feature

FIGURE 27.18

Blending with the Fill Surface

NOTE

In Figure 27.19, a solid starts with a Split line on the surface A sketch is then added, and a fill face is created using the sketch as a constraint and the Split line as the boundary The Merge Resultoption in the Fill PropertyManager has a different significance than it does in a solid featurePropertyManager, but the end result is the same Remember that this is a surface function, and if itdoes not merge, then it is left as a surface feature.

sur-FIGURE 27.19

The Fill PropertyManager for merging a fill surface directly into a solid

Notice that this fill is also adding and removing material at the same time If you had to go throughthese steps manually, then you would use the Replace Face feature to integrate the surface into thesolid

Memory surface

The steps that follow are a very brief overview of one technique that you can use to create moldsplits in SolidWorks without using the Mold Tools functionality

The first step is usually a draft analysis This enables you to correctly place the parting surfacebetween the faces that are pulling from opposite directions It is also important to scale the plasticpart before creating the mold block inserts to compensate for plastic shrinkage

You can create the parting surface in several ways, by extruding a surface, or by using Radiate orRuled surface If you use one of these last two methods, be sure to carefully monitor changes in thelevel of the parting line, because the surface may go in the wrong direction, and this may be diffi-cult to see This is what causes problems for the SolidWorks Mold Tools

Once you create the parting surface, select all of the faces on one side of the part It does not ter much whether it is the cavity or core side; select whichever is easier You can do this by orient-ing the part into a top or bottom view, and window-selecting the faces Knit them together with theparting surface

mat-Close off any pass-throughs (shutoffs) in the part with a surface For complex shutoffs, this maytake some time and effort Simple shutoffs can be done with a Delete Hole, Planar Surface, or FillSurface Knit any shutoffs into the surface body

The rest of this process can be done either in the context of an assembly or as a multibody ment Either way, the parts will likely need to be shown as individual part files in the end, and so

arrange-an assembly may be a better choice (although SolidWorks Mold Tools use the multibody approach,and so the rest of this short technique description also uses the multibody approach)

Make a block around the part representing the mold insert blocks Center the block in the way thatyou want the part cavity to be centered in the actual mold insert block Make sure that the Mergeoption is turned off when the block is created

Use the knitted-together parting surface with the Split feature to split the block in two At thispoint, one side of the split should be correct, and the other should still contain the plastic partimpression Use the Combine feature with the Subtract option to remove the plastic part from thesecond block

This technique is used on the part shown in Figure 27.21 Again, I realize that this is a very simplepart and does not account for the normal complexities that are found in most molded parts

However, it does demonstrate the beginning of the technique that may be extended to includemore complex mold features If you are interested in this technique, you can open the part fromthe CD-ROM in the Chapter 27 folder The filename is Chapter 27 – Mold.SLDPRT