Wiley SolidWorks 2009 Bible Part 5 pot

289 Patterning and Mirroring 8 FIGURE 8.3 The Linear Pattern PropertyManager FIGURE 8.4 The Circular Pattern PropertyManager 290 Building Intelligence into Your Parts Part II Mirroring in a Sketch Mirroring in a sketch is a completely different matter from patterning in a sketch. It offers superior performance, and the interface is better developed. Mirrored entities in a sketch are an instrumen- tal part of establishing design intent. Two methods of mirroring items in a sketch are discussed here, along with a method to make enti- ties work as if they have been mirrored when in fact they were manually drawn. Mirror Entities Mirror Entities works by selecting the entities that you want to mirror along with a single center- line, and clicking the Mirror Entities button on the Sketch toolbar. It is a simple and effective tool that you can use on existing geometry. This method is the fastest way to use the tool but there are other methods. You can preselect or post select, using a dialog box to select the mirror line, which does not need to be a centerline. One feature of Mirror Entities may sometimes cause unexpected results. For example, in some situ- ations, Mirror Entities will mirror a line or an arc and merge the new element with the old one across the centerline. This happens in situations where the mirror and the original form a single line or a single arc. SolidWorks may delete certain relations and dimensions in these situations. Dynamic Mirror As the name suggests, Dynamic Mirror mirrors sketch entities as they are created. You can activate it by selecting a centerline and clicking the button on the Sketch toolbar. Dynamic Mirror is not on the toolbar by default; you need to select Tools ➪ Customize ➪ Commands to add it to the toolbar. You can also access Dynamic Mirror through the menus at Tools ➪ Sketch Tools ➪ Dynamic Mirror. When you activate this function, the centerline displays with hatch marks on the ends and remains active until you turn it off or exit the sketch. Figure 8.5 shows the centerline with hatch marks. FIGURE 8.5 The Dynamic Mirror centerline with hatch marks 291 Patterning and Mirroring 8 Symmetry sketch relation I have covered the Symmetry sketch relation in previous chapters on sketching, but I mention it here because it offers you a manual way to mirror sketch entities. There are editing situations when you may not want to create new geometry, but instead use existing entities with new relations driving them. To create the Symmetry sketch relation, you must have two similar items (such as lines or endpoints) and a centerline selected. Mirroring in 3D sketches Chapter 31 deals with 3D sketches in more detail, but I discuss the mirror functionality here to connect it with the rest of the mirroring and patterning topics. 3D sketches can contain planes and if you are sketching on a plane in a 3D sketch, you can mirror items on it. You cannot mirror general 3D sketch entities. Sketch patterns are also unavailable in the 3D sketch, but starting with the 2009 release, you can use the Move, Rotate, and Copy sketch tools on planes in 3D sketches. Combining one questionable functionality (3D sketches) with another (sketch patterns) does not usually improve either one. Geometry Pattern The SolidWorks Help file says that the Geometry Pattern option in feature patterns results in a faster pattern because it does not pattern the parametric relations. This claim is valid only when there is an end condition on the patterned feature such that the feature will actually pattern the end condition’s parametric behavior. The part shown in Figure 8.6 falls into this category. The improved rebuild time goes from .30 to .11 seconds. Although a 60 percent reduction is signifi- cant, the most compelling argument for the use of the Geometry Pattern is to avoid the effect of patterning the end-condition parametrics. Because of this speed differential, you need to be careful about using the Geometry Pattern option. SolidWorks turns this option on by default for some patterns where you may not wish to use it for rebuild time reasons. Under some conditions, Geometry Pattern will not work. One example is any time a patterned face merges with an unpatterned face. These situations can be difficult to identify. Figure 8.7 shows a pattern that cannot be created using the Geometry Pattern option. The boss merges with the side face of the block, which generates the error message shown in the figure. The circular part shown in the image is an exception where the partial cylindrical bosses merge with the side of the cylin- der, but Geometry Pattern works. In some situations, SolidWorks error messages may send you in a loop. One message may tell you that the pattern cannot be created with the Geometry Pattern turned on, so you should try to turn it off. When you do that, you may get another message that says the pattern will not work, and that you should try to use the Geometry Pattern setting. In cases like this you may try to use a dif- ferent end condition, or change the selection of features patterned along with the feature, such as fillets. You may also try to pattern bodies or even faces rather than features. 292 Building Intelligence into Your Parts Part II FIGURE 8.6 A geometry pattern test Geometry pattern off — Parametrics are patterned Geometry pattern on — Parametrics not patterned FIGURE 8.7 Merged faces 293 Patterning and Mirroring 8 Patterning Bodies I cover multiple bodies in depth in Chapter 26, but need to deal with it briefly here. Any discus- sion of patterning is not complete without a discussion of bodies because using bodies is an avail- able option with all the pattern and mirror types. SolidWorks parts can contain multiple solid or surface bodies. A solid body is a solid that comprises a single contiguous volume. Surface bodies are defined differently, but they can also be patterned and mirrored as bodies. There are both advantages and disadvantages to mirroring and patterning bodies instead of fea- tures. The advantages can include the simplicity of selecting a single body for mirroring or pattern- ing. In cases where the geometry to be patterned is complex or there is a large number of features, patterning bodies also can be much faster. However, in the example used earlier with patterning features in a 20-by-20 grid of holes, when done by patterning a single body of 1" × 1" × .5" with a .5" diameter hole, patterning bodies gives a rebuild time of about 130 seconds with or without Verification On Rebuild. It is the function that combines the resulting bodies into a single body that takes most of the time. This says that for large patterns of simple features, patterning bodies is not an efficient technique. Although I do not have an experiment in this chapter to prove it, I believe that creating a pattern of a smaller number of complex bodies using a large number of fea- tures in the patterned body would show a performance improvement over patterning the features. Another disadvantage of patterning or mirroring bodies is that it does not allow you to be selective. You cannot mirror the body minus a couple of features without doing some shuffling of feature order in the FeatureManager. Another disadvantage is that if the base of the part has already been mirrored by a symmetrical sketch technique, then body mirroring is not going to help you mirror the subsequent features. Also, the Merge Bodies option within the mirror feature does not work as you would want it to. It merges only those bodies that are part of the mirror to bodies that are part of the mirror. Pattern Bodies does not even have an option to merge bodies. Both of these func- tions are often going to require an additional combine feature (for solid bodies) or knit (for surface bodies) to put the final results together. Some of these details may seem obscure when you’re reading about them, but when you begin to work patterning bodies and begin trying to merge them into a single body, read over this section again. The inconsistency between the Merge option existing in Mirror but not in Pattern is unex- plainable, and a possible opportunity for an enhancement request. CROSS-REF CROSS-REF Bodies are discussed in more detail in Chapter 26. Surface modeling is covered in Chapter 27. Patterning Faces Most of the pattern types have an option for Pattern Faces. This option has a few restrictions, the main limitation being that all instances of the pattern must be created within the boundaries of the same face as the original. Figure 8.8 shows an example of the Pattern Faces option working with a Circular Pattern feature. 294 Building Intelligence into Your Parts Part II FIGURE 8.8 A circular pattern using the Pattern Faces option To get around this limitation, you can knit and pattern the surface body, as shown in Figure 8.9. FIGURE 8.9 Patterning a surface body Split in face means faces from feature on side cannot be patterned all the way around 295 Patterning and Mirroring 8 CROSS-REF CROSS-REF Working with surface bodies is covered in Chapter 27. Patterning Fillets You may hear people argue that you cannot pattern fillets. This is partially true and partially untrue. It is true that fillets as individual features cannot be patterned. For example, if you have a symmetrical box and a fillet on one edge and want to pattern only the fillet to other edges, this does not work. However, when fillets are patterned with their parent geometry, they are a perfectly acceptable candidate for patterning. This is also true for the more complex fillet types, such as vari- able radius and full radius fillets. You may need to use the Geometry Pattern option, and you may need to select all the fillets affecting a feature, but it certainly does work. Understanding Pattern Types Up to now, I have discussed patterns in general; differentiated sketch patterns from feature pat- terns, face patterns, and body patterns; and looked at some other factors that affect patterning and mirroring. I will now discuss each individual type of pattern to give you an idea of what options are available. Linear Pattern The Linear Pattern feature has several available options: n Single direction or two directions. Directions can be established by edge, sketch entity, axis, or linear dimension. If two directions are used, the directions do not need to be per- pendicular to one another. n Spacing. The spacing represents the center-to-center distance between pattern instances, and can be driven by an equation. n Number of Instances. This number represents the total number of features in a pattern, which includes the original seed feature. It can also be driven by an equation. Equations are covered in detail in Chapter 9. n Direction 2. The second direction works just like the first, with the one exception of the Pattern Seed Only option. Figure 8.10 shows the difference between a default two- direction pattern and one using the Pattern Seed Only option. n Instances to Skip. This option enables you to select instances that you would like to leave out of the final pattern. Pink dots are the instances that remain, and the red dots are the ones that have been removed. Figure 8.11 shows the interface for skipping instances. You may have difficulty distinguishing the red and pink colors on the screen. 296 Building Intelligence into Your Parts Part II FIGURE 8.10 Using the default two-direction pattern and the Pattern Seed Only Option Original feature Pattern seed only FIGURE 8.11 Using the Instances to Skip option n Propagate Visual Properties. This option patterns the color, texture, or cosmetic thread display, along with the feature to which it is attached. n Vary Sketch. This option in patterns is often overlooked and not widely used or under- stood. While it may have a niche application, it is a powerful option that can save you a lot of time if you ever need to use it. Vary Sketch allows the sketch of the patterned feature to maintain its parametric relations in each instance of the pattern. It is analogous to the Geometry Pattern. Where Geometry Pattern disables the parametric end condition for a feature, Vary Sketch enables the para- metric sketch relations for a pattern. To activate the Vary Sketch option, the Linear Pattern must use a linear dimension for its Pattern Direction. The dimension must measure in the direction of the pattern, and add- ing the spacing for the pattern to the direction dimension must result in a valid feature. The sketch relations must hold for the entire length of the pattern. Figure 8.12 shows the sketch relations and the resulting pattern. The preview function for this feature does not work. 297 Patterning and Mirroring 8 FIGURE 8.12 Using the Vary Sketch option ON the CD-ROM ON the CD-ROM To better understand how this feature works, open the sample file from the CD-ROM called Chapter 8 Vary Sketch.sldprt, and edit Sketch2. Edit the .40-inch dimension. Double-click it and use the scroll arrow to increase the dimension; watch the effect on the sketch. If a sketch does react to changes properly, then it cannot be used with the Vary Sketch option. In this case, the .40-inch dimension is used as the direction. The direction dimension has to be able to drive the sketch in the same way that this one does. These dimensions cannot pass through the Zero value and cannot flip directions or move into negative values. To make the sketch react this way to changes in the dimension, the slot was created using the bi- directional offset that was demonstrated in an earlier chapter, which means that the whole opera- tion is being driven by the construction lines and arcs at the centerline of the slot. Sketch points along the model edges are kept at a certain distance from the ends of the slots using the .50-inch dimensions. The arcs are controlled by an Equal Radius relation and a single .58-inch radius dimension. The straight lines at the ends of the slots are controlled by an Equal Length relation. This type of dimensioning and relation creation is really what parametric design is all about. The Vary Sketch option takes what is otherwise a static linear pattern and makes it react parametrically in a way that would otherwise require a lot of setup to create individual features. If you model everything with the level of care that you need to put into a Vary Sketch pattern feature sketch, then your models will react very well to change. Circular Pattern The Circular Pattern feature requires a circular edge or sketch, a cylindrical face, a revolved face, a straight edge, an axis, or a temporary axis to act as the Pattern Axis of the pattern. All the other options are the same as the Linear Pattern — except that the Circular Pattern does not have a Direction 2 option, and the Equal Spacing option works differently. [...]... the entire part Figure 8.22 shows the RealView tab of the Task Manager with some of the Cosmetic Pattern options CROSS-REF You can find more details about RealView appearances in Chapter 5 FIGURE 8.22 Cosmetic Pattern options in the RealView tab of the Task Manager 3 05 8 Part II Building Intelligence into Your Parts Mirroring in 3D Because symmetry is an important aspect of modeling parts in SolidWorks, ... Mirror Part command creates a brand new part, by mirroring an existing part The new part does not inherit all the features of the original, and so any changes must be created in the original part If you want different versions of the two parts, you need to use Configurations, which have not been covered yet in this book CROSS-REF Configurations are covered in detail in Chapter 10 You can use the Mirror Part. .. the list that is satisfied is returned by the SWITCH function For example, switch (x>2, 1 .5, x>1, 5 x . the Task Manager 306 Building Intelligence into Your Parts Part II Mirroring in 3D Because symmetry is an important aspect of modeling parts in SolidWorks, mirror functions are a commonly used. creates a brand new part, by mirroring an existing part. The new part does not inherit all the features of the origi- nal, and so any changes must be created in the original part. If you want different. because the new part will have a relationship to the part Origin, based on the plane on which it was mirrored. The Mirror Part command is found in the Insert menu. When mirroring a part, you can