CHAPTER 1 AutoCAD Productivity Considering the complexity of AutoCAD, it’s not surprising that many people GH TE D MA TE RI AL who use it miss something important along the way. Many users had little training on the software before being expected to start producing useful work, and these users in turn have trained others based on what they figured out on their own. Even the most experienced AutoCAD users have likely forgotten some useful things they once knew.
■ chapter 1: AutoCAD Productivity Design Standards CAD software is used in so many fields of design that it would be impossible to develop extensive standards that apply to all of them. I’ve trained people who use AutoCAD to design quilts, hearing aids, doll clothes, houses, barns, commercial buildings, M16s, submarine hatches, and the myriad components of machinery. But there are some foundational rules that represent a consensus among serious users of CAD.
design standards ■ 3 Figure 1.1 Conventional break for long part belongs). They could drag the value right or left so it could be seen in one of the viewports. (See Figure 1.1.) The entire part is shown at the bottom, with the conventional break created with two floating viewports above. Draw Existing Features “as Built” This tip probably seems obvious, but I’ve been asked more than once what I recommend when designing for renovations or additions to existing structures.
■ chapter 1: AutoCAD Productivity tolerance—at least, they’re supposed to. The question is, where in that range should you create your accurate-to-15-decimal-places geometry when using a CAD system? (You know it’s impossible to make anything an exact size. If you think you can, you’re not using a precise enough measuring tool.) There are several possibilities. Some people draw objects in the middle of their size tolerance range.
autocad best practices METRIC IS EVERYWHERE I’ve been predicting since 1976 that the U.S. was about to go fully metric. I keep making that prediction, and I’m getting less and less wrong. That may not be as good as being right, but it’s possible that you’ll have to deal with the metric/inch conflict at some point.
■ chapter 1: AutoCAD Productivity Use the Help System The AutoCAD Help system has become one of the best Help systems available in any software. If I had to identify one AutoCAD feature as the single most underused, this is it. I’ve gotten many phone calls from people who have an AutoCAD question that I answer by simply going to the AutoCAD Help system. Use it. It keeps getting better and better. It’s a model for what a Help system should be.
autocad best practices HELP SYSTEM I’m not exaggerating when I say I answer many questions from confused users by bringing up the AutoCAD Help system—often while I’m on the phone with them. The most recent was a call from a frustrated user who was using AutoCAD 2006 to edit text in a vertical title block. The version of AutoCAD they had upgraded from displayed the text horizontally; but AutoCAD 2006 displayed the text in place, which meant he had to tilt his head to the side to read it.
■ chapter 1: AutoCAD Productivity LAYER MANIPULATION Consider the following example from a residential floor plan. Layer names all begin with a field that designates the floor of the residence: FL1, FL1-DIM; FL2, FL2-DIM; FND, FND-DIM. Each floor has a number of associated layers for hidden lines, center lines, dimensions, appliances, electrical, and so on.
autocad best practices Plot from Layouts in Paper Space Read Chapter 6, “Plotting,” for the full story; but for now, follow these steps in sequence when you create a new drawing file: 1. Create your geometry full size in Model Space, but don’t add dimensions, text, or hatches. 2. Set up a layout with all views at the proper plot scale. 3. Add dimensions, text, hatches, and schematic symbols to your drawing from a layout with a properly scaled viewport.
■ chapter 1: AutoCAD Productivity Don’t Use the Name Standard The name Standard is used as a default name for the text style, dimension style, table style, and probably a few other things in AutoCAD. It’s misleading, because it’s a standard only in the sense that it always shows up in an AutoCAD environment. Never does the name represent a real standard in any discipline. To avoid a nasty surprise down the road, build a template file that banishes Standard as a name for anything.
autocad best practices Control Imperial vs. Metric Settings Starting from scratch with either an imperial (acad.dwt) or metric (acadiso.dwt) template controls the files used for linetypes and hatch patterns. ACAD.lin and ACAD.pat are used for imperial, and ACADISO.lin and ACADISO.pat are used for metric. You can change this using the MEASUREMENT variable. The imperial setting is 0; the metric setting is 1. Changing this doesn’t change the limits or the default dimstyle after the fact.
■ chapter 1: AutoCAD Productivity 3. I used QSELECT to select all text containing a front slash (all the dates) and put them on their own layer. This required using the * wildcard match operator (nice to know some DOS). By placing */* in the Value window, you get all text containing a front slash anywhere in the string.
feature review (all releases) Drawing Efficiency At the heart of a CAD system is the ability to create accurate geometry. Speed is always secondary to accuracy, but it’s possible for one user to be much more efficient than another in creating geometry while still maintaining accuracy. That efficiency isn’t merely the result of being fast with a mouse and keyboard—it’s the result of planning strategies for approaching each new object to be drawn.
■ chapter 1: AutoCAD Productivity Rectangular Arrays Figure 1.5 Precision array at an angle When you’re creating a rectangular array, it’s easier than you think to confuse columns and rows when you’re asked to specify their distance. Columns are vertical, and the icon illustrates that in the dialog box. Keep in mind that the distance between rows and columns is the distance from a point on one item to the same point on the next item.
feature review (all releases) DISPLAY PRECISION Don’t be fooled by the integer of 27 shown for the angle in Figure 1.6. The actual angle may be different. Why? Because the default precision for angle display is 0, which means all angles are rounded to a whole number for display purposes only. If you change the angular precision using either the variable AUPREC or the Units dialog box, you’ll see the angle in this case is actually 27.37591770°.
■ chapter 1: AutoCAD Productivity Because WCS is the default, you can type UCS and press the Enter key twice—once to execute the command, and once to accept the default. Polar Arrays Geometry with a repeated angular pattern is often found in mechanical applications and sometimes in architectural and civil applications. To create polar arrays efficiently, avoid repeating the same set of editing operations for each feature arrayed. Start by identifying a repeatable pattern on the object.
feature review (all releases) ■ 17 REDUCE CONSTRUCTION LINES Try to use as few construction lines as possible when creating geometry. The more lines you use to locate points or edges, the more chances that you may confuse one or more for actual lines, or leave lines behind that are on top of each other. I’ve seen this lead to subtle, but often important, errors.
■ chapter 1: AutoCAD Productivity ALTERNATIVE TO PEDIT You can create regions with the BOUNDARY command or with the REGION command. Either way, you can also use regions to create complex objects quickly by using the SUBTRACT, INTERSECT, and UNION commands. The shape shown in Figure 1.9 was created in under one minute (actually, 38 seconds). To create regions from existing closed plines or circles, use the REGION command and select the objects.
feature review (all releases) ■ 19 Note that in this case, Increment Angle is set to one (1). This is a small angle, and it isn’t easy to work with, but it can be used. If the angles you’re using are based on larger increments, use them. It’s much easier to use an angle increment of 5, 15, or 45; but any increment can be typed into the window, including values so small they are completely unusable as angles. That’s one of the things I love about AutoCAD.
■ chapter 1: AutoCAD Productivity You can change the default direction of angles from counterclockwise to clockwise to do this kind of drawing when it’s easier to draw clockwise. But if you change the angular direction from counterclockwise to clockwise to simplify drawing a single shape, make sure you change it back to avoid confusion later.
feature review (all releases) ■ 21 Figure 1.13 Circle TTR for tangent arcs One overlooked feature of the FILLET command is its ability to quickly close two parallel lines with a tangent arc. Select both lines, and AutoCAD will calculate the size of an arc that it will use to join them on the end nearer your selection. DTEXT Most justification options are logical. Every line of text has four vertical locations for justification: Top, Middle, Baseline, Bottom, in that order.
■ chapter 1: AutoCAD Productivity PEDIT You can use the PEDIT command to create a closed pline from several line and arc segments. To do so, issue the command, pick one of the lines, answer Yes when asked if you want to turn it into a pline, select the JOIN option, and pick the other segments with a window. Remember: • All segments must be touching but not overlapping. • You can’t have segments on top of each other. • The resulting pline should be closed.
feature review (all releases) In Figure 1.15, it took 25 seconds to get the total area of the object with all internal shapes removed. Here are the steps: 1. Create regions from the existing geometry using the BOUNDARY command. 2. Use the SUBTRACT command to remove the holes from the large object by selecting them all with a window. 3. Use the Object option of the AREA command, and select the resulting region. You can also find the area as a property of the region in the Properties palette.
■ chapter 1: AutoCAD Productivity TIME TIME gives you the total time during which a drawing has been open for editing. You can also use it as a running timer by selecting the Reset option before beginning something new. Use this timer as you try to develop more drawing speed. Pick one object, and draw it several times using different strategies. The TIME command can tell you if you’re getting any faster.
feature review (all releases) G↵ at any selection prompt followed by the name of the group you created (make the names short and memorable). However, the group must be selectable. You can change whether a group is selectable using the Group dialog box. PICKSTYLE The settings of the AutoCAD variable PICKSTYLE determine how other members of a group are treated, including associated hatch patterns, whenever any member of the group is selected.
■ chapter 1: AutoCAD Productivity changes. You can change any of the properties of the entire group. You could do the same for all the circles in a drawing or within a selection set, and change their diameters. CHAMFER and FILLET You can use either of these commands to clean up sharp corners or extend two unconnected lines into sharp corners by setting their values to 0. As of AutoCAD 2006, you have the following option: Hold down the Shift key while selecting the second line to create a sharp corner.
feature review (all releases) EXPLODE You can use EXPLODE with the following entities: blocks, hatches, mlines, plines, solid objects, and blocks of text created with the MTEXT command. Any blocks can be exploded except those placed using the MINSERT command. For that reason, MINSERT should not be used unless you want a block that can’t be exploded. When you use EXPLODE, be careful not to select more objects than you want. The TXTEXP Express Tool can explode individual pieces of text into vectors.
■ chapter 1: AutoCAD Productivity ROTATE The remarkably useful and often overlooked option of ROTATE is Reference. You can use the Reference option by entering any angle at the keyboard or by picking two points on the screen. You then type the angle to which you want the selected points to align. Instead of typing the new angle, you can also make one more selection. It becomes the second point on a new angle, using the first point selected as a reference for a base point.
feature review (all releases) UNDO The UNDO command displays the following options at the command prompt: Auto/Control/BEgin/End/Mark/Back: Auto Auto requires an additional specification of On or Off. When Auto is on, any opera- tion taken from the menu, no matter how complicated, is treated as a single command, reversible by a single U command. Back Back takes the drawing back to the state it was in when the most recent mark was entered.
■ chapter 1: AutoCAD Productivity LENGTHEN This interesting command can be used to change the length of a line, polyline, or an arc. It’s the only way to quickly create an arc with a specific arc length. To do that, create the arc, and use the Total option of LENGTHEN to change the total length to whatever you want.
feature review (all releases) ORDINATE Ordinate dimensions are used to set dimensions as coordinates in the X and Y axes. Ordinate dimensioning is used most often in mechanical drawing, but it’s increasingly being used in architectural and other fields as well. When I draw a structure that I’ll be building myself, I always dimension it with ordinate dimensions rather than with continuous dimensions, which is the traditional method.
■ chapter 1: AutoCAD Productivity DIMASSOC has three settings: • 0—Dimensions are exploded as they’re placed, which is a bad idea unless you have a very good reason. • 1—Dimensions have the traditional defpoint association, but they’re not associated with objects and aren’t connected to Model Space when a dimension is placed in Paper Space. • 2—Dimensions move with objects and reflect true size when placed in Paper Space.
feature review (all releases) Not everyone can touch-type; however, I appreciate being able to. (This may be a good time to thank my mother for insisting that I take high school typing in 1967—an era when the manual typewriters used in classrooms had blank keys so you wouldn’t hunt and peck.
■ chapter 1: AutoCAD Productivity If some of your entities have linetypes that aren’t scaled to your liking, instead of changing that with LTSCALE, use PROPERTIES to make changes to each individual object in a viewport in the layout. Linetype problems are often the result of confusion between metric and imperial units. If you need an LTSCALE of 25 or so to see linetypes properly in a layout, you’ve probably started your drawing in imperial units but are drawing objects measured in millimeters.
feature review (all releases) • Lineweight should be set to BYLAYER. A default value of .20mm and an object-line value of .40mm usually give a good lineweight distinction. • A button on the Layers toolbar makes the layer of a selected object current. • A button on the Layers toolbar restores the previous layer state.
■ chapter 1: AutoCAD Productivity Because holding down the middle wheel allows panning in all directions, the Windows scrollbars aren’t useful and often get in the way. Turn them off under the Display tab of the Options dialog box, and you’ll get a 4 percent increase in screen area.
feature review (all releases) quickly change all names created when binding external references (if you used the Bind option for binding, which I recommend you do, and not the Insert option). For example, if you bind an externally referenced drawing named STP123.dwg to a host drawing, the block definitions have names like STP123$0$BLOCK1, STP123$0$BLOCK2, STP123$0$BLOCK3, STP123$0$BLOCK4, and STP123$0$BLOCK5.
■ chapter 1: AutoCAD Productivity CHSPACE This command is indispensable, and it has finally evolved from an Express Tool into a native command in AutoCAD 2007. It lets you change objects between Paper Space and Model Space while retaining their relative scales. This makes it possible to place text or dimensions wherever it’s convenient while working and then move them to their permanent home later. If you ever decide you placed something in the wrong space, you need this command.
feature review (all releases) ■ 39 You can also change the overwritten dimensions automatically, which may cause even more problems if you don’t notice what got updated. The problem is that the value is probably overridden because the geometry is wrong. SYSVDLG The System Variables editor is a wonderful tool. It gives you a concise list of each system variable, tells you where its value is stored, and describes what it does.
