AutoCAD/AutoCAD LT Tips

Know (and set) your limits

A surprising number of AutoCAD users don't set limits properly in their drawings. Don't be one of the foolish many! Know your limits and set them in every drawing. (A reasonably competent drawing setup program, such as the one that comes with Softdesk 8, sets limits automatically.)

The limits represent the rectangular working area that you'll draw on, so it usually corresponds to the paper size. Setting limits correctly gives you the following advantages:

When you turn on the grid, the grid displays in the rectangular limits area. With the grid on and the limits set correctly, you always see your working area and don't accidentally "color outside the lines". The All option of the ZOOM command zooms to the greater of the limits or the drawing extents. (The drawing extents are the corners of an imaginary rectangle that just surrounds all of the objects in the drawing.) When you set limits properly and "color within the lines", ZOOM All gives you a quick way to zoom to your working area. When you plot, limits are the quickest, most reliable plotting area (if you've set limits correctly!). Extents will work 97% of the time, but you'll encounter situations where a stray object messes up your extents plot area. AutoCAD and clueless users who don't understand the COPY command control the extents. You control the limits. Efficient, predictable CAD depends on controlling the drawing. Ergo, plot limits, not extents.

To set the limits in a drawing, type LIMITS and press ENTER, then type or pick the lower left and upper right corners of the desired limits area. For example, if you're setting up a 1/8" = 1'-0" drawing (drawing scale factor = 96) to be plotted on a 24" x 36" sheet in landscape orientation, the upper-right corner of the limits should be 36" times 96, 24" times 96. OK, pencils down. The correct answer is 3456,2304 (or 288',192').

Command: limits ENTER
Reset Model space limits:
Specify lower left corner or [ON/OFF] <0'-0",0'-0">: ENTER
Specify upper right corner <1'-0",0'-9">: 288',192' ENTER

First posted 20-Mar-2000. If your cursor no longer moves smoothly across the screen (e.g., as you move the mouse, the cursor hangs briefly and then shoots across the screen), then you probably need to clean your mouse's innards. Fortunately, the procedure isn't as disgusting as it sounds. Many books tell you to clean the mouse ball, but the problem usually results from dirty mouse ball rollers. Here's how to clean them.

1. Turn the mouse over and remove the little cover that keeps the ball from falling out

2. Remove the mouse ball. If it does happen to be dirty, clean it.

3. Look inside the hole where the mouse ball lives. You should see three little rollers, and they'll probably be caked with crud. Use a dull, non-abrasive object (e.g., the end of a small screwdrive) to clean all of the crud off.

4. Replace the mouse ball and cover.

5. Whack the eraser dust, potato chip crumbs, and anything else off of your mouse pad (so that you don't have to perform this same procedure two days later).

Feeling WMiFfed?

The AutoCAD and LT WMFOUT command provides the most reliable way to paste all or part of drawing into a word processing document. There are three tricks to creating usable WMF files in AutoCAD or LT:

• Set your LT background color to white. R14/LT98/LT97: PREFERENCES, Color tab, Graphics Window Background. A2K/LT2K: OPTIONS, Display tab, Color, Model tab background or Layout tabs background.

• Make all graphical objects black. R14/LT98/LT97: PREFERENCES, Color tab, Monochrome Vectors. A2K/LT2K: LAYER, select all layers, change layer color to black.

• Adjust the size, shape, and zoom resolution of the drawing area. Resize the AutoCAD LT program or document window, and then choose View, Zoom, Extents to display the entire drawing (or ZOOM to the specific area that you want to include in the WMF file).

The TRIM and EXTEND commands normally allow you to select only one object at a time for trimming or extending. The one exception is that you can type F and press ENTER to use the Fence object selection mode. Fence is useful for trimming or extending a large group of objects in one fell swoop.

Although Autodesk doesn't deem the DONUT command important enought to put it on the Draw toolbar, it's a useful and interesting command:

• If you want to draw a filled circle (to represent the section or end view of a piece of concrete reinforcing bar, for example), use the DONUT command and specify an inside diameter of 0. You might think of this special case as the "jelly-filled donut" option.

• The DONUT command is just a fancy way to draw polylines. There's no such object as a "Donut" in the AutoCAD drawing database. Instead, the DONUT command draws an LwPolyline or Polyline object (depending on the current setting of the PLINETYPE system variable) composed of two semi-circular arcs that form a circle. The difference between the inside diameter and outside diameter that you specify when drawing a donut determines the thickness of the arc segments. (You can confirm that I'm not making all this up by drawing a donut and then using the LIST command to list its properties.)

• You can snap to the center of a donut (i.e., polyline arc segments) using the CENter object snap mode.

• The DONUT command is available from the Draw menu, but keyboard aficionados can enter it by typing DONUT, DO, or, for you purists in matters of spelling or breakfast food, DOUGHNUT.

Minimize text window status bar clutter

You've probably noticed that when the AutoCAD text window opens (either because you press the F2 key or because an AutoCAD command, such as LIST, opens it automatically), the new window adds a button to the Windows taskbar. If you're fussy about extra buttons cluttering up your taskbar, you might prefer that the button go away after you close the text window. Unfortunately, if you simply press F2 to toggle the text window off, the taskbar button doen't go away. Fortunately, you can close the text window and get rid of the taskbar button by treating the text window as a separate "program" and closing it. Instead of pressing F2 to close the twxt window, either: click the Close button (the little X) at the upper-right corner of the text window's title bar, or Press ALT+F4 (while the text window has focus).