Design Engineering

AutoCAD Quick Tips

Autodesk software guru, Ralph Grabowski, solves common CAD conundrums.

September 26, 2011   by Ralph Grabowski

In addition to his day jobs as a veteran CAD journalist and author, Ralph Grabowski often fields technical queries from readers. The following Quick Tips are gleaned from his more than two decades of working on computers and CAD software.

“Instant” Dimensions

Quick Tip: If you need place a lot of continuous dimensions on floor or elevation plans — to indicate the spacing of columns, beams, and other repeating details, example — you could use the DimContinue command, but it might be faster to use QDim. This command “instantly” dimensions a series of features; AutoCAD uses Endpoint or Intersection osnap to recognize the edges of features. The command’s settings let you specify the kind of continuous dimensioning, such as baseline, offset, and ordinate.

The catch is that QDim cannot find blocks, but here is a workaround for evenly spaced blocks: Draw a line along the blocks to be dimensioned. This creates a path for the Measure command, which you use to place points at a spacing that you specify — the same spacing as the blocks, in this case. Now QDim will “find” the blocks by finding the points, and dimension the blocks in a flash.


(Measure is available in pretty much all versions of AutoCAD, LT, Bricscad, ARES, IntelliCAD, and related CAD systems.)

Measure for Measure

Quick Tip: Related to the previous tip, when you need to place a lot of regularly-spaced CL (center line) or other symbols in a drawing, again use the Measure command for this task. The problem, however, is that Measure only places regularly-spaced points or blocks — and not text or other objects. The workaround is to turn the symbol into a block, and then specify the Block option during Measure.

AutoCAD 2012 users have an alternative in the Copy command. It now has an Array option that creates linear arrays of any object, and you don’t need to first draw a path object. You might prefer this approach, but Measure has the advantage that the path it works with can be non-linear, such as a spline or circle.

“Boost” AutoCAD Performance

Quick Tip: To make your workstation run faster for not a lot of money, consider using the ReadyBoost feature in Windows Vista and 7. ReadyBoost uses an external memory source, such as USB thumbdrive or SD memory card, as a cache for programs and their data. Just plug in the drive or card, and if the memory is fast enough, Windows will offer to let you turn it into a ReadyBoost drive through AutoPlay.

(If it does not display AutoPlay, then you can sometimes force Windows to use the drive by right-clicking the drive’s name in File Explorer, choosing Properties, and then selecting the ReadyBoost tab. Click the Dedicate this device to ReadyBoost option.)

ReadyBoost is a cache, which means it speeds up things after they’ve been opened once. In my informal testing, I found that Windows opens AutoCAD roughly 5x faster, and smaller applications load instantly. You should notice a similar speed up with drawings and other files that you access repeatedly, because Windows is accessing the relatively slow hard drive less often.

There are two catches. Windows 7 seems to handle an unlimited amount of memory for ReadyBoost (and even accepts multiple ReadyBoost drives), but Vista supports a maximum of 4GB; Microsoft recommends that ReadyBoost be 1x-2x the amount of system RAM. (Windows uses compression to double the effective amount of memory available through ReadyBoost.) If Windows 7 seems to limit the amount on a large thumbdrive to 4GB, then reformat with with NTFS.

The other catch is that the thumbdrive or card needs to be fast enough for Windows to accept the device. Thumbdrive vendors don’t report the speed of their USB devices, unfortunately, but I found that brand name devices (Verbatim, imation, Lexar, etc) tend to be fast enough, while the free ones you get at trade shows are not. SD memory cards should be at least Class 4 in speed.

(ReadyBoost is not available on Mac or Linux systems.)

Autosave Auto-quiting

User Question: We have a persistent problem with Autosave turning itself off. My hope was that we could somehow add it to the ACAD2010doc.lsp to force it to be turned on when AutoCad is launched. We tried adding this string (setvar ‘savetime>5) to the ACAD2010doc.lsp with no luck – what would the correct line be?

Ralph’s Answer: The correct syntax for saving the drawing every five minutes is:

(setvar “savetime” 5)

Change the 5 to any number of minutes you like, although 5 is certainly the smallest. Otherwise, AutoCAD spends most of its time saving.

Linetype Troubles

User Question: I need a linetype with two different letters:

Is that possible?

Ralph’s Answer: AutoCAD cannot have two different letters in complex linetypes with a line segment between them. However, you could fake it by adding text dash marks so that the shapes read: [s — 150] between the line segments.

Ralph Grabowski is a CAD journalist and the author of 140 books on computer-aided design. Check out his blog at

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