AutoCAD’s Circle command provides five different ways to draw a circle:

Center Radius: You specify the center, then the radius (type as a distance or pick a point)

Center Diameter: Specify the center, then choose the diameter option and type the diameter length or pick a point.

2 Points (2P): Specify one point on the circumference, then a second point on the circumference. The two points will be the diameter.

3 Points (3P): Specify three points on the circumference.

TTR (Tangent Tangent Radius): You are prompted to pick a point on first object you want your circle to be tangent to, then to pick a point on the second tangent object. Then enter a radius.

If these five options aren’t enough, a TTT (tan tan tan) option is available when you select Circle from the Draw menu. It lets you draw a circle tangent to three objects.

Caption: Six circle options are available when you select Circle from the Draw menu.

Caption: Results of the tan tan tan circle choice. You can get similar results using the 2P or 3P options.

If you need to quickly create a filled 2D shape, try the Solid command (despite its name, it doesn’t create a 3D solid. You can, however, add thickness to an object you create with the Solid command.) The Solid command creates shapes with straight edges. When the FILL system variable is on, AutoCAD fills the shape with a solid fill. When you start the command (type Solid at the command line), AutoCAD prompts you for first, second, third, and fourth points. These are specified in zigzag order, not in order around the perimeter of the shape. To get the object below, for example, you’d pick the first point at upper left, the second point at bottom left, the third point at the upper right, and the fourth point at bottom right.

Caption: The Solid command makes filled rectangular objects.

Once you select the fourth point, the command continues to prompt for third and fourth points, so you can continue to create adjacent solids, if you like.

Caption: You can select additional points to add on to your Solid object. You can then grip edit the object.

The CUI (Customize User Interface) command, introduced in AutoCAD 2007, provides two options that can get you out of trouble when your interface customizations go awry. Start the CUI by typing CUI at the command line, or click the Workspace button on the status bar, then select Customize. At the top of the tree in the upper left window is your main customization file (for example, ACAD). Right-click on this file (the topmost entry in the tree). The shortcut menu that appears displays options to Restore ACAD.CUI or Reset ACAD.CUI.

Caption: Click on your main customization file at the top of the tree in the upper left panel to see options to Restore and Reset.

The difference? Restore replaces the current CUI file (ACAD.CUI) with an incremental backup of your CUI file—basically the last saved version of your CUI file. It uses a CUI backup file named ACAD.BAK.CUI that is saved to your local Application Data folder (in Windows XP, for example, you can find it here:

C:\Documents and Settings\username\Application Data\Autodesk\product name\enu\Support)

Reset ACAD.CUI replaces the current CUI file with a pristine out-of-the-box version of the CUI. That means any customizations you’ve made will be gone.

Your best bet is to start with Restore to see if that will fix your problem. Resort to Reset only when necessary.

Note: Periodically back up your ACAD.CUI file to a safe location. That will also make it easier to transfer your settings if you switch computers or update your AutoCAD version.

Besides your main menu file, you will also want to back up CUSTOM.CUI, which is a partial customization file that works in conjunction with the main file. ACAD.MNR holds the BMP files for toolbar and menu icons. ACAD.MNL holds AutoLISP routines used by your menus.

If you’re using a pre-2007 version of AutoCAD, you will want to back up any files named ACAD and CUSTOM with the following extensions, particularly because there’s no magic Restore button:

• MNU: Menu template file.
• MNS: Menu source file compiled by AutoCAD from the MNU file. Contains any customizations you make.
• MNR: Menu resource file for bitmap images.
• MNL: AutoLISP routines used by menu options and/or toolbar buttons

In AutoCAD releases prior to 2007, customized menus are stored in MNU and MNS files. To use these older menus in a version of AutoCAD with the CUI, select the Transfer tab in the CUI dialog box (type CUI at the command line. Select Open from the Customizations in New CUI File pull-down menu.

Caption: Select Open in the top right panel of the CUI Transfer tab.

Select the old menu file (make sure Files of Type is set to find Menu files) and click on Open.

Caption: Browse to your menu file and select it.

The old file should now display in the top pull-down window with the CUI file extension.

Caption: The menu file should now appear in the top right pull-down window with a CUI extension.

Next, load the file by typing CUILOAD at the command line. Note: You need to unload the current customization file before you can load yours. Select the file in the Load/Unload Customizations dialog box and click on Unload. Then browse to your newly converted file and click on Load.

Caption: Load your converted menu file with the Load/Unload CUI command. Be sure to unload the current files first.

Alternatively, you can use the Menu command (type Menu at the command line) to automatically convert menu files. In the Select Customization File dialog box, choose Legacy Menu Template (MNU) or Legacy Menu File (MNS) from the Files of Type pull-down menu. Select your old file, and AutoCAD will open as a CUI file.

In the beginning, there was only the LTSCALE system variable to control the display of linetypes. Over the years, more and more SCALE system variables were added to AutoCAD. Here’s a quick rundown of the different SCALE variables and what they do. They may or may not be available, depending on your version of AutoCAD.

LTSCALE controls the overall linetype scaling of displayed objects. Its setting determines the global linetype scale factor, which means it changes the scale factor of the linetypes for all objects in a drawing. The default value is 1, and it cannot equal zero. Change the scale by typing LTSCALE at the command line and typing in a scale. Note that any change to the variable will make the drawing regenerate.

PSLTSCALE stands for paper space linetype scale. It controls linetype scaling for objects that are displayed in paper space viewports. Its default value is 1. Note that the drawing does not regenerate when you change this variable. You must use the Regen or Regenall commands to do so.

MSLTSCALE stands for model space linetype scale. It scales linetypes that are displayed in model space by the annotation scale. When MSLTSCALE is set to 1 (the default), linetypes displayed on the model tab are scaled by the annotation scale.

Note: MSLTSCALE is set to 0 when you open drawings created in AutoCAD 2007 and earlier (pre-annotation scale drawings).

CELTSCALE stands for current element linetype scale. This system variable sets the linetype scaling factorfor new objects relative to the LTSCALE command setting. This allows you to override the LTSCALE setting for a particular object. To change the current object linetype scale, type CELTSCALE at the command line, then enter a scale.

Note that when the global linetype scale (LTSCALE) is set to a value other than one, AutoCAD will multiply the CELTSCALE by the LTSCALE to determine the final value. For example, when LTSCALE is 6 and CELTSCALE is 0.5, objects you draw will end up with a linetype scale of 3.

If you have an existing object and want to change its linetype scale, select the object and open the Properties palette. Click Linetype Scale and type in the new value. The LTSCALE setting will not be affected.