Autodesk 00128-051462-9310 User Guide - Page 2210

Imprecise Geometry As is the case with unjoined polylines, any endpoints that appear to coincide should actually do so. Small tolerance discrepancies can cause other editing operations to fail. Make sure that geometry that meets visually also meets at a high degree of precision. One way to ensure coincidence is to turn on Nearest, Endpoint, and Midpoint object snap modes, and then adjust the geometry using its grip points. Naming Blocks The names of blocks containing detail component content should have a namespace prefix to avoid conflicts with other blocks. For example, all blocks in libraries provided with AutoCAD Architecture use "AecDtl_" as the namespace prefix. If you are creating your own blocks, you should use a unique prefix. Base Points for Blocks Each block should have a base point that is logically positioned for inserting the block in relation to other geometry in a drawing; that is, the base point location should allow the user to insert the block using an object snap on some other piece of geometry as an insertion point. If possible, the base point location should also facilitate repeated placement of the item. For example, a block representing a paver should not have the base point in the middle of the block, because you would not likely want the middle of the block inserted at any object snap on existing geometry. Likewise, a base point in the upper-left corner only makes sense if the item is to be placed under some other geometry. However, if the base point is at the lower-left corner, the user can snap to the ground plane, and repeated insertions are easy. Collecting Similar Blocks Similar or closely related block definitions should be collected in a single DWG file. For example, in the details block library supplied with AutoCAD Architecture, the block definitions for all the different sizes of nails are collected in a block library drawing file called AecDtlLib_Nails.dwg, and all block definitions detailing carpet accessories are in a file called AecDtlLib_CarpetAcc.dwg. As shown below, for each block definition, the drawing should include a block reference inserted on a horizontal line to show how the block's base point is used to position the block in relation to other geometry. For each block reference, there should also be a text label containing the name of the block. Setting up block library drawings this way makes it easy for the user to quickly survey the entire library. It also helps you in the process of cleaning up the drawing, which is explained in a subsequent section (see "Removing Unnecessary Objects" on page 2171). Block Properties In most cases, blocks should be defined to have their component entity properties set as follows: Layer=0 Color=BYBLOCK Linetype=BYBLOCK Linetype Scale=1.0 Lineweight=BYBLOCK To accomplish this after a block has been defined, right-click the block reference, and click Set Nested Objects to ByBlock. 2170 | Chapter 52 Customizing and Adding New Content for Detail Components