By Dennis Collin
Many AutoCAD users are aware of the Purge command which is a useful utility to clean a drawing of superfluous information from a drawing, typically unused settings like layers and blocks.
This is a frequent task when in receipt of third-party drawings and the drawing needs to be tidied before further work can start, or to remove an excessive number of redundant layers etc.
Sometimes however, some elements will not purge and remain listed even though no physical entities with those properties are apparent. The reason for this is often due to nested blocks with dependencies preventing those settings to be removed. With newer versions of AutoCAD and LT the Purge command does list some possible reasons why certain entities cannot be removed.
Although there is a Layer Delete function, caution needs to be exercised because that command will find entities on layers and their dependencies and will delete them, resulting potentially in lost critical information! However, there is a more satisfactory solution, Layer Merge. This command reduces the number of layers in a drawing by merging them together. Objects on merged layers are moved to the target layer and the original layers are purged from the drawing. It is possible to select several layers either graphically or from a list and have them combine to a new target layer. The old, merged layers disappear from the list and are 'purged'. Any blocks with dependencies are redefined to layer 0 and are not deleted.
Layer Merge along with other useful tools can be found on the Layers panel, within the 2D AutoCAD workspace.