The following compilation of tips comes from programming forum moderator, Opie. Thank you!
Blocks, Images or Xrefs not inserting correctly?
Have you inserted Blocks, Images or Xrefs only to find they scale automatically to a different scale from what you specified?
AutoCAD makes use of the following system variables when inserting any of the three above mentioned Objects...
INSUNITS - Specifies a drawing-units value for automatic scaling of blocks, images, or xrefs inserted or attached to a drawing.
INSUNITSDEFSOURCE - Sets source content units value when INSUNITS is set to 0. Valid range is 0 to 20.
INSUNITSDEFTARGET - Sets target drawing units value when INSUNITS is set to 0. Valid range is 0 to 20.
These system variables allow AutoCAD to automatically scale Blocks, Images or Xrefs, thus reducing your need to scale them to your current working scale.
The following are some links that shed some more light on the subject.
AutoCAD Knowledge Base:
ID: TS1050553 - Automatic scaling of blocks
ID: TS20081 - Using the Insert Units option for blocks inserted from AutoCAD DesignCenter
ID: TS30666 - Set drawing units for inserted blocks and images
ID: TS1050419 - New or changed system variables in AutoCAD 2006
ID: TS1056208 - INSUNITS change after reopening drawing
AUGI Forums:
Scale changes when block is inserted
Inserting Xrefs Scaling Problems
Set INSUNITS to Metric when opening a drawing
Setting insertion units at open
Blocks scaling when inserted from Tool Palette
unit-scaling inserted database?
Inserts scaled wrong
Unit problems when XREFing drawings that have block units set different
Symbol Scale Inserting Issue
Loading Xrefs come in at different locations
Unit Conversion; Block Scaling when Inserting or X-refing
Macro - Scale problem between AutoCAD 2005 to 2006
When Blocks are Inserted they come in too small
Xref reloading problems
Blocks come in at different Scales in different drawing files.
2004 & 2006 Xref's come in at different locations ?
Blocked Inserted is Wrong Scale
Inserted Blocks in 2007 come in at different scales
Blocks insert larger in one drawing file than another
Block being inserted at wrong scale
Insert units won't change
AutoCAD 2007 Drawing Units with regarding Blocks and Insert command
Best practises for Templates, Design Center and Tool Palettes
Symbols coming in at wrong scale
Paste As Block creates a Block 32x bigger
Blocks inserting at different scales?
Insert a Layout via Designcenter, the Border / Titleblock scales up by 25.4
