The CAD Times

An AutoCAD Newsletter for CAD Users

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Without further ado…

XREF – Attach or Overlay?

If you’ve ever used the xref manager (type: xref at command prompt) to attach a drawing as an external reference, you’ve probably seen these two options for attaching a drawing: as an “Attachment” or an “Overlay”.

Deciding which one to use really depends on what the desired final outcome of your drawing is.

Let me explain…

First off, xref’s are a great alternative to attaching large blocks -- since the attachment does not reside in the drawing as a block does; thus saving valuable space in your drawing.

The external reference is a link of another drawing residing outside your drawing file that can be viewed in your current drawing.

When you Attach an external reference to your drawing, you are enabling your attachment to “show through” any external references that may be attached to it as well. Confused?

Let’s put it this way:

Say you have a drawing of a typical room layout. That layout is xref’d into another drawing of a floor plan shell and is copied about inside the floor plan shell to reflect multiple rooms.

Now, say your current drawing is a site plan and you wish to have the floor plan shell drawing appear on the site plan.

If you xref the floor plan into the site plan as an Attachment, you will also see the typical room layout (that is an external reference inside the floor plan shell drawing) in the site plan.

But… if you xref the floor plan as an Overlay, the typical room layout will not show up.

With an Overlay, the buck stops at the current external reference.

With an Attachment, you see all the “nested” external references that are also attachments.

Play with it for a while… you’ll see the useful differences between Attaching xrefs and Overlaying xrefs for yourself.

Using Attributes for Schedules

It’s not uncommon for schedules (door schedules, room schedules, BOM, etc.) to cover an entire A0 size sheet. That’s a pretty big schedule.

Working on a schedule that size, in vanilla AutoCAD (plain ACAD), can really do a number on your eyes when trying to input information. i.e. Row 27, column 18 – edit 1 one number.

Some time later you finally locate it and make a change. Now you only have 400 more to edit. Feeling bug eyed yet.

Simple advice...

Make your life easier with attributes:

1. Create 1 row of your schedule with multiple columns and create attributes to populate the schedule information.

2. Make a block of the above that you can array multiple rows down to prepare your schedule. (That little bit of up front work will do wonders once you start editing your schedule.)

3. Fill in the door numbers or room numbers, or whatever on the schedule in AutoCAD, then save all the more grueling editing for after you export your schedule to a spreadsheet.

4. Use the Express Tool: Blocks > Export Attribute Information. Export all the rows (which you’ve created as blocks) to a text file that can be opened in Excel. (Data inputting and editing will be much less painless and much faster.)

5. All done editing in Excel? (Make sure you save the file back to text format in Excel).

6. Now use the Express Tool: Blocks> Import Attribute Information… and ….Presto! Updated schedule.

See you next time :)