AutoCAD 101 Series – Blocks – What and Why?

This is the 1st article in my AutoCAD 101 series – to read about the origination for this series, see the first post here: <Intro>

This month is all about Blocks (4 weeks – Define, Create, Edit, and Important Stuff)

• What are and are not blocks (What and why)
• Blocks are easy!!  Here is how….
• Blockeditor (BE, BLOCKEDITOR)
• Layer usage and flexibility in blocks (Layers, linetypes, colors, annotation scaling and Tips and Tricks) (redefining others blocks, macro and script usage)

What are Blocks?

AutoCAD defines Blocks as:  A collection of objects that are combined into a single named object. These objects can be symbols or details that are used to create representations of real world objects.  Typically, each of these blocks is an individual drawing file, perhaps saved in a folder with similar drawing files. When you need to insert one into your current drawing file, you use the INSERT command (or enter ‘I’ in the command window).

Examples of items that would be great as Blocks:

Furniture/Appliances/Equipment:

• Desks
• Bathtubs
• Desks
• Chairs
• Electrical Panels
• Air Handlers
• Etc…

Drawing Symbols:

• Section Cuts
• North Arrows
• Arrow heads
• Column Bubbles
• Light fixtures
• Outlets
• Etc…

Details:

• Fire Proofing
• Control Diagrams
• Wall Sections
• Equipment Connections
• Structural footings
• Etc…

What are NOT Blocks?

Basic line work that is drawn using standard drawing tools like line, rectangle, circle, etc. that are drawn and/or grouped together to represent one of the above items and copied around the drawing.  The issue is that these are just linework – not “Named objects” and therefore not Blocks.  They look pretty, but their also pretty useless.

• Rectangles are NOT desks, bathtubs, light fixtures, etc…
• Rectangles are NOT BLOCKS, but BLOCKS can be rectangles
• Circles are NOT down lights, bollards, columns, sinks, manholes, etc…
• Circles are NOT BLOCKS, but BLOCKS can be circles
• Polygons are NOT Revision triangles, Section symbols, note tags, etc…
• Polygons are NOT BLOCKS, but BLOCKS can be polygons
• A bunch of lines drawn in to the shape of a chair is NOT a BLOCK, but a BLOCK can be made up of a bunch of lines drawn in to the shape of a chair

The above are all examples of linework that is drawn to look like something, then is inefficiently copied around to make a bunch of useless “copies”.  BUT, Hey – they look pretty!  Yes they do, but lets look at why this is a bad idea and why blocks are sooo much better.

Why use Blocks?

• Let’s say you use a rectangle to represent a 2×4 light fixture and copy this around the drawing 60 times to represent your lighting plan.   No lets say the plan is reviewed and someones requires that you change the look of the rectangle – like add an offset line, change its color, add a hatch, add some detail to it – whatever…  To change the look, you would modify one of the rectangles and re-copy it to the other 59 locations – effectively starting over.  If this Light fixture (rectangle) was a block, you would just redefine it and as soon as you save it, all 60 get updated!  Yea!  And to add to it, you can then use this symbol over and over again in other projects!   What’s not to love?  Some of you are going Duh!!  Yea… well I see rectangles used as $#%&$ light fixtures waaayyy too often.  This same concept can be applied to nearly any item you create with linework.  Anytime you draw something that you intend to use again or “possibly” use again – make it a block.  I do this even for ‘one-off’ items.  I am sure you have drawn something on a job, then later,  wish you had that same thing on another job.  You typically go back and copy it and then paste it into the new job.  Depending on how you do it, you will end up with copies of linework again or an anonymous block if you “paste as block”.
• Blocks reduce storage requirements  – In AutoCAD, each line, arc, ellipse, text, etc. uses up memory, both for storage and RAM memory usage.  If a chair is composed of 50 lines, arcs, etc and is copied around the drawing, multiple the number of lines by each copy – 6 times = 300 lines.  A BLOCK having the same amount of lines will be counted once and then a pointer will be used to reference all the other locations.
• Objects (BLOCKS) are easier to move than linework – Try selecting all the copies of chairs or lights composed of basic linework vs selecting individual blocks. Even using the SELECTSIMILAR command, which depending on how you have it set will take possibly one selection vs many.  With linework you typically would use a window or crossing to select your items, which means you have a high probability of selecting other items as well.  Blocks can be grabbed with a single pick selection for each item or in multiples by using SELECTSIMILAR.

You may be tempted to use the Copy and “paste as block” option (Ctrl-Shift-V) to make temp blocks. that look like:  A$C19F91F38  This is not a BLOCK!

OK – it is a BLOCK, but it is a temporary block made by copying and pasting objects as a block. This is a sad example of a block – Why?

• Does the name “A$C19F91F38” mean anything to you? – Nope – not to anyone else either…
• Can you control the insertion point? – yes but only if you edit it in the Block Editor – it would have just been easier to make it a standard block
• Can you rename it? – Yes, but you will need to list it and try to remember the Number and letter sequence in the RENAME dialogue – do this a lot and this is what you will see:

 

 

 

 

 

 

 

 

 

 

Now, if you are in to making dumb drawings and wasting time, then you are good to go, but if not, then you should know that Blocks are way easy to create!

And in the next post I’ll show you how…

WES