AutoCAD 101 Series – Blocks Week 4 – Important Stuff

Are you new to AutoCAD? Have you been using AutoCAD for years but only use the blocks, styles, layers and tools that others have created?  Do you want to learn more or step up your game on features you’re not very strong in and pick up some practical examples of best practices?  If so, this series is for you.  Over the course of 12 months and maybe more I will cover the basics of a lot of AutoCAD tools and features that many may want or need to learn more about.

This is the 5th article in my AutoCAD 101 series – to read about the origination for this series, see the first post here: <Intro>  The last post in this series was about how to use AutoCAD’s Block editor <link>, this post will be about some important “stuff” when creating or fixing existing blocks.

There are some key things that you can do when creating blocks that will make your work easier and will make your blocks less likely to be exploded by other users later.  Two items that I believe are foundationally the most important are Insertion Points and original creation layer.  We will get into a lot more about layers in some future posts, but for now know that layer “0” (zero) will most commonly be the best block creation origination layer.

Origination Layer

Let’s start with the layer issue.  When creating an object many think or believe that the block should be created on the layer it will be used on – this is not your best option. Let’s look at our 2x4_light block that we have been working with.

If you’re an architect, you may like your lights on a lighting layer like ‘A-Lights’ or maybe you like to put everything on the ceiling on one layer like ‘A-CLG’ (please don’t do this, it’s a nightmare for anyone else using you ceiling plan). So when creating your block you create it on one of these named layers and set the color to Bylayer.  The good aspect of this is that the layer, if it doesn’t exist will get automatically added when you insert this block. That’s pretty much the end of the good points.  Now if the layer did not exist prior to inserting this block, you couldn’t insert it on that layer anyway as it did not exist until you inserted the block.  You will have to move at least the first block after insertion.

Let’s look ahead, a good practice to do when making blocks. If you at some point in the future are going to do an existing lighting layer, a new lighting layer and/or a demo lighting layer, how do you visually differentiate between them with the light fixture block?  You can create these layers and assign them different colors and line types, but since your block was created on say ‘A-Lights’, your block will maintain the properties of the ‘A-Lights’ layer no matter where it is inserted.

Let’s go back and create this block on the ‘0’ layer, often referred to as the ‘Chameleon layer’ due to its special properties.  When a block created on layer ‘0’ is inserted in to a drawing, it takes on the properties of the layer it is inserted on. So if your ‘A-Lights’ layer is yellow with a continuous line type your light fixture will be yellow and continuous. If you insert it on an ‘A-lights-Demo’ layer that is Cyan with a hidden linetype, your block will come in as Cyan with a hidden linetype, and so on…

Although you could create this block as a dynamic block with various color and line type definitions you will lose the ability to isolate blocks by their layer location.

There may be instances where specific details in the Block need to be hard coded to certain colors and line types, due to printing standards, but the first best choice is creating it on Layer ‘0’ and set color and line type to ‘Bylayer’.

NOTE: For some additional flexibility, create the block on Layer ‘0’ and set the color and linetype to ‘BYBLOCK’.  When the block is inserted, it will assume the color and linetype of the Layer inserted on, but the ‘BYBLOCK’ option allows it to be over-ridden.  Use this option with caution however, as lazy drafters will insert the block on the wrong layer and then manually change the color and/or linetype to what it should have been had it been inserted on the correct layer.  This will defeat your ability to isolate blocks by layer or select by properties.  Imagine a demo layer being Cyan/Hidden and a light fixture block is inserted on the ‘A-LIGHT’ and manually over-ridden to Cyan and Hidden.  You freeze the ‘A-LIGHT’ and it appears some demos lights go away – just one an example of what could happen.

Another potential issue is future standards changes and client standards requirements.  If you at some point decide to change your layer naming convention, all your blocks utilizing the old layers will have to be redefined.  With blocks created on layer ‘0’ the standards change is a non-issue.

If you’re not the team leader, and work as a sub consultant (electrical engineers, contractors, lighting designers) for a client and they require final drawings to maintain certain layer, color and line type standards, more issues will crop up with hard coded blocks.  The 2x4_light block created on layer ‘0’ is usable by all parties.

Insertion Point

The next big item I often see that is a bad practice is the blocks defined origin or insertion point.  Short of creating a block using the dynamic multipoint option (which in some situations is a great option) you need to choose an insertion point that makes sense. We will cover the multipoint insertion option during our dynamic block track.

For our 2×4 light fixture, it will most likely be inserted in a 2×2 or 2×4 grid.  With this in mind, creating the insertion point on one corner of the block is an excellent option.  You don’t want to make the insertion point off the edge of the block or the middle point of a line, because it will rarely, if ever, match up to a straightforward insertion point on your grid.

Bad insertion points will lead to blocks being ‘eye-balled’ on insert or inserted and moved, creating extra steps.

With blocks, you can’t just use the lower left or midpoint of a block as a standard insertion point, because each block has unique insertion properties. For example tank type toilets, counter sinks and beds are a few items that may be centered on a wall or stall, but are typically shown from 1″ to 3″ off the wall that they are up against.  Wall mounted toilets, sinks, and urinals may also be centered, but will actually be snapped on to the wall.

Janitor’s sinks are usually tucked in to a corner of a janitor’s closet or mechanical space, so it would make sense that their insertion point be on the back corner of the janitors sink.  The proper insertion points for blocks can vary greatly, but how the block is most commonly used is what should dictate the insertion point.  See image below for block examples with their insertion points shown (blue square/grip).







Figure 1

These two items are just a couple important items, to consider when creating blocks, but there are some other items to consider as well as some best practices to follow when making blocks for your master library.

  • Unmark ‘allow exploding’
  • Set dimension styles, text styles, and table styles to ‘Standard’ and set the line type to ‘Continuous’
  • Set the current layer to ‘0’
  • Purge the block drawing of any unused line types, styles, dimensions, etc. so that they do not get carried forward like an infection into future drawing files. (This is a common issue for drawing bloat, especially in 2013 and newer drawings without the DGN hot fix installed).
  • When creating blocks with attributed text, make sure you check the worst case scenario for text length/size to avoid ‘Ugly’ blocks (see Figure 2).
  • Also for attributed text blocks, choose an appropriate text justification (see Figure 2).







Figure 2

Much of the above cleanup could be automated in a script which we will cover in a future customization post.

Follow these steps when making your blocks and you will have cleaner drawings and happier users.


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