How to Use AutoCAD Blocks - AutoCAD Tutorial
AutoCAD Blocks - Video Tutorial
What are blocks?
Ok, in this tutorial we are going to get stuck into blocks. You can check out my other hubs or the CAD Training Blog for more tutorials.
Now, a lot of drawing programs have the ability to group objects together, where clicking one item in the group selects all the line segments in the group. Other drawing programs have styles, allowing you to change a line weight or color universally throughout a drawing or drafting project. AutoCAD blocks are like object grouping and object styles on steroids.
Let's Get Started
First, the basics - when you define an object made of line segments in AutoCAD, you can group them together; by hitting Ctrl-G. After that, any time you click on a grouped object in the window, you select all of them, and you can drag it around as needed. You can mirror, rotate, transform, etc.
So what does the Block command do? Well, let's assume you've got a drawing of a commonly used element in an array; the classic example is a classroom with chairs, though it most often shows up in fabrication layouts in the real world. You can define that object as a block, and any changes you make to it are replicated across all instances of that object in the design drawing.
So, setting up a Block looks like this:
First, we select all the objects that we want to add to the block and type in Block in the AutoCAD Commands window, and hit "Enter"
The window that pops up will prompt us for a number of fields, but the most important is "Name". For example "School Chair". There will be three options for handling objects. The first is "Retain" - this is effectively using the "Group" command to group all objects into one "thingy" for manipulation. Convert to Block gets rid of all the separate instances that make up the object, but makes it a block. "Delete" is really horribly misnamed. It converts the object to a block, and then deletes it from the current drawing - but it's still loaded up and ready to be replicated throughout the drawing.
To insert a saved block, go to the Insert menu, then Blocks, and select the name of the saved block you want to include; it'll appear at the point that you last clicked with the mouse. When the Block Definition window is opened, you can click the button by the words "Base Point" and define the default position in the drawing for inserted blocks to appear, which can be a real time saver. You should also make sure that the units selected from the drop down menu match the units you're doing your drawing in; it's generally going to match by default, but it's the first place to look when you're tweaking something that's not working.
The last choice you have is on selecting a preview icon. Preview icons are handy if you're dealing with a lot of blocks in a drawing, because they don't take as much screen real estate to display; they otherwise have no real impact on block creation.
Now, you can select your blocks and cut and paste (or use Insert Block) to move them around on the drawing. Use of the Array command will help set up a lot of replicated blocks quickly - remember, the purpose of these tools is to make it easy to do repetitive things!
And now, the real reason why blocks are cool - let's say you've replicated a block 30 or 60 times in a drawing, and you have an extensive set of changes to make on each instance of the block. Doing this by hand would be a major time sink. However, since this is done with blocks, you can make the change once, re-define it as a block with the same name, and it propagates across the entire drawing. This can be a real time saver!
Ok, that's it for this tutorial on AutoCAD Blocks. But you can head to my site for some free autocad tutorials on AutoCAD, including one on how to use blocks.
Until next time, happy cadding.
P.S. If you have any feedback or a request for more tutorials drop me a comment below or use the request a hub feature. Oh and if you wanna let me know how I did give me a rating below, thumb's up only ;-)