Draw constrained to angle

Sometimes you’ll want to draw a line at a specific angle, and it is surprising how many people do it the long way by drawing the line, and then rotating it.

So, if this is you, you’re in luck as you’re about to be amazed!

Whenever you want to constrain drawing to a particular angle, press the less than key (<) followed by the angle that you want to use. Then, you can pick anywhere on screen, and the line will be drawn at the angle specified. Of course for commands such as LINE you’ll have to pick a basepoint first.

So, I hope this helps someone – its really handy to know sometimes!


Layer Freeze/Thaw vs On/Off

There are two ways to change the visibility of layers – turning it off using the little light-bulb, and freezing it using the little snowflake. Many times I’ve been asked, “What’s the difference between freezing a layer and turning it off?”. For years I had no idea what the difference was, or if in fact there was a difference at all! I simply got in the habit of just using the ON/OFF setting, but having found out what the subtle difference between them is, I’ve changed over to mainly freezing layers because it usually more accurately fits my intent.

Turning a layer off using the ON/OFF setting makes the objects on that layer hidden, but these object will still be considered part of the drawing. For example, you may have noticed that objects that have been turned off are still selectable in the drawing. Selecting it directly on screen of course still isn’t possible, as you’ve nothing to click on. But other ways of selecting objects will still pick it up – try a SELECTALL for example, and your objects that are turned off will be selected.

Frozen layers on the other hand are completely off. They are not considered part of the drawing at all, and are therefore not selectable.

Due to the different ways that AutoCAD® handles these layer properties, each carries a different overhead. Objects on an off layer are basically just as usable in a drawing as if that layer was on, and therefore AutoCAD® has to still prepare the objects in the same way as if they were on. For example, when AutoCAD® regens, these objects will be regenerated too. Frozen layers are meant to be completely ignored, and therefore carry no such overhead.

There are some other interesting consequences of these two layer visibility toggles. ZOOM EXTENTS for example will zoom to the extent of objects in the drawing. As layers that are turned off are still considered part of the drawing, they will affect zoom extents. Frozen layers on the other hand will not.

Finally, there are some differences to how visibility is affected within blocks. Lets say I have a block with objects on layer BLUE and GREEN, and the block itself is inserted on layer RED. Toggling the visibility of BLUE and GREEN works as expected for both methods. However, there is a difference when toggling the insertion layer of the block. If the layer RED is turned off using the ON/OFF toggle, the objects on BLUE and GREEN will still be visible. However, if RED is frozen, all of the objects in the block will be hidden, regardless of their layer.

But why have these two different methods? It is less of an issue now, but historically these were added when regenerating a drawing took a lot longer. Therefore it was helpful to have the option to turn things off without the drawing requiring regeneration every time. Thus, the ON/OFF toggle was helpful for showing what you want, but keeping them available to be displayed quickly.

Hopefully you found this post both interesting and useful. However, I’m a realist – if it was only one of those adjectives, that still aint bad! But if you have your own adjective for describing this post that you’d like to add, please feel free to submit a comment below! 🙂

And on the rare occasion that you did find this post interesting or useful, or indeed both, I encourage you to join the literally tens of others that have subscribed.

Thats all for today,


The OVERKILL Command

Someone came to me with a problem yesterday – they had a drawing, and somebody had pasted in some content… twice. The drawing had two versions of the same set of lines on top of each other. We’ve all come across the situation where two (or more) lines are coincident – it can be a real pain to deal with.

There is a command which was designed to combat this problem called OVERKILL. This command will analyse the entities you select, and remove any overlapping superfluous geometry. The method it uses to detect what should be removed is customisable by the user too:


Although this is a really handy tool, I tend to avoid putting too much trust in tools like this. Automatic processes have a tendency to get confused easily, so if it is important that it be done correctly (which it usually is), make sure you have plenty of sanity-checks along the way. In the case of having duplicate content, you’d expect to end up with precisely half the number of objects you started with, assuming you aren’t combining co-linear objects. If you do want to combine them, I’d personally be inclined to do it in two stages – remove the duplicates and check you end up with precisely half the number of entities, and then run the command again to combine them.

I hope this post was helpful – please subscribe to below to get more tips like this in future sent directly to your email address.


AutoCAD® – The LAYERDLGMODE System Variable

I’m not one that likes to scroll horizontally – so my layer dialog box fills the whole screen so that I can see all the layer names and all the properties of the layer. Not surprising then that I’m not fond of the new(ish) palette version of the layer dialog box, as docking it anywhere isn’t totally practical. Also, having it docked to the screen means it needs to be kept up to date so you are working from up to date information. Therefore, docking it to the screen adds more overhead to AutoCAD® – something I try to minimise as much as I can.

So, if like me you want to revert back to the old layer dialog, you need to set LAYERDLGMODE to 0. Setting it to 1 will use the palette version.