Jump to content
Bill Tillman

UCS Information

Recommended Posts

Bill Tillman

I have read the AutoCAD Bible for both 2007 and 2009, the book Mastering AutoCAD 2009 and countless tutorials and seem to be missing the parts where they define that you cannot trim, extend, mirror, etc....many commands unless the UCS is set to the right orientation.

 

Don't get me wrong, I'm not saying that there is no information on how to adjust the UCS. It's just that I cannot seem to find anywhere that states, for example, if you want to mirror objects, the mirror line must lie within the XY plane of the current UCS. This may be something that is self explanatory but as for me I had to figure it out by trial and error.

 

In any case, all the trial and error has taught me to check the current UCS before I start commands. In the 3D work I'm presently doing I'm constantly changing the UCS. Would perhaps UCSDETECT be of use in this? And can anyone recommend a good tutorial that goes into depth on the UCS?

Share this post


Link to post
Share on other sites
Bill Tillman

Okay, I tried setting UCSDETECT to 1 and that indeed helped. Most of my mirror commands take place while I'm 3DFORBIT'ing around in the model and it's much simpler to just do a mirror rather than set the UCS each time. At least this first exercise was resolved by setting UCSDETECT to 1. Now I just have to remember to set it back to zero when it's not needed.

Share this post


Link to post
Share on other sites
rgarjr

Books will not explain everything, so that's why you need to play around with the commands.

Share this post


Link to post
Share on other sites
Patrick Hughes

Hi Bill,

 

I see you are struggling with a few things in this regard, not to worry you'll pick it up. Something you might want to keep in mind is when you mirror some objects such as circles and arcs the resultant objects end up having a negative extrusion vector. That is why in some cases you will experience difficulty in joining elements into polylines for extrusion. You might see an error message that tells you the selected objects are not coplanar. Play around with things and see what happens when you do certain things. If you get a message like I just stated execute the "list" command on the objects and look for negative values.

 

 

While orbiting can be a useful tool for viewing your model it may add to some problems during construction of the model. Limit yourself to specific views for construction and if you find and area that is obstructed then use orbit but when you are done return to your previous viewpoint.

 

Always have your UCS icon on. Always examine your UCS Icon before constructing objects.

 

Manipulation of the UCS is key to success in 3D modelling.

 

Always create geometry using Osnaps and point filters. Guessing at a point location is not allowed.

 

If you have some experience with autolisp I have a free program you can download from my website that might be of help. It's called AutoUCS.lsp and it makes it very easy to rotate your UCS around the x,y, and z axis very easy in 90 degree increments as well as aligning to objects, 3 point align, viewing plan etc.

Share this post


Link to post
Share on other sites
Patrick Hughes

Something I neglected:

 

If you are in a busy drawing it may be difficult to even see your UCS Icon if it is set to follow where the location of the icon follows the origin you place it at. I personally have this turned off so my Icon is always in the lower left corner.

 

And, finally (for now):

 

Always set you UCS back to world before exiting the drawing. You'll come to appreciate this when inserting drawings.

Share this post


Link to post
Share on other sites
Bill Tillman

Once again, thanks to all for your replies. It does indeed take practice and each day I learn 100% more than I knew yesterday.

 

I have also found that trim, extend, etc...commands work depending on what view I'm using. When I 3DFORBIT around the model to see a line or point I'm after, I can't always trim or extend a line like I want to. But then simply changing to one of the orthographic views the command will work like I want it.

 

Like the man said, Practice, Practice, Practice....and then Practice some more.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×