In the previous tutorial, drawing limits were mentioned while explaining the use of the zoom all command. When the zoom all command is chosen, AutoCAD zooms to the extent of the user defined limits. Limits can be thought of as the extent of the drawing area. The AutoCAD drawing area is, in theory, infinite. As long as you continue to draw, AutoCAD will continue to give you the drawing space.
If thought of in practical terms, if we were to manually pencil draw a 1:1 scale (full size) drawing of a wrist watch, why draw it on an A0 sized sheet of paper when A4 size is adequate? AutoCAD drawing limits follow the same logic. We can tell AutoCAD the drawing space we require (although we have the option to increase this if we so desire at a later stage). AutoCAD will display a grid to the extent of the drawing limits specified.
Lets have a go:
1) Start a new AutoCAD drawing.
2) Start the line command
3) For the start point , enter 0.2,0.2 For the next point enter @0,0.52
4) For the next point enter @0.37,0
5) For the next point enter @0,-0.52
6) To close the box, we’ll try a new technique. Normally, we would now enter @-0.37,0 to draw a horizontal line back to the start position to close the box. As we have drawn all 3 lines keeping the line command open, there is a quicker way to draw the box. Type the letter c in the command line (the c stands for close) to draw a line from the current location back to the start point.
Your screen should be similar to the screen shown below (You may have to zoom extents to see the entire drawing).
7) Now try using the zoom all command. The drawing will be barely visible (if at all). This is because the default limits are not set correctly for our drawing. We need to enter new drawing limits.
8) Type limits directly into AutoCAD’s command line. You will be asked to specify the lower left co-ordinates (remember – in relation to the UCS). Hit enter to accept the default value of 0.0000,0.0000.
9) AutoCAD now wants us to specify the upper right limit co-ordinates. There is no right or wrong value, but it should be set to a sensible value for the drawing size. Our drawing is only 0.52m x 0.37m. Lets enter an upper limit of say, 1m,1m from the UCS. Enter 1,1 into the command line and hit enter.
10) Now try the zoom all command again. The view should be much closer as it is set to the drawing limits.
Some professional AutoCAD users manage to go their whole careers without ever altering AutoCAD’s limit setting, and quite frankly:- it’s easily done! There will be many times (especially if like me, you never use the zoom all command and grid!) that adjusting AutoCAD’s default limit settings has no advantage.
Why mention it then? well… occasionally while panning your pan icon may gain a line next to it (dependant on the pan direction) and you can’t pan any further. This is because the limits have been reached and AutoCAD refuses to let you see beyond your defined drawing areas. You may then require to enter the limits command and change the default setting.
Try panning away from the drawing we just made, as soon as you hit the 1m drawing limit we set, we can’t pan any further.
Just in case you were curious, the drawing is of a DVD case (520mmx370mm). If we were to have drawn the case in millimetres instead of metres (i.e we decide one AutoCAD unit shall equal 1mm instead of 1m – perfectly acceptable to do) then a much larger upper right drawing limit would have been required, perhaps 1000,1000.
That’s about all there is to know about drawing limits!
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