Making “Smart” Drawings with Parametric Tools - Mastering AutoCAD for Mac - page 441

FIGURE 16.7
Without the hori-
zontal constraint,
both lines change
as the arc is edited.
T H E P A R A L L E L C O N S T R A I N T
In the previous exercises, you have seen that when you moved the arc, the lines connecting the
two arcs followed along. But what if you wanted the lines to remain parallel to each other? The
parallel constraint will fix that. Let's see how it works:
1. Click and hold on the Coincident tool on the Tool Sets palette. A drop-down will
open. Select the Parallel tool. You can also choose Parametric  Geometric Constraints 
Parallel from the menu bar or type GEOMCONSTRAINT ↵ PA ↵. (You can also type
GCPARALLEL ↵.)
2. At the Select first object: prompt, click the upper line.
3. At the Select second object: prompt, click the lower line.
4. The lines are now constrained so that they cannot lose their parallelism.
5. If you stretch the arc, you will now see that the lines maintain a parallel status; the end-
points will be always connected and remain tangent to the arcs.
T H E H O R I Z O N T A L C O N S T R A I N T
If you click on one of the lines and drag it upward or down, you will see that the lines maintain
tangency and stay parallel to each other. But what if you wanted the lines to stay horizontal no
matter what? Follow these steps:
1. Click and hold on the Coincident tool on the Tool Sets palette. A drop-down will open.
Select the Horizontal tool. You can also choose Parametric  Geometric Constraints 
Horizontal from the menu bar or type GEOMCONSTRAINT ↵ H ↵. (You can also type
GCHORIZONTAL ↵.)
2. At the Select an object or [2Points] <2Points>: prompt, click the upper line.