In the sketch below, if I change the 18" dimension at the bottom to 20', the right side of the sketch moves to the right by 2". How can I add a constraint so the left side moves to the left by 1" and the right side moves to the right 1"? Also, how do you use the Symmetry contraint? I did some searching and I can't find anything on it. Below the screenshot is a link to my sketch.
Here's a link to the sketch:
I think the easiest suggestion is to create a line of symmetry, trim half of the sketch and then mirror. The mirror command will automatically add symmetric constraints for you.
Check out this screencast for further detail:
The way that the symmetric constraint works is:
1. Select the Symmetric Constraint from the palette
2. Select the two sketch entities that should be mirrored
3. Select a line about which the sketch entities will be mirrored
Sounds easy right? However, if the sketch already contains dimensions and sketch constraints, you will be prone to the over-constrained conditions. Then you will have to start deleting dimensions and constraints in order to get the symmetric constraint to work. This is why I would suggest using the mirror command.
I hope this suggestion helps. Let me know if you have any questions.
