This may have been discussed somewhere else, but in a 2 minute search, I couldn't find it.
I am using SW 2018 SP5
OK, I use "Make equal" for lines all the time. I prefer to use it instead of adding two dimensions and linking one to the other.
However, I just ran into a situation where it confuddled me. And created something that, if I hadn't caught it, would have cost us some money in rework.
I have two lines in 2 different revolve sketches that I want to be equal length.
These two lines are NOT on parallel planes. The planes are 35 degrees from each other. I thought that it was impossible to make lines equal length if they were not on parallel planes. However, when I selected it, I wasn't even thinking about that and it worked!
Here are the two lines:
The length of the line on the right is 0.12475" long (creating a diameter of 0.2495" once revolved).
The line that I matched it to after "Make Equal" has been applied, is 0.1022" long. Which the projected length of the first line, when you project it onto a plane at 35 degrees. Example:
So, when I asked it to "make equal" it not only let me do it, but then proceeded to make the line the incorrect length and instead made it the projected length.
I am glad that I noticed it. However, I may not have if the 2 planes were 1 or 2 degrees from each other.
Here is a test:
The 2 planes are 45 degrees to each other. The 1st line drawn is 2" long.
Drawing a line on the angled plane and making it "equal length", makes the line 1.414" long:
Simply changing the angle of the angled plane to 10 degrees changes the length of the line to 1.97":
In the case that I originally used, it was an easy catch, and now that I know that this happens (it only happens to 2D sketches and NOT 3D sketches), I can prevent it.
However, if I could imagine a scenario in which I have an imported model and I am sketching on 2 different surfaces and they are off by half a degree or so, this could be dangerous.
Things to watch out for in the future.