Too complex for constraints?

Hi !
I have a sketch. I want it to make resizeable.
It,s like on the picture.
I wanted to make it possible to make it available for future modification like: extending it up, or extending it t sides (maintaining the same round edges, and sime 10mm space between outer lines of this object.

I tried puting

  • parallel constraint with
  • perpendicular angles, with
  • tangents between archs and lines (not all are possible to apply
  • horiz / verticval
  • equaities for the lines

I tried all of them when possible, or some of them.
But this model either doesnt work whn I move one of the dots to extend line, or sometimes it worked and then stopped.It’s strange.

Sometimes I see that after some modifications line ends go and missalign to some archs. (from far it shows doble dot, but when I zoom in extremly near I see that line actually ends 0,002-3 mm too far.
Sometimes the angle changes to 89,9991 degr.

Any clues ?

Ok, I gave it one more (th) time. And seems It works now.
I constrained (Arch angles, Arch sizes, space between lines to 10mm, made all lines horiz/vertical). Now by druging line left right, up down. The whole model adjusts itself…


Pay very close attention to grid size and lock it when doing extremely precise alignments. Use tangency more often. H/V constraints are not always necessary.
This way, you can zoom in and out without having to worry about grid size acting all silly.

More seriously: from what I see, I can tell that you should focus on locked/unlocked parts as well as connected/disconnected parts of your sketch.
Locking a few points prevents them to move when they don’t have to, but locking whole lines, arcs, circles and splines is too much.
Having parts connected without a ton of constraints gives you a lot of flexibility over the shape, no matter if you need to resize or modify in any other way. Oh, and offsets almost always behave unlike the original sketch …

It’s my old CAD guy opinion, and you should ask others. Maybe move this to another forum section with more visibility?

Meanwhile, you can refresh your sketching skills. Here’s a cool workshop (check out official “constraints 1” and “constraints 2” video series as well) to help you: