Sketch showing as underconstrained

[correntejunk]

I'm trying to add a simple rectangle on a sketch and it keeps showing as underconstrained.  Figured it would be easiest to demonstrate in a video, so here it is:

[davebYYPCU · Accepted solution]

Too much clutter.

After selecting the face to sketch on, hide the body.

window select and delete all sketch articles except bottom long line

Rectangle will constrain to the only other horizontal article in the sketch, (your construction line is same thing)

Might help...

[correntejunk]

It did - I just don't know why.  I normally hide the body after creating the sketch, I just didn't in the video.  But I've never cleared all the sketch articles that come over automatically.  Good to know.

Still not sure I get it.  The bottom line was the only existing object I was interacting with - why would deleting the other object have any effect?  

I'll just assume it's magic since it's working now.  Thanks for your help.

[davebYYPCU]

Opinion only:

Select Through

will cause the new rectangle to snap to the midpoint of the body edge,

(Body priority? not sure - but not in the current sketch) 

so, its anchored, but the sketch engine doesn't know about body edges. 

Hide the body, you then could also snap to the blue shading edge at the midpoint, but would be complicated to explain, when I just know how to get you going. 

Sketch - collect projections you want, then hide the clutter, and the current sketch articles are all that it can see.

Might help....