Topics created by UncleMonkey

Gaieus beat me to it!
😮
Your component has it's axes facing the wrong way.
Blue must be out of the wall, red horizontal [to right] and green is up.
Select a component and right-click context-menu 'change axes' and fix.
Subsequently placed components will then glue properly and then allow you to punch too...Capture.PNG

@unclemonkey said:

......though as far as I can see, the gap is way smaller than the difference in dimensions indicates.....

The gap that Jim noticed is (only) 1mm, exactly the difference between the overall length and the sum of the 2*160+inner wall length. It's not way smaller.

@driven said:

First thing I spotted was you had profiles set to 2, which can give minor discrepancies at 0.000....etc, as SU can snap to either side of your 'thick line'.

I had to check this out so I set profiles to 20. It made no difference at all to accurately reproduce UncleMonkey's wall, incuding the gap and all its dimensions.
I don't think profile thickness has to do with accurate modeling.
Maybe UncleMonkey had length snap ON and set to something like 1mm?

Jeff is right. If an edge is in a drawing plane (in plane with two axes or parallel to that plane) you'll be able to get 3 different dimensions in that plane. One of them being the 'Perpendicular' one reading the edge length. The other two in the drawing plane are along both axes of that plane.