Need help with simple revolve

[lemonbug]

Hiya-

Two-part question here. First, how do I set the distance between both sides of my shape so it is equidistant at all points? I want there to be 6mm between the upper and lower line and curves. It looks like the curves get narrower at one point to me.

Screen Shot 2018-09-20 at 12.55.31 PM.png (54.12 KiB) Viewed 387 times

Second, when I tried to reolved this 180 deg it says revolved axis intersects sketch.

Thanks, j

OS: Mac OS X
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.13519 (Git)
Build type: Release
Branch: (HEAD detached at 1a8b868)
Hash: 1a8b868018f45ea486c0023fdbfeb06febc1fb89
Python version: 2.7.14
Qt version: 5.10.1
Coin version: 4.0.0a
OCC version: 7.2.0
Locale: English/UnitedStates (en_US)

[Willem]

Hi, for the first problem give the two arcs a coincident constraint.
When you rotate you get a warning and in the sketch you can see that it intersects while rotating so fix an edge to the Y-axis and that problem is also solved

Screen Shot 2018-09-20 at 12.55.31 PM.png (33.08 KiB) Viewed 383 times

[lemonbug]

Thank you kind sir!