Can't reference the edge of curved surfaced (e.g. cylinder) for constraints or dimensioning

jacob_sheffield

I am trying to use the edge of a cylinder as a reference for a different sketch, but can't reference it in anyway. Instead I have to dimension back to the center axis. Other software seems to allow you to reference the profile of curved surfaces for constraints or dimensioning to other sketches. Is there a way to do this? I work with curved surfaces often and this causes an annoyance always having to dimension back to center axis.

For example, in this image below, you can't use a coincident constraint to align it with the edge of this extruded cylinder. If it were any other shape or edge it would allow it. Instead, the only work around is to dimension it back to the center axis and use the same radius of the cylinder.  

brian_brady

Use the "Use" (project) tool to add that edge to the current sketch. I usually first toggle the line type to "construction" before using.

bradley_sauln

Hey @jacob_sheffield, you can most certainly reference the edge of a cylinder as a reference for a different sketch. The one thing you are missing here is the use/intersection commands: 
https://cad.onshape.com/help/Content/sketch-tools-intersection.htm?tocpath=Desktop Help|Part Studios|Sketch Tools|_____18

https://cad.onshape.com/help/Content/sketch-tools-use.htm?cshid=sketch_tools_use

Both have very useful use cases as in your needs above.