Dimensions from rounded edges / curved faces

I’m trying to pull the dimensions from this component. Having trouble getting them out of this component that has rounded edges and curved faces. I’m new to sketchup.

[SHDR-01] Center Covering.skp (261.5 KB)

You could temporarily show the hidden edgers on, do your dimensioning then turn them off,

Select View on the Menu, then Hidden Geometry

When I show hidden edges I see more lines showing on the example object. Still can not pull dimensions from the example object. When I click on what looks like an arc only a small section line becomes selected (turns blue).

The geometry of the original arc has exploded and become segments during an editing procedure.All circles and curves are made up of a editable number of segments until one or more of the segments is moved or edited, From my experience it can retain a curve status but you can no longer edit the number of segments, then or straightaway with further editing become exploded segments.

edit: there is an extension tool you can import from the extension warehouse called “weld” that will turn the lines back to curve, which may be required for 3D printing

There are some problems with your geometry.
Firstly you are working at too small a scale for Sketchup. Many of the measurements you want are smaller than 1/64 of an inch, you will have better luck with decimal.
You need to work at a larger size then scale down when finished.
Sketchup is originally an Architecture program so it works best at people size rather than ant size.

Somehow you have created geometry within the same context that isn’t actually connected, if you look at this gif all this section is in the same component but by triple clicking it it doesn’t all select when it should.

I imagine you are experiencing clipping issues as well, when parts of the model disappear when you zoom in or orbit certain ways.

That is an excellent gif, really good. I did not create the original CAD files, the original files were created using SolidWorks 2014. I used a SolidWorks extension to import them into SketchUp Pro 2015.

Here is the original file, you will have to rename .zip to .SLDPRT.
[SHDR-01] Center Covering.zip (365.5 KB)

If you are interested these are Mini Johnny Five CAD files from Short Circuit 2. The head and laser were modeled from an actual prop. Only 20% has been CADed.