I'm having difficulty creating the core and cavity for this part. The parting surface is sitting right on top of the cavity surface and I'm stumped. Please help!
The parting surface must be as large (or larger) than the core/cavity block you are trying to create. And the reason you are getting the knitting error is because you have not given the system anything to knit together. Solidworks will try to take the surfaces in the "Cavity Surface Bodies" folder and the surfaces in the "Parting Surfaces Bodies" folder and knit them together to form a body that it can then use as a "cut with surface" tool to form the cavity (and same for the core, using the Core Surface Bodies & the Parting Surface Bodies).
Also, your parting surface will not work...it results in a cavity the will not be easily manufactured and, if manufactured per the model, will never release the part. You part is also not properly drafted (inside hole is not all drafted for the cavity, outside edge of part is not all drafted for the core), and it has some mismatch (2 places) on the outside of it.
Lastly, your sketches are undefined...bad, bad modeling habit to have.
Attached is an example of your part split, done in Solidworks 2014. (With the parting line coming off the correct edge of the part, not the edge you had selected.)
maybe he is making an RTV mold?
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