Joined surface instead of solid

 From:  OSTexo
6497.11 
Hello,

You can see your naked edges here. I see that you have a draft to that part( 2°? ), so it might be good to extrude out your cylinder with that taper and then start building out a tapered helical cutting curve or surfaces. Building out then carving away from your part should leave you with some good surfaces.

Attachments: