I'm working on a part to be then create a mold of, using fiberglass. As you know, there must not be any negative angle in , say, holes of the part because then after mold material of fiberglass are covered, they become locked in the part and you can't get them easily out.
This part is a face-like, with eyes and nose holes. I thought that after making the holes, I will use draft tool to create the desired angle / tapper. Surprisingly, now I can't acheive this in any way (tested on 1 eye):
1. I used draft and tried various setting and every time Inventor reports errors (no obvious hint so I can figure out why)
2. I tried then to again close that part of material, using boundary patch bottom, top and sculp in between: error again!
3. tried to patch the bottom of the eye hole, then thicken as a new solid, then extend its surface up: error!
Now got no more idea how to solve this problem, may be I must do it different from the beginning? I made the sphere for the face, then created a 2D sketch and drew the eyes, etc. and used split solid to cut them out of the face and the negative angles are there as a cutting method result. May be a different cutting method is necessary here?
I attach the part, please help to get rid of negative angles!