I have been trying to create spheres or parts of spheres but there always seems to be missing facets or other extraneous matter. To create a hemisphere (for example) I start with a circle. I give it a good number of segments (say, 50). I then draw a quadrant at right angles to the circle with its base centred on the circle. Then I select the circle and use Follow Me on the quadrant.
I may be trying to do this at too small a scale. Most recently I tried to create the head of a dome headed nut with a diameter of 20mm. If that causes problem, a workaround might be to model it very much larger and then scale it down. But should that be necessary?
Here’s a typical result without scaling:
Am I doing anything wrong?