Difference - Boolean operations

Every time I have used the difference tool, it worked fine but this time, it didnt work out very good.
As you can see on the image, my goal was to create some sort of a tower and I had to create the holes you see.
For that I used the spin tool and then the difference tool.
But as you see, it doesnt make all the holes, just some of them. I can’t understand this and I already tried other things… but it was in vain.
Help me please…

Are’nt those just loose parts in the holes that are still closed? If not just select the verts in edit mode and delete them then build the faces closed.


I select the vertices and hit “x” than face and nothing happens, ate least, nothing visible for my eyes.
Do you have any idea regarding how to do this without the spin and difference tools?

Using the pic above as ref: Add a circle with the same amount of verts as your model (inside diameter of top), Extrude and scale outside to make the outside diameter. Extrude down to make the top ring. A to deselect all then select every other pillar and extrude down to the bottom of the holes. Repeat for the rest of the pillars. Make faces between pillars at bottom of holes. Extrude down to make bottom ring.