New answers tagged bolts
A typical toilet has a flange that's bolted to the floor and stays there. Bolts are then turn upside down, with the head down, and the toilet sits on these. The threaded end faces up and the nut goes onto it. So, a typical toilet install is closet bolts that have threads facing up. No need to go under the floor, be it a 3rd floor bathroom, a 1st floor ...
You might want to look at the pivots intended for use when building "glider" chairs, though that would probably be overkill for this application. Most woodworking supply catalogs I've seen recently have these.
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