This was the subject of a talk to the Dorchester & Weymouth BKA a few days ago, provided by Malcolm Blake. As usual, I occupied a seat in the front row for easy heckling. It was held in Stratton Village Hall and the room was full with about a score of us.
Rather than use the horrible Powerpoint, Malcolm made use of an overhead projector to display a few diagrams he had made of hives with top and with bottom bee space. Most of the time it was turned off so he could talk and interact with us and show us the examples of equipment he had brought along.
I mentioned that, playing with bees, I had been checking the distance between naturally spaced combs. In one example the combs are spot on the width of a narrow spacer, but in another they are wider than that.
I had heard Malcolm’s talk on the subject a couple of years ago, which was why I came to hear it again as it is interesting, practical and well illustrated.