Has the size of the gap in queen excluders been changed over the years? If naything, it is a little smaller than Root was recommending in 1890.

ABC XYZ, 1983 says at least.1565" and a maximum of .1620"

ABC XYZ, 1959 says wire excluder should have a .163" gap, though he recommends .162" for wire.

ABCX XYZ, 1890 refers to the first zinc excluders  made in England using .18" -- but this was found to be slightly too large. Then, 5/32" or .16 was tried and accepted. Root says he finds this a little tight and fixes the correct size at .165".

I obtained several drill bits and attempted to measure the gap.
The ones I measured include an eight frame wire one in excellent condition, a new wire one, and a new zinc one.

The new wire appeared to be about 20 gauge or .161"
The old eight frame was tight at .166", probably its about .161 to .163
The new zinc would not quite accept a 19 gauge , so it could be about .163 to .165

Anyone else care to make some measurements?

PB