Old imperial conduit thread sizes

[SUNRAY]

I thought that as well - and I still have dad's conduit thread taps and dies.

No they were/are not the same. there may be similarities at some point but I don't see how:
19.05mm x 16tpi (conduit) = 20.955mm x 14tpi (1/2" barrel)
Metric conduit = 20mm x 1.5mm or as near as dammit 17 tpi.

Adapters are freely available at wholesalers but usually about 20mm will show.
How about filling the unused ports with lead? lead free solder?

 

[ban-all-sheds]

Does he still have ports to fill after a year?

 

[SUNRAY]

Does he still have ports to fill after a year?

Who knows?
I thought I'd got this from the current part of electrics but I guess I managed to click on the selection below.