John in Philly has commented quite a few times, and we've run into each other around the net-world on occasion.
He mentioned some work he had done, and then sent a blog worthy run down to me via email. With pictures, yet!
I asked permission to repost and here it is, for your enjoyment:
The Lampshade project.
This is the brass finial that won't fit on the new shade.
This is not the shade, but shows how the center ring should fit up into the finial, and then the knurled ring will push the triple arms up the slots.
But the new shade has a center ring that is larger than the original and will not fit up into the brass finial.
Yes, there's a shoulder in there.
John in Philly.
Here is a quick tutorial on internal threading by Professor Pete
All in all, a successful project, and a happy missus. Win - win!!
Thanks for letting me post this, John. Job well done!