Gentle Galoots,
I agree with others that 6 tpi is too fine for 1-1/2" threads. But they do have
their uses.
I have a local friend who is an amateur bookbinder. Several years ago he showed
me a finishing press he had purchased, made of fine hardwood. It looked great,
but the threads were seized. He was about to throw it in the fireplace, even
though he had paid something like $300 for it. The threads were 1-1/2 by 6 tpi,
so I figured it was made from one of the Taiwanese threading kits of that size.

We made a deal:  If I could repair it, he would pay for the threading kit (about
$50 IIRC) and bind a book for me. I managed to unstick the threads slowly and
re-cut the threads. The results weren't as pretty as I would have liked, but he
was happy with the result because he now has a usable finishing press. I was
happy because I now have a 1-1/2" threading kit and a very nicely rebound copy
of my 1896 edition of "Norie's Navigation:  A Complete Epitome of Practical
Navigation and Nautical Astronomy".
Chuck Taylornorth of Seattle USA