OK, back on the original subject now, I found the thread size chart I was looking for:
Here is it is:
[ATTACH=CONFIG]477142[/ATTACH]
So the 30wt and Size 50 threads are the same. I thought so by the way the looked and felt. And in my other machines that use 15x1 needles they work fine through the size14s.
On the 9W-7 they work fine through the size 16 Singer 127x1's but not the Schmetz size 14 MY1014B's.
Here is my theory. The Schmetz MY1014 B needles have such a large scarf that the needle is basically too far from the hook to properly form the loop. So it gets cut or broken.
I have a couple of Organ brand MY1014B needles that have a much smaller scarf I'll try next. Might be educational.
I also have another 9W-7 that has been altered so it can use 15x1 needles. I'm thinking of switching to that one to do a needle / thread test. I have all the sizes I need in the 15x1s.
Joe