I finally made a bell mouth for my dust collector pipe at the lathe.
It works so much better than the plain pipe (and plain pipe was better than the big gulp box thing).
Someone did point out that I have reduced my pipe from 4″ down to 3″. I may someday have to get bigger PVC. But this is working just fine, so it may never change.
I sanded this piece (from the bottom tenon up to that pencil line) from 120 up to 400. You can see the dust on the banjo that the dust collector didn’t catch. The rest went in the pipe.