Dear Ron,
Actually, you don't have to scrunch up the fabric along the tube. Firmly sew a length of thread to one end of the fabric after sewing it. Make sure that the thread is long enough to come out the other end of the tube. Thread the tube into the fabric. Drop the needle through the tube, and gently start pulling it. Once the turned fabric is visible at the other end of the tube, you can grasp onto it to complete turning it.
I once had to turn enough fabric to make panes for 20 Renaissance garments. I used a piece of pipe, and had it turned in no time at all. I have also used straws for tiny items.
Why? I had a set of commercial tube turners that we used in class, but my students were so rough on them, the handles came off the hook things that come with the tubes. So we devised this method, improvising when we needed larger or smaller sizes than were in the set.
Teri