This came about from a thread on knittinghelp.com. I mentioned how I create a center pull ball of yarn without using a store-bought yarn winder, so I thought I would put together a photo tutorial for those who wanted to see how. Here goes:
Start off by putting 6 inches of your yarn into the center of a paper towel tube. I prefer a paper towel tube over a toilet paper tube because the length gives you something substantial to hold on to.
Next, hold the yarn against the tube with your thumb.
Begin winding the yarn perpendicularly around the tube. Go slowly with the first few wraps, these will lock in the yarn tail that you were holding down with your thumb.
Once you have a few wraps established so the yarn is secure on the tube (about 10 wraps) begin winding the yarn around the tube at an angle.
Once you have another 10 wraps at an angle, turn the tube 1/4 turn and begin wrapping again at the same angle.
After you have these two sets of wraps done, you can begin to slowly turn the tube while you continue to wrap. This will form a more uniform ball than if you continue to wrap multiple times in the same place.
As your ball begins to grow, you can shape it by changing where you place your wraps. If you wrap the yarn slightly away from the tube, a "corner" will form and the ball will begin to take on a cylindrical shape. Keep wrapping the yarn near the "corner" to keep that shape. If you move the yarn closer to the tube, your ball will end up rounder and be less likely to stay put as you pull the yarn from the center.
When your ball is a big as you want it or your yarn is gone, fish the yarn tail out of the tube and lay it on the outside of the ball. I find this helps to keep the tail in order; if you leave it in the tube as you pull the ball off, it falls into the center of the ball and you have to fish it out of the yarn instead of a nice smooth paper tube.
All that's left is to slide the ball off the tube and you're ready to go!