Convenient & Quick - Eliminate tedious hand winding - Easily wind hanks of yarn into center-pull skeins - Create flat bottom balls that stack neatly - Rewind messy partial skeins into tidy center-pull skeins - Wind thin yarns together to create custom sizes or colors - Winds all sizes and weights of yarn Fully automatic - Labor-saving motor means less stress on arms, hands and wrists - Rheostat allows turn-rate to be adjusted as needed You can also view all Boye Electric Yarn Ball Winder.
I got one for Christmas, and tried using it on two different weights of yarn. It required way to much "nursing" along to warrant keeping it. If I spend another $35 I can get a heavy duty wood and metal geared one that will probably last a lifetime (mine!). My trusty blue and white plastic one held up admirably for 10 years. My kids grew up with the loud clacking noise it used to make and new when mom was winding yarn! :)
After finally getting everything set up perfectly (right tension, height etc.) works really well. And as a bonus my hand/arm isn't tired. It is very noisy, but since it only took me an hour to wind my entire stash, I thought it worth it.
I have found the ball winder to be very noisy and somewhat tempermental. Jeanne is correct that your swift has to be very loose and the yarn has to be loose on the swift but if you get it too loose then the yarn gets tangled. You really can't leave it while it is winding. You have to hold the yarn to provide tension.