I own a plain, unadulterated Bailey 13 which is on a GMQ Pro frame. Great little machine that does exactly what it is meant to do. Quilt!
Bobbins are a standard size (Class 15, I think) but I have never wound one on the Bailey. I stand to quilt, so when I need to wind bobbins I sit down at my 20+ year old New Home and run through about 30 bobbins. I keep plenty wound. Some big quilts will use as many as 10 or more bobbins. Lots of stitching!
Quilting is fun..............
June