While you guys where posting, I was looking for a Link......... LOL
Here is a Link that may 'tye everything together'............... sorry, just popped into my head!
http://www.flyanglersonline.com/alcampbell/ac051302.php
# Excerpt........ thread tension

While your bobbin tension should usually be set fairly light, your thread tension while tying will often be heavier than the bobbin tension. Certain tying steps require light and loose tension to keep the materials from spinning on the hook, while other materials will need a firmer tension. Better than half the time, you'll want to squeeze the bobbin or drag a finger on the spool to keep the tension fairly close to the braking point of the thread. That's the best way to insure that your fly is tightly tied.
Some folks intentionally break the thread a few times when they first start tying with a new spool or bobbin, or when they tie their first fly for the day. That's their method of determining how much tension the thread can take. If you're new to fly tying, it's a good idea to know how much tension is required to break the thread you're using. It's all part of learning. .................................................. ...............................................