Re: I keep breaking thread!
beerbrewer- flat waxed nylon has a breaking strength of around 5lbs, which is pretty strong compared to most threads, (but not as strong as some others like kevlar or gsp). I use FWN on most of the SW stuff i tie.
Assuming you're not really cranking down on it, as others have said, it sounds like a burr on the bobbin, and it's especially likely if it's a cheap import.
When working with Flat waxed nylon when it breaks on me, if it's not a problem with a burr it's usually because:
-Brushing the hook point with the thread,
-Arms of the bobbin are too tight (you can bend them out a bit to loosen), -----Thread is wrapped around one of the arms of the bobbin.