I always use 50 wt. thread. I am sometimes alarmed by those who profess going at "breakneck " speed. I have two very large fabric grocery bags and I have to watch new baggers who think that just the bag is large they must fill them to the top. Just because you can, doesn't mean you should. I would be afraid that a needle would break and a piece of metal fly in my eye. Why can't we enjoy the journey and not be in a race to the finish? (IMHO).