Have an older Wead Eater straight shaft trimmer with a saw blade to cut bigger weeds and grass.  Is not working very well.  Had to take the shield off to make it work at all.  Those of you that run grass trimmers, what have you found that works well for weeds and grass?  Have another lighter duty curved shaft string trimmer and I don't think it will like some of the pig weeds and Kochia that have grown up around machinery, plus will have to constantly be reloading string.  Looked on ebay at various makes and models of heads but not sure what would be the best.  Thanks for your time!